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5. Prospective in silico study of the feasibility and dosimetric advantages of MRI-guided dose adaptation for human papillomavirus positive oropharyngeal cancer patients compared with standard IMRT

Author

Mohamed, Abdallah S.R., Bahig, Houda, Aristophanous, Michalis, Blanchard, Pierre, Kamal, Mona, Ding, Yao, Cardenas, Carlos E., Brock, Kristy K., Lai, Stephen Y., Hutcheson, Katherine A., Phan, Jack, Wang, Jihong, Ibbott, Geoffrey, Gabr, Refaat E., Narayana, Ponnada A., Garden, Adam S., Rosenthal, David I., Gunn, G. Brandon, and Fuller, Clifton D.

Published
2018
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17. Automated Segmentation of Tissues Using CT and MRI: A Systematic Review

Author

Lenchik, Leon, primary, Heacock, Laura, additional, Weaver, Ashley A., additional, Boutin, Robert D., additional, Cook, Tessa S., additional, Itri, Jason, additional, Filippi, Christopher G., additional, Gullapalli, Rao P., additional, Lee, James, additional, Zagurovskaya, Marianna, additional, Retson, Tara, additional, Godwin, Kendra, additional, Nicholson, Joey, additional, and Narayana, Ponnada A., additional

Published
2019
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19. Serial Cerebral Metabolic Changes in Patients With Ischemic Stroke Treated With Autologous Bone Marrow Derived Mononuclear Cells

Author

Haque, Muhammad E., primary, Gabr, Refaat E., additional, George, Sarah D., additional, Boren, Seth B., additional, Vahidy, Farhaan S., additional, Zhang, Xu, additional, Arevalo, Octavio D., additional, Alderman, Susan, additional, Narayana, Ponnada A., additional, Hasan, Khader M., additional, Friedman, Elliott R., additional, Sitton, Clark W., additional, and Savitz, Sean I., additional

Published
2019
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26. Loss of Consciousness Is Related to White Matter Injury in Mild Traumatic Brain Injury

Author

Wilde, Elisabeth A., primary, Li, Xiaoqi, additional, Hunter, Jill V., additional, Narayana, Ponnada A., additional, Hasan, Khader, additional, Biekman, Brian, additional, Swank, Paul, additional, Robertson, Claudia, additional, Miller, Emmy, additional, McCauley, Stephen R., additional, Chu, Zili David, additional, Faber, Jessica, additional, McCarthy, James, additional, and Levin, Harvey S., additional

Published
2016
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27. Cortical Thickness in Mild Traumatic Brain Injury

Author

Govindarajan, Koushik A., primary, Narayana, Ponnada A., additional, Hasan, Khader M., additional, Wilde, Elisabeth A., additional, Levin, Harvey S., additional, Hunter, Jill V., additional, Miller, Emmy R., additional, Patel, Vipul Kumar S., additional, Robertson, Claudia S., additional, and McCarthy, James J., additional

Published
2016
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28. Stochastic Dynamic Causal Modeling of Working Memory Connections in Cocaine Dependence

Author

Ma, Liangsuo, Steinberg, Joel L., Hasan, Khader M., Narayana, Ponnada A., Kramer, Larry A., and Moeller, F. Gerard

Subjects
Adult, Male, Models, Statistical, Brain, Prefrontal Cortex, Bayes Theorem, Middle Aged, Magnetic Resonance Imaging, Article, Neostriatum, Cocaine-Related Disorders, Young Adult, Memory, Short-Term, Connectome, Humans, Female
Abstract

Although reduced working memory brain activation has been reported in several brain regions of cocaine-dependent subjects compared with controls, very little is known about whether there is altered connectivity of working memory pathways in cocaine dependence. This study addresses this issue by using functional magnetic resonance imaging-based stochastic dynamic causal modeling (DCM) analysis to study the effective connectivity of 19 cocaine-dependent subjects and 14 healthy controls while performing a working memory task. Stochastic DCM is an advanced method that has recently been implemented in SPM8 that can obtain improved estimates, relative to deterministic DCM, of hidden neuronal causes before convolution with the hemodynamic response. Thus, stochastic DCM may be less influenced by the confounding effects of variations in blood oxygen level-dependent response caused by disease or drugs. Based on the significant regional activation common to both groups and consistent with previous working memory activation studies, seven regions of interest were chosen as nodes for DCM analyses. Bayesian family level inference, Bayesian model selection analyses, and Bayesian model averaging (BMA) were conducted. BMA showed that the cocaine-dependent subjects had large differences compared with the control subjects in the strengths of prefrontal-striatal modulatory (B matrix) DCM parameters. These findings are consistent with altered cortical-striatal networks that may be related to reduced dopamine function in cocaine dependence. As far as we are aware, this is the first between-group DCM study using stochastic methodology.

Published
2012

29. Human Brain Iron Mapping using Atlas-based T2 Relaxometry

Author

Hasan, Khader M., Walimuni, Indika S., Kramer, Larry A., and Narayana, Ponnada A.

Subjects
Adult, Brain Chemistry, Male, Analysis of Variance, Brain Mapping, Adolescent, Iron, Middle Aged, Magnetic Resonance Imaging, Article, Atlases as Topic, Reference Values, Postmortem Changes, Linear Models, Humans, Female, Retrospective Studies
Abstract

Several in vivo quantitative magnetic resonance imaging (qMRI) techniques have been proposed as surrogate measures to map iron content in the human brain. The majority of in vivo qMRI iron mapping methods utilized the age-dependent iron content data based on postmortem data. In this work we fused atlas-based human brain volumetry obtained on a large cohort of healthy adults using FreeSurfer with T2 relaxation time measurements. We provide a brain atlas-based T2 relaxation time map which was subsequently used along with published postmortem iron content data to obtain a map of iron content in subcortical and cortical gray matter. We have also investigated the sensitivity of the linear model relating transverse relaxation rate with published iron content to the number of regions used. Our work highlights the challenges encountered upon using the simple model along with postmortem data to infer iron content in several brain regions where postmortem iron data are scant (e.g. corpus callosum, amygdale).

Published
2011

33. Multi-modal MRI of mild traumatic brain injury

Author

Narayana, Ponnada A., primary, Yu, Xintian, additional, Hasan, Khader M., additional, Wilde, Elisabeth A., additional, Levin, Harvey S., additional, Hunter, Jill V., additional, Miller, Emmy R., additional, Patel, Vipul Kumar S., additional, Robertson, Claudia S., additional, and McCarthy, James J., additional

Published
2015
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34. Inhibitory behavioral control: A stochastic dynamic causal modeling study comparing cocaine dependent subjects and controls

Author

Ma, Liangsuo, primary, Steinberg, Joel L., additional, Cunningham, Kathryn A., additional, Lane, Scott D., additional, Bjork, James M., additional, Neelakantan, Harshini, additional, Price, Amanda E., additional, Narayana, Ponnada A., additional, Kosten, Thomas R., additional, Bechara, Antoine, additional, and Moeller, F. Gerard, additional

Published
2015
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35. Three Element Phased Array Coil for Imaging of Rat Spinal Cord at 7T

Author

Mogatadakala, Kishore V., Bankson, James A., and Narayana, Ponnada A.

Subjects
Male, Quantitative Biology::Tissues and Organs, Physics::Medical Physics, Transducers, Reproducibility of Results, Equipment Design, Image Enhancement, Magnetic Resonance Imaging, Sensitivity and Specificity, Article, Rats, Equipment Failure Analysis, Rats, Sprague-Dawley, Magnetics, Spinal Cord, Animals
Abstract

In order to overcome some of the limitations of an implantable coil, including its invasive nature and limited spatial coverage, a three element phased array coil is described for high resolution magnetic resonance imaging (MRI) of rat spinal cord. This coil allows imaging both thoracic and cervical segments of rat spinal cord. In the current design, coupling between the nearest neighbors was minimized by overlapping the coil elements. A simple capacitive network was used for decoupling the next neighbor elements. The dimensions of individual coils in the array were determined based on the signal-to-noise ratio (SNR) measurements performed on a phantom with three different surface coils. SNR measurements on a phantom demonstrated higher SNR of the phased array coil relative to two different volume coils. In-vivo images acquired on rat spinal cord with our coil demonstrated excellent gray and white matter contrast. To evaluate the performance of the phased array coil under parallel imaging, g-factor maps were obtained for two different acceleration factors of 2 and 3. These simulations indicate that parallel imaging with acceleration factor of 2 would be possible without significant image reconstruction related noise amplifications.

Published
2008

36. Phase-Sensitive T1 Inversion Recovery Imaging: A Time-Efficient Interleaved Technique for Improved Tissue Contrast in Neuroimaging

Author

Hou, Ping, Hasan, Khader M., Sitton, Clark W., Wolinsky, Jerry S., and Narayana, Ponnada A.

Subjects
Brain
Abstract

BACKGROUND AND PURPOSE: High tissue contrast and short acquisition time are desirable when scanning patients. The purpose of this report is to describe the implementation of a new technique for generating high gray matter (GM) and white matter (WM) contrast in a short scan time, make a quantitative evaluation of the contrast efficiency, and explore its potential applications in neuroimaging. METHOD: A fully interleaved T1-weighted inversion recovery (T1IR) sequence with phase-sensitive reconstruction (PS-T1IR) is implemented. This sequence is compared with conventional T1-weighted spin-echo imaging (T1SE) and T1-weighted fluid-attenuated inversion recovery (T1FLAIR). The time efficiency and contrast enhancement have been quantitatively analyzed in normal volunteers. The performance of the sequence is evaluated in >30 patients with neurologic disorders. The sensitivity of PS-T1IR relative to T1SE in detecting gadolinium enhancements is also evaluated. RESULTS: PS-T1IR is more time-efficient than T1SE and generates better GM-WM contrast. It results in the best contrast-to-noise ratio (CNR) efficiency (1.16) compared with T1FLAIR (0.73) and T1SE (0.23). For a typical clinical protocol, PS-T1IR takes only 1:30 minutes versus 2:40 minutes for T1SE imaging for the whole brain coverage. Although gadolinium enhancements are detected with comparable sensitivity on both PS-T1IR and T1SE sequences, in certain instances, the latter sequence appears to be more sensitive in demonstrating gadolinium enhancements within WM. CONCLUSION: PS-T1IR has the highest CNR efficiency compared with T1FLAIR and T1SE. It is a very practical technique for neuroradiologic applications.

Published
2005

38. Serial Atlas-Based Diffusion Tensor Imaging Study of Uncomplicated Mild Traumatic Brain Injury in Adults

Author

Hasan, Khader M., primary, Wilde, Elisabeth A., additional, Miller, Emmy R., additional, Kumar Patel, Vipul, additional, Staewen, Terrell D., additional, Frisby, Melisa L., additional, Garza, Hector M., additional, McCarthy, James J., additional, Hunter, Jill V., additional, Levin, Harvey S., additional, Robertson, Claudia S., additional, and Narayana, Ponnada A., additional

Published
2014
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39. Mission Connect Mild TBI Translational Research Consortium

Author

TEXAS UNIV HEALTH SCIENCE CENTER AT HOUSTON, Narayana, Ponnada A, TEXAS UNIV HEALTH SCIENCE CENTER AT HOUSTON, and Narayana, Ponnada A

Abstract

Both human and animal MRI scans were performed as a part of specific aims 1 and 2. Two types of animal studies were performed. In the first study we investigated the effect of hemorrhagic shock on animals with traumatic injury. In the second study we investigated the neuroprotective effects of Epo on the injury outcome. In humans MRI data were acquired on both orthopedic controls and mTBI subjects at baselone (within 24 hours after injury) and at three months. The multi-modal MRI measures included include regional and global volumetry using tensor-based morphometry, tissue microstructural integrity using diffusion tensor imaging (DTI), and T2-weighted images for lesion volumes in animals, and magnetic resonance spectroscopy (MRS) for investigating the metabolic changes, and magnetization transfer imaging (MTR) for assessing the state of myelin (only in humans). In animals with hemorrhagic shock, significant atrophy was detected in some gray matter structures, including the ipsilateral parietal cortex and parts of amygdaloid nucleus and suprachiasmatic nucleus away from the injury site. Significant reduction in FA in the white matter tracts closest to site of injury: ipsilateral external capsule, internal capsule, splenium, body and genu of corpus callosum were also observed. Based on MRS, Epo appears to show some neuroprotective effect. In humans, mean diffusivity (MD), based on DTI, showed group differences between orthopedic controls and mTBI subjects at baseline. These differences appear to resolve on the month 3 scans. We did not observe any group differences on any of the other MRI measures. These studies resulted in two abstract and one publication. Two more manuscripts are under preparation., The original document contains color images.

Published
2013

44. Increased Orbitofrontal Brain Activation after Administration of a Selective Adenosine A2A Antagonist in Cocaine Dependent Subjects

Author

Moeller, F. Gerard, primary, Steinberg, Joel L., additional, Lane, Scott D., additional, Kjome, Kimberly L., additional, Ma, Liangsuo, additional, Ferre, Sergi, additional, Schmitz, Joy M., additional, Green, Charles E., additional, Bandak, Stephen I., additional, Renshaw, Perry F., additional, Kramer, Larry A., additional, and Narayana, Ponnada A., additional

Published
2012
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