Cerebral Blood Flow in AIDS-Related Neurotoxoplasmosis: A Preliminary 99mTc-HMPAO SPECT Study

Cerebral blood flow (CBF) was evaluated by gamma camera 99mTc-HMPAO SPECT in 11 patients with AIDS-related neurotoxoplasmosis and correlated with neurological findings and the results of CT and MRI. Evident CBF abnormalities were observed in all patients with involvement of at least two cerebral lobes. In 10 patients the abnormalities were bilateral and in 8 patients basal ganglia were involved; no specific hypoperfusion pattern was however evident. Focal lesions were found in 7 patients by CT (sensitivity: 63.6%) and in 10 patients by MRI (sensitivity: 90.9%). It may be concluded that neurotoxoplasmosis in AIDS patients is associated with a high prevalence of focal cortical and subcortical hypoperfusion but that the scintigraphic findings are not specific; that H M PAO SPECT may show focal hypoperfusion in patients with normal CT studies and/or non-focal MRI abnormalities; that the hypoperfusion may be more extensive than the corresponding MRI lesion(s) and that it may be present even in areas with normal MRI signals; and that more experience and longitudinal studies are needed to assess the possible impact of HMPAO SPECT on follow-up and therapy monitoring.