Name : mersad
Family : mehrnahad
Affiliation :shahid beheshti medical university,shohadaye tajrish hospital,radiology department
Academic Degree : the second year radiology resident
Resident : mersad mehrnahad
Gender : Male
Age : 33
33 yrs old man with headache and seziure
A necrotic tumoral mass with calcified foci is seen in right frontal lobe with faint enhancement and peripheral edema with pressure effect on frontal horn of the lateral ventricle
General imaging differential considerations include:
•dysembryoplastic neuroepithelial tumour (DNET)
•pleomorphic xanthoastrocytoma (PXA)
•cerebritis/herpes simplex (HSV) encephalitis
•cerebral arteriovenous malformation (AVM)
Discussion (Related Text)
Oligodendrogliomas (ODs) are intracranial tumours that account for 5-25% of all gliomas and 5-10% of all primary intracranial neoplasms.
Demographics and clinical presentation
These are usually tumours of middle-aged adults, occurring most commonly in the 4th and 5th decades of life. Due to their usual cortical involvement, presentation is most frequently as a result of seizures
Tumours are typically located supratentorially (85%), involving the white matter and overlying cortex. They are most commonly found in the frontal lobes.
Non contrast CT
Tumours are of mixed density (hypodense to isodense). High-attenuation areas within the tumour are likely from calcification (70-90% of ODs are calcified) or, less commonly, haemorrhage. Calcification can be located centrally, peripherally or they can be ribbon-like 4. The overlying skull may show pressure erosion.
Post contrast CT
50% of ODs enhance: degree of enhancement is extremely variable (no enhancement to striking).
Tumours in which 1p/19q is intact show more homogenous signal on T1 and T2 images and have sharper borders than tumours with 1p/19q deletions. Calcification and haemorrhage are difficult to distinguish on MR. Peritumoral vasogenic oedema is minimal.
•T1: typically hypointense
•T2: typically hyperintense (except calcified areas)
•T2*: calcium seen as areas of "blooming."
•C+ (Gd): contrast enhancement is common but it is not a reliable indicator of tumour grade, with only 50% of ODs enhancing to a variable degree, and usually heterogeneously
◦typically no diffusion restriction
◦DWI can be used to help differentiate ODs (generally lower grade) from astrocytomas (generally higher grade); astrocytomas have higher ADC values probably because of their higher cellularity 5
•MR perfusion: increased vascularity "chicken wire" network of vascularity results in elevated relative cerebral blood volume (rCBV) of grade II vs grade III on PWI; PWI has a sensitivity of 95% and PPV or 87% for distinguishing grade II from grade III ODs 1; a threshold of 1.75, rCBV above this threshold demonstrate more rapid tumour progression