Nuclear medicine applications in AIDS

Full text: Aids patients are liable to more than one medical problem at anyone time as the number of CD4 cells decrease and the viral load increases. Problems are related to multiple causes of opportunistic Infections, malignant lymphoma and Kaposi sarcoma. Laboratory tests, sputum analysis and bronchial lavage have problems of decreased sensitivity. morphologic Imaging modalities such as chest X-ray, CT or MRI has problems of specificity. Nuclear medicine techniques has the advantage of total body functional imaging that can visualize more than one organ. The use nuclear medicine imaging is recommended when the diagnosis is uncertain and for initiation of proper treatment. Gallium-67 citrate total body scans acquired at 4 hours following the IV injection and at 24-48 hours has been very useful for the early diagnosis of opportunistic infections such as PCP, TB, Disseminated Mycobacterium avii complex; MAI, malignant lymphoma and various forms of AIDS related colitis. Sequential thallium and gallium scan help to differentiate Kaposi sarcoma (thallium positive, gallium negative) from opportunistic infections (gallium positive, thallium negative) and malignant lymphoma (thallium and gallium positive). Gallium is the most convenient radiopharmaceutical for the diagnosis of malignant lymphoma of the heart. Thallium and Tc-99m Sestamibi are useful for the differentiation of intracranial toxoplasmosis from malignant lymphoma. The presentation will illustrate different examples and will explain the limitations of all these tests. (author)