Contrast-enhanced intraoperative ultrasound (CE-IOUS) plays an increasingly important role in the surgical therapy planning of primary liver lesions as well as liver metastases.

The present study was designed to evaluate the significance of CE-IOUS by specificity and sensitivity and particularly the impact it exerts on the surgical strategy.

A secondary aim was assessing the outcome relevance of surgeries influenced by CE-IOUS.

CE-IOUS has been used during hepatobiliary surgery for almost 25 years. During this time, it has proven to be an excellent diagnostic tool for detecting and characterising previously unknown lesions.

It is still unclear to what extent the findings of this imaging modality impacts the strategy of such operations.

The currently planned study is intended to evaluate the impact of contrast-enhanced intraoperative ultrasound on the surgical procedure in hepatic surgery.

For this purpose, patient data of the time period between 2017 and 2019 was prospectively analysed.

Another aim of the study was to measure the outcome relevance of CE-IOUS. This assessment was carried out by comparing an intervention cohort with a control cohort. The control cohort consisted of patients that were operated due similar liver lesions as the intervention cohort however did not receive CE-IOUS during the operation. Aspects like the recurrence free time and overall survival rate of the two cohorts were compared together with the patients' characteristics of the groups themselves.

Inclusion Criteria:

• Operations during study period from 01/2017 until 12/2019
• Elective liver surgery in the department of surgery at the University Hospital Regensburg
• Liver resections due to primary hepatic tumours (benign, malignant) or hepatic metastases
• Liver surgery with intraoperative use of CE-IOUS

Exclusion Criteria:

• Intraoperative use of CE-IOUS outside the department of surgery
• Liver transplantations
• Use of CE-IOUS only for exclusion of hepatic metastasis

All patients that received elective liver surgery in the study centre during the study period