Additional value of contrast enhanced intraoperative ultrasound for colorectal liver metastases

Background: Substantial recurrence rates following partial liver resection for colorectal liver metastases (CRM) imply that small metastases remain undetected using intraoperative ultrasound (IOUS). The aim of this study was to evaluate the additional value of contrast enhanced IOUS (CE-IOUS) when compared to preoperative contrast enhanced computed tomography (CE-CT) and IOUS in liver surgery for CRM. Methods: After obtaining informed consent, 39 consecutive patients with CRM were included prospectively for evaluation. The study population consisted of 26 male and 13 female patients with a median (range) age of 62 (49-83) years. A lesion-per-lesion analysis was performed with histopathological examination as the reference standard after resection and follow-up for unresected lesions. The added value of CE-IOUS in correctly diagnosing malignant lesions was statistically evaluated, using receiver operating characteristic curves. Results: A total of 234 lesions were identified, 137 of which were malignant, according to the reference standard. The addition of CE-IOUS did not improve the diagnostic accuracy when compared to the combination of CE-CT and IOUS (P = 0.617). In one of two patients with newly detected lesions on CE-IOUS the extent of resection changed. Conclusions: The addition of CE-IOUS to preoperative CE-CT and IOUS does not improve the ability to characterize already detected lesions. In a small number of patients it appears to facilitate the detection of new metastatic lesions with implications on surgical strategy