Role of imaging in the evaluation of vascular complications after liver transplantation

Abstract

Clinical manifestations of liver transplantation complications can be subtle and non-specific. Medical imaging, mainly Doppler ultrasound, plays an important role to detect and grade these. Colour Doppler ultrasound exams are routinely performed at 24-48 h, on the 7th day, the first and third month after transplantation. MDCT and MR images are acquired based on the Doppler ultrasound (DUS) findings, even in the absence of abnormal liver function. As vascular complications appear early after surgery, DUS should be performed by experience personnel. Diagnostic angiography is seldom performed. This pictorial review illustrates the key imaging findings of vascular complications in patients with liver transplantation: hepatic artery complications (such as thrombosis, stenosis of the anastomosis and pseudoaneurysms), portal vein abnormalities (such as occlusion and stenosis) and hepatic veins and/or inferior vena cava flow changes (Budd-Chiari syndrome).

Keywords: Doppler ultrasound; Graft complications; Liver imaging; Liver transplantation; Vascular abnormalities.

Fig. 1

a, b US control. Postoperative CDUS is performed at 24 h, 48 h, 1 day, and 7 days after surgery. Images show a normal portal and hepatic artery flow

Fig. 2

Anastomotic thrombosis. Artery thrombosis is the most serious complication of orthotopic liver transplantation. It can be demonstrated as an absence of flow in Doppler ultrasound examination (a). CT can depict the thrombus and also the absence of distal flow (b). Multiplanar reconstructions and volume rendering images can be useful to ensure diagnosis (c–e)

Fig. 3

a, b After treatment control. Control performed after thrombolysis and angioplasty of patient in Fig. 2. Normal arterial flow is seen. Resistive index shows normal values (0.6)

Fig. 4

The usefulness of spectral curves on the assessment of hepatic artery stenosis. Even in cases of normal colour Doppler examination (a), spectral curves should be obtained. They show a characteristic pattern before and after the stenosis. In the prestenotic segment (b), we can appreciate high peaks and an elevated resistive index. In the poststenotic segment (c), we can see a parvus et tardus pulse and a low resistive index. Angiography can help confirm the diagnosis (d) and perform the treatment (e)

Fig. 5

Multifocal stenosis. The hepatic artery can present more than one point of stenosis. In these cases, each one should be treated separately. In this example, angiography demonstrated two points of stenosis (a, b). Two stents were placed for treatment. Control CT showed that stents had been correctly placed and there is distal artery flow as seen in the MIP reconstruction (c) and in volume rendering reconstruction (d)

Fig. 6

Hepatic artery stenosis leading to splenic artery steal syndrome. Postsurgical US shows a turbulent flow of the hepatic vein. The hepatic artery cannot be clearly identified (a). An arterial phase CT is performed, showing severe focal stenosis of the hepatic artery and filiform enhancement of its branches (b, c). The increased size of the splenic artery should also be noted. Increased splenic artery blood flow explains the increased turbulent portal flow. Angiography confirms both stenosis of the hepatic artery and the increased size of the splenic artery (d, e). Distal embolisation of the splenic artery was performed as a treatment

Fig. 7

Hepatic artery pseudoaneurysm. Pseudoaneurysms can be discovered using ultrasound (a). It shows a characteristics appearance in Doppler ultrasound, due to the turbulent forward and backward flow (b). Arterial phase CT shows arterial enhancement of the pseudoaneurysm (c). A coil is placed to block entering the blood and to prevent rupture (d).

Fig. 8

Intrahepatic artery pseudoaneurysm complicated with portal fistula. On these images, an intrahepatic false aneurysm is presented. It shows turbulent flow on colour Doppler examination (a) and arterial enhancement on CT (b). One of the possible complications of this entity is the development of portal or biliary fistulas. In this case, a porta fistula is seen (portal branches show arterial enhancement). Multiplanar and volumetric reconstructions help to find the exact location of the fistula (c–e).

Fig. 9

Portal vein thrombosis. Echogenic material is observed on ultrasound examination (a). This finding is confirmed in axial CT (b). Multiplanar reconstructions help in the assessment of the extension (c)

Fig. 10

Usefulness of spectral curves on the assessment of portal vein stenosis. Ultrasound examination shows multiple points of stenosis (a). Colour Doppler demonstrates turbulent flow (b). Spectral curves show a characteristic pattern before and at the stenosis. In the prestenotic segment (c), we can appreciate a low flow. In the stenotic segment (d), high-speed flow is seen (peak velocity over 125 cm/s). Stenotic/prestenotic ratio is a useful measurement. In this case, the result is clearly more than three

Fig. 11

Portal vein stenosis. Portal vein stenosis is demonstrated on CT, both on axial images (a) and in multiplanar reconstructions (b). After stent placement, a control ultrasound is performed (c). It shows normalisation of the portal flow. Control MRI (d) shows metallic artefact of the stent. Normal contrast enhancement is seen both proximal and distal to the stent

Fig. 12

a, b Thrombosis of the inferior vena cava. Thrombosis of the inferior vena cava was discovered through an axial ultrasound examination. Sagittal examination helps to asses its extension.

Fig. 13

a, b Stenosis of the inferior vena cava. Stenosis of the inferior vena cava is seen on the axial and sagittal images. It affects hepatic vein confluence. Difficulty with venous drainage produces ascites. Percutaneous angioplasty is performed for treatment

Fig. 14

a, b Thrombosis of the right hepatic vein. The right suprahepatic vein is more echogenic than the middle hepatic vein. After contrast administration, there is an enhancement of the middle hepatic vein, showing normal flow. The right hepatic vein does not enhance because of thrombosis