Increased diagnostic confidence with use of magnetic resonance contrast agents

MRI with the use of intravenous gadolinium contrast agents is extremely accurate for liver lesion detection and characterization. Liver MRI protocols combine the use of unenhanced sequences - such as T1 in-phase and out-of-phase, fat-suppressed T2, and diffusion-weighted imaging - with dynamic 3D contrast-enhanced T1-weighted sequences. One of the advantages of MRI over CT is that it can be used with a vast array of contrast agents for liver imaging. These agents include extracellular gadolinium chelates, such as gadopentetate dimeglumine, gadodiamide, gadoteridol, gadobenate dimeglumine (Gd-BOPTA), and gadoversetamide, which are the most frequently used agents, and liver-specific agents, including gadoxetate disodium (Gd-EOB-DTPA, which has approximately 50% liver uptake) and Gd-BOPTA (which has a 3-5% liver uptake). In addition, reticuloendothelial agents, such as superparamagnetic iron oxide particles, have been used by several groups, but they are currently not available in the United States. The choice of the contrast agent depends on availability, local expertise, and cost. There is considerable experience and literature on the use of extracellular agents for liver lesion detection and characterization. Experience with liver-specific agents is growing. As in many other centers, we are increasingly using gadoxetate disodium as the first-line contrast agent for liver imaging, with a few exceptions. One exception is for patients with advanced liver disease (Child-Pugh C cirrhosis) or biliary obstruction. Due to decreased liver function (in cirrhosis) or cholestasis, the agent will not be taken up by hepatocytes as well as it would be in the normal liver. The second exception is for patients with suspected or known portal vein or hepatic vein occlusion, in whom we prefer the use of extracellular gadolinium agents, due to better dynamic venous phase. (As there is no increased liver signal, the vessels will appear bright with the extracellular agent and isointense to hypointense with gadoxetate disodium during the venous/equilibrium phases.) Additionally, at this time, gadoxetate disodium is more expensive compared with extracellular gadolinium agents, preventing its implementation in all liver MRIs used to screen and diagnose HCC. However, the value of gadoxetate disodium is especially evident in "problem-solving cases," when it is necessary to differentiate between HCC and benign cirrhotic nodules, and to map liver metastases before surgery and/or local ablation.