New lesions detected by intraoperative ultrasound during liver resection for hepatocellular carcinoma.

During liver resection for hepatocellular carcinoma (HCC), it is not uncommon for examinations by intraoperative ultrasound (IOUS) to detect small new lesions that were not found by preoperative examinations. Although a differential diagnosis is critical, it has not yet been established if IOUS is useful for this purpose with such small lesions. A total of 90 new lesions detected by IOUS in 79 liver resections were analysed. IOUS was performed on all of these cases and the features were recorded. The histologic characteristics of these 90 new lesions were checked by needle biopsy and their relations to the clinical data were analyzed. The IOUS pattern of the lesion was hypoechoic in 36 cases, hyperechoic in 49 and mosaic in 5. A total of 24 HCC lesions were detected and the incidences of malignancy for each type were 30.6%, 18.4% and 80.0%, respectively. Multiple regression analysis revealed that the IOUS features of the new lesions were the only significant factors in predicting the histology. IOUS should be mandatory in liver resection for HCC because it is useful for finding new lesions and might contribute to prediction of the histologic features.