Novel radiation-sparing imaging techniques in transcarotid stenting.

Transcarotid artery revascularization is increasingly prevalent, but relies on fluoroscopic guidance for placement of carotid stents. With increasing awareness about the hazards of radiation exposure, we aimed to explore the prior literature regarding alternative and adjunct imaging methods in carotid stenting. These have included fusion with preoperative computed tomography angiography, fully contrast-sparing procedures with preoperative magnetic resonance angiography and fusion using plain fluoroscopy, and ultrasound-assisted transfemoral carotid stenting. All methods demonstrated excellent technical results but have achieved very limited adoption. We also reviewed literature on the use of ultrasound-guided stent and device deployment in other vascular beds, including inferior vena cava (IVC) filter placement, endovascular aneurysm repair, and peripheral arterial stenting, suggesting that ultrasound is a feasible method for intraoperative guidance. However, with lack of widespread adoption, further modifications may be required to improve usability in the operative setting. Finally, our group explored a novel frontier in ultrasound-guided transcarotid stenting, using preoperative computed tomography angiography imaging in conjunction with live ultrasound imaging. Fusion of the live and preoperative imaging allows the user to see the exact location of their ultrasound imaging plane superimposed on a 3-dimensional model of the carotid, taking significant uncertainty out of real-time ultrasound imaging. This novel registration technology may significantly improve the ability of surgeons to use ultrasound in the deployment of carotid stents, thereby reducing radiation exposure in the procedure. In addition, the same technology may be extrapolated to other areas of vascular pathology in the future.