Oligodendroglioma MRI

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]Sujit Routray, M.D. [3]

Overview

Brain MRI is helpful in the diagnosis of oligodendroglioma. On brain MRI, oligodendroglioma is characterized by a mass which is typically hypointense on T1-weighted images and hyperintense on T2-weighted images. Calcification is observed as areas of "blooming" on T2 decay component of MRI. T1 C + gadolinium shows heterogeneous contrast enhancement and diffusion weighted images help differentiate lower grade oligodendrogliomas from higher grade astrocytomas which have higher ADC values because of lower cellularity and greater hyaluronan proportion. MRperfusion (PWI) is 95% sensitive for diagnosis of oligodendrogliomas and 87% sensitive for distinguishing grade II from grade III oligodendrogliomas. On PWI, "chicken wire" network of vascularityresults in elevated relative cerebral blood volume (rCBV) of grade II vs grade III and rCBV above the threshold of 1.75 demonstrates more rapid tumor progression.

MRI

• Brain MRI may be helpful in the diagnosis of oligodendroglioma
• Findings on MRI suggestive of oligodendroglioma are listed below:

MRI component	Findings
T1	Typically hypointense
T2	Typically hyperintense (except calcified areas) Enlargement of the lateral ventricles and the third ventricle with periventricular high intensity signal suggestive of transependymal absorption or tumor spreading
T2 decay	Calcification observed as areas of "blooming"
T1 C + gadolinium	Heterogeneous contrast enhancement Not a reliable indicator of tumor grade Only 50% of oligodendrogliomas enhance to a variable degree
Diffusion weighted images (DWI)	Typically no diffusion restriction Helps differentiate lower grade oligodendrogliomas from higher grade astrocytomas: Astrocytomas have higher ADC values because of: Lower cellularity Greater hyaluronan proportion
MR perfusion (PWI)	Generally 95% sensitive for diagnosis of oligodendrogliomas Increased vascularity "Chicken wire" network of vascularity results in elevated relative cerebral blood volume (rCBV) of grade II vs grade III on PWI 87% sensitivity for distinguishing grade II from grade III oligodendrogliomas Threshold of 1.75, rCBV above this threshold demonstrate more rapid tumor progression

MRI axial FLAIR showing a relatively well circumscribed mass involving the temporal lobe and insular cortex, without convincing enhancement, and minimal restricted diffusion Source: Dr. Frank Gaillard. Radiopaedia

MRI including post contrast sequences demonstrates a large mass involving the majority of the left frontal lobe, which exerts significant mass effect resulting in midline shift and effacement of the frontal horn of the lateral ventricle. The mass is heterogeneous, but predominantly hyperintense on T2 with a surrounding mantle of tumor edema. Following contrast there is heterogeneous moderate enhancement.Source: Dr. Frank Gaillard. Radiopaedia	A left frontal lobe mass with central haemorrhagic component is present (intrinsic high T1, low T2) with a peripheral region of enhancement and high T2 signal. Some of the enhancement may be in reaction to the haemorrhage, depending on the time course.Source: Dr. Henry Knipe and Dr. Frank Gaillard et al. Radiopaedia	A sharply defined zone of abnormal slightly heterogeneous signal in the left parietal lobe extends to involve the medial cortex of the superior parietal lobule. Inferiorly it abuts and distorts the cingulate gyrus. Superiorly it is significantly posterior to the precentral gyrus and slightly posterior to the left post central gyrus. Posterior and laterally it extends to and distorts the left intraparietal sulcus. It extends to within 1 cm of the parieto-occipital fissure postero-medially, slightly posteriorly bowing it. It exhibits no restricted diffusion and no pathological contrast enhancement.Source: Dr. Henry Knipe and Dr. Frank Gaillard et al. Radiopaedia	MRI including post contrast sequences demonstrates a large mass involving the majority of the left frontal lobe, which exerts significant mass effect resulting in midline shift and effacement of the frontal horn of the lateral ventricle. The mass is heterogeneous, but predominantly hypointense on T1 with a surrounding mantle of tumor edema. Following contrast there is heterogeneous moderate enhancement.Source: Dr. Frank Gaillard. Radiopaedia
MR perfusion demonstrates significantly increased CBV (area 'under' the purple curve) compared to the other side.Source: Dr. Frank Gaillard. Radiopaedia	MR perfusion of the brain.Source: Dr. Frank Gaillard. Radiopaedia

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