Unidentified liver metastases at ultrasonography or computed tomography.

Sixty-six patients with hepatic metastases, examined by ultrasonography (US) and computed tomography (CT) with an interval of a few days between the two examinations, showed discrepancies between the US and CT findings. The US and CT images were compared lesion by lesion, and the reasons why a metastasis was missed at US or CT were analysed. Lesions larger than 3 cm in diameter could be detected at technically successful examinations with both methods. The unreliable imaging regions with US were the ventrocranial aspect of the right lobe, the caudate lobe, and in obese patients the dorsal part of the right lobe. With CT, the caudal aspect of the left lobe, the area surrounding the gallbladder, and portions beneath the ribs were most unreliably imaged. Sometimes, at either US or CT, the image characteristics of the metastasis were too similar to those of the normal parenchyma to be differentiated.