Detection and differential diagnosis of pulmonary infections and tumors in patients with AIDS: value of chest radiography versus CT.

OBJECTIVE: The purpose of this study was to compare the sensitivity and specificity of chest radiography with those of CT in the detection of pulmonary infections and tumors in patients with AIDS.

MATERIALS AND METHODS: The study was retrospective and included the radiographs and CT scans of 139 patients. Eighty-nine had one proven thoracic complication, 17 had two proven thoracic complications, and 33 had no active intrathoracic disease at the time of the examinations. The radiographs and CT scans were interpreted blindly by two independent observers from different institutions. The observers assessed for the presence or absence of intrathoracic disease and recorded the most likely diagnosis and the degree of confidence in that diagnosis.

RESULTS: The patients were more commonly correctly identified as having or not having intrathoracic disease on the basis of CT findings than on the basis of radiographic findings ( p < .01, chi-square test). Of the 106 patients with intrathoracic complications, 90% (191 of 212 interpretations) were correctly identified by the two observers on the radiograph and 96% (204 of 212 interpretations) at CT. Of 33 patients without intrathoracic disease, 73% (48 of 66 interpretations) were correctly identified at radiography and 86% (57 of 66 interpretations) at CT. Of 89 patients with one proved thoracic complication, the observers confident in their first-choice diagnosis in 34% of the cases (61 of 178 interpretations) at chest radiography and in 47% (83 of 178 interpretations) at CT. This diagnosis was correct in 67% (41 of 61) of confident radiographic interpretations as compared with 87% (72 of 83) of interpretations at CT (p < .01, chi-square test).

CONCLUSION: CT is superior to chest radiography in allowing identification of patients with and without thoracic disease and in the differential diagnosis of pulmonary complications of patients with AIDS. However, the improvement in differential diagnosis is modest. Because in most cases the radiographs and CT scans were obtained as part of the clinical evaluation, the study is probably biased toward problematic clinical cases. In the majority of patients, the chest radiograph provides adequate information and CT is not warranted.