Radionuclide imaging in pulmonary complications of Human Immunodeficiency Virus infection

Abstract

The spectrum of pulmonary disorders associated with HIV infection includes both infectious and noninfectious diseases (table 1) [1,2]. In 1993, Pneumocystis carinii pneumonia (PCP) is still the most common HIV-related pulmonary infection in Europe and in the United States; other opportunistic pathogens are less frequent (although their relative incidence is increasing as the number of patients under PCP prophylaxis has risen and survival has been prolonged) [2]. Usual pathogens are also frequently found, particularly in Africa, and the frequency of tuberculosis is increasing elsewhere [2]. However, it must be kept in mind that the differential diagnosis of a suspected infection still includes several noninfectious complications (table 1) such as symptomatic pulmonary Kaposi sarcoma (KS) [1]. Furthermore, most of the patients have multiple infectious and noninfectious pulmonary complications simultaneously or alternately during the course of their HIV disease [1,2]. Since each pulmonary disorder requires a specific treatment, a definite diagnosis should be made each time a complication occurs and may often need repeated fiberoptic investigations [1,2]. Unfortunately, chest X-ray may be normal, clinical and radiological data are often non-specific and results obtained from pulmonary testing are neither specific nor sensitive in detecting pulmonary disease [1,2]. This emphasizes the need for new noninvasive procedures to limit the number of patients who really require exhaustive pulmonary diagnostic evaluation. In this context, two different radionuclides, gallium-67 citrate and technetium-99m diethylenetriamine pentaacetate (Tc-DTPA), have been used for assessment of the lungs of patients with HIV infection [3–5]. Gallium was used first as a means of detecting whether or not lung disease was present [6–18]. Tc-DTPA was then used, initially for research purposes, to study the permeability characteristics of the lung parenchyma, [19–22] but it has recently been considered more sensitive than gallium to detect PCP in HIV infected patients [23,24].