Browsing by Author "Saini, J"

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    Conventional and advanced magnetic resonance imaging in tumefactive demyelination
    (ACTA RADIOLOGICA, 2011) Saini, J; Chatterjee, S; Thomas, B; Kesavadas, C
    Background: Tumefactive demyelination (TD) is a relatively uncommon entity which mimics other focal intracranial lesions. Conventional radiological findings in tumefactive demyelination have been well described. However, DTI and MRS findings in TD have not been studied in detail. Purpose: To evaluate the usefulness of conventional magnetic resonance imaging (MRI), multivoxel 1H spectroscopy (MRS) and diffusion tensor imaging (DTI) in diagnosis and follow-up of TD of the brain. Material and Methods: Clinical and imaging findings of 18 patients were reviewed. MR imaging data which included conventional imaging as well as MRS and DTI were reviewed. At TE 135ms MRS various metabolite ratios were calculated at different depths of the demyelinating lesions. At TE 30 ms, glutamate-glutamine (GLX-2.1-2.5 ppm) was compared in the lesion to the contralateral normal side. DTI data were available for 15 patients and Day (mean diffusivity) and trace values were recorded from central and peripheral layers of the index lesion. Histopathological (9 patients) and therapeutic response (9 patients) on follow-up imaging were taken as the diagnostic criterion. In addition, the follow-up MRI scans available were also reviewed. Results: Characteristic peripheral 'broken ring' type of contrast enhancement was noted in 12 cases. Two or three concentric distinct zones were noted on imaging with distinct metabolic and structural signature in most cases. On TE 135ms, the central part showed variable Choline (Cho) and significantly low N-Acetyl Aspartate (NAA). DTI demonstrated high Day and very low trace value in this zone. The intermediate area showed higher Cho and lower NAA compared to contralateral normal side. The outermost layer, which corresponded to the contrast enhancing areas on MRI, showed high Cho, lower NAA, and restricted diffusion on DTI. The GLX increase was noted in tumefactive lesions. Lactate was observed in all patients and it appeared higher at the center compared to the periphery of lesions. Follow-up imaging showed shrinkage of index lesions, disappearance of contrast enhancement, and diffusion restriction. MRS showed, persistent abnormalities on follow-up imaging. Conclusion: Tumefactive demyelinating lesions reveal different microstructural changes at different depths of the lesion and this unique feature may be useful in differentiating them from other focal lesions of brain.
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    Differentiation of tubercular infection and metastasis presenting as ring enhancing lesion by diffusion and perfusion magnetic resonance imaging
    (JOURNAL OF NEURORADIOLOGY, 2010) Chatterjee, S; Saini, J; Kesavadas, C; Arvinda, HR; Jolappara, M; Gupta, AK
    Background and purpose. - As both tuberculoma and metastasis can manifest as solitary or multiple ring-enhancing intra-axial lesions that are difficult to differentiate by conventional magnetic resonance imaging (MRI), we hypothesized that the use of diffusion and perfusion MRI would make differentiation of these pathologies possible. Materials and methods. - Diffusion and T2*-weighted dynamic contrast-enhanced perfusion MRI scans from 11 patients with histologically proven tuberculoma or metastasis were retrospectively reviewed by two radiologists who were blinded to the pathology. All patients had a ring-enhancing lesion on conventional MRI. Apparent diffusion coefficient (ADC) values and regional cerebral blood volume (rCBV) were calculated from the walls of the lesions. Results. - Lesions showed different perfusion characteristics depending on whether they were due to tuberculosis or metastasis. The mean rCBV ratio between the lesion periphery and normal white matter was inferior to one for tubercular lesions and greater than five for metastases. However, ADC values were similar. Conclusion. - Measuring rCBV obtained by T2*-weighted dynamic contrast-enhanced perfusion MRI can help in differentiating intracranial tubercular mass lesions and metastases. (C) 2009 Elsevier Masson SAS. All rights reserved.