CT and MRI Manifestations of Primary Central Nervous System Lymphomas

Objective To evaluate CT and MRI manifestations of primary central nervous system lymphomas (PCNSL) in pathologically confirmed patients,so as to improve imaging diagnostic accuracy of PCNSL. Methods The CT and MRI findings in 16 patients with pathologically confirmed PCNSL were analyzed retrospectively from January 2008 to August 2009. Of these patients,4 underwent CT plain scan,9 had MRI examination,and 3 underwent both CT and MRI examinations. Results All patients were diffuse larger B-cell lymphoma of B cell lymphoma pathologically. Twenty-nine lesions were identified in 16 patients,11 (69%) were identified to have solitary tumor foci and the other 5 (31%) presented a multifocal form with a total of 18 lesions. The most frequent locations were the cerebral hemispheres (41.4%),periventricular white matter (24.1%) and the corpus callosum (10.3%). In 5 cases,the tumor presented isodensity or slight hypodensity without hemorrhage or calcification on plain CT images. Nineteen (75.9%) lesions with isointense or hypointense signals on T1-weighted and isointense or slightly hypointense signals on T2-weighted images were detected on MR Imaging of 12 cases (25 lesions),which were similar to meningioma. All lesions showed no blood flow. Most lesions presented obvious homogenous enhancement,the typical cases presented incision sign and angular sign,especially for these lesions adjacent to the subarachnoid space. Three lesions were showed microcystic foci and the presence of ring sign after gadolinium injection. Conclusion CT imaging has limited values to qualitative diagnosis of PCNSL,and conventional MRI plays an important role to make accurate diagnosis in most patients with PCNSL,final diagnosis of the entity depended on pathology.