Ga-67 scintigraphy and computed tomography in the diagnosis of pneumocystis carinii pneumonia in patients with AIDS. A prospective comparison.

A prospective evaluation of Ga-67 scintigraphy and transmission computed tomography was performed in 70 consecutive patients with AIDS who were suspected of having Pneumocystis carinii pneumonia. Studies were evaluated independently by two observers. Receiver operating characteristic curves were plotted. Although scintigraphy had a higher true-positive ratio at any false-positive ratio, statistically the areas under the two receiver operating characteristic curves were not significantly different. However, at an FP rate of 15% to 20% (one in the clinically reasonable range), the sensitivity for scintigraphy was 0.84 and for CT 0.80; corresponding specificities were 0.82 and 0.64, respectively, for the two modalities. It seems from these data that gallium imaging is probably superior to CT in detecting P. carinii pneumonia in this group of patients.