[Magnetic resonance imaging features of primary brain lymphoma:a report of nine cases]

Primary brain lymphoma, a rare tumor, is often misdiagnosed as malignant glioma or metastases before operation. A definite preoperative diagnosis of primary brain lymphoma is of great significance because of its sensitive to chemotherapy and irradiation. This study was to analyze the magnetic resonance imaging (MRI) features of primary brain lymphoma to improve the diagnosis and differential diagnosis accuracy.

MRI findings in 9 patients with pathologically proved primary brain lymphoma were analyzed for the number of lesions, tumor site, signal intensity, peritumoral edema, mass effect and contrast enhancement patterns.

Of the 9 patients, 8 had supratentorial solitary lesion, and 1 had supratentorial and infratentorial solitary lesion. On plain MRI, 8 lesions were hypo-intense and 1 iso-intense on T1WI, while 6 displayed iso-intense, 1 hypo-intense and 2 slightly hyper-intense on T2WI. Necrosis was seen in 2 lesions. The peritumoral edema was mild in 5 lesions, moderate in 3 lesions, and severe in 1 lesion. On Gd-DTPA-enhanced MRI, 4 lesions displayed obvious homogeneous mass-like enhancement, 3 lobular enhancement and 2 ring-like enhancement.

Primary brain lymphoma in immunocompetent patients has typical MRI features. Correct diagnosis could be made before operation when imaging findings are considered together with clinical data.