What various vascular complications can be detected with color spectral Doppler imaging of the liver?
Similar to renal transplants, US is commonly the first study of choice for detecting vascular complications following liver transplantation. US can detect hepatic artery stenosis as a PSV >200 to 300 cm/sec in the artery. More distally, an intrahepatic tardus parvus waveform may be detected. Portal hypertension in both the native and transplant liver results in progressively slower flow and eventually hepatofugal (away from the liver) flow in the portal vein. The main portal vein may also increase in diameter (>13 mm) with portal hypertension. Portal vein thrombosis with absence of color spectral Doppler flow is also readily detected with US. Alterations of the normal hepatic venous waveform can also reflect both cardiac (i.e., tricuspid regurgitation, congestive heart failure) and hepatic parenchymal disease (i.e., cirrhosis, steatosis).