Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications

Abstract

The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions. The main indications for the method include: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up.

Keywords: Focal hepatic lesions; Hepatobiliary contrast; Magnetic resonance imaging.

Figure 1

Female, 40-year-old patients presenting with liver steatosis and multiple, well-defined focal hypervascular lesions, with intermediate signal intensity on T2- weighted sequence, with poor lesion-organ contrast-enhancement. However, the presence of intralesional fat was detected on out-of-phase T1-weighted sequence. The presence of intralesional fat is not usually found in FNH and suggests the diagnosis of adenoma – adenomatosis, in the present case –, with a very different prognosis and approach. On the other hand, the lesions showed homogeneous hepatobiliary contrast uptake, hence the highest likelihood of the diagnosis of multiple FNHs.

Figure 2

Female, 36-year-old, asymptomatic patient presenting with a hypervascular liver nodule to be clarified, without intralesional fat and without central scar. Homogeneous hepatobiliary contrast uptake indicates the diagnosis of FNH.

Figure 3

Female, 43-year-old patient undergoing follow-up for metastatic gastrointestinal stromal tumor, with liver nodules to be clarified. The smallest lesion (arrowheads) presents subtle hypersignal on T2-weighted and marked signal loss on out-of-phase T1-weighted sequence caused by the presence of intralesional fat. No hepatobiliary contrast uptake is observed. The presence of intralesional fat and the absence of hepatobiliary contrast uptake indicate a probable diagnosis of adenoma. The largest lesion (arrows) presents high signal intensity on T2-weighted, hyposignal on t1-weighted sequence, and nodular, peripheral and discontinuous uptake in the arterial-phase, and no hepatobiliary contrast uptake that is a typical hemangioma behavior. Hemangiomas do not contain functioning hepatocytes so uptake of this contrast medium is not observed. Also, in the delayed-phase, the fill-in pattern is not observed, which might occur with the utilization of hepatobiliary contrast agent.

Figure 4

Female, 50-year-old patient with liver nodules to be clarified. The caudate lobe lesion (arrowheads) presents subtle hypersignal on T2-weighted sequence and signal loss on T1-weighted out-of-phase sequence caused by the presence of intralesional fat. Such a lesion shows intense and homogeneous contrast uptake in the arterial-phase, with decay in the portal and delayed phases, presenting greater hepatobiliary contrast uptake than the adjacent parenchyma, suggesting FNH as the first diagnostic hypothesis. Considering that the presence of intralesional fat in NFH is rare, the patient will be maintained under imaging follow-up. The lesions in segments VII and VIII (arrows) are similar, with marked hypersignal on T2-weighted, hyposignal on T1-weighted sequence, and nodular, peripheral and discontinuous uptake in the arterial phase, a characteristic of hemangiomas.

Figure 5

Male, 46-year-old patients presenting with chronic hepatopathy and liver nodule to be clarified, adjacent to the gallbladder, as seen at ultrasonography. Small nodules are observed adjacent to the gallbladder, with hyposignal on T2-weighted sequence, without expression on the other sequences and on the conventional dynamic study, but with hepatobiliary contrast uptake, leading to the diagnosis of regenerative nodules. Well-differentiated HCCs show hepatobiliary contrast uptake, requiring imaging follow-up.

Figure 6

Male, 61-year-old patient presenting with chronic C virus hepatopathy. Two liver nodules are seen in the segment VIII (arrows) as well as a larger nodule, in the segment VI (arrowheads), all of them contrast-enhanced in the arterial-phase, washout in the delayed-phase, and without uptake in the hepatobiliary-phase, characterizing HCCs. Poorly differentiated or undifferentiated HCCs do not contain functioning hepatocytes so hepatobiliary contrast uptake is not observed.

Figure 7

Male, 70-year-old patient presenting with colon cancer and multiple metastases, with hyposignal on T1-weighted, and subtle hypersignal on T2-weighted sequence. Hypovascular metastases with diffusion restriction. In the hepatobiliary-phase, the liver parenchyma shows contrast uptake and becomes hyperintense. The metastatic implants that do not contain hepatocytes become hypointense. Note the capacity of hepatobiliary contrast to detect very small lesions which cannot be visualized on the other sequences.

Figure 8

Female, 53-year-old patient presenting with colon cancer. Two hypervascular lesions (arrows) are seen with intermediate signal intensity on T1- and T2- weighted sequences, showing contrast uptake in the hepatobiliary-phase. Such lesions present functioning hepatocytes, suggesting FNHs as the main diagnostic hypothesis and ruling out the possibility of metastatic implants. The avascular lesion (arrowhead) is secondary to post-treatment alteration.