Browsing by Author "Radhakrishnan, Vishnupuri Venkatraman"

Now showing 1 - 5 of 5
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    Can diffusion tensor metrics help in preoperative grading of diffusely infiltrating astrocytomas? A retrospective study of 36 cases
    (NEURORADIOLOGY, 2011)
    Diffusion weighted imaging and diffusion tensor imaging (DTI) give information about the amount and directionality of water diffusion occurring in a given tissue. Here we study the role of diffusion tensor metrics including fractional anisotropy (FA) and spherical anisotropy (CS) in preoperative grading of diffusely infiltrating astrocytomas.We performed DTI in 38 patients with pathologically proven diffusely infiltrating astrocytomas, who were classified into two groups, i.e., 15 patients with high-grade astrocytoma (HGAs, WHO grade III and IV) and 23 patients with low-grade astrocytoma (LGAs, WHO grade II). We measured maximum FA and minimum CS values in all cases from tumor. Histopathological diagnosis was established in all cases.The mean maximum FA values were higher in HGA (0.583 +/- 0.104) than LGA (0.295 +/- 0.058), while mean minimum CS values were lower in HGA (0.42 +/- 0.121) than LGA (0.722 +/- 0.061). The difference in the diffusion tensor indices between HGA and LGA was found to be statistically significant with P value of < 0.001. Keeping cutoff FA value of 0.4, all HGAs showed higher maximum FA values, and all LGAs showed lower maximum FA values. Also, all HGAs showed minimum CS values less than a cutoff value of 0.6, and all LGAs showed minimum CS values higher than 0.6.Diffusion tensor metrics such as maximum FA and minimum CS can help to differentiate HGA from LGA.
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    Changing signal intensity of a craniopharyngioma
    (NEUROLOGY INDIA, 2010)
    Craniopharyngiomas can present as suprasellar cystic lesion with varied imaging appearance. In magnetic resonance imaging using T1-weighted sequence, the cyst can show hypointense, isointense or hyper intense signals depending on the cyst content. We report a case where the T1 signal intensity of a craniopharyngioma changed over time. The hypointense lesion had become hyper intense in the follow-up scan after six months. Such change in signal intensity is described with Rathke's cleft cyst but has not been reported with craniopharyngioma. The possible reason for this change in signal intensity is discussed.
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    Fatal post-operative gastro intestinal hemorrhage because of angio-dysplasia of small intestine in aortic regurgitation.
    (Interactive cardiovascular and thoracic surgery, 2004)
    Gastrointestinal bleeding due to angiodysplasia of the large intestine associated with calcific aortic stenosis is a well-known entity. Angiodysplasias are artero-venous malformations and they form one of the common causes of occult gastro-intestinal bleeding in the elderly. A 59-year-old man underwent aortic valve replacement for severe aortic regurgitation, developed severe gastro intestinal bleeding. Selective angiography was inconclusive. Exploratory laparotomy revealed angiodysplasia of the terminal ileum, which was resected. We report this case to draw attention to this rare cause of gastro intestinal bleeding and the difficulty in arriving at a diagnosis by the usual investigations.
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    Imaging Findings in Intracranial Aspergillus Infection in Immunocompetent Patients
    (WORLD NEUROSURGERY, 2010)
    AIM: To study the neuroimaging features of craniocerebral aspergillosis infection in immunocompetent patients.MATERIALS AND METHODS: The clinical and imaging data of 12 patients of aspergillus fungal infection were retrospectively reviewed. Diagnosis of fungal infection was confirmed by histopathologic examination of surgically excised specimen, stereotactic biopsy material, or endoscopic sinus biopsy. The radiologic studies were evaluated for anatomic distribution of lesions, signal intensity, contrast enhancement, presence of hemorrhage, diffusion restriction, perfusion, and spectroscopy characteristics. Medical records, biopsy reports, and autopsy findings were also reviewed.RESULTS: Twelve cases of aspergillosis infections in immunocompetent patients were diagnosed at our hospital over a period of 10 years. Lesions could be classified based on imaging of lesions of sinonasal origin, intracranial mass lesion including both parenchymal or extraparenchymal meningeal based and stroke. Coexisting meningitis was also noted in one patient. Disease of sinonasal origin commonly showed invasion of the cavernous sinus and orbital apex resulting in visual symptoms and multiple cranial nerve palsies. Intracranial mass lesions without sinonasal involvement were seen in five cases that included isolated parenchymal lesion in two patients and dural-based mass lesions in three patients. Isolated intraparenchymal lesions included two cases of fungal cerebritis. Dural-based lesions were large granulomas with a significant mass effect. Infarcts were seen in three patients and angiography showed vessel narrowing or occlusion in all the three patients. CT demonstrated isodense to hyperdense attenuation of primary sinus disease with evidence of bone destruction in all the cases of sinonasal origin. Primary parenchymal lesions showed heterogenous attenuation with predominantly low-density areas. Dural-based lesions showed isodense to hyperdense attenuation. Magnetic resonance imaging revealed isointense to hypointense signal intensity on both T(1)-weighted (T1W) and T(2)-weighted (T2W) images in all lesions of sinonasal origin and isolated dural-based mass lesions. Primary parenchymal lesions showed heterogenous signal intensity pattern with predominantly hypointense signal on T1W and hyperintense signal on T2W images. Diffusion weighted imaging, magnetic resonance spectroscopy, and perfusion-weighted imaging gave valuable ancillary information in these cases.CONCLUSION: Sinonasal disease with intracranial extension is the commonest pattern of aspergillus infection followed by intracranial mass lesions. Hyperdense sinonasal disease with bone destruction and intracranial extension on computed tomography, hypointense signal intensity of the lesions on T2W magnetic resonance images, presence of areas of restricted diffusion, decreased perfusion on perfusion-weighted imaging, and presence of hemorrhages are key to the imaging diagnosis of fungal infection.
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    T1 Hyperintense Cystic Lesion - an Epidermoid or an Abscess?
    (CLINICAL NEURORADIOLOGY, 2010)