41 results on '"Narayana, Ponnada A."'
Search Results
2. 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
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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.
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- 2018
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3. Altered anterior cingulate cortex to hippocampus effective connectivity in response to drug cues in men with cocaine use disorder
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Ma, Liangsuo, Steinberg, Joel L., Cunningham, Kathryn A., Bjork, James M., Lane, Scott D., Schmitz, Joy M., Burroughs, Thomas, Narayana, Ponnada A., Kosten, Thomas R., Bechara, Antoine, and Moeller, F. Gerard
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- 2018
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4. Long-term follow-up of a randomized study of combination interferon and glatiramer acetate in multiple sclerosis: Efficacy and safety results up to 7 years
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Lublin, Fred D., Cofield, Stacey S., Cutter, Gary R., Gustafson, Tarah, Krieger, Stephen, Narayana, Ponnada A., Nelson, Flavia, Salter, Amber R., and Wolinsky, Jerry S.
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- 2017
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5. A preliminary longitudinal study of white matter alteration in cocaine use disorder subjects
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Ma, Liangsuo, Steinberg, Joel L., Wang, Qin, Schmitz, Joy M., Boone, Edward L., Narayana, Ponnada A., and Moeller, F. Gerard
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- 2017
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6. Regional gray matter atrophy in relapsing remitting multiple sclerosis: Baseline analysis of multi-center data
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Datta, Sushmita, Staewen, Terrell D., Cofield, Stacy S., Cutter, Gary R., Lublin, Fred D., Wolinsky, Jerry S., and Narayana, Ponnada A.
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- 2015
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7. Is 3D MPRAGE better than the combination DIR/PSIR for cortical lesion detection at 3 T MRI?
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Nelson, Flavia, Poonawalla, Aziz, Datta, Sushmita, Wolinsky, Jerry, and Narayana, Ponnada
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- 2014
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8. Oxygen-enhanced MRI in temporal lobe epilepsy: Diagnosis and lateralization
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Kalamangalam, Giridhar P., Nelson, Jeffrey T., Ellmore, Timothy M., and Narayana, Ponnada A.
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- 2012
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9. Deep gray matter atrophy in multiple sclerosis: A tensor based morphometry
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Tao, Guozhi, Datta, Sushmita, He, Renjie, Nelson, Flavia, Wolinsky, Jerry S., and Narayana, Ponnada A.
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- 2009
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10. Are multi-contrast magnetic resonance images necessary for segmenting multiple sclerosis brains? A large cohort study based on deep learning.
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Narayana, Ponnada A., Coronado, Ivan, Sujit, Sheeba J., Sun, Xiaojun, Wolinsky, Jerry S., and Gabr, Refaat E.
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MAGNETIC resonance imaging , *ARTIFICIAL neural networks , *DEEP learning , *GRAY matter (Nerve tissue) , *MULTIPLE sclerosis , *COHORT analysis , *NATALIZUMAB - Abstract
Magnetic resonance images with multiple contrasts or sequences are commonly used for segmenting brain tissues, including lesions, in multiple sclerosis (MS). However, acquisition of images with multiple contrasts increases the scan time and complexity of the analysis, possibly introducing factors that could compromise segmentation quality. To investigate the effect of various combinations of multi-contrast images as input on the segmented volumes of gray (GM) and white matter (WM), cerebrospinal fluid (CSF), and lesions using a deep neural network. U-net, a fully convolutional neural network was used to automatically segment GM, WM, CSF, and lesions in 1000 MS patients. The input to the network consisted of 15 combinations of FLAIR, T1-, T2-, and proton density-weighted images. The Dice similarity coefficient (DSC) was evaluated to assess the segmentation performance. For lesions, true positive rate (TPR) and false positive rate (FPR) were also evaluated. In addition, the effect of lesion size on lesion segmentation was investigated. Highest DSC was observed for all the tissue volumes, including lesions, when the input was combination of all four image contrasts. All other input combinations that included FLAIR also provided high DSC for all tissue classes. However, the quality of lesion segmentation showed strong dependence on the input images. The DSC and TPR values for inputs with the four contrast combination and FLAIR alone were very similar, but FLAIR showed a moderately higher FPR for lesion size <100 μl. For lesions smaller than 20 μl all image combinations resulted in poor performance. The segmentation quality improved with lesion size. Best performance for segmented tissue volumes was obtained with all four image contrasts as the input, and comparable performance was attainable with FLAIR only as the input, albeit with a moderate increase in FPR for small lesions. This implies that acquisition of only FLAIR images provides satisfactory tissue segmentation. Lesion segmentation was poor for very small lesions and improved rapidly with lesion size. [ABSTRACT FROM AUTHOR]
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- 2020
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11. Automated Segmentation of Tissues Using CT and MRI: A Systematic Review.
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Lenchik, Leon, Heacock, Laura, Weaver, Ashley A., Boutin, Robert D., Cook, Tessa S., Itri, Jason, Filippi, Christopher G., Gullapalli, Rao P., Lee, James, Zagurovskaya, Marianna, Retson, Tara, Godwin, Kendra, Nicholson, Joey, and Narayana, Ponnada A.
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Rationale and Objectives: The automated segmentation of organs and tissues throughout the body using computed tomography and magnetic resonance imaging has been rapidly increasing. Research into many medical conditions has benefited greatly from these approaches by allowing the development of more rapid and reproducible quantitative imaging markers. These markers have been used to help diagnose disease, determine prognosis, select patients for therapy, and follow responses to therapy. Because some of these tools are now transitioning from research environments to clinical practice, it is important for radiologists to become familiar with various methods used for automated segmentation.Materials and Methods: The Radiology Research Alliance of the Association of University Radiologists convened an Automated Segmentation Task Force to conduct a systematic review of the peer-reviewed literature on this topic.Results: The systematic review presented here includes 408 studies and discusses various approaches to automated segmentation using computed tomography and magnetic resonance imaging for neurologic, thoracic, abdominal, musculoskeletal, and breast imaging applications.Conclusion: These insights should help prepare radiologists to better evaluate automated segmentation tools and apply them not only to research, but eventually to clinical practice. [ABSTRACT FROM AUTHOR]- Published
- 2019
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12. Promoting Collaborations Between Radiologists and Scientists.
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Yu, John-Paul J., Spieler, Bradley M., Chan, Tiffany L., Johnson, Elizabeth M., Gulani, Vikas, Sandler, Kim L., Narayana, Ponnada A., Mar, Winnie A., Brian, James M., Ng, Chin K., and Hardy, Peter A.
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Radiology as a discipline thrives on the dynamic interplay between technological and clinical advances. Progress in almost all facets of the imaging sciences is highly dependent on complex tools sourced from physics, engineering, biology, and the clinical sciences to obtain, process, and view imaging studies. The application of these tools, however, requires broad and deep medical knowledge about disease pathophysiology and its relationship with medical imaging. This relationship between clinical medicine and imaging technology, nurtured and fostered over the past 75 years, has cultivated extraordinarily rich collaborative opportunities between basic scientists, engineers, and physicians. In this review, we attempt to provide a framework to identify both currently successful collaborative ventures and future opportunities for scientific partnership. This invited review is a product of a special working group within the Association of University Radiologists-Radiology Research Alliance. [ABSTRACT FROM AUTHOR]
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- 2018
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13. Magnetic Resonance Spectroscopy at Term-Equivalent Age in Extremely Preterm Infants: Association With Cognitive and Language Development.
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Bapat, Roopali, Narayana, Ponnada A., Zhou, Yuxiang, and Parikh, Nehal A.
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DEVELOPMENT of premature infants , *NUCLEAR magnetic resonance spectroscopy , *COGNITIVE development , *LANGUAGE acquisition , *LOW birth weight , *COHORT analysis , *METABOLITES - Abstract
Background: Proton magnetic resonance spectroscopy can be used to assess brain integrity and maturation with age. Objective: To compare regional cerebral magnetic resonance spectroscopy metabolite ratios in extremely low birth weight and healthy term control infants measured at term-equivalent age and to evaluate association between magnetic resonance spectroscopy metabolites and cognitive and language development at 18-22 months' corrected age. Methods: Single-voxel point-resolved spectroscopy sequence was performed in a prospective cohort of 43 infants. Magnetic resonance spectroscopy metabolite ratios of N-acetylaspartate to choline-containing compounds and N-acetylaspartate to myo-inositiol in the hippocampus, cortex, and subventricular zone were associated with Bayley mental, cognitive, and language scores at 18-22 months' corrected age. Results: The mean (±S.D.) gestation of the 31 extremely low birth weight population was 25 (±1.1) weeks and mean (±S.D.) birth weight was 749 (±133.9) g. Compared with healthy term control infants, extremely low birth weight infants exhibited consistently lower N-acetylaspartate-to-choline-containing compounds ratios in our three regions of interest, with differences reaching statistical significance for the subventricular zone and cortex regions. In multiple linear regression analyses, N-acetylaspartate-to-choline-containing compounds ratio in the subventricular zone, N-acetylaspartate-to-choline-containing compounds ratio in the cortex, and N-acetylaspartate-to-myo-inositiol ratio in the subventricular zone were significantly associated with Bayley mental scores at 18-22 months' corrected age. Conclusions: Magnetic resonance spectroscopy metabolite abnormalities at term-equivalent age appear to be significantly associated with cognitive and language development in extremely low birth weight infants. [ABSTRACT FROM AUTHOR]
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- 2014
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14. Chronic cocaine administration causes extensive white matter damage in brain: Diffusion tensor imaging and immunohistochemistry studies.
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Narayana, Ponnada A., Herrera, Juan J., Bockhorst, Kurt H., Esparza-Coss, Emilio, Xia, Ying, Steinberg, Joel L., and Moeller, F. Gerard
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COCAINE , *DRUG administration , *WHITE matter (Nerve tissue) , *BRAIN damage , *DIFFUSION tensor imaging , *IMMUNOHISTOCHEMISTRY - Abstract
Abstract: The effect of chronic cocaine exposure on multiple white matter structures in rodent brain was examined using diffusion tensor imaging (DTI), locomotor behavior, and end point histology. The animals received either cocaine at a dose of 100mg/kg (N=19), or saline (N=17) for 28 days through an implanted osmotic minipump. The animals underwent serial DTI scans, locomotor assessment, and end point histology for determining the expressions of myelin basic protein (MBP), neurofilament-heavy protein (NF-H), proteolipid protein (PLP), Nogo-A, aquaporin-4 (AQP-4), and growth associated protein-43 (GAP-43). Differences in the DTI measures were observed in the splenium (scc) and genu (gcc) of the corpus callosum (cc), fimbria (fi), and the internal capsule (ic). A significant increase in the activity in the fine motor movements and a significant decrease in the number of rearing events were observed in the cocaine-treated animals. Reduced MBP and Nogo-A and increased GAP-43 expressions were most consistently observed in these structures. A decrease in the NF-H expression was observed in fi and ic. The reduced expression of Nogo-A and the increased expression of GAP-43 may suggest destabilization of axonal connectivity and increased neurite growth with aberrant connections. Increased GAP-43 suggests drug-induced plasticity or a possible repair mechanism response. The findings indicated that multiple white matter tracts are affected following chronic cocaine exposure. [Copyright &y& Elsevier]
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- 2014
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15. Is 3D MPRAGE better than the combination DIR/PSIR for cortical lesion detection at 3T MRI?
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Nelson, Flavia, Poonawalla, Aziz, Datta, Sushmita, Wolinsky, Jerry, and Narayana, Ponnada
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Abstract: Background and objectives: Based on the application of newer magnetic resonance imaging (MRI) acquisition sequences, the detection of cortical lesions (CL) in multiple sclerosis (MS) has significantly improved. Double inversion recovery (DIR) at 3T has increased the detection sensitivity and classification specificity when combined with phase sensitive inversion recovery (PSIR). Previous findings with 3D magnetization prepared rapid acquisition with gradient echo (MPRAGE) sequences, showed improved classification specificity of purely intracortical (IC) and mixed (MX) lesions, compared to the classification based on DIR/PSIR. Direct comparison between the detection of CL by 3D MPRAGE and by DIR/PSIR at 3T has not been evaluated. Methods: Eleven subjects were imaged on a 3T magnet. DIR/PSIR and 3D MPRAGE images were reviewed independently. Each image set was reviewed twice; only lesions detected on both sessions were scored. Review time per scan was ~5min for DIR/PSIR and ~15min for 3D MPRAGE. Results: We identified 141 CL (62 IC+79 MX) based on DIR/PSIR images vs. 93 (38 IC+55 MX) based on MPRAGE from all eleven patients. MPRAGE under-detected the number of CL in seven cases and over-detected the number of CL in three, only one case had the same number of CL on both sets of images. Conclusions: Combination DIR/PSIR at 3T is superior to 3D MPRAGE for detection of cortical gray matter lesions in MS. The contrast-to-noise ratio of CL appears to be inferior on the MPRAGE images relative to DIR/PSIR [Copyright &y& Elsevier]
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- 2014
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16. Effect of cocaine on structural changes in brain: MRI volumetry using tensor-based morphometry
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Narayana, Ponnada A., Datta, Sushmita, Tao, Guozhi, Steinberg, Joel L., and Moeller, F. Gerard
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COCAINE abuse , *EFFECT of drugs on the brain , *MAGNETIC resonance imaging of the brain , *BRAIN anatomy , *VOXEL-based morphometry , *PATHOLOGY , *JACOBIAN matrices , *COHORT analysis , *CONTROL groups - Abstract
Abstract: Magnetic resonance imaging (MRI) was performed in cocaine-dependent subjects to determine the structural changes in brain compared to non-drug using controls. Cocaine-dependent subjects and controls were carefully screened to rule out brain pathology of undetermined origin. Magnetic resonance images were analyzed using tensor-based morphometry (TBM) and voxel-based morphometry (VBM) without and with modulation to adjust for volume changes during normalization. For TBM analysis, unbiased atlases were generated using two different inverse consistent and diffeomorphic nonlinear registration techniques. Two different control groups were used for generating unbiased atlases. Independent of the nonlinear registration technique and normal cohorts used for creating the unbiased atlases, our analysis failed to detect any statistically significant effect of cocaine on brain volumes. These results show that cocaine-dependent subjects do not show differences in regional brain volumes compared to non-drug using controls. [ABSTRACT FROM AUTHOR]
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- 2010
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17. In vivo diffusion tensor imaging of thoracic and cervical rat spinal cord at 7 T
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Mogatadakala, Kishore V. and Narayana, Ponnada A.
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DIFFUSION tensor imaging , *LABORATORY rats , *ECHO-planar imaging , *CERVICAL vertebrae , *THORACIC vertebrae , *PERIAQUEDUCTAL gray matter , *ALGORITHMS - Abstract
Abstract: In vivo diffusion tensor imaging (DTI) of rat cervical and thoracic spinal cord was performed using a three-element phased array coil at 7 T. The magnetic field was shimmed over the spinal cord in real time using an in-house developed automatic algorithm. Echo planar imaging (EPI)-based diffusion-weighted images (DWIs) were acquired with 21 gradient encoding directions. The DWIs were tensor encoded, and diffusion tensor metrics, fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (λ 0) and transverse diffusivity (λ ⊥) were determined for both white matter (WM) and gray matter (GM). The results on six normal rats indicated no significant differences in the diffusion tensor metrics between thoracic and cervical regions. However, the DTI-derived metrics in cervical spinal cord from our study are somewhat different from the published results in rats. The possible reasons for these differences are suggested. [Copyright &y& Elsevier]
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- 2009
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18. Diffusion tensor imaging of cocaine-treated rodents
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Narayana, Ponnada A., Ahobila-Vajjula, Pallavi, Ramu, Jaivijay, Herrera, Juan, Steinberg, Joel L., and Moeller, F. Gerard
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COCAINE , *NARCOTICS , *LABORATORY rats , *ANIMAL experimentation - Abstract
Abstract: Studies in cocaine-dependent human subjects have shown differences in white matter on diffusion tensor imaging (DTI) compared with non-drug-using controls. It is not known whether the differences in fractional anisotropy (FA) seen on DTI in white matter regions of cocaine-dependent humans result from a pre-existing predilection for drug use or purely from cocaine abuse. To study the effect of cocaine on brain white matter, DTI was performed on 24 rats after continuous infusion of cocaine or saline for 4 weeks, followed by brain histology. Voxel-based morphometry analysis showed an 18% FA decrease in the splenium of the corpus callosum (CC) in cocaine-treated animals relative to saline controls. On histology, significant increase in neurofilament expression (125%) and decrease in myelin basic protein (40%) were observed in the same region in cocaine-treated animals. This study supports the hypothesis that chronic cocaine use alters white matter integrity in human CC. Unlike humans, where the FA in the genu differed between cocaine users and non-users, the splenium was affected in rats. These differences between rodent and human findings could be due to several factors that include differences in the brain structure and function between species and/or the dose, timing, and duration of cocaine administration. [Copyright &y& Elsevier]
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- 2009
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19. Mohr diagram interpretation of anisotropic diffusion indices in MRI
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Bilgen, Mehmet and Narayana, Ponnada A.
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DIFFUSION , *ANISOTROPY , *IMAGING systems - Abstract
Descriptions of diffusion anisotropy in MR Diffusion Tensor Imaging are often based on scalar indices such as surface-to-volume ratio, volume ratio, fractional anisotropy and rotational anisotropy. Recently, Mohr diagram was introduced to visualize the anisotropic diffusion information, but in a graphical form. Even though both scalar indices and the Mohr diagram are derived from the elements of the diffusion tensor, so far, the relationships between these measures and the key aspects of the Mohr diagram have not been established. This paper demonstrates these relationships both qualitatively and quantitatively for two microscopically heterogeneous biologic tissues, kidney and spinal cord. [Copyright &y& Elsevier]
- Published
- 2003
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20. Global optimization of mutual information: application to three[hyphen]dimensional retrospective registration of magnetic resonance images
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He, Renjie and Narayana, Ponnada A.
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MAGNETIC resonance imaging , *GENETIC algorithms - Abstract
A global optimization technique for image registration, based on mutual information, that can be used in conjunction with a multi[hyphen]resolution paradigm is described. This technique combines genetic algorithm in continuous space, which is a stochastic method and is very efficient in large search space, with dividing rectangle, which is a deterministic method that theoretically guarantees global optimization and is efficient in small search space. Calculations were performed for determining the optimum parameters for implementing this method. This technique was applied to register magnetic resonance images of brain. For comparison, the registration results using AIR, a commonly employed software package, are presented. [Copyright &y& Elsevier]
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- 2002
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21. 93: Tissue graft materials for skin patch during in-utero spina bifida repair in a sheep model.
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Mann, Lovepreet, Won, Jong, Fletcher, Stephen A., Jain, Ranu, Patel, Rajan, Herrera, Juan, Narayana, Ponnada, and Papanna, Ramesha
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SPINA bifida ,SKIN grafting ,SHEEP - Published
- 2020
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22. 486: Cryopreserved Human Umbilical Cord (HUC) patch for in-utero spina bifida repair preserves posterior column tracts and improve spinal cord function.
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Papanna, Ramesha, Mann, Lovepreet K., Won, Jong H., Vu, Thai, Fletcher, Stephen, Jain, Ranu, Bockhorst, Kurt H., Patel, Rajan, Narayana, Ponnada, and Grill, Raymond J.
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- 2018
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23. 86: Functional and anatomical integrity of spinal cord after in-utero spina bifida repair using cryopreserved human umbilical cord (HUC) Patch vs. Conventional repair (CR) in a Sheep Model.
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Papanna, Ramesha, Mann, Lovepreet K., Won, Jong H., Vu, Thai, Fletcher, Stephen, Jain, Ranu, Jr.Moise, Kenneth J., Johnson, Anthony, Patel, Rajan, Narayana, Ponnada, and Grill, Raymond
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- 2018
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24. DTI-based segmentation and quantification of human brain lateral ventricular CSF volumetry and mean diffusivity: Validation, age, gender effects and biophysical implications.
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Hasan, Khader M., Moeller, F. Gerard, and Narayana, Ponnada A.
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IMAGE segmentation , *DIAGNOSTIC imaging , *BRAIN imaging , *CEREBRAL ventricles , *BIOPHYSICS , *HISTOGRAMS , *DISEASES - Abstract
Abstract: The human brain lateral ventricular (LV) cerebrospinal fluid (CSF) volume has been used as a neuroimaging marker of brain changes in health and disease. The LV CSF diffusivity may offer a useful quality assurance measure and become a potential noninvasive marker of deep brain temperature. In this work we sought to validate a method for human brain lateral ventricular (LV) cerebrospinal fluid (CSF) using diffusion tensor imaging (DTI) contrast to provide LV volume and corresponding DTI metrics. We compared LV volume obtained using DTI with that obtained using validated segmentations of the LV on T1-weighted data. DTI and T1-weighted data were acquired at 3T on 49 healthy males and 56 age-matched females aged 18–59years. We showed histogram distributions of LV DTI metrics to establish quality assurance measures. We also analyzed the age and gender effects of LV volume and diffusivity. LV volumes estimated using both T1-weighted and DTI correlated strongly in males and females (ICC=0.99; median Dice index ~80%). The LV-to-intracranial volume percentage increased significantly with age only in males, using the DTI-based approach (r=0.39; p=0.005). LV CSF Mean diffusivity was greater in males than females ((~1.2%; p=0.03). Mean diffusivity of lateral ventricular CSF decreased significantly with age in healthy adults (r=−0.30; p=0.02). Our results highlight the importance of age and gender-based analyses and the potential of LV diffusivity measures as a quantitative marker. [Copyright &y& Elsevier]
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- 2014
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25. Perfusion in rat brain at 7 T with arterial spin labeling using FAIR-TrueFISP and QUIPSS
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Esparza-Coss, Emilio, Wosik, Jarek, and Narayana, Ponnada A.
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CEREBRAL circulation , *PERFUSION , *LABORATORY rats , *SPIN labels , *BRAIN imaging , *LONGITUDINAL method , *FEASIBILITY studies , *SIGNAL-to-noise ratio - Abstract
Abstract: Measurement of perfusion in longitudinal studies allows for the assessment of tissue integrity and the detection of subtle pathologies. In this work, the feasibility of measuring brain perfusion in rats with high spatial resolution using arterial spin labeling is reported. A flow-sensitive alternating recovery sequence, coupled with a balanced gradient fast imaging with steady-state precession readout section was used to minimize ghosting and geometric distortions, while achieving high signal-to-noise ratio. The quantitative imaging of perfusion using a single subtraction method was implemented to address the effects of variable transit delays between the labeling of spins and their arrival at the imaging slice. Studies in six rats at 7 T showed good perfusion contrast with minimal geometric distortion. The measured blood flow values of 152.5±6.3 ml/100 g per minute in gray matter and 72.3±14.0 ml/100 g per minute in white matter are in good agreement with previously reported values based on autoradiography, considered to be the gold standard. [Copyright &y& Elsevier]
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- 2010
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26. Impulsivity and BOLD fMRI activation in MDMA users and healthy control subjects
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Valdes, Ignacio H., Steinberg, Joel L., Narayana, Ponnada A., Kramer, Larry A., Dougherty, Donald M., Swann, Alan C., Barratt, Ernest S., and Moeller, Frederick Gerard
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DIAGNOSTIC imaging , *MAGNETIC resonance imaging , *NONINVASIVE diagnostic tests , *MEDICAL imaging systems - Abstract
Abstract: The correlation between scores on the Barratt Impulsiveness Scale (BIS) and activation measured by functional magnetic resonance imaging in a dorsolateral prefrontal cortical (DLPFC) activating task was examined in 15 MDMA-using subjects and 19 controls. A significant correlation between BIS scores and DLPFC activation was found, supporting a role for the DLPFC in BIS-measured impulsivity. [Copyright &y& Elsevier]
- Published
- 2006
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27. In vivo assessment of blood-spinal cord barrier permeability: serial dynamic contrast enhanced MRI of spinal cord injury
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Bilgen, Mehmet, Dogan, Bulent, and Narayana, Ponnada A.
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SPINAL cord injuries , *MAGNETIC resonance imaging - Abstract
Serial in vivo dynamic contrast enhanced (DCE) MRI studies were performed on spinal cord injured rats on post-injury Days 0, 10, 20 and 30 to determine the distribution of gadopentetate-dimeglumine (Gd) concentration in injured cord tissue. A two-compartment pharmacokinetic model was fitted to the time course of the concentration data at the epicenter of injury for each post-injury day. From these fits, the rates of the Gd transport between plasma and injured cord tissue were determined as a measure of blood-spinal cord barrier (BSCB) permeability. The results indicated that Gd transport rates decrease steadily with a concomitant improvement in motor functions of the rats with post-injury time. Specifically, the rates of Gd accumulation in injured SC tissue and its clearance correlated with the neurobehavioral scores with correlation coefficients of ρ = −0.96 and −0.79, respectively, suggesting a significant link between the neurobehavioral function and the restoration of BSCB integrity as a result of the ongoing repair and recovery processes within the injured cords. [Copyright &y& Elsevier]
- Published
- 2002
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28. MRI acoustic noise-modulated computer animations for patient distraction and entertainment with application in pediatric psychiatric patients.
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Gabr, Refaat E., Zunta-Soares, Giovana B., Soares, Jair C., and Narayana, Ponnada A.
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COMPUTER-generated imagery , *NOISE , *DISTRACTION - Abstract
To reduce patient anxiety caused by the MRI scanner acoustic noise. We developed a simple and low-cost system for patient distraction using visual computer animations that were synchronized to the MRI scanner's acoustic noise during the MRI exam. The system was implemented on a 3T MRI system and tested in 28 pediatric patients with bipolar disorder. The patients were randomized to receive noise-synchronized animations in the form of abstract animations in addition to music (n = 13, F/M = 6/7, age = 10.9 ± 2.5 years) or, as a control, receive only music (n = 15, F/M = 7/8, age = 11.6 ± 2.3 years). After completion of the scans, all subjects answered a questionnaire about their scan experience and the perceived scan duration. The scan duration with multisensory input (animations and music) was perceived to be ~15% shorter than in the control group (43 min vs. 50 min, P < 0.05). However, the overall scan experience was scored less favorably (3.9 vs. 4.6 in the control group, P < 0.04). This simple system provided patient distraction and entertainment leading to perceived shorter scan times, but the provided visualization with abstract animations was not favored by this patient cohort. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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29. Altered white matter in cocaine-dependent subjects with traumatic brain injury: A diffusion tensor imaging study.
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Ma, Liangsuo, Steinberg, Joel L., Keyser-Marcus, Lori, Ramesh, Divya, Narayana, Ponnada A., Merchant, Randall E., Moeller, F. Gerard, and Cifu, David X.
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WHITE matter (Nerve tissue) , *BRAIN injuries , *DIFFUSION tensor imaging , *COCAINE , *MEDICAL education - Abstract
Background Diffusion tensor imaging (DTI) is a useful technique for non-invasively investigating the microstructural organization of white matter (WM), and the most consistent DTI finding regarding cocaine-related WM alterations is in the corpus callosum (CC). WM injury has also been observed in subjects with traumatic brain injury (TBI), including in the CC. Methods We used DTI to test if the WM microstructure is relatively more impaired in cocaine-dependent subjects who had suffered a mild TBI (mTBI). Fractional anisotropy (FA), which reflects the degree of alignment of cellular structures within fiber tracts and their structural integrity, was compared across cocaine-dependent subjects with mTBI (COCTBI group, n = 9), matched cocaine-dependent subjects without TBI (COC group, n = 12), and matched healthy controls (CTL group, n = 12). Results The COCTBI group had significantly lower FA in the genu, body, and splenium of CC, than the CTL group whenever the education was controlled or not. The COC group had significantly lower FA in the left and right anterior corona radiata than the CTL group only when the education was controlled. There was no significant difference in FA between the COC and COCTBI groups. Conclusion Cocaine dependence (or mTBI) related WM impairments in the CC were not detectable in this small subject sample. The significant finding in the CC suggests that the concurrence of cocaine dependence and mTBI might result in more severe damage to the CC, which could even be detected in small sample size. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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30. Lateral ventricular cerebrospinal fluid diffusivity as a potential neuroimaging marker of brain temperature in multiple sclerosis: a hypothesis and implications.
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Hasan, Khader M., Lincoln, John A., Nelson, Flavia M., Wolinsky, Jerry S., and Narayana, Ponnada A.
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VENTRICULAR aneurysms , *CEREBROSPINAL fluid , *MULTIPLE sclerosis , *DIFFUSION tensor imaging , *TEMPERATURE effect - Abstract
In this retrospective study we tested the hypothesis that the net effect of impaired electrical conduction and therefore increased heat dissipation in multiple sclerosis (MS) results in elevated lateral ventricular (LV) cerebrospinal fluid (CSF) diffusivity as a measure of brain temperature estimated in vivo using diffusion tensor imaging (DTI). We used validated DTI-based segmentation methods to obtain normalized LV-CSF volume and its corresponding CSF diffusivity in 108 MS patients and 103 healthy controls in the age range of 21–63 years. The LV CSF diffusivity was ~ 2% higher in MS compared to controls that correspond to a temperature rise of ~ 1 °C that could not be explained by changes in the CSF viscosity due to altered CSF protein content in MS. The LV diffusivity decreased with age in healthy controls (r = − 0.29; p = 0.003), but not in MS (r = 0.15; p = 0.11), possibly related to MS pathology. Age-adjusted LV diffusivity increased with lesion load (r = 0.518; p = 1 × 10 − 8 ). Our data suggest that the total brain lesion load is the primary contributor to the increase in LV CSF diffusivity in MS. These findings suggest that LV diffusivity is a potential in vivo biomarker of the mismatch between heat generation and dissipation in MS. We also discuss limitations and possible confounders. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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31. Evaluation of fiber tracking from subsampled q-space data in diffusion spectrum imaging.
- Author
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Tefera, Getaneh Bayu, Zhou, Yuxiang, Juneja, Vaibhav, and Narayana, Ponnada A.
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DIFFUSION , *SPECTRUM analysis , *SAMPLING (Process) , *DISTRIBUTION (Probability theory) , *LONGITUDINAL method , *SET theory - Abstract
Abstract: Diffusion spectrum imaging (DSI) is capable of resolving crossing and touching fiber bundles in a given voxel. Acquisition of DSI data involves sampling large number of points in the q-space which significantly increases scan times. The scan times can be reduced by exploiting the symmetry of the q-space. In this study the fiber pathways for five (fornix, cingulum, superior longitudinal fasciculus, corticospinal tract, and crossing fibers in the centrum semiovale region) fiber bundles derived using three subsampled data sets of different sizes derived from the 257 samples in the q-space are compared. The coefficient of variation of the ratio of the number of fiber pathways for each subsample data set to the original data points, averaged over all the 10 subjects, was used for quantitatively investigating the effect of subsampling on the tractography. The effect of threshold angles on tractography is also investigated. The effect of subsampling on the orientation distribution function (ODF) was quantitatively evaluated using both scalar and vector measures derived from the ODF. A streamline tractography method that improves the curvature problem and reduces the local truncation error to further improve the mapping of fiber pathways is adapted. Analysis of the fiber pathways in ten normal subjects, based on qualitative and quantitative methods, shows that the 129 and 198 q-space points provide very similar result with angle of threshold between 41° and 45°. Based on the scan time advantage, 129 subsampled points appear to be adequate for tractography. [Copyright &y& Elsevier]
- Published
- 2013
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32. Diffusion tensor tractography indices in patients with frontal lobe injury and its correlation with neuropsychological tests
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Pal, Deepa, Gupta, Rakesh K., Agarwal, Shruti, Yadav, Abhishek, Ojha, Bal K., Awasthi, Ashish, Rathore, Ram K.S., Pandey, Chandra M., and Narayana, Ponnada A.
- Subjects
- *
FRONTAL lobe injuries , *NEUROPSYCHOLOGICAL tests , *T-test (Statistics) , *STATISTICAL correlation , *DIFFUSION tensor imaging , *MEDICAL statistics - Abstract
Abstract: Objectives: Diffusion tensor tractography (DTT) was performed to quantify diffuse axonal injury (DAI) in major white matter (WM) fiber bundles (FBs) of patients with frontal lobe injury and to correlate these changes with neuropsychological tests (NPT) at 6 month follow-up. Patients and Methods: DTT was performed in 21 patients with moderate traumatic brain injury (TBI) within week and after 6 month follow-up, and in controls. DTI indices were calculated from the entire FBs in patients as well as controls. Bonferroni multiple comparisons Post hoc test was performed for determining the changes in DTI indices. Paired t-test was performed between DTI indices at baseline and follow-up. Pearson''s correlation was performed between NPT scores and DTI indices. Results: Significant changes in DTI indices were observed in some of the FBs as compared to controls which incompletely recovered at 6 month follow-up. DTI indices of different WM FBs correlated significantly with some of the NPT. Conclusion: We conclude that DTT based quantification helps in assessment of DAI in patients with moderate frontal lobe injury. Some of the FBs recover partially at 6 month follow-up and correlate with NPT scores. [Copyright &y& Elsevier]
- Published
- 2012
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33. Human brain atlas-based multimodal MRI analysis of volumetry, diffusimetry, relaxometry and lesion distribution in multiple sclerosis patients and healthy adult controls: Implications for understanding the pathogenesis of multiple sclerosis and consolidation of quantitative MRI results in MS
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Hasan, Khader M., Walimuni, Indika S., Abid, Humaira, Datta, Sushmita, Wolinsky, Jerry S., and Narayana, Ponnada A.
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- *
MAGNETIC resonance imaging of the brain , *COMBINED modality therapy , *VOLUME (Cubic content) , *MULTIPLE sclerosis , *HEALTH of adults , *CENTRAL nervous system diseases , *ETIOLOGY of diseases - Abstract
Abstract: Multiple sclerosis (MS) is the most common immune-mediated disabling neurological disease of the central nervous system. The pathogenesis of MS is not fully understood. Histopathology implicates both demyelination and axonal degeneration as the major contributors to the accumulation of disability. The application of several in vivo quantitative magnetic resonance imaging (MRI) methods to both lesioned and normal-appearing brain tissue has not yet provided a solid conclusive support of the hypothesis that MS might be a diffuse disease. In this work, we adopted FreeSurfer to provide standardized macrostructure or volumetry of lesion free normal-appearing brain tissue in combination with multiple quantitative MRI metrics (T2 relaxation time, diffusion tensor anisotropy and diffusivities) that characterize tissue microstructural integrity. By incorporating a large number of healthy controls, we have attempted to separate the natural age-related change from the disease-induced effects. Our work shows elevation in diffusivity and relaxation times and reduction in volume in a number of normal-appearing white matter and gray matter structures in relapsing–remitting multiple sclerosis patients. These changes were related in part with the spatial distribution of lesions. The whole brain lesion load and age-adjusted expanded disability status score showed strongest correlations in regions such as corpus callosum with qMRI metrics that are believed to be specific markers of axonal dysfunction, consistent with histologic data of others indicating axonal loss that is independent of focal lesions. Our results support that MS at least in part has a neurodegenerative component. [Copyright &y& Elsevier]
- Published
- 2012
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34. Working memory fMRI activation in cocaine-dependent subjects: Association with treatment response
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Moeller, F. Gerard, Steinberg, Joel L., Schmitz, Joy M., Ma, Liangsuo, Liu, Shijing, Kjome, Kimberly L., Rathnayaka, Nuvan, Kramer, Larry A., and Narayana, Ponnada A.
- Subjects
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SHORT-term memory , *MAGNETIC resonance imaging of the brain , *COCAINE abuse , *CAUDATE nucleus , *BRAIN function localization , *THALAMUS , *DOPAMINE - Abstract
Abstract: Functional magnetic resonance imaging (fMRI) studies of early abstinence cocaine users offer information about the state of the brain when most cocaine users seek treatment. This study examined the relationship between pretreatment brain function and subsequent treatment response in 19 treatment-seeking early abstinence cocaine-dependent (CD) subjects. These subjects and 14 non-drug-using control subjects underwent fMRI while performing a working memory task with three levels of difficulty. CD subjects were then randomized to treatment studies. Results showed CD subjects had significantly lower (random effects, corrected for multiple comparisons) brain activation in caudate, putamen, cingulate gyrus, middle and superior frontal gyri, inferior frontal gyrus pars triangularis and pars opercularis, precentral gyrus, and thalamus compared with non-drug-using controls. Within CD subjects, thalamic activation significantly correlated with treatment response. This study shows CD subjects in early abstinence have alterations of brain function in frontal, striatal, and thalamic brain regions known to be part of a circuit associated with motor control, reward, and cognition. Subjects with pretreatment thalamic deactivation showed the poorest treatment response, possibly related to thalamic involvement in mesocortical and mesolimbic dopamine projections. [Copyright &y& Elsevier]
- Published
- 2010
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35. Diffusion tensor imaging in cocaine dependence: Regional effects of cocaine on corpus callosum and effect of cocaine administration route
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Ma, Liangsuo, Hasan, Khader M., Steinberg, Joel L., Narayana, Ponnada A., Lane, Scott D., Zuniga, Edward A., Kramer, Larry A., and Moeller, F. Gerard
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DIFFUSION tensor imaging , *COCAINE abuse , *CORPUS callosum , *DRUG administration , *PHYSIOLOGICAL effects of narcotics , *EFFECT of drugs on the brain , *BRAIN anatomy , *LINEAR statistical models , *ANALYSIS of covariance , *PHYSIOLOGICAL effects of alcohol , *BRAIN imaging - Abstract
Abstract: Recent studies demonstrated that diffusion tensor imaging (DTI) can provide information regarding white matter integrity of the corpus callosum (CC). In this study, DTI parameters were compared between cocaine dependent subjects (CDs) and non-drug using controls (NCs) in midsagittal CC. DTI images were acquired from 19 CDs and 18 age-matched NCs. The midsagittal CC was segmented into: genu, rostral body, anterior midbody, posterior midbody, isthmus, and splenium. Linear mixed models analyses showed that, relative to NCs, CDs had lower fractional anisotropy (FA), higher radial diffusivity (λ ⊥), and higher mean diffusivity (D av) in the isthmus; higher λ⊥ and D av in the rostral body; and lower FA in the splenium. After including mass of lifetime alcohol use in the mixed model analysis of covariance (ANCOVA) as a covariate, significant between group differences in λ ⊥ in the rostral body and isthmus remained. These results suggest that alterations in λ ⊥ in the rostral body and isthmus were mainly due to cocaine use, consistent with previous studies showing that cocaine may alter myelin integrity. Between group differences in FA in the isthmus and splenium, and D av in the rostral body and isthmus became non-significant after inclusion of alcohol use as a covariate. This is suggestive of alcohol influencing these values, or may be related to the decreased degrees of freedom for these effects. Consistent with clinical data of greater severity of drug use in smoked versus intranasal cocaine, subjects who smoked cocaine showed lower FA and higher λ ⊥ compared to intranasal CDs. [Copyright &y& Elsevier]
- Published
- 2009
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36. Symmetric inverse consistent nonlinear registration driven by mutual information
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Tao, Guozhi, He, Renjie, Datta, Sushmita, and Narayana, Ponnada A.
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MEDICAL imaging systems , *GAMES equipment , *EQUIPMENT & supplies , *CHESS equipment - Abstract
Abstract: A nonlinear viscoelastic image registration algorithm based on the demons paradigm and incorporating inverse consistent constraint (ICC) is implemented. An inverse consistent and symmetric cost function using mutual information (MI) as a similarity measure is employed. The cost function also includes regularization of transformation and inverse consistent error (ICE). The uncertainties in balancing various terms in the cost function are avoided by alternatively minimizing the similarity measure, the regularization of the transformation, and the ICE terms. The diffeomorphism of registration for preventing folding and/or tearing in the deformation is achieved by the composition scheme. The quality of image registration is first demonstrated by constructing brain atlas from 20 adult brains (age range 30–60). It is shown that with this registration technique: (1) the Jacobian determinant is positive for all voxels and (2) the average ICE is around 0.004 voxels with a maximum value below 0.1 voxels. Further, the deformation-based segmentation on Internet Brain Segmentation Repository, a publicly available dataset, has yielded high Dice similarity index (DSI) of 94.7% for the cerebellum and 74.7% for the hippocampus, attesting to the quality of our registration method. [Copyright &y& Elsevier]
- Published
- 2009
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37. Targeting white matter neuroprotection as a relapse prevention strategy for treatment of cocaine use disorder: Design of a mechanism-focused randomized clinical trial.
- Author
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Schmitz, Joy M., Lane, Scott D., Weaver, Michael F., Narayana, Ponnada A., Hasan, Khader M., Russell, DeLisa D., Suchting, Robert, and Green, Charles E.
- Subjects
- *
COCAINE-induced disorders , *WHITE matter (Nerve tissue) , *CLINICAL trials , *PEROXISOME proliferator-activated receptors , *COGNITIVE ability , *COGNITIVE therapy - Abstract
Cocaine use continues to be a significant public health problem with limited treatment options and no approved pharmacotherapies. Cognitive-behavioral therapy (CBT) remains the mainstay treatment for preventing relapse, however, people with chronic cocaine use display cognitive impairments that are associated with poor response to CBT. Emerging evidence in animal and human studies suggests that the peroxisome proliferator-activated receptor-gamma (PPAR- γ) agonist, pioglitazone, improves white matter integrity that is essential for cognitive function. This project will determine whether adjunctive use of pioglitazone enhances the effect of CBT in preventing relapse during the early phase of recovery from cocaine use disorder. This paper describes the design of a mechanism-focused phase 2 randomized clinical trial that aims first to evaluate the effects of pioglitazone on targeted mechanisms related to white matter integrity, cognitive function, and cocaine craving; and second, to evaluate the extent to which improvements on target mechanisms predict CBT response. Positive results will support pioglitazone as a potential cognitive enhancing agent to advance to later stage medication development research. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
38. Treatment-Induced Plasticity in Cerebral Palsy: A Diffusion Tensor Imaging Study
- Author
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Trivedi, Richa, Gupta, Rakesh K., Shah, Vipul, Tripathi, Mukesh, Rathore, Ram K.S., Kumar, Manoj, Pandey, Chandra M., and Narayana, Ponnada A.
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DIFFUSION tensor imaging , *CEREBRAL palsy , *NEUROPLASTICITY , *SPASTIC paralysis , *PYRAMIDAL tract , *PEDIATRIC neurology - Abstract
Diffusion tensor imaging is used as a measure of white-matter organization to probe mechanisms underlying clinical responses. Diffusion tensor imaging and clinical assessment in 8 patients with spastic quadriparesis (mean age, 6.13 years) was performed before and 6 months after therapy (botulinum injection, followed by physiotherapy). All patients were graded on the basis of gross motor function. Serial diffusion tensor imaging was also performed on 10 age/sex-matched controls at baseline and after 6 months. Regions of interests were placed on corticospinal tracts at different levels (i.e., corona radiata, posterior limb of internal capsule, midbrain, pons, and upper medulla) and on other major white-matter tracts, in both patients and controls. A significant increase in fractional anisotropy was evident in corticospinal tracts at the level of the posterior limb of the internal capsule and periventricular white matter of the temporal lobe, relative to baseline values in the patient group. Gross motor function classification system grades improved in all patients during follow-up relative to baseline values. The increase in fractional anisotropy in corticospinal tracts, along with improved clinical motor scores, suggests plasticity of the central motor pathway after combined therapy. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
39. Generalized fuzzy clustering for segmentation of multi-spectral magnetic resonance images
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He, Renjie, Datta, Sushmita, Sajja, Balasrinivasa Rao, and Narayana, Ponnada A.
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MAGNETIC resonance imaging , *FUZZY algorithms , *COMPUTATIONAL complexity , *MEDICAL imaging systems - Abstract
Abstract: An integrated approach for multi-spectral segmentation of MR images is presented. This method is based on the fuzzy c-means (FCM) and includes bias field correction and contextual constraints over spatial intensity distribution and accounts for the non-spherical cluster''s shape in the feature space. The bias field is modeled as a linear combination of smooth polynomial basis functions for fast computation in the clustering iterations. Regularization terms for the neighborhood continuity of intensity are added into the FCM cost functions. To reduce the computational complexity, the contextual regularizations are separated from the clustering iterations. Since the feature space is not isotropic, distance measure adopted in Gustafson–Kessel (G–K) algorithm is used instead of the Euclidean distance, to account for the non-spherical shape of the clusters in the feature space. These algorithms are quantitatively evaluated on MR brain images using the similarity measures. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
40. Diffusion tensor imaging eigenvalues: Preliminary evidence for altered myelin in cocaine dependence
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Moeller, F. Gerard, Hasan, Khader M., Steinberg, Joel L., Kramer, Larry A., Valdes, Ignacio, Lai, Lingo Y., Swann, Alan C., and Narayana, Ponnada A.
- Subjects
- *
COCAINE abuse , *BRAIN imaging , *CORPUS callosum , *EIGENVALUES - Abstract
Abstract: Reduced fractional anisotropy (FA) in Diffusion Tensor Imaging (DTI) has been reported in cocaine dependent subjects compared to non-drug using controls. There are several pathological mechanisms that could be responsible for these findings, since FA can be reduced through damage to axonal tracts and by neuronal loss. One way of obtaining more information about pathology underlying changes in FA on DTI is diffusion tensor eigenvalues, representing diffusion along the fiber tract (λ 1) or perpendicular to the fiber tract (λ T). Thirteen cocaine dependent subjects and 18 healthy controls underwent full brain DTI. Eigenvalues λ 1 and λ T of the corpus callosum were compared between cocaine users and controls. For λ T there was a significant interaction of group×region of corpus callosum. Exploratory analysis of the subregions showed higher λ T in the genu of the anterior corpus callosum of cocaine dependent subjects compared to control subjects. For λ 1 there was no significant interaction of group×region of corpus callosum. Based on prior studies suggesting that alteration or damage to myelin increases diffusion perpendicular to the direction of fiber tracts (λ T) with minimal effect on λ 1 these findings are consistent with altered myelin in the corpus callosum in cocaine dependent subjects. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
41. In vivo diffusion tensor imaging of rat spinal cord at 7 T
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Elshafiey, Ibrahim, Bilgen, Mehmet, He, Renjie, and Narayana, Ponnada A.
- Subjects
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SPINAL cord , *MAGNETIC resonance imaging - Abstract
In vivo diffusion tensor imaging of normal rat spinal cord was performed using a multi-segmented, blipped EPI sequence at 7 T field strength. At high diffusion weighting, the signal exhibited a non-monoexponential decay that was fitted to a biexponential function, associated with the fast and slow components of diffusion in the cord tissue, using a nonlinear regression analysis along with a constrained optimization procedure. From the measured tensors, the eigenvalues and the maps of invariant scalar measures (fractional anisotropy, relative anisotropy, volume ratio, and trace) were calculated and analyzed statistically. The results were combined to quantitatively characterize the anisotropic properties of the fast and slow diffusions in white- and gray matter of live spinal cords. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
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