Pulmonary nodules causing false-positive liver scans. Preoperative and postoperative scintigraphic findings in three cases.

False-positive liver scans may occur due to intrinsic hepatic anatomy, extrinsic impression on the liver from adjacent structures, or external attenuation of gamma rays. However, reports of false-positive scans due to external attenuation by pulmonary nodules are very few, and postoperative changes in liver scintigraphy have not been reported. We experienced three such cases. In each case, a pulmonary mass was located in the right posterior basal segment. The preoperative liver scan showed a focal "cold" area in the upper portion of the right lobe. This "cold" area was seen only in the posterior view, and after resection of the tumor it usually disappeared promptly unless direct liver invasion was present.