MRI findings of primary CNS lymphoma in 26 immunocompetent patients

Abstract

Objective: To record the MR imaging features of primary central nervous system lymphoma (PCNSL) and compare these features in monofocal and multifocal disease.

Materials and methods: Twenty-one cases of monofocal disease were compared to five cases of multifocal disease. All patients were examined by non-enhanced and contrast-enhanced MRI. Tumor location, tumor size, signal intensity, enhancement characteristics, age distribution, peritumoral edema, cystic changes, and the presence of calcifications were assessed. The MRI features were compared between the monofocal and multifocal disease cases.

Results: The 26 cases, including both the monofocal and multifocal cases, exhibited 37 lesions. Contrast-enhanced images showed variable enhancement patterns: homogeneous enhancement (33 lesions), ring-like enhancement (2), and 'open-ring-like' enhancement (2). The 'notch sign' was noted in four of 33 homogeneously enhancing lesions. One case of hemorrhage and three cases of cystic formation were observed. Intra-tumoral calcification was not found. The frontal lobe, the corpus callosum and the basal ganglia were commonly affected in both the monofocal and multifocal groups. Tumor size differed significantly between the two groups (t = 3.129, p < 0.01) and mildly or moderately enhanced lesions were more frequently found in the monofocal group (p < 0.05). There was no statistical difference between perifocal edema (p > 0.05) and the signal characteristics (p > 0.05) between the two groups.

Conclusion: Our data show that PCNSL has a variable enhancement pattern on MR images. We first reported two lesions with an 'open-ring' enhancement as well as four cases with a 'notch sign'. Monofocal PCNSL cases typically have larger sized tumors with mild or moderate enhancement.

Keywords: Brain neoplasm; Computed tomography (CT); Lymphoma; Magnetic resonance (MR).

Fig. 1

Images of 52-year-old man with lymphoma of left basal ganglia including plain CT image (A), axial T1-weighted image (B), T2-weighted image (C), FLAIR (D) and postcontrast axial T1-weighted image (E). Abnormally deep depression at tumor margin (notch sign) (arrow) was found on post-contrast axial T1-weighted image and plain CT image.

Fig. 2

Images of 71-year-old woman with lymphoma of left temporal lobe including pre-contrast axial T1-weighted image (A), post-contrast axial T1-weighted image (B). 'Notch sign' (arrow) was found on post-contrast T1-weighted image.

Fig. 3

Images of 49-year-old woman with primary central nervous system lymphoma including pre-contrast axial T1-weighted image (A), pre-contrast T2-weighted image (B), post-contrast axial T1-weighted image (C). 'Notch sign' (arrow) was found after contrast injection.

Fig. 4

Images of 57-year-old man with lymphoma of right frontal lobe including plain CT image (A), contrast CT image (B), axial T1-weighted image (C), FLAIR (D), postcontrast axial T1-weighted image (E) and sagittal T1-weighted image (F). On plain CT image; lesion was hyperdense. 'Open-ring' enhancement (arrows) was found and was characterized as thick and not uniform.

Fig. 5

Images of 56-year-old woman with lymphoma involving frontal lobe bilaterally including pre-contrast axial T1-weighted image (A), pre-contrast T2-weighted image (B) and post-contrast axial T1-weighted image (C). 'Open-ring' enhancement (arrow) was found and was characterized as thick and not uniform.