Patient variability in intraoperative ultrasonographic characteristics of colorectal liver metastases

Objective: To determine the distribution of echogenicity (hypoechoic, isoechoic, or hyperechoic) and predominant intraoperative ultrasonography (IOUS) echogenic appearance of colorectal liver metastasis. The interpatient and intrapatient variability of tumor IOUS echogenicity was assessed. Design: Retrospective review of prospectively collected database. Setting: Tertiary cancer center. Patients: Between January 1998 and July 2001, 99 patients (194 tumors) underwent hepatic resection for colorectal metastases. Main Outcome Measures: During surgery, IOUS of the liver was performed and the images were digitally recorded. Images were randomly coded, blindly reviewed, and scored for echogenicity and ultrasonographic appearance pattern. Results: The ultrasonographic appearance of the colorectal liver metastasis was hypoechoic in 52.0%, isoechoic in 35.7%, and hyperechoic in 12.3% of cases. Most colorectal liver metastases appeared homogeneous (50.8%). Less commonly, identified lesions were characterized by a target or "bull's-eye" appearance (20%) or contained calcifications (19%). Clinicopathologic characteristics, including patient age and sex, as well as tumor size, number, and location and presence of hepatic steatosis, did not correlate with tumor echogenicity or ultrasonographic appearance pattern (all P>.05). Lesions within patients were more similar in echogenicity than lesions between patients (P<.001). Similarly, intrapatient variability in appearance pattern was significantly less than the variability between patients (P=.002). Conclusions: The ultrasonographic characteristics of hepatic metastases within patients were more similar than between patients. Such information is important because it suggests that, in patients with more than 1 metastasis, the echogenic appearance of an index lesion may predict the echogenic appearance of additional occult disease.