Liver-tumor detection with ultrasound contrast: a blinded prospective study in rabbits.

Abstract

Ultrasound has evolved into a frontline modality in most applications except for the detection of focal liver disease. Despite the wide availability, portability, relatively low cost, and high patient acceptance of ultrasound, CT and MR are currently considered the standards for detection and characterization of focal liver lesions (1). The superiority of MR and particularly CT is in part due to the availability of IV contrast material. Contrast agents promote lesion visualization by increasing image contrast owing to the differences in their wash-in and washout rates between normal and abnormal tissues. Others and we have demonstrated that ultrasound contrast agents can provide gray-scale enhancement of vessels and tissues, including those of the liver (2-5). We have also shown that the contrast agent can be observed filling the hepatic arteries, the portal veins, and then the hepatic parenchyma in real time (5). This triple-phase enhancement pattern increases the conspicuity of vascular tumors that become brighter than liver during the arterial phase, potentially expanding the role of sonography in tumor diagnosis and characterization. Proof that resection of colorectal liver metastases increases survivorship heightens the need not only to recognize their presence, but also to detect all lesions. Since the number and size of metastases determines resectability (1),