Browsing by Author "James, JS"

Now showing 1 - 8 of 8
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    A review of neuroimaging biomarkers of Alzheimer's disease
    (NEUROLOGY ASIA, 2013) Varghese, T; Sheelakumari, R; James, JS; Mathuranath, PS
    Neuroimaging biomarkers have potential role in the early diagnosis as well as periodic follow-up of neurodegenerative diseases such as Alzheimer's disease (AD). Structural imaging biomarkers can be used to predict those who are at risk or in preclinical stages of AD. It could possibly be useful even in predicting the conversion of Mild Cognitive Impairment (MCI) an early stage of AD to AD. In addition there has been a lot of progress in molecular imaging in AD. This article presents a review of recent progress in selected imaging biomarkers for early diagnosis, classification, and progression, of AD. A comprehensive integrative strategy initiated early in the cognitive decline is perhaps the most effective method of controlling progression to Alzheimer's disease.
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    Analyzing functional, structural, and anatomical correlation of hemispheric language lateralization in healthy subjects using functional MRI, diffusion tensor imaging, and voxel-based morphometry
    (NEUROLOGY INDIA, 2015) James, JS; Kumari, SR; Sreedharan, RM; Thomas, B; Radhkrishnan, A; Kesavadas, C
    Context: To evaluate the efficacy of diffusion fiber tractography (DFT) and voxel-based morphometry (VBM) for lateralizing language in comparison with functional magnetic resonance imaging (fMRI) to noninvasively assess hemispheric language lateralization in normal healthy volunteers. Aims: The aim of the present study is to evaluate the concordance of language lateralization obtained by diffusion tensor imaging (DTI) and VBM to fMRI, and thus to see whether there exists an anatomical correlate for language lateralization result obtained using fMRI. Settings and Design: This is an advanced neuroimaging study conducted in normal healthy volunteers. Subjects and Methods: Fifty-seven normal healthy subjects (39 males and 18 females; age range: 15-40 years) underwent language fMRI and 30 underwent direction DTI. fMRI language laterality index (LI), fiber tract asymmetry index (AI), and tract-based statistics of dorsal and ventral language pathways were calculated. The combined results were correlated with VBM-based volumetry of Heschl's gyrus (HG), planum temporale (PT), and insula for lateralization of language function. Statistical Analysis Used: A linear regression analysis was done to study the correlation between fMRI, DTI, and VBM measurements. Results: A good agreement was found between language fMRI LI and fiber tract AI, more specifically for arcuate fasciculus (ArcF) and inferior longitudinal fasciculus (ILF). The study demonstrated significant correlations (P < 0.05) between blood-oxygen-level dependent (BOLD) fMRI activations, tract-based statistics, and PT and HG volumetry for determining language lateralization. Conclusions: A strong one-to-one correlation between fMRI, laterality index, DTI tractography measures, and VBM-based volumetry measures for determining language lateralization exists.
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    Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children
    (NEURORADIOLOGY, 2015) Sreedharan, RM; Menon, AC; James, JS; Kesavadas, C; Thomas, SV
    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms-visual verb generation and word pair task-were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 +/- 654.75 mm(3)) as compared to the right (1824.11 +/- 582.81 mm(3)) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities.
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    Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy
    (EPILEPSY RESEARCH, 2015) James, JS; Radhakrishnan, A; Thomas, B; Madhusoodanan, M; Kesavadas, C; Abraham, M; Menon, R; Rathore, C; Vilanilam, G
    Purpose: Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population. Methods: DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively. Results: Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 +/- 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 +/- 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 +/- 2.03 mm (range: 26.4-32.8 mm) and was 28.92 +/- 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was <= 38 mm on the right and <= 35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs. Conclusions: DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability. (C) 2014 Elsevier B.V. All rights reserved.
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    MAPPING AND VOLUMETRY OF HESCHL'S GYRUS BY VBM AIDS IN PLANNING TEMPORAL LOBE RESECTION IN PATIENTS WITH "TLE WITH AUDITORY AURA"
    (EPILEPSIA, 2015) Radhakrishnan, A; James, JS; Sundar, A; Thomas, B; Menon, R; Vilanilam, C; Abraham, M
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    MAPPING AND VOLUMETRY OF HESCHL'S GYRUS BY VOXEL BASED MORPHOMETRY AIDS IN PLANNING TEMPORAL LOBE RESECTION IN PATIENTS WITH "TLE WITH AUDITORY AURA"
    (EPILEPSIA, 2013) Radhakrishnan, A; James, JS; Madhusoodanan, M; Thomas, B; Kesavadas, C; Abraham, M; Radhakrishnan, K
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    Utility of diffusion tensor imaging tractography in decision making for extratemporal resective epilepsy surgery
    (EPILEPSY RESEARCH, 2011) Radhakrishnan, A; James, JS; Kesavadas, C; Thomas, B; Bahuleyan, B; Abraham, M; Radhakrishnan, K
    Purpose: To assess the utility of diffusion tensor imaging tractography (DTIT) in decision making in patients considered for extratemporal resective epilepsy surgery. Methods: We subjected 49 patients with drug-resistant focal seizures due to lesions located in frontal, parietal and occipital lobes to DTIT to map the white matter fiber anatomy in relation to the planned resection zone, in addition to routine presurgical evaluation. We stratified our patients preoperatively into different grades of risk for anticipated neurological deficits as judged by the distance of the white matter tracts from the resection zones and functional cortical areas. Results: Thirty-seven patients underwent surgery; surgery was abandoned in 12 (24.5%) patients because of the high risk of postoperative neurological deficit. DTIT helped us to modify the surgical procedures in one-fourth of occipital, one-third of frontal, and two-thirds of parietal and multilobar resections. Overall, DTIT assisted us in surgical decision making in two-thirds of our patients. Conclusions: DTIT is a noninvasive imaging strategy that can be used effectively in planning resection of epileptogenic lesions at or close to eloquent cortical areas. DTIT helps in predicting postoperative neurological outcome and thereby assists in surgical decision making and in preoperative counseling of patients with extratemporal focal epilepsies. (C) 2011 Elsevier B.V. All rights reserved.
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    VOXEL-BASED OPTIMIZED MORPHOMETRY (VBM) IN THE IDENTIFICATION OF SUBTLE FOCAL CORTICAL DYSPLASIAS (FCDs) IN PATIENTS WITH REFRACTORY SEIZURES
    (EPILEPSIA, 2010) Radhakrishnan, A; James, JS; Kesavadas, C; Thomas, B; Radhakrishnan, K