Intraoperative ultrasonography of the liver.

Intraoperative ultrasound of the liver is a versatile and valuable adjunct to surgical inspection and palpation. The technique allows visualization of lesions that cannot be detected by routine cross-sectional imaging studies, allowing for more efficient and effective patient management. Demonstration of the proximity and the interrelationship of lesions to surrounding important vascular structures can be invaluable to the surgeon in choosing the most appropriate therapeutic option and in planning segmental resections. Specially developed intraoperative ultrasound probes can be used on standard diagnostic ultrasound B-mode machines. Electronic linear and curved-array scanners are most commonly used, with a 5-MHz frequency being optimal for liver imaging. Additional intraoperative uses for liver ultrasound include ultrasound-guided tumor cryoablation, ethanol injection, biopsy guidance, and laparoscopic ultrasound.