MRI of Hepatocellular Carcinoma: Cross-regional Perspectives on Trends and Opportunities.

Management of hepatocellular carcinoma (HCC) can vary substantially by region. The authors highlight differences between Eastern and Western health care systems in the use of MRI for surveillance, diagnosis, and treatment monitoring in patients with HCC. These regional differences reflect variations in disease prevalence, treatment practice patterns, and reimbursement policies as well as the evolving role of MRI in the care continuum, for which global consensus has not yet been achieved. Although variations are not uncommon, even within regions or countries, some general observations can be made and are represented by national or regional practice guidelines. For instance, in East Asia, where hepatitis B is the predominant cause of HCC and locoregional tumor ablation is preferred, guidelines emphasize high diagnostic sensitivity. Consequently, they employ broader screening criteria with MRI. Conversely, in Western regions where liver transplant for HCC is prioritized and the stakes for specificity are high, guidelines emphasize high pretest probabilities and stricter criteria for "definite HCC." Although HCC diagnostic criteria remain somewhat divergent, the criteria for assessment of treatment response have transcended regional differences to evolve globally in tandem, shifting away from measuring the gross reduction in tumor size toward assessment based on features of tumor viability. This shift has been instrumental for adoption of immunotherapy, in which conventional size criteria may allow underestimation of its therapeutic benefit. Recognition of these regional variations is important in interpretation of multicenter international studies and to facilitate global collaboration in MRI-based management of HCC.