Diagnostic accuracy and inter-reader reliability of the MRI Liver Imaging Reporting and Data System (version 2018) risk stratification and management system

SA Journal of Radiology ISSN: (Online) 2078-6778, (Print) 1027-202X Page 1 of 6 Original Research Diagnostic accuracy and inter-reader reliability of the MRI Liver Imaging Reporting and Data System (version 2018) risk stratification and management system Authors: Ranjit Singh1 Mitchell P. Wilson1 Florin Manolea1 Bilal Ahmed1 Christopher Fung1 Darryn Receveur1 Gavin Low1 Background: Hepatocellular carcinoma (HCC) can be diagnosed non-invasively, provided certain imaging criteria are met. However, the recent Liver Imaging Reporting and Data System (LI-RADS) version 2018 has not been widely validated. Affiliations: 1 Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Canada Method: This retrospective study was conducted between 2018 and 2020. A total of 50 contrast enhanced liver magnetic resonance imaging (MRI) studies evaluating focal liver observations in patients with cirrhosis, hepatitis B virus (HBV) or prior HCC were acquired. The standard of reference was a consensus review by three fellowship-trained radiologists. Diagnostic accuracy including sensitivity, specificity, positive predictive value (PPV), negative predictive values (NPV) and area under the curve (AUC) values were calculated per LI-RADS category for each reader. Kappa statistics were used to measure reader agreement. Corresponding author: Ranjit Singh, Dates: Received: 27 Dec. 2021 Accepted: 18 Feb. 2022 Published: 19 May 2022 How to cite this article: Singh R, Wilson MP, Manolea F, et al. Diagnostic accuracy and inter-reader reliability of the MRI Liver Imaging Reporting and Data System (version 2018) risk stratification and management system. S Afr J Rad. 2022;26(1), a2386. https://doi.org/10.4102/sajr. v26i1.2386 Copyright: © 2022. The Authors. Licensee: AOSIS. This work is licensed under the Creative Commons Attribution License. Objectives: This study aimed to evaluate the diagnostic accuracy and reader reliability of the LI-RADS version 2018 lexicon amongst fellowship trained radiologists compared with an expert consensus reference standard. Results: Readers demonstrated excellent specificities (88% – 100%) and NPVs (85% – 100%) across all LI-RADS categories. Sensitivities were variable, ranging from 67% to 83% for LI-RADS 1, 29% to 43% for LI-RADS 2, 100% for LI-RADS 3, 70% to 80% for LI-RADS 4 and 80% to 84% for LI-RADS 5. Readers showed excellent accuracy for differentiating benign and malignant liver lesions with AUC values > 0.90. Overall inter-reader agreement was ‘good’ (kappa = 0.76, p < 0.001). Pairwise inter-reader agreement was ‘very good’ (kappa ≥ 0.90, p < 0.001). Conclusion: The LI-RADS version 2018 demonstrates excellent specificity, NPV and AUC values for risk stratification of liver observations by radiologists. Liver Imaging Reporting and Data System can reliably differentiate benign from malignant lesions when used in conjunction with corresponding LI-RADS management recommendations. Keywords: liver; cirrhosis; hepatocellular carcinoma; magnetic resonance imaging; reliability; neoplasm. Introduction Hepatocellular carcinoma (HCC) is the sixth most common malignancy and the second most common cause of malignancy-related mortality worldwide.1 Unlike most other cancers, HCC can be confidently diagnosed non-invasively on imaging without mandatory pathology confirmation provided strict imaging criteria are met.2 The Liver Imaging Reporting and Data System (LI-RADS), first released in 2011 by the American College of Radiology (ACR), is an imaging reporting algorithm designed to standardise radiology reporting of HCC in high-risk patients in terms of screening, surveillance, diagnosis and treatment response assessment.1,3 The LI-RADS categories have the ability to accurately stratify the probability of HCC and overall malignancy without potential risks of biopsy, including inadequate sampling, haemorrhage and biopsy tract seeding.4,5 Accordingly, there has been increasing reliance upon imaging and radiologists for both early and accurate diagnosis of HCC, using a universal reporting language.6 Read online: Scan this QR code with your smart phone or mobile device to read online. However, some literature has questioned the accuracy and reliability of the LI-RADS risk stratification.6,7 Furthermore, the updated LI-RADS version 2018 has not been widely validated.8,9,10,11 This retrospective study aims to evaluate the diagnostic accuracy and inter-reader reliability of http://www.sajr.org.za Open Access Page 2 of 6 the current LI-RADS version 2018 lexicon amongst board certified fellowship trained body imaging radiologists as compared with an expert consensus reference standard. Research methods and design Patient selection The University of Alberta Hospital Picture Archiving and Communication System (PACS) was reviewed for all cases with contrast-enhanced MRI studies evaluating the liver, performed between 01 January 2018 and 31 March 2020. Cases with observations found in patients with a high-risk feature for HCC including cirrhosis, chronic hepatitis B viral infection or current or prior HCC and at least 1 year of crosssectional imaging follow-up were selected for inclusion. Observations in patients under the age of 18 years, those with absence of high-risk factors and those with cirrhosis caused by non-hepatitis aetiologies were excluded as per the ACR CT/MRI LI-RADS v2018 core guidelines.7 For the purposes of this study, only LI-RADS categories 1 to 5 were considered, with cases involving other malignancy (LR-M), tumour in vein (LR-TIV) and treatment response (LR-TR) categories also excluded. The 50 cases included in the study consisted of those lesions with typical representative features for each of the LI-RADS categories. All MRI studies were of good technical quality and in line with the ACR recommendations.7 A total of 50 non-consecutive cases were selected by consensus from a Steering Committee of two authors with 6- and 13-years experience. Cases were chosen to represent a mix of classic imaging features and equivocal and challenging features in order to reflect a range of cases, which may be seen in a routine tertiary hospital setting. Only a single lesion per case was considered. When multiple lesions were present on a single case, only the lesion with the highest suspicion score was considered and annotated for review. Liver MRI protocol All liver MRI examinations included in this study were performed by using 1.5-T MRI scanners (GE Healthcare, Milwaukee, Wis; HD, GE Healthcare). Pre-contrast sequences included axial DWI (b values: 0, 50, 150 and 500) with ADC images, axial T2-weighted images with single-shot fast spin echo (FSE) technique, gradient echo (GRE) T1-weighted outphase and in-phase axial images and axial pre-contrast breath hold fat saturated spoiled-GRE images. Fat saturated post-contrast dynamic images were acquired in late arterial (30–40 s), portal (60–90 s), late portal (120–150 s) and delayed phases (180–2 (...truncated)