EP22.04: The accuracy of ultrasound in diagnosing adhesions around omental metastatic lesions of ovarian cancer

We investigated whether US combined with CT could improve the diagnostic accuracy of adhesions of ovarian cancer omental metastatic lesions to the transverse colon (T/C) and to abdominal wall. This study was approved by the School of Medicine of Chiba University Ethics Review Board (#4178). Study 1 is a retrospective study of 110 patients with advanced ovarian cancer between 2015 and 2020, all of whom underwent both CT and US, to determine the presence of adhesions, with US using conventional criteria; “positive when mobility between the omental metastatic lesions and T/C or abdominal wall is not confirmed.” Based on a review of the misdiagnosed cases in Study1, revised criteria for US were established; “positive if the boundary echoes disappear at sites where omental metastatic lesions contact T/C or abdominal wall”. Study 2 is a prospective study using revised criteria to determine whether it would improve diagnostic accuracy. This study included new ovarian cancer cases (n = 80) from 2021 to 2022. US and CT were performed by a sonographer and radiologist, respectively. The revised criteria for US were used, while the CT criteria were the same as in Study 1. Study 1: The accuracy of CT in diagnosing adhesion between the lesion and the T/C, and between the lesion and the abdominal wall was 80% and 76%, respectively. The accuracy of CT+US in diagnosing the same site was 85% and 89%, respectively. Study 2: CT+US was significantly more accurate than CT alone in diagnosing adhesion between lesions and T/C (96% vs 83%; p < 0.005). CT+US was also more accurate than CT alone in diagnosing adhesions between lesions and the abdominal wall (96% vs 78%; p < 0.001). The diagnostic accuracy of US combined with CT, especially with our new boundary echoes-focused US criteria, has improved the diagnostic accuracy of lesion-to-TC and lesion-to-abdominal wall adhesions.