Browsing by Author "Kannath, SK"

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    Quantification of diffusion and anisotropy in intracranial epidermoids using diffusion tensor metrics and p: q tensor decomposition
    (JOURNAL OF NEURORADIOLOGY, 2016) Srinivasan, K; Thomas, B; Shah, D; Kannath, SK; Menon, G; Sandhyamani, S; Kesavadas, C; Kapilamoorthy, TR
    Purpose: To quantitatively evaluate the diffusion tensor metrics p, q, L and fractional anisotropy in intracranial epidermoids in comparison with normal white matter in the splenium of the corpus callosum. Methods: This retrospective study included 20 consecutive patients referred to our institute. All patients had a magnetic resonance imaging (MRI) study on a 1.5-Tesla MR system. A spin echo echo-planar DTI sequence with diffusion gradients along 30 non-collinear directions was performed. The eigen values (lambda(1), lambda(2), lambda(3)) were computed for each voxel and, using p: q tensor decomposition, the DTI metrics p, q and L-values and fractional anositropy (FA) were calculated. The region of interest (ROI) (6 pixels each) was placed within the lesion in all the cases and in the splenium of the corpus callosum. Results: The mean FA in the lesion and splenium were 0.50 and 0.88 respectively, with a statistically significant difference between them (P< 0.01). On p: q tensor decomposition, the mean p-value in the epidermoid was 1.55 +/- 0.24 and 1.35 +/- 0.20 in the splenium; the mean q-values in the epidermoid was 0.67 +/- 0.13 and 1.27 +/- 0.17 in the splenium; the differences were statistically significant (P=0.01 and <0.01 respectively). The significant differente between p- and q-values in epidermoids compared with the splenium of callosum was probably due to structural and orientation differences in the keratin flakes in epidermoids and white matter bundles in the callosum. However, no significant statistical difference in L-values was noted (P=0.44). Conclusion: DTI metrics p- and q have the potential to quantify the diffusion and anisotropy in various tissues thereby gaining information about their internal architecture. The results also suggest that significant differences of DTI metrics p and q between epidermoid and the splenium of the corpus callosum are due to the difference in structural organization within them. (C) 2016 Published by Elsevier Masson SAS.
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    Transient ventricular bigeminy during vertebral artery catheterization
    (NEUROLOGY INDIA, 2012) Harsha, KJ; Jayadevan, ER; Kannath, SK
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    Utility of 3D SPACE T2-weighted volumetric sequence in the localization of spinal dural arteriovenous fistula
    (JOURNAL OF NEUROSURGERY-SPINE, 2016) Kannath, SK; Alampath, P; Rajan, JE; Thomas, B; Sarma, PS; Raman, KT
    OBJECTIVE The aim of this study was to investigate the utility of a heavily T2-weighted volumetric MRI sequence (3D sampling perfection with application-optimized contrasts using different flip-angle evolutions [SPACE]) in the feeder localization of spinal dural arteriovenous fistula (SDAVF). METHODS Patients who were diagnosed with SDAVF and who had 3D SPACE source images available for review were identified from a retrospective review of medical records. A total of 16 patients were identified, and MR images were analyzed separately by 2 blinded observers. The accuracy of the observation and interobserver agreement were measured by Kendall's tau and kappa statistics. RESULTS The site of fistula was accurately predicted by Observers 1 and 2 in 81% and 88% of cases, respectively, which improved to 94% when the level was considered within 1 vertebral level. The observer agreement with gold-standard angiography and interobserver agreement were found to be highly significant (p < 0.0001). CONCLUSIONS The 3D SPACE MRI sequence is valuable in the precise detection of the site of SDAVF. It may help to tailor digital subtraction angiography and thereby reduce the radiation exposure, contrast load, and study time.