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Imaging :Imaging used for- 1. Differential diagnosis based on imaging characteristics and anatomic site; 2. Precise anatomic localization for surgical or radiotherapeutic planning; 3. Measurement of residual tumor size after surgery, radiation or chemotherapy; 4. Detection of late effects of therapy. Facts - § MRI and CT - major neuro-imaging techniques used.§ For most tumors, gadolinium-enhanced MRI is the modality of choice because of higher sensitivity to pathologic alterations in brain tissue and superior anatomic resolution.§ Tumors are contrast enhancing when the BBB is disrupted. Contrast-enhancement provides information regarding high or low grade malignancies.§ Most low-grade gliomas (except-pilocytic astrocytomas) do not enhance on CT or MRI scan.§ Almost all enhancing lesions are high grade.Newer MRI techniques- Can provide additional information They are - 1. Magnetic resonance spectroscopy (MRS)- images the regional distribution of chemicals associated with tumor metabolism. This can distinguish tumor cells from necrosis or treatment effect. 2. Dynamic contrast-enhanced MRI- by quantization of the uptake of gadolinium contrast agent into the lesion, can distinguish the slow rate of uptake of radiation injury from the rapid rate of uptake seen in malignant tumors 3. Diffusion-perfusion MRI - cause restricted water diffusion in the brain to help differentiate malignant tumor from radiation effect. 4. Functional MRI - exploits small, localized changes in blood flow that occur in the brain during neurologic activity to image language, sensory, and motor areas directly. This enables better protection of normal brain function during a resection.
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Brain Tumour Foundation Of India Tata Memorial Hospital,
Ernest Borges Marg, Parel, Mumbai - 400 012, INDIA
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