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Editorial for “A New Reporting System for Diagnosis of Hepatocellular Carcinoma in Chronic Hepatitis B With Clinical and Gadoxetic Acid‐Enhanced MRI Features”

Editorial for “A New Reporting System for Diagnosis of Hepatocellular Carcinoma in Chronic Hepatitis B With Clinical and Gadoxetic Acid-Enhanced MRI Features” Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. Uniquely among solid tumors, its diagnosis can be established without pathologic confirmation. The Liver Imaging Reporting and Data System (LI-RADS, LR) defines eight diagnostic categories to communicate the relative probability of HCC, with the LR-5 (Definite HCC) category providing a positive predictive value (PPV) of 95%. The high PPV of LR-5 comes at the expense of modest sensitivity, ranging from 67% to 84%. Many authors have attempted to improve the sensitivity of LI-RADS for the diagnosis of HCC by proposing modified imaging criteria, but most such proposals have resulted in impaired specificity. Therefore, the goal of improved sensitivity without sacrificing specificity remains elusive. In this issue of JMRI, Hwang and colleagues have proposed a novel solution to this long-standing dilemma by integrating five imaging features with two common laboratory tests, alpha-fetoprotein (AFP) and platelet levels. The authors report that in patients with chronic hepatitis B virus (HBV), their systems improve sensitivity for HCC diagnosis without reducing specificity. As seen in Table 3, the system enables noninvasive diagnosis of the so-called hypovascular HCC, namely HCC without arterial phase hyperenhancement (APHE), provided the following criteria are met: size ≥20 mm, low signal intensity on the portal venous and hepatobiliary phases, diffusion restriction, AFP >200, and platelets >100 K. The noninvasive diagnosis of hypovascular HCC represents an advance, as it is not possible currently using LI-RADS or most other diagnostic systems, which require APHE for definitive diagnosis of HCC. Thus, if validated in more diverse cohorts, the approach of integrating imaging and laboratory features could inform refinements of LI-RADS and other systems. Another compelling advantage of the proposed system is its simplicity, allowing for easy implementation in clinical practice. The system proposed by Hwang and colleagues has limitations. As acknowledged by the authors, it was validated in a cohort of patients with HBV and well-compensated disease, where over 90% had Child-Pugh Class A, and unclear how many had cirrhosis. Further research is needed to assess the performance of the system in patients with other etiologies of liver disease or advanced degrees of cirrhosis. The study has additional limitations, not mentioned by the authors. The system applies only to MRI with gadoxetate. The data used for model building and for the primary conclusion of specificity preservation were derived from consensus scoring of three radiologists, which does not reflect clinical practice. Indeed, when assessed on per-reader bases, the specificity of the proposed system was significantly lower than LR-5 for four of six radiologists. Sensitivity, however, was increased for all. Finally, while the ability to diagnose hypovascular HCC is an advance, this capability is applicable only to lesions ≥20 mm. However, hypovascular HCCs ≥20 mm are rare, accounting no more than 5% of all HCCs, which limits clinical impact of the proposed system. In this study, the majority of patients had a single lesion, and it is not yet clear how well the system will perform with multiple lesions, as two of the assessed factors are patient-level (AFP and platelet count). However, this is unavoidable challenge for any system that attempts to integrate per-lesion imaging data with laboratory values assessed at per-patient level. Similar to LI-RADS, the proposed system does not allow for the diagnosis of subcentimeter HCC, a diagnostic dilemma that remains unsolved. A drawback compared with LI-RADS is the difficulty of diagnosing 10–19 mm HCC. In the proposed system, a 10–19 mm observation with APHE and washout cannot be diagnosed as HCC based on imaging alone; the diagnosis would require an abnormal AFP level and/or platelet count, depending on the exact imaging feature combination. By comparison, LI-RADS allows for the