Contrast enhancement of round atelectases

Purpose: To find out if round atelectases (RAs) of a lung enhance more than pulmonary malignant tumors. Material and Methods: Twelve patients with RA and 16 patients with malignant lung tumor (MLT) evidenced on CT examination were selected (14 RAs and 16 MLTs). Two patients had 2 RAs. The examination data were reviewed on a work station and the attenuation values of RAs and tumors were measured. Results: At enhanced CT the density of RAs varied from 88 to 190 HU whereas for MLTs the density varied from 30 to 71 HU. The difference between attenuation values of RAs and MLTs was statistically significant. Conclusion: The attenuation values of RAs after contrast enhancement seem to differ from those of MLTs, at least during the first minute after contrast injection, and thus serve as a useful aid in the differential diagnosis of these masses.