Evaluating Potential Autologous Bypass Grafts with Tomographic Three-Dimensional Ultrasound Compared with Standard Color Duplex

Abstract

Vein mapping using duplex ultrasound (DUS) is a routine in selecting optimal autologous bypass grafts (aBG) but is time consuming and operator-dependent. Tomographic three-dimensional (3D) ultrasound (tUS), using free-hand electromagnetic tracking, allows cardiac and vascular surgeons to view 3D images of the entire length of the potential bypass graft. This study compares tUS with DUS in the evaluation of potential autologous grafts for coronary and lower limb bypass. Both DUS and tUS imaging of 434 potential autologous grafts (364 long, 22 short saphenous veins, and 48 radial artery) immediately before bypass surgery were compared. The time in minutes to evaluate each aBG was recorded. Surgeons scored the quality of the aBG at operation. A score of 5 was in complete agreement with preoperative imaging with scores of 4 considered "good". Most operating surgeons (113, 57%) preferred interpreting the tUS images and felt that this technology could replace DUS completely. The choice of aBG would have been changed as a result of tUS images in 64 (32%) cases. DUS imaging took a mean (+/-sd) of 08:26±04:44minutes compared with only 01:00±00:25minutes for tUS (P<0.001). However, processing the tUS images, which is currently done manually by the vascular scientist, took significantly longer at 19:31±12:41minutes compared with 09:03±09:12minutes for reporting DUS (P<0.001). Surgeons preferred to see tUS images of the potential aBG themselves rather than relying on DUS reports. tUS images were significantly quicker than DUS to acquire but needed more processing time.