Dual–Contrast Agent Liver MRI for Liver Lesion Characterization

Focal liver lesion (FLL) evaluation is a common indication for liver MRI. The choice of contrast agent is critical, as extracellular agents (ECAs) and hepatobiliary agents (HBAs [eg, gadoxetate]) have different strengths and weaknesses. ECAs are useful in depicting progressive centripetal enhancement (eg, hemangiomas), whereas HBAs are useful for identifying hepatocyte-containing lesions (eg, focal nodular hyperplasia) and offer high sensitivity for detectinghepatocyte-deficient lesions (eg, hepatic metastases). MRI with HBAs can result in uncertainty in distinguishing hemangiomas from metastases, as some hemangiomas are hypoenhancing at venous and transitional phases and both lesion types are hypointense at the hepatobiliary phase (HBP). There may also be uncertainty in distinguishing between hepatic adenomas and focal nodular hyperplasia if an ECA is used, necessitating a follow-up evaluation with an HBA. Additionally, HBAs can induce transient arterial phase motion, potentially obscuring arterial phase hyperenhancement. Hybrid agent imaging with gadobenate provides ECA-like behavior during dynamic imaging, but the HBP requires a 1-hour delay, often with a less robust HBP. A sequential dual–contrast agent protocol, imaging dynamically with an ECA followed by an HBA for HBP imaging, offers the advantages of both types of agents and is ideally suited for the initial characterization of FLLs. The authors describe the benefits and pitfalls of single–contrast agent FLL imaging, the rationale for dual–contrast agent FLL imaging, and the specifics of a dual–contrast agent protocol. Advantages of a dual–contrast agent technique are illustrated through case examples. The reader will be empowered to adopt a dual–contrast agent liver MRI protocol for greater diagnostic confidence and accuracy in initial FLL characterization.