Intracranial lymphoma: CT and MR findings.

The purposes of the present study were to describe CT and MR findings of intracranial lymphoma, to define imaging characteristics of primary and secondary intracranial lymphomas, and to compare CT and MR findings in the same patients. CT and MR studies of 26 patients with the diagnosis of intracranial lymphoma at King Chulalongkorn Memorial Hospital from 1988 to 2000 were reviewed. There were 22 cases of primary lymphoma (21 non-AIDS and 1 AIDS) and 4 cases of secondary lymphoma. Fifty-eight lesions were found. In primary lymphoma, most lesions were in the periventricular areas, appearing as multiple large well-defined margin masses with minimal surrounding edema and dense homogeneous enhancement on both CT and MR studies. The masses were hyperdense on CT scan, isointense on T1W images, and hyperintense to gray matter on T2W MR images. In one AIDS patient, rim enhancement of the lesion was found. Other uncommon findings included intratumoral hemorrhage, isolated mass in the brain stem and extracerebral locations. In secondary lymphoma, smaller and more lesions were noted. Diffuse ependymal enhancement was demonstrated in one case. The results suggest that MRI is more sensitive than CT scan in detecting intracranial lesions of lymphoma.