Hyperdense CT foci in treated AIDS toxoplasmosis encephalitis: MR and pathologic correlation.

Five AIDS patients with previously diagnosed and treated toxoplasmosis presented with hyperdense precontrast CT approximately 6 months after the initial CNS infection. An MR study was performed in all cases. The CT hyperdensities were characterized on MR by a high signal intensity on T1 images in four cases. In two of these, pathological correlation confirmed hemorrhage. In the fifth case, MR findings were consistent with calcification, which was verified by pathological examination.