MRI findings of primary intracranial lymphoma on immunologically normal patients

Magnetic resonance (MR) images of 14 consecutive patients with pathologically proven primary intracranial lymphoma were reviewed. All patients had a brain MR imaging before any treatment and were immunologically competent. MR images were acquired using 2.0 T (n=6) or 0.5 T (n=8) machine. The MR images were reviewed regarding the location, multiplicity, size, signal intensity, margin, shape, and the extent of surrounding edema of the lesions. Seven patients had multi lesions, 2 to 4 in number. A total of 26 lesions was found; 25 were parenchymal lesions and one was dural lesion. The location of tumor was either central (n=11) or peripheral (n=14). The size of tumor was variable raging from 0.6 cm to 6.0 cm in its maximal diameter. The tumors were isointense (n=19) or hypointense (n=7) relative to gray matter om T1-weighted images, isointense (n=24) or hypointense (n=2) on proton-density weighted images, and isointense (n=21) or hypointense (n=5) on T2-weighted images. On gadolinium-enhanced T1- weighted images of 13 patients, strong enhancement was seen in 22 of 23 lesion. Nineteen lesions showed smooth, well-defined margin, whereas remaining 7 lesions showed irregular, ill-defined margin. The shape of the tumor was diverse; round of ovoid (n=15), lobulated (n=9), or short linear (n=2). These results suggest that one should consider the diagnosis of CNS lymphoma in case with single or multiple masses that abut CSF space and show iso- or similar intensity to gray matter with strong enhancement on MR images