Caren van Roekel

26 Chapter 2 or non-perfusion of a target volume (44). There are various CBCT protocols. The CBCT acquisitions in the liver are mostly obtained following intravascular contrast administration through a catheter that is placed in the vessel of interest. Several types of 3D images can be obtained: unenhanced, angiographic, and images of the liver parenchyma during arterial, portal venous and delayed phases(43). Van den Hoven et al. have developed an acquisition protocol for CBCT imaging that provides a combination of these images. In their study, a continuous infusion of contrast agent, a variable scan delay based on the time to parenchymal enhancement on DSA, and a 10-second high-dose scan setting resulted in images that contain both contrast enhancement of the arterial tree and liver parenchyma. They also show gastrointestinal shunting and provide sufficient contrast between perfused and non-perfused liver territories (44). The study of Grözinger et al. has shown that the CBCT approach is superior to the angiographic determination of vascular supply of specific segments, mainly segments 1 and 4 (45). The main limitation of CBCT is the limited field of view compared to conventional CT. Other limitations are the greater risk of motion artifacts and the increased procedural time (43). FIGURE 3. Work-up procedure in the angiography suite. Image reproduced from angiofellow.com , with permission from M. Smits.