AbstractIn order to examine the liver during thoracotomy, a new intraoperative imaging technique called “transdiaphragmatic liver scanning” was developed. Trans‐diaphragmatic scanning performed with high‐frequency transducers provided clear visualization of the entire liver from the thoracic cavity through the diaphragm. In our study, transdiaphragmatic scanning was used in 27 thoracotomy operations performed for the treatment of malignant diseases, including lung and esophageal cancers. One 5‐mm liver cyst, one 3‐mm × 4‐mm hemangioma, and one 5‐mm × 6‐mm ill‐defined lesion (possible metastasis), all of which were unrecognized preoperatively, were detected. In 3 operations, preoperatively suspected liver metastases were excluded by transdiaphragmatic scanning. Because transdiaphragmatic scanning provides high‐resolution images of the liver and is the only method capable of examining the liver during thoracotomy, this intraoperative scanning technique may become a useful tool in the evaluation of liver metastases from thoracic or m