Hyperperfusion and early technetium-99m-HMPAO SPECT appearance of central nervous system toxoplasmosis

Three correlative 99mTc-HMPAO brain SPECT studies were performed on an AIDS patient from the early stage of a CNS toxoplasma lesion to its resolution after specific therapy. A hyperactive area in the right parieto-occipital lobe appeared in the first SPECT study, matching the heterogeneous T2-weighted image with Gd-DTPA enhancement reported on MRI. Both studies were performed 3 days after the onset of neurological symptoms when no abnormalities were found on a CT scan. This fact can be explained by the hyperemia that occurs in the acute stage of inflammation. Three months later, along with clinical improvement under specific treatment, both MRI and brain SPECT were normal. No hypoperfusion was seen in SPECT images, probably because the necrotic phase of the toxoplasma lesion was not reached in this case.