Magnetic resonance angiography in liver transplant patients. Follow-up of vascular anastomoses].

Twenty liver transplant patients were examined with MRA and color-Doppler US 18 to 40 days after surgery to investigate the onset of vascular complications after surgical liver revascularization. Vascular anastomoses are the most frequent location for such complications as stenoses, occlusions, pseudoaneurysms and vessel ruptures. In liver transplant there are 4 vascular anastomoses, i.e. hepatic artery, portal vein and superior and inferior anastomoses of the inferior vena cava. MRA images were acquired with a superconductive unit operating at 1.5 T, using fast low angle shot (FLASH) 2D sequences on the coronal plane; all images were postprocessed with the MIP algorithm. The presence of a paramagnetic artifact, the "double black spot sign", caused by the suture wire used to make the vascular anastomoses, allowed us to precisely detect the site and the flow pattern alterations at this level. MRA images were studied by two independent observers and vascular anastomosis depiction was rated as "good", "fair" and "poor". The demonstration of portal vein anastomoses was good in the whole series (20/20 patients). The superior anastomosis of the inferior vena cava was clearly depicted in 19 cases and fairly depicted in only 1 patient. The inferior anastomosis of the inferior vena cava was clearly depicted in 19 patients and fairly depicted in 1 case. Hepatic artery anastomoses were far more difficult to demonstrate than the others, considering their caliber and flow pattern, but its depiction was nevertheless good in 12 cases, fair in 6 and poor in only 2 patients. In our series, only one portal vein stenosis was observed, which was clearly depicted on both MRA and US images. In conclusion, MRA is a useful and reliable noninvasive diagnostic tool to study vascular anastomoses in liver transplant patients.