LI-RADS Treatment Response Algorithm: Performance and Diagnostic Accuracy

Abstract

epatocellular carcinoma (HCC) is the most common primary liver malignancy and the second-most common cause of cancer-related death worldwide (1,2). For patients with stage T2 HCC who are not candidates for surgical resection, liver transplantation offers the best chance for disease-free survival (3). The limited availability of donor organs and increasing demand for these organs result in long waiting-list times, during which many patients become ineligible for transplantation because of tumor progression beyond stage T2 (4). This has prompted the widespread use of local-regional bridging therapies such as percutaneous ablation, transcatheter bland arterial embolization, chemoembolization, radioembolization, and radiation therapy to maintain a patient's eligibility for transplantation (5,6). The Liver Imaging Reporting and Data System (LI-RADS) is a system of standardized imaging criteria developed for the evaluation of patients at risk of developing HCC. The 2017 version of LI-RADS introduced a Treatment Response (LI-RADS Treatment Response [LR-TR]) algorithm for the assessment of lesions that have been previously treated with local-regional therapies (7,8). These lesions are categorized as LR-TR Nonviable, Equivocal, or Viable according to their imaging features, including focal arterial phase hyperenhancement (APHE), washout, and enhancement similar to pretreatment enhancement (9). While similar to the modified Response Evaluation Criteria in Solid Tumors (mRECIST) (10), the LR-TR algorithm clarifies tumor status at the level of individual lesions, rather than making an overall categorization of disease burden (11). However, there are currently no published data that evaluate the performance of the Treatment Response algorithm for predicting the degree of local-regional

Hepatocellular carcinoma Liver Imaging Reporting and Data Systems treatment response assessment: Lessons learned and future directions

“…Chaudhry et al[ 60 ] reported that 81% of HCC post-TACE which were categorized as LR-TR Nonviable demonstrate 100% necrosis on pathology. Similarly, Shropshire et al[ 62 ], reported that 67%-71% of tumors categorized as LR-TR Nonviable after TAE were 100% necrotic at pathology. The reported incidence is not surprising, since the gold standard histopathology would call anything less than 100% necrotic as viable disease.…”

“…Inter-reader agreements are slightly lower when comparing LR TR categorization after non-radiation arterial-based therapy for HCC. Seo et al[ 61 ], in which 78.6% of tumors were treated with TACE and imaged with either CT or MRI and Shropshire et al[ 62 ] in which all tumors were treated with TAE and imaging with MRI, reported kappas of 0.69 (CT) and 0.56 (MRI), and 0.55, respectively. These differences in inter-reader agreement between thermal ablation and arterial therapy is not surprising, since the expected imaging appearance post-ablation is simpler compared to the often complex imaging features seen after transcatheter arterial based therapies.…”

“…These studies also reported high sensitivity and specificities when evaluating the radiology-pathology concordance with LR TR Viable categorization. Chaudhry et al[ 60 ] report 73% of treated lesions characterized as viable disease had < 99% necrosis and Shropshire et al[ 62 ] report 60%-65% of disease reported as LR TR viable had < 99% necrosis.…”

“…The LR-TR Equivocal category has a relatively low sensitivity for predicting tumor necrosis. Radiology-pathology correlation after thermal ablation report that 83% of treated tumors categorized as LR TR Equivocal demonstrate viable neoplasm at pathology; similarly, after TAE, 71% of treated lesions categorized as LR TR Equivocal demonstrate viable neoplasm at pathology[ 60 , 62 ]. Seo et al[ 61 ] report that 93%-100% of the HCC’s treated with TACE, RFA or in combination, which were categorized as LR-TR Equivocal, demonstrated viable disease.…”

Interreader Reliability of Liver Imaging Reporting and Data System Treatment Response: A Systematic Review and Meta-Analysis

“…Notwithstanding the importance of the diagnostic performance, it is essential that the LR-TR has high interreader reliability if it is to be used for determining treatment response and deciding on a proper management strategy in patients with HCC. Prior studies have reported on the interreader reliability of the LR-TR [10][11][12][13][14][15][16][17], but their results are subject to limitations because of their relatively small sample sizes and between-study variability in the reported data. Given the increased attention to LR-TR in clinical practice, we consider it timely and important to determine the interreader reliability of LR-TR and to understand any differences among the published studies.…”