technetium-tc-99m-exametazime and AIDS-Related-Opportunistic-Infections

Anticardiolipin antibodies (ACA) belong to a heterogeneous group of antibodies directed against negatively charged phospholipids. In patients with rheumatic disorders, their presence has been correlated to the occurrence of thromboembolic complications, thrombocytopenia, abortions and other disease manifestations. Several studies have revealed the detection of mostly high-titre ACA in a significant proportion of HIV-infected patients without any known clinical relationship. In our study, ACA were detected in 17/34 HIV-infected patients, and their presence was significantly associated with the detection of cerebral perfusion abnormalities by 99mTc-HMPAO SPECT. SPECT scans were classified as normal or as focal or diffuse defects in uptake. Most patients (13/16) with cerebral perfusion defects had elevated ACA titres in contrast to 4/18 patients with normal SPECT findings (P = 0.002). Focal uptake defects were always associated with the presence of ACA. No correlation to clinical features or other laboratory parameters was evident. Our results suggest a possible implication of autoimmune mechanisms in the pathogenesis of cerebral perfusion abnormalities detected by SPECT scanning in HIV-infected patients. However, further studies are needed to evaluate the clinical significance and to develop possible therapeutic consequences.

Topics: Adult; AIDS-Related Opportunistic Infections; Antibodies, Anticardiolipin; Antigen-Antibody Complex; Autoimmunity; beta 2-Microglobulin; Biopterins; Brain; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; HIV Infections; Humans; Immunoglobulins; Male; Middle Aged; Neopterin; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Thrombocytopenia; Tomography, Emission-Computed, Single-Photon

Topics: Adult; AIDS-Related Opportunistic Infections; Atrophy; Blindness; Brain; Female; Humans; Meningitis, Cryptococcal; Optic Nerve; Prognosis; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

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.

Topics: Adult; AIDS-Related Opportunistic Infections; Brain; Cerebrovascular Circulation; Female; Humans; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Toxoplasmosis, Cerebral