99mTc red blood cell scintigraphy in evaluating focal liver lesions.

To determine the accuracy of blood-pool imaging in the diagnosis of hepatic hemangiomas, 39 patients with various focal hepatic lesions were studied. The diagnoses in these patients were made by biopsy, angiography, surgical exploration, or clinical stability for a minimum of 14 months. The diagnoses were: hemangiomas (13 patients), hepatoma (three), metastases (19), abscesses (two), and liver cysts (two). After modified in vivo labeling of red blood cells with 20 mCi (740 MBq) of 99mTc pertechnetate, an initial flow study and early (1-15 min) and delayed (1-2 hr) static images were obtained. Increased blood-pool activity with a discordant flow pattern was seen in 11 of 13 patients with hemangiomas. False-negative scans occurred in two hemangiomas with extensive fibrosis. Two of three hepatomas had increased blood-pool activity associated with increased flow in a pattern identical to the increased blood-pool activity. None of the metastatic, abscess, or cystic lesions had increased blood-pool activity at any time after injection. It is concluded that 99mTc red blood cell imaging can distinguish hemangiomas from other focal liver lesions.