MRI evaluation of AIDS-related encephalopathy: toxoplasmosis vs. lymphoma

The spectrum of cranial MRI findings was evaluated in 113 patients with the acquired immunodeficiency syndrome, assessing lesion number, size, location, and configuration in association with the autopsy and/or biopsy results. Correlation of cranial MRI and CT was performed in 32 patients. MRI was shown to be superior in sensitivity of lesion detection demonstrating more lesions than CT in 14 studies (44%) and equivalent information in 18 studies (56%). In no case did CT demonstrate lesions not detected on MRI. We conclude that MRI should be the study of choice in evaluating AIDS-related encephalopathy. Multiple lesions that involve both deep gray matter and white matter suggest the possibility of CNS lymphoma. The "target" appearance on MRI is not helpful in distinguishing toxoplasmosis from lymphoma.