Intra-operative freehand real-time elastography for small focal liver lesions: visual palpation

摘要

BACKGROUND: Freehand real-time elastography (RTE) has seldom been used to visualize abdominal organs due to their complicated structure and difficulty in freehand compression. We describe a novel, intra-operative imaging system for performing freehand RTE of the liver. METHODS: An RTE system was designed using a spatial, cross-correlation method equipped with a feedback function that checks the quality and quantity of the external compression. Intra-operative freehand RTE was performed for 27 adenocarcinomas, 18 hepatocellular carcinomas (HCCs), and 11 benign lesions after routine B-mode intra-operative ultrasonography (IOUS). Elasticity images were classified into 4 types, from type A (more or comparable strain relative to the background) to type D (no strain), according to the degree of strain contrast with the surrounding liver. We then evaluated the compliance of the RTE findings with the pathologic diagnosis. RESULTS: RTE images were obtained for all the lesions except for 1 metastatic adenocarcinoma. Fourteen of the 18 HCCs were classified as type B or C, with a sensitivity of 83%, a specificity of 76%, and an accuracy of 61%, while 22 of the 26 adenocarcinomas were classified as type D, with a sensitivity of 85%, a specificity of 86%, and an accuracy of 86%. For 15 lesions, clear images were difficult to obtain using B-mode IOUS, whereas RTE visualized clearly the differences in elasticity. CONCLUSION: Our new RTE system facilitated the successful freehand RTE of liver lesions in an intra-operative setting, enabling visual palpation B mode IOUS.