Imaging aspects of primary central nervous system lymphomas

Th CT and MRI appearence of 196 lymphomatous histologically proved lesions were rewied in 127 patients. A post contrast study was performed in all patients studied with CT; 118 lesions were also assessed before an iodine contrast injection. 40 lesions were both studied with CT and MRI, and 12 only with MRI. There is a single lesion in 86 % of the cases with a supratentorial location in 87 %. The lesion size is over 1 cm in 90 % and 87 % of the lesions appear with regular and sharp demarcation. A mild edema is associated in 86 %. Most of the lesions dysplay an infiltrative pattern with a soft mass effect on the surrounding cerebral parenchyma. The basal ganglion, corpus callosum and trigone location, or an infiltration of the periventricular ependyma, or a mirror pattern, appear strongly suggestive for a lesion of lymphomatous origin. The CT post contrast enhancement of the lesion is present in 99 % and homogeneous in 82 %.