The utility of laparoscopic ultrasound during minimally invasive liver procedures in patients with malignant liver tumors who have undergone preoperative magnetic resonance imaging.

Background: The aim of this study was to assess the utility of laparoscopic ultrasound (LUS) during minimally invasive liver procedures in patients with malignant liver tumors who underwent preoperative magnetic resonance imaging (MRI).

Methods: Medical records of patients with malignant liver lesions who underwent laparoscopic liver surgery between October 2005 and January 2018 and who underwent an MRI examination at our institution within a month before surgery were collected from a prospectively maintained database. The size and location of tumors detected on LUS, as well as whether they were seen on preoperative imaging, were recorded. Univariate and multivariate regression analyses were performed to identify factors that were associated with the detection of liver lesions on LUS that were not seen on preoperative MRI.

Results: A total of 467 lesions were identified in 147 patients. Tumor types included colorectal cancer metastasis (n = 53), hepatocellular cancer (n = 38), neuroendocrine metastasis (n = 23), and others (n = 33). Procedures included ablation (67%), resection (23%), combined resection and ablation (6%), and diagnostic laparoscopy with biopsy (4%). LUS identified 39 additional lesions (8.4%) that were not seen on preoperative MRI in 14 patients (10%). These were colorectal cancer (n = 20, 51%), neuroendocrine (n = 11, 28%) and other metastases (n = 8, 21%). These additional findings on LUS changed the treatment plan in 13 patients (8.8%). Factors predicting tumor detection on LUS but not on MRI included obesity (p = 0.02), previous exposure to chemotherapy (p < 0.001), and lesion size < 1 cm (p < 0.001).

Conclusion: This study demonstrates that, despite advances in MRI, LUS performed during minimally invasive liver procedures may detect additional tumors in 10% of patients with liver malignancies, with the highest yield seen in obese patients with previous exposure to chemotherapy. These results support the routine use of LUS by hepatic surgeons.