Browsing by Author "Arvinda, HR"

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    3D-CISS MRI in a purely intracanalicular cochlear schwannoma
    (JOURNAL OF NEURORADIOLOGY, 2008) Thomas, B; Krishnamoorthy, T; Arvinda, HR; Kesavadas, C
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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.
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    Glioma grading: sensitivity, specificity, positive and negative predictive values of diffusion and perfusion imaging (Retracted article. See vol. 114, pg. 255, 2013)
    (JOURNAL OF NEURO-ONCOLOGY, 2009) Arvinda, HR; Kesavadas, C; Sarma, PS; Thomas, B; Radhakrishnan, VV; Gupta, AK; Kapilamoorthy, TR; Nair, S
    Purpose The purpose of our study was to determine the statistical significance of thresholds of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC) and ADC ratios in grading cerebral gliomas. Materials and methods In this retrospective study, 51 patients with histopathologically confirmed primary cerebral gliomas who had undergone conventional MR imaging, dynamic contrast-enhanced T2*-weighted perfusion MR imaging and diffusion MR imaging were included. A retrospective blinded analysis of the imaging findings including the perfusion and diffusion parameters was done. The rCBV measurements were obtained from regions of maximum perfusion. Minimum ADC values were obtained from the region of maximum hypointensity within the tumor and from the corresponding opposite white matter. Tumor grade determined with the two methods were then compared with the histopathologic grade. Mann-Whitney tests were performed to compare the DWI and PWI between tumor types. Receiver operating characteristic analyses were performed to determine optimum thresholds for tumor grading and also to calculate the sensitivity, specificity, PPV, and NPV for identifying high-grade gliomas. Results Statistical analysis demonstrated a threshold value of 2.91 for rCBV to provide sensitivity, specificity, PPV, and NPV of 94.7, 93.75, 90.0, and 96.8%, respectively, in determining high-grade gliomas. An ADC value of 98.50 mm(2)/s was defined as a threshold below which tumors were classified as high-grade gliomas and a sensitivity, specificity, PPV, and NPV of 90, 87.1, 81.81 and 93.10% respectively, were obtained. Significant differences were noted in the rCBV ratios, ADC and ADC ratios between low- and high-grade gliomas (P < 0.0001). Conclusion Combining PWI and DWI with conventional MR imaging increases the accuracy of pre-operative imaging grading of glial neoplasms. The rCBV measurements had the most superior diagnostic performance in predicting glioma grade. Absolute ADC values or ADC ratios were also helpful in preoperative grading of gliomas. Threshold values can be used in a clinical setting to evaluate tumors preoperatively for histologic grade and provide a means for guiding treatment and predicting postoperative patient outcome.
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    Glioma grading: sensitivity, specificity, positive and negative predictive values of diffusion and perfusion imaging (Retraction of vol 94, pg 87, 2009)
    (JOURNAL OF NEURO-ONCOLOGY, 2013) Arvinda, HR; Kesavadas, C; Sarma, PS; Thomas, B; Radhakrishnan, VV; Gupta, AK; Kapilamoorthy, TR; Nair, S
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