Optimal Acquisition Delay for Dynamic Contrast-Enhanced MRI of Hypervascular Hepatocellular Carcinoma

OBJECTIVE. The purpose of this study was to prospectively determine the optimal acquisition delay for imaging of hypervascular hepatocellular carcinoma with multiphasic dynamic contrast-enhanced MRI. SUBJECTS AND METHODS. One hundred twenty patients with chronic hepatic disease underwent three-phase dynamic contrast-enhanced MRI of the liver, which revealed 49 hypervascular hepatocellular carcinomas. Abdominal aortic contrast arrival time was determined with test bolus imaging. Patients were assigned to one of the following four groups according to acquisition delay determined from abdominal aortic contrast arrival time to the middle of the k-space for the early, late hepatic arterial, and portal venous phases: 0, 12, and 49 seconds ( group 1); 3, 15, and 52 seconds ( group 2); 6, 18, and 55 seconds ( group 3); and 9, 21, and 58 seconds ( group 4). Each phase of imaging took 12 seconds. Contrast enhancement in the abdominal aorta, portal vein, hepatic parenchyma, and hepatocellular carcinoma was evaluated. Peritumoral sinusoidal enhancement (i.e., coronal enhancement) also was assessed. RESULTS. Intense enhancement of hepatocellular carcinoma with little background parenchymal enhancement occurred at 9-12 seconds ( p < 0.05) after arrival of contrast material in the abdominal aorta. Hepatocellular carcinoma-to-liver contrast began to decline at 15 seconds and decreased to less than zero at 49 seconds. The conspicuity of coronal enhancement was greater 21 seconds after contrast administration than in earlier phases. CONCLUSION. With the injection protocol used in this study, optimal acquisition delay-determined from abdominal aortic contrast arrival time to the middle of the k-space acquisition-for imaging of hypervascular hepatocellular carcinoma was 9-12, 21 or more, and 49 seconds for the early, late hepatic arterial, and portal venous phases.