Intra-operative uses of contrast-enhanced ultrasound.

Intra-operative ultrasound (IOUS) is considered to be the most sensitive imaging modality for detection of focal liver lesions. It has been shown to affect the clinical management of patients with hepatic colorectal metastases and primary liver tumours undergoing exploratory laparotomy and segmental resection. However, small, and especially iso-echoic lesions are still missed and characterization of subcentimetre lesions is difficult. The improvement of detection and characterization of focal liver lesions using second-generation gas-containing contrast agents with specific non-linear detection modes in transabdominal scanning can be expected to apply to IOUS. Initial experience of contrast-enhanced IOUS based on use of conventional abdominal probes provided impressive results. The recent development of high-frequency linear array probes for small parts use with contrast-specific software enables the detection of lesions as small as 2-3 mm and allows characterization of small lesions. Though only preliminary experience is available, this appears to be an exciting and promising new application.