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Vanderbilt University
1.
Xie, Yuan.
Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients.
Degree: MS, Biomedical Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/13868 
► Dermatomyositis (DM) and polymyositis (PM) patients experience intramuscular inflammation and necrosis, eventually progressing to fat infiltration. The gold standard for MRI assessment of fat tissue…
(more)
▼ Dermatomyositis (DM) and polymyositis (PM) patients experience intramuscular inflammation and necrosis, eventually progressing to fat infiltration. The gold standard for MRI assessment of fat tissue infiltration is quantitative fat-water MRI. Fat tissue is also detectable using standard contrast-based clinical MRI sequences; however, typical analyses of these data are qualitative. Texture analysis is a quantitative method for analyzing signal variations in contrast-based images. The goals of this study were to determine which MRI and tissue parameters explain variations in texture parameters and to use texture analysis of contrast-based MR images to predict the fat fraction (Ffat), as determined by quantitative fat-water MRI. Fat signal-suppressed (FS) T1 and T2 maps, Ffat maps, and T2-weighted MR images were acquired from 5 DM patients, 8 PM patients, and 13 control subjects. Images were acquired at mid-thigh. The Grey Level Co-occurrence Matrix (GLCM) and Grey Level Run-length Matrix (GLRM) were calculated and used to derive 11 texture features. Regression analysis focused on the log(Energy) parameter, derived from the GLCM, and the High Gray-level Run-length Emphasis (HGRE), derived from the GLRM. 57.4% of the variance in log(Energy) was explained by Ffat variations. For HGRE, 68.6% of its variance was explained by Ffat variations. Finally, using HGRE, Low Gray level run emphasis, and Homogeneity as predictors, we were able to explain 70.3% of the variance in Ffat. These data show that HGRE primarily reflects fat tissue infiltration. Also, texture analysis can be used to predict Ffat from T2-weighted clinical MR images.
Advisors/Committee Members: E. Brian Welch (Committee Chair), Bruce M. Damon (Committee Chair).
Subjects/Keywords: Dermatomyositis; Polymyositis; muscle imaging; T2 weighted MR images; Texture analysis
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APA (6th Edition):
Xie, Y. (2017). Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13868
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):
Xie, Yuan. “Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients.” 2017. Thesis, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/13868.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Xie, Yuan. “Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients.” 2017. Web. 08 Mar 2021.
Vancouver:
Xie Y. Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients. [Internet] [Thesis]. Vanderbilt University; 2017. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/13868.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Xie Y. Quantitative texture analysis of T2- weighted MR images in polymyositis and dermatomyositis patients. [Thesis]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/13868
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
2.
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 March 08, 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. 08 Mar 2021.
Vancouver:
Lankford CL. The Information Content of mcDESPOT. [Internet] [Thesis]. Vanderbilt University; 2011. [cited 2021 Mar 08].
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
3.
Cui, Xuelin (Nick).
An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging.
Degree: MS, Biomedical Engineering, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/15027
► In addition to the inherent chemical phase shift between different proton species, fat-water MRI k-space raw data are corrupted by several sources such as magnetic…
(more)
▼ In addition to the inherent chemical phase shift between different proton species, fat-water
MRI k-space raw data are corrupted by several sources such as magnetic field
inhomogeneity; chemical shift phase accumulated during the data readout window and
trajectory shifts due to non-ideal gradient performance. NMR signal can be modeled within a
single voxel as the mixture of different type protons with all corrupting factors clearly defined.
If multiecho data are acquired, the evolving fat-water signal can be described as a linear
system which can be unmixed. A reversed readout-based method is investigated in this work
to correct the field inhomogeneity for radial fat-water MRI data. In the Cartesian case, the field
map can be estimated using an iterative approach when other corrupting factors are precisely
modeled. In addition, accurate fat-water signal modeling includes the use of a multipeak fat
spectrum, and precise sampling time information. Multipeak fat spectrum information is
obtained from nuclear magnetic spectroscopy, and the precise sampling time information is
based on the employed pulse sequence. On the other hand, fat-water image reconstruction
from radial trajectory data requires non-uniform Fourier transformation including regridding,
density correction and interpolation. All these procedures are inserted as a part of radial
fat-water separation. The artifact caused by imperfect gradients for radial MRI is also
discussed and corrected in this work. Reconstruction results for both Cartesian and radial
data with all corrections applied are displayed and compared.
Advisors/Committee Members: William Grissom (committee member), Mark Dose (committee member), Edward Brian Welch (Committee Chair).
Subjects/Keywords: mri; radial reconstruction; fat-water imaging
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APA (6th Edition):
Cui, X. (. (2011). An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15027
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):
Cui, Xuelin (Nick). “An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging.” 2011. Thesis, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/15027.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Cui, Xuelin (Nick). “An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging.” 2011. Web. 08 Mar 2021.
Vancouver:
Cui X(. An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging. [Internet] [Thesis]. Vanderbilt University; 2011. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/15027.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Cui X(. An Investigation of Raw Data Corrections for Radial Fat-Water Magnetic Resonance Imaging. [Thesis]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/15027
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
4.
Wargo, Christopher Joseph.
High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla.
Degree: PhD, Biomedical Engineering, 2011, Vanderbilt University
URL: http://hdl.handle.net/1803/13444
► Achieving micron resolutions in magnetic resonance imaging is constrained first by limitations in available signal strength as voxel sizes decrease, and second, by acceptable acquisition…
(more)
▼ Achieving micron resolutions in magnetic resonance imaging is constrained first by limitations in available signal strength as voxel sizes decrease, and second, by acceptable acquisition times due to the large data sets required. The latter is problematic due to an increased sensitivity to patient bulk motion and physiological effects, and prevalence of distortion and blurring artifacts caused by susceptibility variation. Signal constraints can be mitigated using ultra-high field strengths, such as 7T, but face field dependent challenges such as increased B1 inhomogeneity and shorter T2* values. Scan times can be minimized using reduced field-of-view (FOV) imaging techniques that localize excitations to smaller regions of an object to achieve diminished imaging dimensions, but have largely been unexplored at 7T.
To address this deficiency with the goal of improving human imaging resolutions, this thesis first implements and compares multiple reduced-FOV methods at 7T, assessing relative ability to localize excitation, suppress unwanted signal, minimize artifacts, and constrain power deposition. Inner-Volume Imaging (IVI) and Outer-Volume Suppression (OVS) methods optimized from this comparison are then synergistically combined with rapid parallel and echo planar imaging (EPI) techniques to obtain 160 to 500 μm2 in vivo images throughout the human brain in 3 to 12 minutes, accelerated 160 to 1400 fold for multi-slice and 3D scans, respectively. Compared to full-FOV scans, this approach demonstrates reduced geometric distortion and motion artifacts, with improved visibility of features at the high resolution. The parallel reduced-FOV method is similarly applied for diffusion tensor and cervical spine imaging prone to motion and susceptibility artifacts to obtain 1mm2 DTI images and 300 μm2 in the spine, with localized measurement of diffusion properties. Overall, the reduced-FOV approach provides reduction in scan times, artifact minimization, and achieves resolutions that exceed prior studies.
Advisors/Committee Members: Adam Anderson (committee member), Victoria Morgan (committee member), Brian Welch (committee member), Seth Smith (committee member), John Gore (Committee Chair).
Subjects/Keywords: Reduced-FOV; High Resolution; Human Brain; MRI; 7 Tesla; Human DTI; Hippocampus MRI; Cervical Spinal Cord
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APA (6th Edition):
Wargo, C. J. (2011). High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13444
Chicago Manual of Style (16th Edition):
Wargo, Christopher Joseph. “High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla.” 2011. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/13444.
MLA Handbook (7th Edition):
Wargo, Christopher Joseph. “High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla.” 2011. Web. 08 Mar 2021.
Vancouver:
Wargo CJ. High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla. [Internet] [Doctoral dissertation]. Vanderbilt University; 2011. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/13444.
Council of Science Editors:
Wargo CJ. High Resolution MRI of the Human Brain Using Reduced-FOV Techniques at 7 Tesla. [Doctoral Dissertation]. Vanderbilt University; 2011. Available from: http://hdl.handle.net/1803/13444
Vanderbilt University
5.
By, Samantha.
Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models.
Degree: PhD, Biomedical Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/13926
► Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that is marked by inflammation, demyelination, gliosis and axonal loss. The damage…
(more)
▼ Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that is marked by inflammation, demyelination, gliosis and axonal loss. The damage to the CNS from these mechanisms can result in an accumulation of sensorimotor impairment. Diffusion magnetic resonance imaging (MRI) offers the potential to reveal the microstructural integrity of the cervical spinal cord resulting from these pathological mechanisms, which would be useful in the diagnosis and management of MS. This dissertation investigates the application of a spectrum of diffusion models. Starting from the conventional signal model diffusion tensor imaging (DTI) and working towards biophysically based models (i.e., NODDI, SMT and DBSI), these methods are assessed based on their reproducibility in healthy controls and sensitivity to distinguish disparity in MS patients. In comparison to healthy controls, decreased axonal volume fractions were estimated in MS patients using NODDI and SMT. Furthermore, these techniques were robust when optimized for shorter acquisition times and increased coverage. Taken together, the work presented here describes the feasibility and potential of novel diffusion MRI methods for the cervical spinal cord, serving as a vital stepping stone towards the clinical implementation of characterizing spinal cord microstructure in vivo.
Advisors/Committee Members: E. Brian Welch (committee member), William A. Grissom (committee member), Adam Anderson (committee member), Richard Dortch (committee member), Seth A. Smith (Committee Chair).
Subjects/Keywords: multiple sclerosis; spinal cord; diffusion; MRI
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APA (6th Edition):
By, S. (2017). Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13926
Chicago Manual of Style (16th Edition):
By, Samantha. “Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models.” 2017. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/13926.
MLA Handbook (7th Edition):
By, Samantha. “Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models.” 2017. Web. 08 Mar 2021.
Vancouver:
By S. Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models. [Internet] [Doctoral dissertation]. Vanderbilt University; 2017. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/13926.
Council of Science Editors:
By S. Diffusion Magnetic Resonance Imaging of the Human Spinal Cord in Vivo: Feasibility and Application of Advanced Diffusion Models. [Doctoral Dissertation]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/13926
Vanderbilt University
6.
Koran, Mary Ellen Irene.
Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome.
Degree: PhD, Human Genetics, 2014, Vanderbilt University
URL: http://hdl.handle.net/1803/10539
► Alzheimer’s Disease is an irreversible, degenerative disease of the brain that accounts for a majority of dementia cases each year, in both the general population…
(more)
▼ Alzheimer’s Disease is an irreversible, degenerative disease of the brain that accounts for a majority of dementia cases each year, in both the general population and in patients with Down Syndrome. The advancement of in vivo imaging modalities that detect the neuropathologies associated with both Down Syndrome and Alzheimer’s Disease present new opportunities to explore these diseases in living human subjects. Imaging biomarkers not only permit earlier, more accurate patient diagnosis, but quantitative, neuropathology-based traits derived from imaging modalities offer increased power to detect associations with large-scale genetic data. This field of investigation has been termed “imaging genetics”. Imaging genetics studies aim to identify novel risk genes and elucidate gene function and novel mechanisms of disease pathology and etiology. In this dissertation, I have conducted imaging genetics studies of the neuropathologies of Alzheimer’s Disease and Down Syndrome in order to increase our understanding of the genetic etiology underlying these pathologies. Furthermore, new biomarkers of these pathologies are still needed. Thus, a magnetic resonance imaging sequence which has been shown to detect amyloid beta plaque in mice is explored in human studies in this dissertation. This work contributes novel findings to the body of research aimed at early identification of patients at risk of Alzheimer’s Disease.
Advisors/Committee Members: Chun Li (committee member), Tricia Thornton-Wells (committee member), Dana Crawford (committee member), Brian Welch (committee member), Jonathan Haines (Committee Chair).
Subjects/Keywords: imaging; genetics; amyloid; alzheimers; aging; down; downs; MRI; PET
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APA (6th Edition):
Koran, M. E. I. (2014). Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10539
Chicago Manual of Style (16th Edition):
Koran, Mary Ellen Irene. “Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome.” 2014. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/10539.
MLA Handbook (7th Edition):
Koran, Mary Ellen Irene. “Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome.” 2014. Web. 08 Mar 2021.
Vancouver:
Koran MEI. Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome. [Internet] [Doctoral dissertation]. Vanderbilt University; 2014. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/10539.
Council of Science Editors:
Koran MEI. Imaging and Genetics of Two Amyloid Related Diseases: Alzheimer’s Disease and Down Syndrome. [Doctoral Dissertation]. Vanderbilt University; 2014. Available from: http://hdl.handle.net/1803/10539
Vanderbilt University
7.
Baheza, Richard Amador.
An MRI based method for detection of microcalcifications in the human breast.
Degree: PhD, Biomedical Engineering, 2013, Vanderbilt University
URL: http://hdl.handle.net/1803/13185
► Purpose: This study evaluates a new magnetic resonance imaging method for detecting calcium deposits, using their characteristic susceptibility effects, in practical conditions to provide insight…
(more)
▼ Purpose: This study evaluates a new magnetic resonance imaging method for detecting calcium deposits, using their characteristic susceptibility effects, in practical conditions to provide insight into its clinical value for detecting breast microcalcifications at high field (7T).
Methods: Signatures of calcium deposits in phase images were detected via cross-correlation between the images and a library of templates containing simulated phase signatures of deposits. The influences of deposit position, signal-to-noise ratio, spatial resolution, high-pass filtering, and fat suppression on the method were determined and used to optimize the method for detecting simulated microcalcifications inserted in silico into breast MRI of healthy controls.
Results: In images acquired with a clinical scanner and acquisition times below 12 minutes, simulated microcalcifications with sizes of 0.8 – 1.0 mm were detected in images with voxel sizes of (0.4 mm)3 and (0.6 mm)3 with sensitivity and specificity of 75-87% and 54-87%, respectively; smaller microcalcifications with sizes of 0.6 – 0.7 mm were detected better in images with voxel size of (0.4 mm)3, with sensitivity and specificity of 87% and 54%, respectively, than in images with voxel size of (0.6 mm)3, with sensitivity and specificity of 56-78% and 44-47%, respectively.
Conclusions: The new method is promising for detecting large microcalcifications (approximately 0.8 – 1.0 mm in longest dimension) within the breast at 7T. Detection of smaller deposits may be possible in images with higher spatial resolution; unfortunately, these images take too long to acquire using current MR methods and therefore are clinically impractical. Although mammography can detect smaller microcalcifications with sensitivity between 74-95%, and specificity between 89-99%, this alternative MRI method does not expose breasts to ionizing radiation, is not affected by breast density, and can be combined with other quantitative MRI exams to increase the diagnostic specificity of breast MRI.
Advisors/Committee Members: mark does (committee member), john gore (committee member), brian welch (committee member), dan gochberg (committee member), Thomas Yankeelov (Committee Chair).
Subjects/Keywords: magnetic susceptibility; breast MRI; cross-correlation; ROC; microcalcification
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APA (6th Edition):
Baheza, R. A. (2013). An MRI based method for detection of microcalcifications in the human breast. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13185
Chicago Manual of Style (16th Edition):
Baheza, Richard Amador. “An MRI based method for detection of microcalcifications in the human breast.” 2013. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/13185.
MLA Handbook (7th Edition):
Baheza, Richard Amador. “An MRI based method for detection of microcalcifications in the human breast.” 2013. Web. 08 Mar 2021.
Vancouver:
Baheza RA. An MRI based method for detection of microcalcifications in the human breast. [Internet] [Doctoral dissertation]. Vanderbilt University; 2013. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/13185.
Council of Science Editors:
Baheza RA. An MRI based method for detection of microcalcifications in the human breast. [Doctoral Dissertation]. Vanderbilt University; 2013. Available from: http://hdl.handle.net/1803/13185
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 March 08, 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. 08 Mar 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 Mar 08].
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 (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 March 08, 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. 08 Mar 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 Mar 08].
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.
Ianni, Julianna Denise.
Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging.
Degree: PhD, Biomedical Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/14556
► High field magnetic resonance imaging (MRI) offers several advantages over imaging at low field strengths, namely increased spectral resolution, better contrast due to longer T1…
(more)
▼ High field magnetic resonance imaging (MRI) offers several advantages over imaging at low field strengths, namely increased spectral resolution, better contrast due to longer T1 relaxation, higher signal to noise ratio (SNR), and better parallel imaging performance. However, many imaging techniques require strong flip angle uniformity and fast readouts, which are susceptible to trajectory errors. Optimization and machine learning methods are introduced to reduce image artifacts and decrease RF inhomogeneities in high field acquisitions. This is accomplished by employing algorithms that 1) exploit redundancies inherent in parallel imaging and 2) exploit redundant information in multi-subject data to learn characteristic relationships between RF and image parameters. First, an algorithm to reduce trajectory errors – Trajectory Auto-Corrected image Reconstruction (TrACR) – is presented. TrACR was evaluated with in vivo 7 Tesla (7T) brain data from non-Cartesian acquisitions. TrACR reconstructions reduced blurring and streaking artifacts and bear similar quality to images reconstructed using trajectory measurements. Second, an extension of TrACR is presented for echo planar imaging acquisitions to reduce trajectory and phase errors. EPI-TrACR is validated in vivo at 7T, at multiple acceleration and multishot factors, and in a time series, and consistently reduces image artifacts. Finally, to improve transmit field uniformity, a method is introduced for predicting tailored RF shims. RF-shim Prediction by Iteratively Projected Ridge Regression (PIPRR) was validated in simulation for single-slice shimming for 100 phantom human heads. PIPPR-predicted shims reduced profile inhomogeneity and maintained comparable specific absorption rate (SAR) efficiency and homogeneity to that of directly designed shims. PIPRR predictions for a new patient require just milliseconds, reducing compute time for RF shimming by orders of magnitude.
Advisors/Committee Members: E. Brian Welch (committee member), David S. Smith (committee member), Bennett A. Landman (committee member), Adam W. Anderson (committee member), William A. Grissom (Committee Chair).
Subjects/Keywords: MRI; optimization; image reconstruction; machine learning
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APA (6th Edition):
Ianni, J. D. (2017). Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14556
Chicago Manual of Style (16th Edition):
Ianni, Julianna Denise. “Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging.” 2017. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/14556.
MLA Handbook (7th Edition):
Ianni, Julianna Denise. “Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging.” 2017. Web. 08 Mar 2021.
Vancouver:
Ianni JD. Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging. [Internet] [Doctoral dissertation]. Vanderbilt University; 2017. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/14556.
Council of Science Editors:
Ianni JD. Trajectory Optimization and Machine Learning Radiofrequency Pulses for Enhanced Magnetic Resonance Imaging. [Doctoral Dissertation]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/14556
Vanderbilt University
11.
Smith, Alex Kenneth.
Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla.
Degree: PhD, Biomedical Engineering, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/14160
► Magnetization transfer (MT) imaging has emerged as a viable alternative to conventional structural MRI indices. It has been shown to be remarkably sensitive to changes…
(more)
▼ Magnetization transfer (MT) imaging has emerged as a viable alternative to conventional structural MRI indices. It has been shown to be remarkably sensitive to changes in myelin associated with pathologies such as multiple sclerosis (MS). Previous work has built a solid foundation to study the MT effect in vivo, however, the existing literature falls short of developing methods that may help provide solutions to elucidating the clinical problems associated with MS. Therefore, the overall goal of this dissertation was to further the understanding of quantitative magnetization transfer (qMT) imaging at clinical MRI field strengths to provide solutions to these clinical problems. Since qMT imaging has been shown to be sensitive to myelin pathology, these metrics were translated to areas outside of the brain, into the optic nerve and spinal cord, where radiological changes may be better correlated with clinical disability. Next, the coverage of a new MT imaging method, inhomogeneous magnetization transfer (ihMT) was expanded to cover a large 3D volume in a clinically reasonable scan time. This new acquisition strategy has been shown to be specific to WM, and thus, may provide a better indicator of changes in myelin than traditional MT imaging over a large volume. Finally, the two pool MT model was investigated to devise several different methods – one based on a new acquisition strategy, and one based on a new modeling methodology – to remove effects that confound the signal of interest in chemical exchange saturation transfer (CEST) spectra. In conclusion, qMT has been shown to be a remarkably important technique towards understanding the properties of myelin. Gaining a fundamental understanding of how myelin is affected by pathologies which affect the macromolecular structure of neural tissues may facilitate advances in the way we diagnose, treat, and hopefully cure disease. qMT may provide key contributions to this puzzle, and the studies described here have hopefully laid a foundation to drive these future discoveries.
Advisors/Committee Members: Adam W. Andersion (committee member), Richard D. Dortch (committee member), Siddharama Pawate (committee member), E. Brian Welch (committee member), Seth A. Smith (Committee Chair).
Subjects/Keywords: Saturation Transfer; Chemical Exchange; Optic Nerve; Spinal Cord; MT; ihMT; CEST; qMT; Multiple Sclerosis
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APA (6th Edition):
Smith, A. K. (2016). Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/14160
Chicago Manual of Style (16th Edition):
Smith, Alex Kenneth. “Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/14160.
MLA Handbook (7th Edition):
Smith, Alex Kenneth. “Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla.” 2016. Web. 08 Mar 2021.
Vancouver:
Smith AK. Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/14160.
Council of Science Editors:
Smith AK. Investigating the Quantitative Nature of Magnetization Transfer in vivo at 3 tesla. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/14160
Vanderbilt University
12.
Gaur, Pooja.
Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies.
Degree: PhD, Chemical and Physical Biology, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/11626
► The goal of the presented work is to develop robust magnetic resonance imaging (MRI) techniques to improve current and enable future applications of thermal therapies.…
(more)
▼ The goal of the presented work is to develop robust magnetic resonance imaging (MRI) techniques to improve current and enable future applications of thermal therapies. Focused ultrasound therapy is an emerging treatment that can noninvasively heat small areas in the body to stimulate or destroy the tissue depending on the dose used. This approach has been applied to treat cancer, essential tremor, and other conditions without surgery.
Fundamentally, though, current treatments are limited by the performance of available temperature monitoring methods. Tracking temperature changes is critical to performing the treatment both successfully and safely. In particular, more accurate and rapid temperature imaging throughout the tissue is needed to support these procedures. Imaging temperature changes throughout a complete area of the body during the few seconds it takes to deliver the treatment requires faster measurements.
This dissertation describes methods to produce accurate heating estimates from undersampled data, which reduces measurement time. By leveraging a constrained temperature model, our approach will avoid both image aliasing artifacts and blurring in time that are incurred by other acceleration methods. To translate faster temperature imaging to focused ultrasound treatments of the brain, which are complicated by additional equipment that is also present in the image, we will adapt the first method to estimate temperature only the brain region while recovering signal from the rest of the image. To improve measurement accuracy, a fast algorithm correcting image and temperature map distortions caused by tissue heating is presented.
Improved measurements will provide a more complete picture of heating in the body, which will directly translate to improvements in safety and efficacy of heating treatments.
Faster temperature imaging will enable volumetric monitoring, which is needed for continuous thermal targeting across a treatment zone and for expanding the zone of currently treatable regions. More accurate temperature imaging will improve both the localization of thermal targets and measurement of the thermal rise generated. MRI-guided focused ultrasound technology has the potential for significant positive impact on patient treatment by offering both reduced tissue damage and recovery time compared to traditional surgery.
Advisors/Committee Members: William A Grissom, PhD (committee member), Charles F Caskey, PhD (committee member), Ted L Anderson, MD PhD (committee member), Thomas E Yankeelov, PhD (committee member), E Brian Welch, PhD (Committee Chair).
Subjects/Keywords: MRI temperature imaging; undersampled data reconstruction; MRI-guided focused ultrasound
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APA (6th Edition):
Gaur, P. (2016). Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11626
Chicago Manual of Style (16th Edition):
Gaur, Pooja. “Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/11626.
MLA Handbook (7th Edition):
Gaur, Pooja. “Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies.” 2016. Web. 08 Mar 2021.
Vancouver:
Gaur P. Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/11626.
Council of Science Editors:
Gaur P. Advancements in MRI Temperature Map Reconstruction for Real-Time Guidance of Thermal Therapies. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/11626
Vanderbilt University
13.
Chodkowski, BettyAnn.
Brain Functional Connectivity in Childhood Obesity.
Degree: PhD, Chemical and Physical Biology, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/10683
► Over the past 30 years, childhood obesity in the US has nearly doubled, while obesity has tripled among adolescents. Given critical differences in neural function…
(more)
▼ Over the past 30 years, childhood obesity in the US has nearly doubled, while obesity has tripled among adolescents. Given critical differences in neural function between adults and children, we studied children to better understand the developing neurobiology of obesity. We hypothesized that unhealthy eating habits and adiposity are associated with disrupted neural functional connectivity as measured by functional magnetic resonance imaging (fMRI). We quantified functional connectivity between brain regions associated with impulsivity, response inhibition, and reward, in children ages 8-13 years old. Functional connectivity was measured using seed-based resting state and psychophysiological interaction (PPI) methods. We assessed the relationship of neural functional connectivity with adiposity, measured by BMI z-score, and eating behaviors, measured by the Child Eating Behaviour Questionnaire (CEBQ) and the Dutch Eating Behaviour Questionnaire for Children (DEBQ-C).
Our results suggest that the developing brain is primed toward food approach and away from food avoidance behavior with increasing adiposity. An imbalance in neural functional connectivity that is associated with unhealthy eating develops during childhood, as early as 8-13 years of age. Our results suggest that ineffective response inhibition-associated neural functional connectivity is characteristic of obesity in children. Furthermore, response inhibition-associated functional connectivity, more so than drive-associated functional connectivity, may be a key functional difference between children who are obese compared to children who are healthy weight. We conclude that, in addition to changing eating habits and physical activity, strategies that overcome altered neural functional connectivity which influence unhealthy eating are needed to maintain a healthy weight. Strengthening response inhibition-associated functional connectivity may contribute to novel, efficacious obesity treatment.
Advisors/Committee Members: Edward Brian Welch, PhD, MBA (committee member), Neil D. Woodward, PhD (committee member), Kevin D. Niswender, MD, PhD (committee member), Ronald L. Cowan, MD, PhD (committee member), Bruce M. Damon, PhD (Committee Chair).
Subjects/Keywords: Neuroimaging; Neuroscience; Neural Circuits; Human Studies; Quantitative Methods
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APA (6th Edition):
Chodkowski, B. (2016). Brain Functional Connectivity in Childhood Obesity. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10683
Chicago Manual of Style (16th Edition):
Chodkowski, BettyAnn. “Brain Functional Connectivity in Childhood Obesity.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/10683.
MLA Handbook (7th Edition):
Chodkowski, BettyAnn. “Brain Functional Connectivity in Childhood Obesity.” 2016. Web. 08 Mar 2021.
Vancouver:
Chodkowski B. Brain Functional Connectivity in Childhood Obesity. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/10683.
Council of Science Editors:
Chodkowski B. Brain Functional Connectivity in Childhood Obesity. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/10683
Vanderbilt University
14.
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 March 08, 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. 08 Mar 2021.
Vancouver:
Poorman ME. Robust Magnetic Resonance Temperature Mapping for Real-Time Guidance of Interventional Therapies. [Internet] [Doctoral dissertation]. Vanderbilt University; 2018. [cited 2021 Mar 08].
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
15.
Gifford, Aliya.
MRI characterization of brown adipose tissue in adult humans with validation by PET-CT.
Degree: PhD, Chemical and Physical Biology, 2016, Vanderbilt University
URL: http://hdl.handle.net/1803/11352
► Brown adipose tissue (BAT) known to function in a non-shivering thermogenic capacity, also performs as an endocrine organ, and assists with glucose homeostatsis and insulin…
(more)
▼ Brown adipose tissue (BAT) known to function in a non-shivering thermogenic capacity, also performs as an endocrine organ, and assists with glucose homeostatsis and insulin sensitivity. Positron emission tomography (PET)-computed tomography (CT) imaging has identified depots of BAT in humans, igniting scientific interest. Our understanding of human BAT is limited because the primary technique for detecting BAT is through 18F-fluorodeoxyglucose (18F-FDG) PET-CT. Although useful for detecting active BAT glucose metabolism, it disregards the fatty acid substrate fuel, and is limited due to the use of ionizing radiation. Therefore to fully understand the function of BAT and its role in whole body energy metabolism, new imaging techniques need to be employed. The purpose of this dissertation is to characterize both active and inactive supraclavicular BAT in adults, and compare the values to those of subcutaneous white adipose tissue (WAT). We obtained 18F-FDG PET-CT and magnetic resonance imaging (MRI) scans of healthy adults. Unlike 18F-FDG PET, which can only detect active BAT, we show MRI is detects both active and inactive BAT. The MRI derived fat-signal fraction (FSF) of active BAT was significantly lower than inactive BAT (mean ± SD): 60.2 ± 7.6% vs. 62.4 ± 6.8%, respectively. This change in tissue morphology was also reflected as a significant increase in Hounsfield Units (HU): -69.4 ± 11.5 HU vs. -74.5 ± 9.7 HU, respectively. Additionally, the CT HU, MRI FSF and MRI R2* values are significantly different between BAT and WAT, regardless of the activation status of BAT. To the best of our knowledge this is the first study to quantify PET-CT and MRI measures of BAT in both active and inactive states in the same adult subjects. Our findings support the use of these metrics to characterize and distinguish between BAT and WAT, and lay the foundation for future MRI analysis with the hope that someday MRI-based delineation of BAT can stand on its own.
Advisors/Committee Members: Bruce M. Damon (committee member), Seth A. Smith (committee member), Alan D. Cherrington (committee member), Malcolm J. Avison (Committee Chair), E. Brian Welch (Committee Chair).
Subjects/Keywords: computed tomography; positron emission tomography; white adipose tissue; brown adipose tissue; fat signal fraction; fat water magnetic resonance imaging; tissue segmentation; tissue classification techniques; image processing
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APA ·
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MLA ·
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APA (6th Edition):
Gifford, A. (2016). MRI characterization of brown adipose tissue in adult humans with validation by PET-CT. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11352
Chicago Manual of Style (16th Edition):
Gifford, Aliya. “MRI characterization of brown adipose tissue in adult humans with validation by PET-CT.” 2016. Doctoral Dissertation, Vanderbilt University. Accessed March 08, 2021.
http://hdl.handle.net/1803/11352.
MLA Handbook (7th Edition):
Gifford, Aliya. “MRI characterization of brown adipose tissue in adult humans with validation by PET-CT.” 2016. Web. 08 Mar 2021.
Vancouver:
Gifford A. MRI characterization of brown adipose tissue in adult humans with validation by PET-CT. [Internet] [Doctoral dissertation]. Vanderbilt University; 2016. [cited 2021 Mar 08].
Available from: http://hdl.handle.net/1803/11352.
Council of Science Editors:
Gifford A. MRI characterization of brown adipose tissue in adult humans with validation by PET-CT. [Doctoral Dissertation]. Vanderbilt University; 2016. Available from: http://hdl.handle.net/1803/11352
. 
Open Access Theses and Dissertations