THE SPECTRUM OF MRI FINDINGS IN CNS CRYPTOCOCCOSIS IN AIDS

We retrospectively reviewed the cranial MRI appearances of 25 patients with AIDS and microbiologically proven central nervous system (CNS) c ryptococcosis. Four patients had a normal scan. Ten patients had dilat ed perivascular Virchow-Robin spaces that were hyperintense on T2-weig hted images. Nine of these patients developed progressive cryptococcom as, eight in the basal ganglia and one in the cerebral white matter. T he cryptococcomas displayed high signal on T2-weighted and intermediat e to low signal on T1-weighted images. None enhanced after dimeglumine gadopentetate. No abnormal dural or leptomeningeal enhancement was de tected in any patient. One patient developed an acquired arachnoid cys t during treatment of CNS cryptococcosis which was thought to represen t a focal collection of organisms and mucoid material within the subar achnoid space. In addition either cerebral atrophy and/or background w hite matter hyperintensity on T2-weighted images was present in 19/25 patients. In two patients the neuropathological findings at autopsy co rrelated well with the imaging abnormalities. In conclusion, this spec trum of MRI appearances in CNS cryptococcosis reflects the pathologica l mechanism of invasion by the fungus, but a normal scan or one with f eatures of CNS HIV infection such as atrophy or white matter hyperinte nsity does not exclude the diagnosis.