You searched for +publisher:"Vanderbilt University" +contributor:("Mark D. Does").
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Vanderbilt University
1.
Kelm, Nathaniel David.
High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain.
Degree: MS, Biomedical Engineering, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/11318 
► This thesis involves the development of an overnight high-resolution 3D diffusion kurtosis imaging protocol for ex vivo whole rat brain imaging. MRI acquisition parameters were…
(more)
▼ This thesis involves the development of an overnight high-resolution 3D diffusion kurtosis imaging protocol for ex vivo whole rat brain imaging. MRI acquisition parameters were optimized in order to obtain high-resolution, high-precision diffusion kurtosis imaging data. This included the programming and development of a 3D diffusion-weighted fast spin-echo pulse sequence. Image data from ex vivo rat brains were collected to verify the efficacy of the imaging protocol. Values of diffusion kurtosis parameters in normal rat brains were similar to those reported in previous imaging studies. Using this protocol, preliminary data were collected from a model of schizophrenia in rats. These data indicated the ability of the protocol to detect changes in diffusion kurtosis parameters that could correlate to changes in white matter microstructure.
Advisors/Committee Members: Adam Anderson (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: high resolution; magnetic resonance imaging; diffusion kurtosis imaging; ultra-high field; ex vivo rat brain
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APA (6th Edition):
Kelm, N. D. (2014). High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11318
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Kelm, Nathaniel David. “High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain.” 2014. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11318.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Kelm, Nathaniel David. “High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain.” 2014. Web. 19 Jan 2021.
Vancouver:
Kelm ND. High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain. [Internet] [Thesis]. Vanderbilt University; 2014. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11318.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Kelm ND. High Resolution 3D Diffusion Kurtosis Imaging of Whole Rat Brain. [Thesis]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/11318
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
2.
Manhard, Mary Katherine.
Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone.
Degree: MS, Biomedical Engineering, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/11298
► Clinically compatible ultra-short echo time (UTE) imaging sequences for quantitative T2-based bound and pore water imaging in bone were implemented and validated on a 3T…
(more)
▼ Clinically compatible ultra-short echo time (UTE) imaging sequences for quantitative T2-based bound and pore water imaging in bone were implemented and validated on a 3T human scanner and a 4.7T small bore system. Pore water images were generated by selectively saturating bound water signals with a T2-selective double adiabatic inversion pulse. Bound water images were generated by nulling the pore water signals with a T2-selective adiabatic inversion recovery preparation. In both cases, the magnetization preparation was integrated into a 3D UTE acquisition, with 16 radial spokes acquired per preparation. Images were acquired from human cadaveric femoral mid-shafts, from which isolated bone samples were subsequently extracted for non-imaging analysis using T2 spectroscopic measurements. The results showed a strong correlation between imaging-derived concentrations of bound and pore water and those determined from the isolated bone samples.
Advisors/Committee Members: Adam Anderson (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: 3T and 4.7T; ultra-short MRI; cortical bone; adiabatic inversion
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APA (6th Edition):
Manhard, M. K. (2013). Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11298
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Manhard, Mary Katherine. “Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone.” 2013. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11298.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Manhard, Mary Katherine. “Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone.” 2013. Web. 19 Jan 2021.
Vancouver:
Manhard MK. Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone. [Internet] [Thesis]. Vanderbilt University; 2013. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11298.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Manhard MK. Validation of Quantitative Bound and Pore Water Imaging in Cortical Bone. [Thesis]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/11298
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
3.
West, Kathryn Louise.
Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T.
Degree: MS, Biomedical Engineering, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/11313
► To apply MWI techniques to excised, fixed rodent brains, multi-exponential T2 (MET2) data were acquired at high (7T) and ultra-high (15.2T) fields with and without…
(more)
▼ To apply MWI techniques to excised, fixed rodent brains, multi-exponential T2 (MET2) data were acquired at high (7T) and ultra-high (15.2T) fields with and without tissue doping with Gadolinium to increase SNR efficiency. From relaxivity measurements, optimal scan parameters are found based on the minimal Cramér-Rao lower bounds (CRLB) of variance of myelin water fraction (MWF). Subsequently acquired MET2 data were analyzed to obtain myelin water fraction (MWF) maps with and without contrast agent at each field strength with various techniques, displaying the potential for MWI in rodent brain in the study of myelin content across whole brain.
Advisors/Committee Members: Daniel F. Gochberg (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: ultra-high field; Muliti-exponential T2; Myelin
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APA (6th Edition):
West, K. L. (2014). Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11313
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
West, Kathryn Louise. “Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T.” 2014. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11313.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
West, Kathryn Louise. “Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T.” 2014. Web. 19 Jan 2021.
Vancouver:
West KL. Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T. [Internet] [Thesis]. Vanderbilt University; 2014. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11313.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
West KL. Multi-exponential T2 Myelin Water Imaging in Ex-Vivo Rodent Brain at 7T and 15.2T. [Thesis]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/11313
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
4.
Lankford, Christopher Lynn.
The Information Content of mcDESPOT.
Degree: MS, Biomedical Engineering, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/14868
► A statistical analysis of the magnetic resonance imaging-based mcDESPOT method for characterizing two exchanging water proton pools – a seven-dimensional problem that fits to multiple flip…
(more)
▼ A statistical analysis of the magnetic resonance imaging-based mcDESPOT method for characterizing two exchanging water proton pools – a seven-dimensional problem that fits to multiple flip angle measurements of both spoiled and refocused gradient echoes – is presented. Theoretical calculations of the Cramer-Rao lower bounds of the variance of fitted model parameters were made using a variety of model system parameters, meant to mimic those expected in human white matter. The results, validated by Monte Carlo simulations, indicated that mcDESPOT signals acquired at feasibly attainable signal to noise ratios cannot provide parameter estimates with useful levels of precision. Precision can be greatly improved by constraining solutions with a priori model information, although this will generally lead to biased parameter estimates with less specificity. These results indicate that previous, apparently successful applications of mcDESPOT to human white matter may have used data fitting methods that implicitly constrained parameter solutions, or that the two-pool model of white matter may not be sufficient to describe the observed water proton signal in mcDESPOT acquisitions. In either case, mcDESPOT-derived estimates of two-pool model parameters cannot yet be unambiguously related to specific tissue characteristics.
Advisors/Committee Members: Mark D. Does (Committee Chair), E. Brian Welch (Committee Chair).
Subjects/Keywords: MRI; mcDESPOT; Cramer-Rao bound
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APA (6th Edition):
Lankford, C. L. (2011). The Information Content of mcDESPOT. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14868
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lankford, Christopher Lynn. “The Information Content of mcDESPOT.” 2011. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14868.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lankford, Christopher Lynn. “The Information Content of mcDESPOT.” 2011. Web. 19 Jan 2021.
Vancouver:
Lankford CL. The Information Content of mcDESPOT. [Internet] [Thesis]. Vanderbilt University; 2011. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14868.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lankford CL. The Information Content of mcDESPOT. [Thesis]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/14868
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
5.
Hormuth, David Andrew II.
A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats.
Degree: MS, Biomedical Engineering, 2012, Vanderbilt University
URL: http://hdl.handle.net/1803/14849
► Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a method that can be used to quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI…
(more)
▼ Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a method that can be used to quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI requires an estimate of the time rate of change of the concentration of the contrast agent in the blood plasma; the so-called vascular input function, or VIF. Measuring the VIF is notoriously difficult as it requires high temporal resolution images limiting the achievable number of slices, field-of-view, spatial resolution, and signal-to-noise. Alternatively, a population-averaged VIF could be used to mitigate the acquisition demands in studies aimed to investigate, for example, tumor vascular characteristics. Eight rats inoculated with C6 glioma cells underwent DCE-MRI at 9.4T. A set of dynamic spoiled gradient-echo images was acquired before, during, and after a bolus injection of Gd-DTPA (Magnevist, Wayne, NJ). Pharmacokinetic parameters (Ktrans, ve, and vp) were extracted from signal-time curves of tumor tissue using both individual and population-averaged VIFs. Standard model voxel values of Ktrans and ve estimated using a population-averaged VIF have a high correlation (concordance correlation coefficient > 0.7852) and a strong linear relationship (Pearson correlation coefficient > 0.9802) with Ktrans and ve values estimated using an individual VIF. Additionally, the extended model voxel values of Ktrans, ve, and vp also showed a high correlation (concordance correlation coefficient > 0.6931) and a strong linear relationship (Pearson correlation coefficient > 0.9159) supporting the use of a population based VIF in DCE-MRI.
Advisors/Committee Members: Mark D. Does (committee member), Thomas E. Yankeelov (Committee Chair).
Subjects/Keywords: Cancer; Imaging; DCE-MRI; MRI
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APA (6th Edition):
Hormuth, D. A. I. (2012). A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14849
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hormuth, David Andrew II. “A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats.” 2012. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14849.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hormuth, David Andrew II. “A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats.” 2012. Web. 19 Jan 2021.
Vancouver:
Hormuth DAI. A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats. [Internet] [Thesis]. Vanderbilt University; 2012. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14849.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hormuth DAI. A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats. [Thesis]. Vanderbilt University; 2012. Available from: http://hdl.handle.net/1803/14849
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
6.
Gao, Yurui.
Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain.
Degree: PhD, Biomedical Engineering, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/11307
► Diffusion tensor imaging (DTI) provides a unique approach to probing the microstructure of biological tissues noninvasively and DTI-based tractography is an irreplaceable tool to measure…
(more)
▼ Diffusion tensor imaging (DTI) provides a unique approach to probing the microstructure of biological tissues noninvasively and DTI-based tractography is an irreplaceable tool to measure anatomical connectivity in human brain in vivo. However, due to the limitations of DTI techniques and tractography algorithms, tracked pathways might not be completely accurate. Thus, quantifying the agreement between DTI tractography and histological measurements of true fiber pathways is critical for progress in the field. A series of validation studies of DTI tractography is presented in this thesis, including (1) assessment of the relationship between DTI tractography-derived corticocortical connectivity and histological 'ground truth' on a regional and voxelwise basis; (2) localizing the divergence between DTI tractography and histology, followed by qualitative analysis of the reasons for those discrepancies. The work presented here is based on a non-human primate animal model, which has comparable parameters to magnetic resonance imaging (MRI) human data, and thus provides an important guide to interpreting the results of DTI-based tractography measures in the human brain.
Advisors/Committee Members: Zhaohua Ding (committee member), Iwona Stepniewska (committee member), Mark D. Does (committee member), Malcolm J. Avison (committee member), Adam W. Anderson (Committee Chair).
Subjects/Keywords: Diffusion tensor imaging; connectivity; tractography; validation; corticocortical connection
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APA (6th Edition):
Gao, Y. (2013). Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11307
Chicago Manual of Style (16th Edition):
Gao, Yurui. “Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain.” 2013. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11307.
MLA Handbook (7th Edition):
Gao, Yurui. “Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain.” 2013. Web. 19 Jan 2021.
Vancouver:
Gao Y. Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain. [Internet] [Doctoral dissertation]. Vanderbilt University; 2013. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11307.
Council of Science Editors:
Gao Y. Validation of Diffusion Tensor Imaging Measures of Corticocortical Connectivity in the Brain. [Doctoral Dissertation]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/11307
Vanderbilt University
7.
Johnson, Lindsay Craig.
Development of a Small-Animal SPECT System with a High-Purity Germanium Detector.
Degree: PhD, Biomedical Engineering, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/14800
► Advantages of high-purity germanium (HPGe) detectors over traditional scintillator detectors include excellent energy resolution, approximately 1% at 140 keV, which allows for better scatter rejection…
(more)
▼ Advantages of high-purity germanium (HPGe) detectors over traditional scintillator detectors include excellent energy resolution, approximately 1% at 140 keV, which allows for better scatter rejection and simple multi-isotope acquisitions, and depth of interaction estimation, which can help reduce parallax error when incorporated into the reconstruction process. An HPGe system that is mechanically cooled, 90 mm in diameter, 10 mm thick, and comprised of two sets of 16 orthogonal strips that are each 4.75 mm wide with a 5 mm strip pitch was characterized. The detector has ~1.5 mm spatial resolution, 0.92% energy resolution at 140 keV, 55.4% intrinsic efficiency at 122 keV and has a flood-corrected integral uniformity of 3%.
The HPGe-SPECT system has a single-pinhole collimator with a 1-mm diameter and a 70 degree opening angle with a focal length variable between 4.5 and 9 cm. An MLEM reconstruction algorithm was developed that utilizes an analytical system matrix derived from the system’s calibration parameters and helical scanning was implemented to allow for an extended axial field of view. Images of a hot-rod phantom and NEMA NU 4-2008 phantom are used to quantify the system’s image quality and one dual-isotope experiment demonstrated the advantage of HPGe’s energy resolution over a commercial system.
Simulations were performed to investigate whether a stacked-detector configuration with both HPGe and a silicon detector, used with
123I (27-32, 159 keV), where little or no multiplexing occurs in the Si projections can help to compensate for the image degradation caused by the multiplexed HPGe projections. Multiple phantoms were simulated to investigate image quality quantitatively, while the differential point response function was used to qualitatively evaluate multiplexing artifacts. Results indicated an improvement in image quality using the stacked-system over HPGe alone, and therefore future work will involve building an HPGe-Si stacked system.
Advisors/Committee Members: Thomas E. Yankeelov (committee member), William A. Grissom (committee member), John C. Gore (committee member), Todd E. Peterson (Committee Chair), Mark D. Does (Committee Chair).
Subjects/Keywords: Small-Animal SPECT; reconstruction; HPGe detector; characterization; system development
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APA (6th Edition):
Johnson, L. C. (2013). Development of a Small-Animal SPECT System with a High-Purity Germanium Detector. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14800
Chicago Manual of Style (16th Edition):
Johnson, Lindsay Craig. “Development of a Small-Animal SPECT System with a High-Purity Germanium Detector.” 2013. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14800.
MLA Handbook (7th Edition):
Johnson, Lindsay Craig. “Development of a Small-Animal SPECT System with a High-Purity Germanium Detector.” 2013. Web. 19 Jan 2021.
Vancouver:
Johnson LC. Development of a Small-Animal SPECT System with a High-Purity Germanium Detector. [Internet] [Doctoral dissertation]. Vanderbilt University; 2013. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14800.
Council of Science Editors:
Johnson LC. Development of a Small-Animal SPECT System with a High-Purity Germanium Detector. [Doctoral Dissertation]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/14800
Vanderbilt University
8.
Manhard, Mary Katherine.
Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk.
Degree: PhD, Biomedical Engineering, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/12436
► The current standard for diagnosing fracture risk comprises measurements of bone mineral density (BMD), primarily by dual-energy X-ray absorptiometry (DXA). However, bone strength is affected…
(more)
▼ The current standard for diagnosing fracture risk comprises measurements of bone mineral density (BMD), primarily by dual-energy X-ray absorptiometry (DXA). However, bone strength is affected by many factors other than BMD, such as architecture, collagen content, and porosity.
Nuclear magnetic resonance (NMR) measures of the water bound to the collagen matrix (bound water) and free water occupying pore space (pore water) have shown promise in further assessing fracture risk. This dissertation work translated NMR based techniques into Magnetic Resonance Imaging (MRI) methods; the Double Adiabatic Full Passage (DAFP) sequence for measuring pore water concentration and the Adiabatic Inversion Recovery (AIR) sequence to measure bound water concentration. These imaging methods can be used to obtain maps of bound and pore water content throughout the cortical bone volume. MRI methods were first validated against NMR methods and shown to have good repeatability in vivo, and then were compared to whole bone material properties and found to show significant correlations with strength and toughness. The AIR and DAFP methods, initially carried out with 3D data acquisition, were further improved by implementing 2D quantitative imaging sequences which significantly reduced scan time. The sequences are being applied in populations of healthy and osteoporotic patients for longitudinal evaluation. In short, measures of bound and pore water concentration have the potential to give a new and more thorough evaluation of bone characteristics and health that is not obtainable with currently used methods.
Advisors/Committee Members: S. Bobo Tanner (committee member), William A. Grissom (committee member), E. Brian Welch (committee member), Jeffry S. Nyman (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: fracture risk; bone; UTE; MRI
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APA (6th Edition):
Manhard, M. K. (2016). Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/12436
Chicago Manual of Style (16th Edition):
Manhard, Mary Katherine. “Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/12436.
MLA Handbook (7th Edition):
Manhard, Mary Katherine. “Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk.” 2016. Web. 19 Jan 2021.
Vancouver:
Manhard MK. Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/12436.
Council of Science Editors:
Manhard MK. Advancements of MRI Measurements of Bound and Pore Water Concentration of Cortical Bone for Evaluation of Fracture Risk. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/12436
Vanderbilt University
9.
Lankford, Christopher Lynn.
Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method.
Degree: PhD, Biomedical Engineering, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/14384
► Due to the need to acquire a series of T2-weighted images, quantitative T2 mapping protocols in magnetic resonance imaging (MRI) suffer from long scan times.…
(more)
▼ Due to the need to acquire a series of T2-weighted images, quantitative T2 mapping protocols in magnetic resonance imaging (MRI) suffer from long scan times. In order to alleviate this problem, fast spin-echo (FSE) imaging protocols can be employed, but the resulting images contain errors in the form of smoothing and ghosting artifacts which propagate to T2 maps. This dissertation presents a new method, dubbed Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC), which explicitly accounts for k-space signal attenuation during the reconstruction step. T2 maps generated by ME-CAMBREC contained reduced artifact compared to those generated by FSE methods, while requiring only a fraction of the scan time of a multiple spin-echo protocol. For moderate-to-high acceleration factors, ME-CAMBREC outperformed parallel imaging and steady-state T2 mapping techniques. Data suitable for ME-CAMBREC can be acquired in multi-slice mode using pulse sequence interleafs, but a slice gap should be employed to limit T2 bias caused by radiofrequency profile effects. Although ME-CAMBREC can be used to generate accurate T2s in the presence of flip angle errors, it was shown that the use of an independent measure of the transmit field (B1+) will improve fitted T2 precision.
Advisors/Committee Members: Bruce M. Damon (committee member), Daniel F. Gochberg (committee member), William A. Grissom (committee member), E. Brian Welch (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: MRI; T2; fast imaging; model-based reconstruction; parametric constraint
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APA ·
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APA (6th Edition):
Lankford, C. L. (2016). Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14384
Chicago Manual of Style (16th Edition):
Lankford, Christopher Lynn. “Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14384.
MLA Handbook (7th Edition):
Lankford, Christopher Lynn. “Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method.” 2016. Web. 19 Jan 2021.
Vancouver:
Lankford CL. Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14384.
Council of Science Editors:
Lankford CL. Multiple Echo, Caesar Cipher Acquisition and Model-Based Reconstruction (ME-CAMBREC): a Novel Accelerated T2 Mapping Method. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/14384
Vanderbilt University
10.
Li, Hua.
Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy.
Degree: PhD, Physics, 2015, Vanderbilt University
URL: http://hdl.handle.net/1803/12743
► Diffusion MRI provides a non-invasive means to characterize tissue microstructure at varying length scales. Apparent diffusion coefficients (ADCs) of tissue water may be measured at…
(more)
▼ Diffusion MRI provides a non-invasive means to characterize tissue microstructure at varying length scales. Apparent diffusion coefficients (ADCs) of tissue water may be measured at relatively long diffusion times with conventional pulsed gradient spin echo (PGSE) methods, or at much shorter effective diffusion times using oscillating gradient spin echo (OGSE) methods. Besides the information provided by single ADC measurements, the manner in which ADC disperses with gradient frequency (or diffusion time) provides information on the characteristic dimensions of structures within the medium. However, despite increasing interest in applying frequency-dependent ADC to derive novel information on tissue, the interpretations of ADC spectra are not always clear. Meanwhile, to better characterize the tissue microstructure, the direct quantitation of restricting dimensions may be more helpful. The contrast and structural information provided by temporal diffusion spectroscopy are comprehensively studied in this thesis, including (1) the structural information revealed by the dispersion of ADC with frequency; (2) the influence of cell membrane permeability on MR diffusion measurements; and (3) the quantification of restricting size in simple one-pool and two-pool models. This work may help better understand the contrast by temporal diffusion spectroscopy and demonstrates its potential for quantitative measurements of tissue microstructure.
Advisors/Committee Members: Junzhong Xu (committee member), Mark D. Does (committee member), Adam W. Anderson (committee member), Daniel F. Gochberg (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: diffusion; MRI
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APA (6th Edition):
Li, H. (2015). Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/12743
Chicago Manual of Style (16th Edition):
Li, Hua. “Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy.” 2015. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/12743.
MLA Handbook (7th Edition):
Li, Hua. “Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy.” 2015. Web. 19 Jan 2021.
Vancouver:
Li H. Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy. [Internet] [Doctoral dissertation]. Vanderbilt University; 2015. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/12743.
Council of Science Editors:
Li H. Towards quantitative measurements of tissue microstructure using temporal diffusion spectroscopy. [Doctoral Dissertation]. Vanderbilt University; 2015. Available from: http://hdl.handle.net/1803/12743
Vanderbilt University
11.
Schilling, Kurt Gregory.
Histological Validation of Diffusion MRI.
Degree: PhD, Biomedical Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/15259
► The ability of diffusion magnetic resonance imaging (dMRI) fiber tractography to non-invasively map the three-dimensional (3D) network of the human brain has proven to be…
(more)
▼ The ability of diffusion magnetic resonance imaging (dMRI) fiber tractography to non-invasively map the three-dimensional (3D) network of the human brain has proven to be a valuable neuroimaging tool, improving our understanding of both normal development and complex brain disorders. However, the process from data acquisition to generation of a 3D map of reconstructed fibers is a multi-step procedure with numerous assumptions and uncertainties that can ultimately affect the ability of this technique to faithfully represent the true axonal connections of the brain. Because of this, validating dMRI tractography is required on many levels. It is necessary not only to measure the ability of these techniques to track white matter fibers from voxel to voxel, but also to quantify the ability of dMRI to assess the underlying fiber orientation distribution (FOD) within each voxel. To do this, we propose to compare diffusion data directly to histology data on both the microstructural scale of tissues and the macrostructural scale of brain connectivity. These experiments will lead to a better understanding of the limitations and pitfalls of dMRI experiments, and provide a quantitative assessment of the reliability of these techniques.
Advisors/Committee Members: Bennett A. Landman (committee member), Mark D. Does (committee member), Iwona Stepniewska (committee member), John C. Gore (committee member), Adam W. Anderson (Committee Chair).
Subjects/Keywords: Validation; Diffusion MRI; Tractography; Histology; Brain
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APA (6th Edition):
Schilling, K. G. (2017). Histological Validation of Diffusion MRI. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15259
Chicago Manual of Style (16th Edition):
Schilling, Kurt Gregory. “Histological Validation of Diffusion MRI.” 2017. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/15259.
MLA Handbook (7th Edition):
Schilling, Kurt Gregory. “Histological Validation of Diffusion MRI.” 2017. Web. 19 Jan 2021.
Vancouver:
Schilling KG. Histological Validation of Diffusion MRI. [Internet] [Doctoral dissertation]. Vanderbilt University; 2017. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/15259.
Council of Science Editors:
Schilling KG. Histological Validation of Diffusion MRI. [Doctoral Dissertation]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/15259
Vanderbilt University
12.
Cobb, Jared Guthrie.
Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging.
Degree: PhD, Biomedical Engineering, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/14019
► Conventional magnetic resonance imaging (MRI) uses contrast that is weighted by the intrinsic tissue parameters T1, and T2. Contrast may also be generated in the…
(more)
▼ Conventional magnetic resonance imaging (MRI) uses contrast that is weighted by the intrinsic tissue parameters T1, and T2. Contrast may also be generated in the rotating frame with the analogous time constants T1ρ or T2ρ. Traditionally T1ρ measurements have been used to investigate low frequency dipolar interactions in the kHz range. However, other biological processes, such as chemical exchange, also occur on this time scale. Recently it has been shown that these processes dominate R1ρ (1/T1ρ) relaxation at high field, and these interactions are of interest as high field imaging systems become increasingly common. We have developed quantitative spin-locking (SL) techniques to probe rotating frame relaxation on clinical and pre-clinical imaging systems. Experiments were performed with these techniques to generate T1ρ maps of pediatric epiphyseal cartilage and mouse brain.
If the power of the SL field is varied, the measured T1ρ values will change in a phenomenon known as T1ρ dispersion. These dispersion profiles vary with tissue properties such as pH and metabolite concentration, and the data may be fit with a model to extract unique parameters such as chemical exchange. Novel methods were developed to generate exchange rate based contrast using the contrast features of T1ρ dispersion profiles. A number of exogenous and endogenous contrast agents were quantitatively compared to chemical exchange saturation contrast (CEST) imaging. CEST and SL techniques were evaluated for their complementary features to determine the experimental conditions where each may be most appropriately used.
Diffusion processes were explored as an additional
contributor to T1ρ dispersion. Various spherical phantoms of different size and material properties were measured with SL techniques to observe their effects on contrast. Methods were developed to separate the effects of diffusion and chemical exchange.
The experiments reported here further elucidate the contributing factors to R1ρ relaxation in a variety of biologically relevant molecules and tissues. Finally, the methods resulting from these experiments are useful for generating novel contrast that is primarily dependent on exchange rates.
Advisors/Committee Members: Daniel F. Gochberg (committee member), Mark D. Does (committee member), Bruce M. Damon (committee member), J. Christopher Gatenby (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: rotating frame; relaxometry; MRI; t1rho
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APA (6th Edition):
Cobb, J. G. (2011). Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14019
Chicago Manual of Style (16th Edition):
Cobb, Jared Guthrie. “Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging.” 2011. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14019.
MLA Handbook (7th Edition):
Cobb, Jared Guthrie. “Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging.” 2011. Web. 19 Jan 2021.
Vancouver:
Cobb JG. Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging. [Internet] [Doctoral dissertation]. Vanderbilt University; 2011. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14019.
Council of Science Editors:
Cobb JG. Quantitative proton relaxometry in the rotating frame with magnetic resonance imaging. [Doctoral Dissertation]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/14019
Vanderbilt University
13.
Horch, Robert Adam.
Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods.
Degree: PhD, Biomedical Engineering, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/14596
► Current clinical bone diagnostic measures rely predominantly on X-ray-based contrast and are primarily sensitive to bone mineral content. Since bone also contains collagen and water…
(more)
▼ Current clinical bone diagnostic measures rely predominantly on X-ray-based contrast and are primarily sensitive to bone mineral content. Since bone also contains collagen and water components, which are heavily implicated in fracture resistance, these X-ray measures are micro-anatomically incomplete and do not identify individuals who will fracture. This dissertation aims to improve clinical bone fracture risk assessment through the use of novel magnetic resonance imaging (MRI) methods, which provide quantitative measures of the non-mineral bone components. The overall goal is to advance our understanding of 1H nuclear magnetic resonance (NMR) relaxation in human cortical bone to the point that diagnostically-relevant parameters may be extracted from in vivo bone MRI measurements. To accomplish this, custom NMR hardware was first developed for a rigorous, NMR relaxation-based characterization of ex vivo cortical bone. Such characterization was used to identify the micro-anatomical origins of cortical bone NMR signal components, which included collagen, bound water, and pore water protons. These signal components correlated well with various bone mechanical properties, indicating diagnostic relevance. Using the well-characterized cortical bone relaxation characteristics, novel and clinically practical methods for quantitative, diagnostic bone MRI were developed and validated. Collectively, this work represents a biophysical basis for cortical bone MRI, which stands ready for translation to clinical and research studies.
Advisors/Committee Members: Bruce M. Damon (committee member), Jeffry S. Nyman (committee member), Daniel F. Gochberg (committee member), John C. Gore (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: MRI; NMR; cortical bone; T2; bound water; pore water
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APA (6th Edition):
Horch, R. A. (2011). Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14596
Chicago Manual of Style (16th Edition):
Horch, Robert Adam. “Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods.” 2011. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14596.
MLA Handbook (7th Edition):
Horch, Robert Adam. “Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods.” 2011. Web. 19 Jan 2021.
Vancouver:
Horch RA. Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods. [Internet] [Doctoral dissertation]. Vanderbilt University; 2011. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14596.
Council of Science Editors:
Horch RA. Studies Of Proton Nuclear Magnetic Resonance Relaxation In Human Cortical Bone: From Ex Vivo Spectroscopy To Clinical Imaging Methods. [Doctoral Dissertation]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/14596
Vanderbilt University
14.
Katwal, Santosh Bahadur.
Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses.
Degree: PhD, Electrical Engineering, 2012, Vanderbilt University
URL: http://hdl.handle.net/1803/15079
► Functional magnetic resonance imaging (fMRI) is a non-invasive imaging technique that has emerged as a powerful tool to identify the brain regions involved in cognitive…
(more)
▼ Functional magnetic resonance imaging (fMRI) is a non-invasive imaging technique that has emerged as a powerful tool to identify the brain regions involved in cognitive processes. FMRI offers spatial and temporal resolutions adequate to measure the location, amplitude and timing of brain activity. FMRI data are commonly analyzed voxel-by-voxel using linear regression models (statistical parametric mapping). This requires information about stimulus timing and assumptions about the shape and timing of the hemodynamic response. This approach may be too restrictive to capture the broad range of possible brain activation patterns in space and time and across subjects. This dissertation presents a multivariate data-driven approach using self-organizing maps that overcome the aforementioned limitations. A self-organizing map is a topology-preserving artificial neural network model that transforms high-dimensional data into a low-dimensional map of output nodes using unsupervised learning. This dissertation proposes novel graph-based visualizations of self-organizing maps for extracting fine spatiotemporal patterns of brain activities from fMRI data to measure relative timings of brain responses.
This approach was employed to identify voxels responding to the task and detect differences as small as 28 ms in the timings of brain responses in visual cortex. It outperformed other common techniques for voxel selection including independent component analysis, voxelwise univariate linear regression analysis and a separate localizer scan. This was verified by observing a statistically strong linear relationship between induced and measured timing differences. The approach was also used to correctly identify and classify task-related brain areas in an fMRI reaction time experiment involving a visuo-manual response task. In summary, the graph-based visualizations of self-organizing maps help in advanced visualization of cluster boundaries in fMRI data, thereby enabling the separation of regions with small differences in the timings of their brain responses and helping to measure relative timings of brain responses.
Advisors/Committee Members: D. Mitchell Wilkes (committee member), Bennett A. Landman (committee member), Mark D. Does (committee member), Zhaohua Ding (committee member), Baxter P. Rogers (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: mental chronometry; stimulus onset asynchrony; relative timing; inverse logit model; Granger causality; functional MRI; fMRI; self-organizing map; SOM visualizations; unsupervised learning; hemodynamic response
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APA (6th Edition):
Katwal, S. B. (2012). Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15079
Chicago Manual of Style (16th Edition):
Katwal, Santosh Bahadur. “Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses.” 2012. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/15079.
MLA Handbook (7th Edition):
Katwal, Santosh Bahadur. “Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses.” 2012. Web. 19 Jan 2021.
Vancouver:
Katwal SB. Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses. [Internet] [Doctoral dissertation]. Vanderbilt University; 2012. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/15079.
Council of Science Editors:
Katwal SB. Unsupervised Spatiotemporal Analysis of FMRI Data For Measuring Relative Timings of Brain Responses. [Doctoral Dissertation]. Vanderbilt University; 2012. Available from: http://hdl.handle.net/1803/15079
Vanderbilt University
15.
Kelm, Nathaniel David.
Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue.
Degree: PhD, Biomedical Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/10551
► Diffusion-weighted MRI (DWI) techniques have demonstrated the ability to non-invasively assess normal and pathological neural tissue. Recently-developed advanced DWI methods have the potential to provide…
(more)
▼ Diffusion-weighted MRI (DWI) techniques have demonstrated the ability to non-invasively assess normal and pathological neural tissue. Recently-developed advanced DWI methods have the potential to provide quantitative biomarkers with improved sensitivity and specificity to changes in tissue microstructure, yet thorough evaluation and validation of these methods have been limited. In this dissertation, two of these DWI methods that are clinically practical, diffusion kurtosis imaging (DKI) and the biophysical white matter tract integrity (WMTI) model, were experimentally evaluated through comparisons to other MRI methods, such as diffusion tensor imaging (DTI), and histological measurements in clinically-relevant animal models of abnormal brain myelination, normally- and abnormally-developing brain, and acute peripheral nerve injury and repair. First, examining hypo- and hypermyelinated adult mouse brain, it was shown that DKI offered additional sensitivity over DTI to changes in myelin content, as well as complementary information regarding diffusion in the intra- and extra-axonal spaces. WMTI exhibited increased specificity to changes in white matter microstructure, including axon fraction and myelin thickness. Next, in normal and abnormal mouse brain development, DKI was shown to better distinguish microstructural changes between different ages and mouse models compared with DTI, and WMTI again provided improved specificity to alterations in axon fraction and myelin thickness. Relationships between DWI metrics and white matter microstructure during development were consistent with those observed in adult mice, meaning these associations are applicable to a wider scope of studies examining brain white matter. Finally, in injured rat sciatic nerve, it was demonstrated that DKI and WMTI were sensitive to each stage of nerve degeneration and regeneration. Additionally, WMTI intra-axonal diffusivity displayed increased specificity to axon structure after injury and repair, making it a useful metric for future studies assessing peripheral nerve injury. Overall, this work provided significant advancement in the experimental knowledge of DKI and WMTI and their potential utility in the assessment of neurological conditions and evaluation of treatments.
Advisors/Committee Members: Adam W. Anderson (committee member), John C. Gore (committee member), Wesley P. Thayer (committee member), Robert P. Carson (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: MRI; myelin; brain; peripheral nerve; diffusion; kurtosis; histology
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APA (6th Edition):
Kelm, N. D. (2017). Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10551
Chicago Manual of Style (16th Edition):
Kelm, Nathaniel David. “Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue.” 2017. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/10551.
MLA Handbook (7th Edition):
Kelm, Nathaniel David. “Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue.” 2017. Web. 19 Jan 2021.
Vancouver:
Kelm ND. Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue. [Internet] [Doctoral dissertation]. Vanderbilt University; 2017. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/10551.
Council of Science Editors:
Kelm ND. Experimental Evaluation of Advanced Diffusion MRI Methods Towards Improved Assessment of Myelinated Neural Tissue. [Doctoral Dissertation]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/10551
Vanderbilt University
16.
Janve, Vaibhav Anil.
Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis.
Degree: PhD, Physics, 2015, Vanderbilt University
URL: http://hdl.handle.net/1803/11234
► Conventional MRI is sensitive to detect brain abnormalities non-invasively through excellent contrast generated by variation in relaxation times and water proton density. However, conventional MRI…
(more)
▼ Conventional MRI is sensitive to detect brain abnormalities non-invasively through excellent contrast generated by variation in relaxation times and water proton density. However, conventional MRI lacks the specificity and quantitation to specific pathologies and tissue components such as myelin. Myelin is the major constituent of white matter ─an insulating macromolecular sleeve wrapped around axons of brain cells. Loss of white matter, specifically myelin leads to severe motor and cognitive deficits in diseases such as multiple sclerosis. Advanced quantitative MRI methods such as quantitative magnetization transfer (qMT) and diffusion tensor imaging (DTI) have emerged as putative biomarkers that improve sensitivity, specificity and provide quantitative metrics to measure myelin. qMT and DTI are model based quantitative techniques, which provide sub-voxel information of the underlying tissue architecture. qMT is sensitive to the tissue macromolecular content, whereas DTI is sensitive to tissue microstructure. Pool size ratio (PSR, a qMT parameter) and radial diffusivity (RD, a DTI parameter) provide an indirect quantitative measure of myelin. However, their relative sensitivities and specificities to myelin are unclear. qMT and DTI are based on different physical principles and may provide complementary information. While histology is the gold standard for myelin quantification, it can only be performed postmortem or through invasive biopsies. Thus, systematic quantitative MRI and histological validation studies are essential to determine the specific sensitivities of non-invasive quantitative metrics. Although, limited data is available on such studies due to their tedious, time intensive and complex nature. My thesis work addresses this gap by performing quantitative MRI and histological validation on a relatively new animal model of multiple sclerosis (MS), which recapitulates the inflammatory and non-inflammatory demyelinating phases seen in patients. The animal model was characterized using structural MRI, qMRI and histological methods. To enable quantitative comparisons amongst MRI and histological parameters, detailed processing protocol were designed and implemented including 3D qMT and DTI protocols and histological pipeline. In vivo and ex vivo studies were performed and qMT and DTI metrics were correlated with histology and among each other to determine their specific sensitivities. Furthermore, in an attempt to translate the animal work to clinical settings, a fast qMT sequence with GRASE readout was tested on human scanners. In conclusion, we found that PSR, and RD are sensitive to histological myelin content with PSR having the strongest correlation.
Advisors/Committee Members: Adam W. Anderson (committee member), David J. Ernst (committee member), Mark D. Does (committee member), John C. Gore (committee member), Daniel F. Gochberg (Committee Chair).
Subjects/Keywords: MRI; magnetization transfer; diffusion; multiple sclerosis; qMT; DTI; quantitative
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APA (6th Edition):
Janve, V. A. (2015). Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11234
Chicago Manual of Style (16th Edition):
Janve, Vaibhav Anil. “Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis.” 2015. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11234.
MLA Handbook (7th Edition):
Janve, Vaibhav Anil. “Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis.” 2015. Web. 19 Jan 2021.
Vancouver:
Janve VA. Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis. [Internet] [Doctoral dissertation]. Vanderbilt University; 2015. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11234.
Council of Science Editors:
Janve VA. Myelin sensitivity in quantitative magnetization transfer and diffusion tensor imaging in an animal model of multiple sclerosis. [Doctoral Dissertation]. Vanderbilt University; 2015. Available from: http://hdl.handle.net/1803/11234
Vanderbilt University
17.
McGough, Madison Ashli Pauline.
In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength.
Degree: PhD, Biomedical Engineering, 2018, Vanderbilt University
URL: http://hdl.handle.net/1803/15510
► Bone grafts are scaffold constructs required for the treatment of bone diseases and fracture when a defect is above a critical size to heal naturally.…
(more)
▼ Bone grafts are scaffold constructs required for the treatment of bone diseases and fracture when a defect is above a critical size to heal naturally. Bone tissue engineering approaches aim to recapitulate the physical, chemical, and mechanical properties of the host tissue in a bone graft that resorbs at a rate that complements osteogenesis. The Guelcher Lab has previously demonstrated lysine-based polyurethane bone grafts promote osteogenesis and support remodeling in vivo. However, these undergo autocatalytic hydrolytic degradation in which acidic breakdown products accelerate resorption and the degradation rate in vivo is unpredictable. The central goal of this dissertation was to develop a lysine-based poly(thioketal urethane) (PTKUR) that degrades in the presence of reactive oxygen species produced by the cells involved in bone healing. A novel, low molecular weight thioketal diol was used to synthesize a PTKUR that degraded selectively in oxidative conditions. PTKUR/ceramic composites were moldable by hand and set to strengths exceeding those of trabecular bone in situ within clinically relevant working times. Histological evidence of osteoclast-mediated resorption of the composites was observed at 6 and 12 weeks in a rabbit femoral condyle plug defect. By modifying the formulation and fabrication procedures of the PTKUR, up to 70 wt% autograft (AG) was incorporated for a compression resistant PTKUR autograft extender that expands the utility of the gold standard. The PTKUR AG extender supported cellular infiltration and remodeling in two rigorous in vivo models and the extender maintained implanted AG in the defect up to 12 weeks post-implantation. Finally, the addition of a nanocrystalline hydroxyapatite (nHA) to the PTKUR microstructure was hypothesized to allow for the addition of porosity without sacrificing material mechanics. Sucrose leaching induced porosity to accelerate cellular infiltration and peripheral remodeling. nHA-PTKUR hybrid polymers degraded selectively in oxidative environments and demonstrated mechanical properties exceeding those of trabecular bone after leaching up to 45 wt% sucrose. nHA-PTKUR composites containing a range of sucrose:ceramic filler component ratios were implanted in rabbit femoral condyle plug defects to explore the addition of slowly-degrading, mechanically robust, osteoconductive ceramic particles and porosity on remodeling in vivo. These materials demonstrated a unique combination of endochondral and intramembranous bone formation as early as four months. Together, this work addresses the limitations of currently available synthetic bone grafts from biomaterial, biological, and mechanical perspectives. The conclusions drawn culminate in a cell-degradable biomaterial that balances osteoconductivity and osteoinductivity with biomaterial properties for optimal bone graft remodeling for given implantation site demands.
Advisors/Committee Members: D.%22%29&pagesize-30">Julie A. Sterling, Ph.
D. (committee member),
D.%22%29&pagesize-30">Ethan S. Lippmann, Ph.D. (committee member),
D.%22%29&pagesize-30">Craig L. Duvall, Ph.D. (committee member),
D.%22%29&pagesize-30">Mark D. Does, Ph.D. (committee member),
D.%22%29&pagesize-30">Scott A. Guelcher, Ph.D. (Committee Chair).
Subjects/Keywords: poly(thioketal urethane); tissue engineering; bone graft
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APA (6th Edition):
McGough, M. A. P. (2018). In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15510
Chicago Manual of Style (16th Edition):
McGough, Madison Ashli Pauline. “In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength.” 2018. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/15510.
MLA Handbook (7th Edition):
McGough, Madison Ashli Pauline. “In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength.” 2018. Web. 19 Jan 2021.
Vancouver:
McGough MAP. In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength. [Internet] [Doctoral dissertation]. Vanderbilt University; 2018. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/15510.
Council of Science Editors:
McGough MAP. In Vivo Remodeling of Settable, Cell-Degradable, and Application-Specific Poly(thioketal urethane) Tissue Engineering Composite Bone Grafts with Bone-Like Strength. [Doctoral Dissertation]. Vanderbilt University; 2018. Available from: http://hdl.handle.net/1803/15510
Vanderbilt University
18.
Sharma, Anuj.
Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging.
Degree: PhD, Biomedical Engineering, 2015, Vanderbilt University
URL: http://hdl.handle.net/1803/12362
► Simultaneous multislice (SMS) imaging is a scan acceleration method where mul- tiple slices are simultaneously excited using a multiband pulse and the aliased slice images…
(more)
▼ Simultaneous multislice (SMS) imaging is a scan acceleration method where mul- tiple slices are simultaneously excited using a multiband pulse and the aliased slice images are separated in reconstruction using the receive coils’ sensitivity maps. At high main field strengths, SMS brain imaging suffers from artifacts caused by non- uniform and subject-dependent transmit RF fields and large magnetic susceptibility differences near air-tissue interfaces such as the frontal sinus and the middle ear. Another significant engineering challenge is the increase in peak power of multiband pulses with the number of excited slices. In this research work, we propose novel radiofrequency pulses and pulse sequences to address these SMS imaging problems. Low peak power multiband spokes excitation pulses are proposed to mitigate the image shading artifacts caused by inhomogeneous transmit RF field in multiple si- multaneously excited slices. Results from simulations and in vivo experiments at 7 T demonstrate that images excited using multiband spokes pulses have reduced center brightening artifact than conventional multiband pulses. We propose a novel pulse sequence called multispectral z-shim to reduce the through-plane signal loss artifact in structural and functional MR imaging. In vivo experiments show that the multispectral z-shim sequence recovers signal in regions of susceptibility difference in multiple brain regions while maintaining signal elsewhere. To reduce the peak power of conventional pulses, we present a method to design root-flipped multiband pulses. Simulations and experiments demonstrate that for a fixed peak amplitude, the root-flipped pulses excite the desired slices with a pulse duration lower than that of pulses proposed earlier. The work presented in this dissertation will improve high field SMS imaging research in areas such as functional MRI, susceptibility-weighted imaging and diffusion-weighted imaging.
Advisors/Committee Members: Manus J Donahue (committee member), Mark D Does (committee member), Adam W Anderson (committee member), Edward B Welch (committee member), William A Grissom (Committee Chair).
Subjects/Keywords: radiofrequency pulses; MRI; multiband; simultaneous multislice; high field MRI
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APA (6th Edition):
Sharma, A. (2015). Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/12362
Chicago Manual of Style (16th Edition):
Sharma, Anuj. “Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging.” 2015. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/12362.
MLA Handbook (7th Edition):
Sharma, Anuj. “Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging.” 2015. Web. 19 Jan 2021.
Vancouver:
Sharma A. Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging. [Internet] [Doctoral dissertation]. Vanderbilt University; 2015. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/12362.
Council of Science Editors:
Sharma A. Radiofrequency pulses for improved simultaneous multislice magnetic resonance imaging. [Doctoral Dissertation]. Vanderbilt University; 2015. Available from: http://hdl.handle.net/1803/12362
Vanderbilt University
19.
Boyer, Richard Brandon.
Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair.
Degree: PhD, Biomedical Engineering, 2015, Vanderbilt University
URL: http://hdl.handle.net/1803/11945
► This dissertation is a compilation of two studies on the topic of reconstruction of traumatic peripheral nerve injuries. In the first study, I evaluate the…
(more)
▼ This dissertation is a compilation of two studies on the topic of reconstruction of traumatic peripheral nerve injuries. In the first study, I evaluate the effects of two neurotrophic factors, Nerve Growth Factor and Glial-Derived Neurotrophic Factor, as adjuvant therapeutics in nerve allograft repair. Unlike prior studies of neurotrophic factor therapy, this study evaluates their regenerative effects in gap injuries reconstructed with acellular nerve allografts. Over the last several years, acellular nerve allografts have become the preferred method to bridge large nerve gaps, because of reduced morbidity and operative timesaving. In this study, I explore the complex interaction of neurotrophic factor signaling and extracellular matrix composition in the altered microenvironment of the acellular nerve matrix. In the first half of this study, I hypothesize that Nerve Growth Factor or Glial-Derived Neurotrophic Factor may have improved regenerative effects in acellular nerve matrix due to removal of inhibitory glycosaminoglycans. Using a combination of in vitro dorsal root ganglion cell and in vivo rat sciatic nerve injury experiments, I find that adjuvant Nerve Growth Factor has significant pro-regenerative effects in both sensory and motor neurons in acellular nerve matrix. In the latter half of this study, I investigate the ability of acellular nerve allografts to deliver Nerve Growth Factor via extracellular matrix affinity. Using a combination of ex vivo Nerve Growth Factor release studies and in vitro bioactivity assays, I show that acellular nerve allografts maintain release of the neurotrophin over several weeks. I complete this study with an in-vivo evaluation of NGF-eluting acellular nerve allografts in a rat sciatic nerve gap injury, and ultimately find that these allografts are capable of enhancing early nerve regeneration.
The second study in this dissertation is on the characterization of peripheral nerve injury and repair using high-resolution diffusion tensor imaging. Diffusion tensor imaging, which is an MRI sequence that enhances anisotropy of water diffusion in axonal tracts, is a well-accepted clinical tool for evaluation of central nervous system injuries. Since prior investigations are limited to nerve crush or compression, I first evaluate the effects of different degrees of nerve severance on diffusion tensor imaging and tractography using a microsurgically-repaired rats sciatic nerve injury model. In addition to finding high sensitivity of diffusion tensor imaging to nerve severance, I find that specific measures may be useful for grading injury severity. In the last experiment, I use diffusion tensor imaging to evaluate regeneration of axons through NGF-eluting and control acellular nerve allografts. The results of these experiments support the conclusion that NGF-eluting acellular nerve allografts accelerate axon regeneration in peripheral nerve injuries.
Advisors/Committee Members: D.%22%29&pagesize-30">Craig L. Duvall, Ph.
D. (committee member),
D.%22%29&pagesize-30">Lillian B. Nanney, Ph.D. (committee member),
D.%22%29&pagesize-30">Richard D. Dortch, Ph.D. (committee member),
D.%22%29&pagesize-30">Mark D. Does, Ph.D. (Committee Chair),
D.%2C%20Ph.D.%22%29&pagesize-30">Wesley P. Thayer, M.D., Ph.D. (Committee Chair).
Subjects/Keywords: Nerve regeneration; neurotrophic factors; nerve growth factor; nerve repair; peripheral nerve; neurography; diffusion tensor imagin
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APA (6th Edition):
Boyer, R. B. (2015). Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11945
Chicago Manual of Style (16th Edition):
Boyer, Richard Brandon. “Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair.” 2015. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11945.
MLA Handbook (7th Edition):
Boyer, Richard Brandon. “Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair.” 2015. Web. 19 Jan 2021.
Vancouver:
Boyer RB. Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair. [Internet] [Doctoral dissertation]. Vanderbilt University; 2015. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11945.
Council of Science Editors:
Boyer RB. Neurotrophic Factor Eluting Nerve Allografts for Peripheral Nerve Repair. [Doctoral Dissertation]. Vanderbilt University; 2015. Available from: http://hdl.handle.net/1803/11945
Vanderbilt University
20.
West, Kathryn Louise.
Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.
Degree: PhD, Biomedical Engineering, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/14525
► Advanced neuroimaging techniques provide the possibility to non-invasively understand and monitor white matter during development and disease. While data from quantitative MRI techniques, such as…
(more)
▼ Advanced neuroimaging techniques provide the possibility to non-invasively understand and monitor white matter during development and disease. While data from quantitative MRI techniques, such as multiexponential T2 (MET2) and quantitative magnetization transfer (qMT), correlate with myelin content, neither provide an absolute measure of the myelin volume fraction (MVF). Additionally, in preclinical studies, despite time-intensity and small tissue samples, histology remains the gold standard for quantitatively assessing changes in myelin content and white matter microstructural properties, such as myelin thickness and the g-ratio (ratio of axon radius to myelinated fiber radius). Therefore, the work in this dissertation first established and validated methods for MVF imaging from MET2 and qMT against quantitative electron microscopy. We show strong agreement in adult, control mice along with three mouse models of white matter disease. Next, we applied MVF imaging in mice during normal development and observe good agreement between MET2 and qMT and with expected myelin development. To further investigate specific changes in myelin microstructure, recent methods proposed measuring the g-ratio from MRI (gMRI). We revised the model and displayed with quantitative histology that gMRI provides an axon-area-weighted g-ratio. Calculating gMRI requires an accurate measure of MVF; thus, we utilize our MVF imaging techniques to measure gMRI in mouse brain and detect changes in g-ratio with disease in agreement with quantitative histology. In short, we develop and validate measures of MVF and g-ratio from MRI which have the potential to non-invasively provide more specific and thorough assessment of white matter not obtainable with currently used methods.
Advisors/Committee Members: Adam W. Anderson (committee member), Kevin C. Ess (committee member), Daniel F. Gochberg (committee member), John C. Gore (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: magnetization transfer; multiexponential T2; myelin; MRI; neuroimaging; histology; g-ratio
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APA (6th Edition):
West, K. L. (2016). Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14525
Chicago Manual of Style (16th Edition):
West, Kathryn Louise. “Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14525.
MLA Handbook (7th Edition):
West, Kathryn Louise. “Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains.” 2016. Web. 19 Jan 2021.
Vancouver:
West KL. Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14525.
Council of Science Editors:
West KL. Development and Evaluation of Relaxation-Based Measures of Myelin Content and Microstructure in Rodent Brains. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/14525
Vanderbilt University
21.
Poorman, Megan Elizabeth.
Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies.
Degree: PhD, Biomedical Engineering, 2018, Vanderbilt University
URL: http://hdl.handle.net/1803/13503
► Minimally-invasive thermal therapies, such as focused ultrasound, laser, or RF ablation, are a viable alternative to more invasive surgical procedures. These interventional therapies can be…
(more)
▼ Minimally-invasive thermal therapies, such as focused ultrasound, laser, or RF ablation, are a viable alternative to more invasive surgical procedures. These interventional therapies can be used treat everything from cancer to hippocampal epilepsy but are currently hindered by a lack of spatially-resolved real-time temperature monitoring during treatment. Magnetic resonance imaging (MRI) temperature mapping techniques can provide this critical feedback. However, current methods are limited to specific use cases in water-based tissues such as brain or muscle. Many methods fail in more difficult treatment scenarios such as fatty breast tissues or near metallic needles and ablation probes. Additionally, progress on novel ablation techniques such as focused ultrasound is hindered by a lack of well-validated, accessible systems for proof of concept studies. In this work I have developed MR thermometry algorithms and an open-source MR-guided focused ultrasound system to address these needs. This includes novel temperature map reconstruction methods to perform online correction of temperature mapping errors in fatty tissues, pulse sequence development to recover image signal and temperature precision near metallic probes, and validation of a custom MR-guided focused ultrasound system for preclinical studies.
Advisors/Committee Members: Charles F. Caskey (committee member), Mark D. Does (committee member), E. Brian Welch (committee member), Adam W. Anderson (committee member), William A. Grissom (Committee Chair).
Subjects/Keywords: water fat separation; focused ultrasound; magnetic resonance; thermometry; metal artifacts
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APA (6th Edition):
Poorman, M. E. (2018). Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13503
Chicago Manual of Style (16th Edition):
Poorman, Megan Elizabeth. “Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies.” 2018. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/13503.
MLA Handbook (7th Edition):
Poorman, Megan Elizabeth. “Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies.” 2018. Web. 19 Jan 2021.
Vancouver:
Poorman ME. Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies. [Internet] [Doctoral dissertation]. Vanderbilt University; 2018. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/13503.
Council of Science Editors:
Poorman ME. Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies. [Doctoral Dissertation]. Vanderbilt University; 2018. Available from: http://hdl.handle.net/1803/13503
Vanderbilt University
22.
Johnson, Lindsay Craig.
Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography.
Degree: MS, Biomedical Engineering, 2010, Vanderbilt University
URL: http://hdl.handle.net/1803/11760
► Imaging protocols for detection of breast cancer metastases to bone in clinical imaging have long been standardized, but to date small animal imaging still uses…
(more)
▼ Imaging protocols for detection of breast cancer metastases to bone in clinical imaging have long been standardized, but to date small animal imaging still uses a variety of imaging modalities and protocols. Although imaging with modalities such as computed tomography (CT), positron emission tomography (PET), and single photon emission computed tomography (SPECT) are commonly performed, there has been little investigation into the quantitative capability of each modality. The first part of this project investigated the ability to quantify bone volume changes using longitudinal CT scans of mice that were injected in the tibia with MDA-MB-231 cancer cells. CT images were acquired weekly for four weeks for both a treatment and a control group. Tibial volumes were calculated by applying a bone threshold to reconstructed images. Statistically significant differences were found between the untreated lesion and control limb volumes (p<0.0001) and between the treated and untreated lesion limb volumes (p<0.0001). For the second part of this project, a comparison of PET and SPECT for bone imaging using fluoride-18 and technetium-99m methylene diphosphonate, respectively, was performed based on protocols that delivered the same estimated absorbed radiation dose to bone. A same-day imaging protocol with PET, SPECT, and microCT was developed and implemented on three mice that had previously received a cardiac-injection of cancer cells. Visual inspection and quantitative analysis showed mixed results, implying further investigation is necessary to determine which modality is better suited for this application of bone imaging.
Advisors/Committee Members: Mark D. Does (committee member), Todd E. Peterson (Committee Chair).
Subjects/Keywords: PET; imaging; bone metastases; breast cancer; SPECT; CT
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APA (6th Edition):
Johnson, L. C. (2010). Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11760
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Johnson, Lindsay Craig. “Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography.” 2010. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11760.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Johnson, Lindsay Craig. “Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography.” 2010. Web. 19 Jan 2021.
Vancouver:
Johnson LC. Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography. [Internet] [Thesis]. Vanderbilt University; 2010. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11760.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Johnson LC. Imaging of Osteolytic Breast Cancer Metastases with Computed Tomography, Positron Emission Tomography and Single Photon Emission Computed Tomography. [Thesis]. Vanderbilt University; 2010. Available from: http://hdl.handle.net/1803/11760
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
23.
Skinner, Jack Thomas.
In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema.
Degree: MS, Biomedical Engineering, 2009, Vanderbilt University
URL: http://hdl.handle.net/1803/11742
► MRI provides an excellent way of visualizing muscle inflammation; however, there are few techniques that serve to quantitatively assess edematous muscle. In this thesis, integrated…
(more)
▼ MRI provides an excellent way of visualizing muscle inflammation; however, there are few techniques that serve to quantitatively assess edematous muscle. In this thesis, integrated relaxation measurements were made in vivo on edematous rat muscle with varying degrees of swelling. To investigate the effect of exchange on the observed relaxation parameters a two pool model was created and the Bloch-McConnell equations were solved for the varying amounts of swelling. Results from the simulation of the exchange model were compared to the observed data to extract fitted parameters for the compartmental relaxation times. These simulations also provided a comparison for the observed changes in the long-lived apparent T1. Edematous muscle was found to display both multiexponential T1 and multiexponential T2. Normal muscle, however, was found to exhibit only a single T1-T2 component. It was shown that the apparent T1 of the long-lived signal component in edematous muscle increased monotonically with an increase in the amount of edema. Knowledge of changes in T1 and the exchange kinetics in edematous muscle might help in further characterizing the micro-anatomy of muscle tissue in various stages of injury.
Advisors/Committee Members: Bruce M. Damon (committee member), Mark D. Does (Committee Chair).
Subjects/Keywords: multiexponential T1; muscle; edema; exchange
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APA (6th Edition):
Skinner, J. T. (2009). In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11742
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Skinner, Jack Thomas. “In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema.” 2009. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11742.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Skinner, Jack Thomas. “In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema.” 2009. Web. 19 Jan 2021.
Vancouver:
Skinner JT. In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema. [Internet] [Thesis]. Vanderbilt University; 2009. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11742.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Skinner JT. In Vivo Compartmental Relaxation in a Model of Graded Muscle Edema. [Thesis]. Vanderbilt University; 2009. Available from: http://hdl.handle.net/1803/11742
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
24.
Hong, Xin.
Improved characterization of white matter fiber bundles using diffusion MRI.
Degree: MS, Biomedical Engineering, 2006, Vanderbilt University
URL: http://hdl.handle.net/1803/14955
► Diffusion Tensor Imaging (DTI) has become the primary imaging modality for non-invasive characterization of the microstructure of living tissues, particularly of human white matter. Despite…
(more)
▼ Diffusion Tensor Imaging (DTI) has become the primary imaging modality for non-invasive characterization of the microstructure of living tissues, particularly of human white matter. Despite its success in various research areas and clinical applications, DTI is unable to describe adequately non-Gaussian diffusion. Fiber ORientation Estimated using Continuous Axially Symmetric Tensors (FORECAST), a new approach to High Angular Resolution Diffusion (HARD) analysis, is able to provide reliable estimates of the fiber radial diffusivity and orientation distribution within each voxel. In this study, several techniques were developed to enhance the FORECAST model’s reproducibility. The model’s dependence on various imaging parameters and analysis parameters was tested by Monte Carlo simulation. The optimal parameters for FORECAST analysis was determined based on the simulation results, and verified by in vivo human data.
Advisors/Committee Members: Adam W. Anderson (committee member), Mark D. Does (committee member).
Subjects/Keywords: Central nervous system – Magnetic resonance imaging; anisotropic smoothing; Tikhonov regularization; even-order fitting; Diffusion tensor imaging
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Manager
APA (6th Edition):
Hong, X. (2006). Improved characterization of white matter fiber bundles using diffusion MRI. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14955
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Hong, Xin. “Improved characterization of white matter fiber bundles using diffusion MRI.” 2006. Thesis, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14955.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hong, Xin. “Improved characterization of white matter fiber bundles using diffusion MRI.” 2006. Web. 19 Jan 2021.
Vancouver:
Hong X. Improved characterization of white matter fiber bundles using diffusion MRI. [Internet] [Thesis]. Vanderbilt University; 2006. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14955.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hong X. Improved characterization of white matter fiber bundles using diffusion MRI. [Thesis]. Vanderbilt University; 2006. Available from: http://hdl.handle.net/1803/14955
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
25.
Choe, Ann Sunah.
Validation of diffusion tensor imaging in the central nervous system using light microscopy.
Degree: PhD, Biomedical Engineering, 2010, Vanderbilt University
URL: http://hdl.handle.net/1803/14203
► Diffusion tensor imaging (DTI) provides an indirect measure of tissue structure on microscopic scales. To date, DTI is the only imaging method that provides such…
(more)
▼ Diffusion tensor imaging (DTI) provides an indirect measure of tissue structure on microscopic scales. To date, DTI is the only imaging method that provides such information in vivo, and it has proven to be a valuable tool in both research and clinical settings. In this study, A multi-step procedure was developed to register diffusion tensor imaging (DTI) and histological data in the light microscopy image space, with the ultimate goal of allowing quantitative comparisons of the two datasets. The registration procedure was utilized to investigate the relationship between white matter structures and diffusion parameters measured by DTI. We used micrographs from light microscopy of fixed, myelin stained brain sections as a gold standard for direct comparison with data from DTI. Relationships between microscopic tissue properties observed with light microscopy - fiber orientation, density, and coherence - and fiber properties observed by DTI – tensor orientation and fractional anisotropy (FA) - were investigated. Agreement between the major eigenvector of the tensor and myelinated fibers was excellent in voxels with high fiber coherence. However, the diffusion tensor was not a reliable indicator of fiber geometry where fibers crossed or diverged.
Advisors/Committee Members: Malcolm J. Avison (committee member), Mark D. Does (committee member), John C. Gore (committee member), Iwona Stepniewska (committee member), Adam W. Anderson (Committee Chair).
Subjects/Keywords: registration; MRI; DTI; validation; histology
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APA (6th Edition):
Choe, A. S. (2010). Validation of diffusion tensor imaging in the central nervous system using light microscopy. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14203
Chicago Manual of Style (16th Edition):
Choe, Ann Sunah. “Validation of diffusion tensor imaging in the central nervous system using light microscopy.” 2010. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14203.
MLA Handbook (7th Edition):
Choe, Ann Sunah. “Validation of diffusion tensor imaging in the central nervous system using light microscopy.” 2010. Web. 19 Jan 2021.
Vancouver:
Choe AS. Validation of diffusion tensor imaging in the central nervous system using light microscopy. [Internet] [Doctoral dissertation]. Vanderbilt University; 2010. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14203.
Council of Science Editors:
Choe AS. Validation of diffusion tensor imaging in the central nervous system using light microscopy. [Doctoral Dissertation]. Vanderbilt University; 2010. Available from: http://hdl.handle.net/1803/14203
Vanderbilt University
26.
Hong, Xin.
High angular resolution diffusion imaging of brain white matter and its application to schizophrenia.
Degree: PhD, Biomedical Engineering, 2010, Vanderbilt University
URL: http://hdl.handle.net/1803/11702
► By sampling the self-diffusion of water molecules, diffusion tensor imaging (DTI) is able to characterize the microstructure of brain white matter. Previous DTI studies in…
(more)
▼ By sampling the self-diffusion of water molecules, diffusion tensor imaging (DTI) is able to characterize the microstructure of brain white matter. Previous DTI studies in schizophrenia have reported white matter alterations as measured by changes in fractional anisotropy. However, DTI analysis is not capable of distinguishing between possible causes, such as a change in the fiber orientation coherence, a change in the intrinsic diffusivity of the fibers, or both. Compared with DTI, high angular resolution diffusion imaging (HARDI) provides more detailed structural information of underlying tissues. Fiber ORientation Estimated using Continuous Axially Symmetric Tensors (FORECAST) is a spherical deconvolution method to analyze HARDI data.
Based on Monte Carlo simulations, as well as bootstrap analysis of in vivo human data, the optimal imaging and processing parameters for conducting the FORECAST analysis within typical clinical constraints were determined, and the accuracy of the model was estimated.
In order to compare HARDI measurements between subjects, an algorithm was developed to transform the fiber orientation distribution (FOD) function, based on HARDI data, taking into account not only translation, but also rotation, scaling, and shearing effects of the spatial transformation. The algorithm was tested using simulated data, and intra-subject and inter-subject normalization of in vivo human data. All cases demonstrate reliable transformation of the FOD.
A voxel-based group comparison of the radial diffusivity and intravoxel fiber coherence was performed based on FORECAST analysis of the HARDI images from both healthy controls and patients with schizophrenia. Decreased FA and elevated radial diffusivity were found in a number of white matter regions in patients. Our results suggest that increased radial diffusivity is the major
contributor to the FA reduction, while decreased intravoxel fiber coherence also plays a role in the white matter alterations. This set of techniques, as a step forward from conventional DTI analysis, will likely be helpful in clinical studies of other white matter diseases as well.
Advisors/Committee Members: Zhaohua Ding (committee member), Mark D. Does (committee member), Daniel F. Gochberg (committee member), John C. Gore (committee member), Adam W. Anderson (Committee Chair).
Subjects/Keywords: optimization; FORECAST; spherical deconvolution; HARDI; Diffusion MRI; white matter; spatial normalization; schizophrenia
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APA (6th Edition):
Hong, X. (2010). High angular resolution diffusion imaging of brain white matter and its application to schizophrenia. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11702
Chicago Manual of Style (16th Edition):
Hong, Xin. “High angular resolution diffusion imaging of brain white matter and its application to schizophrenia.” 2010. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/11702.
MLA Handbook (7th Edition):
Hong, Xin. “High angular resolution diffusion imaging of brain white matter and its application to schizophrenia.” 2010. Web. 19 Jan 2021.
Vancouver:
Hong X. High angular resolution diffusion imaging of brain white matter and its application to schizophrenia. [Internet] [Doctoral dissertation]. Vanderbilt University; 2010. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/11702.
Council of Science Editors:
Hong X. High angular resolution diffusion imaging of brain white matter and its application to schizophrenia. [Doctoral Dissertation]. Vanderbilt University; 2010. Available from: http://hdl.handle.net/1803/11702
Vanderbilt University
27.
Colvin, Daniel Christopher.
Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy.
Degree: PhD, Physics, 2009, Vanderbilt University
URL: http://hdl.handle.net/1803/14472
► Diffusion-weighted magnetic resonance imaging (DW-MRI) is a noninvasive imaging technique that can be used to quantify the rate of self-diffusion of water molecules. In biological…
(more)
▼ Diffusion-weighted magnetic resonance imaging (DW-MRI) is a noninvasive imaging technique that can be used to quantify the rate of self-diffusion of water molecules. In biological tissues the mobility of water molecules is hindered by nuclear and cellular membranes, as well as by the presence of intracellular organelles, so the apparent rate of diffusion, described by the apparent diffusion coefficient (ADC), is reduced from that in a simple solution. Measurements of ADC reflect the density and scale of restrictive structures within the local cellular environment and may be used to characterize variations in tissue structure, such as those that accompany pathologies such as stroke or cancer. However, the majority of DW-MRI experiments continue to examine these processes over relatively long diffusion times (tens of milliseconds), such that variations in ADC reflect changes in tissue structure over a broad range of spatial scales, and obscure information about variations that arise on an intracellular scale. We have therefore implemented a novel imaging technique, known as temporal diffusion spectroscopy, in order to probe ADC over time scales as much as two orders of magnitude shorter than those previously reported. These methods, which involve rapid oscillations of the motion-sensitizing gradient fields, have been used to investigate variations in ADC in several biological systems, including cultured human embryonic kidney cells treated with various drugs that alter intracellular structure, as well as in an intracranial model of cancer in rats in vivo prior to and following chemotherapy. The reported results demonstrate the utility of these techniques for revealing details of tissue microstructure obscured by conventional methods, as well as for detecting the response of tumor cells to therapeutic treatment earlier than other methods.
Advisors/Committee Members: Mark D. Does (committee member), Adam W. Anderson (committee member), Bruce M. Damon (committee member), David J. Ernst (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: Diffusion MRI; tissue microstructure; noninvasive biomarker
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Colvin, D. C. (2009). Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14472
Chicago Manual of Style (16th Edition):
Colvin, Daniel Christopher. “Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy.” 2009. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14472.
MLA Handbook (7th Edition):
Colvin, Daniel Christopher. “Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy.” 2009. Web. 19 Jan 2021.
Vancouver:
Colvin DC. Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy. [Internet] [Doctoral dissertation]. Vanderbilt University; 2009. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14472.
Council of Science Editors:
Colvin DC. Examining Tissue Microstructure with Temporal Diffusion Magnetic Resonance Spectroscopy. [Doctoral Dissertation]. Vanderbilt University; 2009. Available from: http://hdl.handle.net/1803/14472
Vanderbilt University
28.
Sengupta, Saikat Tarun.
Dynamic B0 shimming at 7 Tesla.
Degree: PhD, Biomedical Engineering, 2010, Vanderbilt University
URL: http://hdl.handle.net/1803/14967
► Increased main field (B0) strength in MRI leads to increased signal levels but also causes higher field inhomogeneity (delta-B0). This thesis presents the implementation and…
(more)
▼ Increased main field (B0) strength in MRI leads to increased signal levels but also causes higher field inhomogeneity (delta-B0). This thesis presents the implementation and evaluation of ‘Dynamic Shimming’, an advanced field shimming (correction) technique, on a high field human 7 Tesla clinical scanner. In this technique, the shim settings are changed during the acquisition of data from individual sub-volumes leading to better optimized field homogeneity compared to conventional static global shimming. Phantom and invivo experiments have been performed comparing the two shimming techniques. Dynamic shimming was seen to produce lower residual delta- B0 , image distortion and signal losses that static global shimming. In addition, a novel software based prospective method of eddy field compensation applied to higher order shim induced eddy currents has been developed and implemented. The method is shown to significantly reduced eddy fields and related artifacts in dynamic shimming.
Advisors/Committee Members: John C. Gore (committee member), Adam W. Anderson (committee member), Mark D. Does (committee member), Edward B. Welch (committee member), Malcolm J Avison (Committee Chair).
Subjects/Keywords: High Field; Shimming; Dynamic Shimming; MRI
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MLA ·
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APA (6th Edition):
Sengupta, S. T. (2010). Dynamic B0 shimming at 7 Tesla. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14967
Chicago Manual of Style (16th Edition):
Sengupta, Saikat Tarun. “Dynamic B0 shimming at 7 Tesla.” 2010. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14967.
MLA Handbook (7th Edition):
Sengupta, Saikat Tarun. “Dynamic B0 shimming at 7 Tesla.” 2010. Web. 19 Jan 2021.
Vancouver:
Sengupta ST. Dynamic B0 shimming at 7 Tesla. [Internet] [Doctoral dissertation]. Vanderbilt University; 2010. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14967.
Council of Science Editors:
Sengupta ST. Dynamic B0 shimming at 7 Tesla. [Doctoral Dissertation]. Vanderbilt University; 2010. Available from: http://hdl.handle.net/1803/14967
Vanderbilt University
29.
Xu, Junzhong.
Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy.
Degree: PhD, Physics, 2008, Vanderbilt University
URL: http://hdl.handle.net/1803/14401
► Diffusion-weighted magnetic resonance imaging (DWI) provides a unique approach for probing the microstructure of biological tissues and is an important tool for both clinical and…
(more)
▼ Diffusion-weighted magnetic resonance imaging (DWI) provides a unique approach for probing the microstructure of biological tissues and is an important tool for both clinical and research applications, such as for the diagnosis of stroke and detection of cancer. However, conventional DWI measurements using pulsed gradient spin echo (PGSE) methods cannot in practice probe very short diffusion times because of hardware limitations, and this restriction prevents conventional DWI from being able to characterize changes in intra-cellular structure, which may be critical in many applications. The method of diffusion temporal spectroscopy using oscillating gradient spin echo (OGSE) methods has been proposed to probe short diffusion times and to provide additional contrast in diffusion imaging. A comprehensive study of diffusion temporal spectroscopy is presented in this thesis, including (1) a simulation of OGSE methods in cellular systems using an improved finite difference method for more accurate and efficient computation of results ; (2) studies of biological tissues and DWI signals with diffusion temporal spectroscopy in order to predict and interpret data and extract quantitative tissue microstructural information; and (3) demonstration of the increased sensitivity of DWI measurements to variations of intracellular structures, such as nuclear sizes, using the diffusion temporal spectroscopy method. The work presented here provides a framework to interpret DWI data to obtain biological tissue microstructural information and may enhance the ability of diffusion imaging to be used as a biomarker for, for example, assessing the state of tumors in pre-clinical research.
Advisors/Committee Members: Mark D. Does (committee member), Adam W. Anderson (committee member), Vito Quaranta (committee member), Alan R. Tackett (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: DWI
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Xu, J. (2008). Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14401
Chicago Manual of Style (16th Edition):
Xu, Junzhong. “Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy.” 2008. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/14401.
MLA Handbook (7th Edition):
Xu, Junzhong. “Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy.” 2008. Web. 19 Jan 2021.
Vancouver:
Xu J. Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy. [Internet] [Doctoral dissertation]. Vanderbilt University; 2008. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/14401.
Council of Science Editors:
Xu J. Diffusion weighted magnetic resonance imaging by temporal diffusion spectroscopy. [Doctoral Dissertation]. Vanderbilt University; 2008. Available from: http://hdl.handle.net/1803/14401
Vanderbilt University
30.
Zhang, Na.
Biophysical basis of fMRI: insights from high spatial resolution studies of primates.
Degree: PhD, Physics, 2007, Vanderbilt University
URL: http://hdl.handle.net/1803/15090
► In the research described, we developed methods and protocols for high-spatial resolution functional magnetic resonance imaging (fMRI) of cortical activity in the brains of anesthetized…
(more)
▼ In the research described, we developed methods and protocols for high-spatial resolution functional magnetic resonance imaging (fMRI) of cortical activity in the brains of anesthetized non-human primates with sub-millimeter spatial specificity. These methods have been used to study the neural architecture of somatosensory areas in squirrel monkeys using BOLD fMRI at 9.4T. The stability and reproducibility of the fMRI data have been investigated and evaluated within and between different animals. We have shown how these high-resolution fMRI techniques may be combined with invasive electrophysiology and optical imaging methodologies to assess brain function more comprehensively. In addition to positive BOLD signals elicited by vibrotactile stimuli, negative BOLD responses were found adjacent to positive BOLD responses in area 3b. The dependences of both the positive and the negative BOLD responses on stimulus intensity have been quantified. The activity within other regions such as SII has also been evaluated. In a separate study, we evaluated the relaxation behavior of paramagnetic metal ions in different brain regions to assess whether MRI can be used to quantify brain levels of such metals, and how these properties may affect the use of manganese as a tracer for imaging neuronal tracts.
Advisors/Committee Members: David J. Ernst (committee member), Todd E. Peterson (committee member), Mark D. Does (committee member), Malcolm J. Avison (committee member), John C. Gore (Committee Chair).
Subjects/Keywords: iron; rat; manganese; SII; SI; tactile stimulation; somatosensory cortex; non-human primate; fMRI; relaxivity; relaxation rate; modelling
Record Details
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Zhang, N. (2007). Biophysical basis of fMRI: insights from high spatial resolution studies of primates. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15090
Chicago Manual of Style (16th Edition):
Zhang, Na. “Biophysical basis of fMRI: insights from high spatial resolution studies of primates.” 2007. Doctoral Dissertation, Vanderbilt University. Accessed January 19, 2021.
http://hdl.handle.net/1803/15090.
MLA Handbook (7th Edition):
Zhang, Na. “Biophysical basis of fMRI: insights from high spatial resolution studies of primates.” 2007. Web. 19 Jan 2021.
Vancouver:
Zhang N. Biophysical basis of fMRI: insights from high spatial resolution studies of primates. [Internet] [Doctoral dissertation]. Vanderbilt University; 2007. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/1803/15090.
Council of Science Editors:
Zhang N. Biophysical basis of fMRI: insights from high spatial resolution studies of primates. [Doctoral Dissertation]. Vanderbilt University; 2007. Available from: http://hdl.handle.net/1803/15090
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