MRI diagnosis of primary malignant lymphomas in the brain

Objective: To evaluate the role of MRI in the diagnosis of primary malignant lymphomas in the brain. Methods: A retrospective analysis of MRI examinations was performed in 12 patients(5 of them were contrast-enhanced) with histologically proved primary malignant lymphomas in the brain. Results: Solitary lesion was found in 10 cases, and multiple lesions in 2 cases, altogether 14 lesions were identified(13 of them were within cerebral hemispheres and 1 in posterior fossa). Most of the lesions were within the subcortical white matter. Nine lesions involved frontal lobe, 6 lesions involved corpus callum and 2 lesions involved ependyma. On T1WI, 12 lesions were slightly hypointense or isointense while all of the lesions were isointense or slightly hyperintense on T2WI. Among the 5 cases who underwent enhanced MRI scans, 2 lesions were enhanced like fists, 3 lesions were enhanced like masses. The diameter of the lesion was greater than 5cm in 5 lesions, 3～5cm in 7 lesions, smaller than 3cm in 2 lesions. Seven lesions showed minimal edema, 6 lesions showed moderate edema and 1 lesion severe edema. Conclusion: Although there is no characteristic imaging findings of primary malignant lymphomas in the brain, the diagnostic accuracy could be highly improved if we analyze the MRI appearances fully.