A Multicenter Assessment of Interreader Reliability of LI-RADS Version 2018 for MRI and CT.

Background Various limitations have impacted research evaluating reader agreement for Liver Imaging Reporting and Data System (LI-RADS). Purpose To assess reader agreement of LI-RADS in an international multicenter multireader setting using scrollable images. Materials and Methods This retrospective study used deidentified clinical multiphase CT and MRI and reports with at least one untreated observation from six institutions and three countries; only qualifying examinations were submitted. Examination dates were October 2017 to August 2018 at the coordinating center. One untreated observation per examination was randomly selected using observation identifiers, and its clinically assigned features were extracted from the report. The corresponding LI-RADS version 2018 category was computed as a rescored clinical read. Each examination was randomly assigned to two of 43 research readers who independently scored the observation. Agreement for an ordinal modified four-category LI-RADS scale (LR-1, definitely benign; LR-2, probably benign; LR-3, intermediate probability of malignancy; LR-4, probably hepatocellular carcinoma [HCC]; LR-5, definitely HCC; LR-M, probably malignant but not HCC specific; and LR-TIV, tumor in vein) was computed using intraclass correlation coefficients (ICCs). Agreement was also computed for dichotomized malignancy (LR-4, LR-5, LR-M, and LR-TIV), LR-5, and LR-M. Agreement was compared between research-versus-research reads and research-versus-clinical reads. Results The study population consisted of 484 patients (mean age, 62 years ± 10 [SD]; 156 women; 93 CT examinations, 391 MRI examinations). ICCs for ordinal LI-RADS, dichotomized malignancy, LR-5, and LR-M were 0.68 (95% CI: 0.61, 0.73), 0.63 (95% CI: 0.55, 0.70), 0.58 (95% CI: 0.50, 0.66), and 0.46 (95% CI: 0.31, 0.61) respectively. Research-versus-research reader agreement was higher than research-versus-clinical agreement for modified four-category LI-RADS (ICC, 0.68 vs 0.62, respectively; P = .03) and for dichotomized malignancy (ICC, 0.63 vs 0.53, respectively; P = .005), but not for LR-5 (P = .14) or LR-M (P = .94). Conclusion There was moderate agreement for LI-RADS version 2018 overall. For some comparisons, research-versus-research reader agreement was higher than research-versus-clinical reader agreement, indicating differences between the clinical and research environments that warrant further study. © RSNA, 2023 Supplemental material is available for this article. See also the editorials by Johnson and Galgano and Smith in this issue.

Imaging Findings in Cirrhotic Liver: Pearls and Pitfalls for Diagnosis of Focal Benign and Malignant Lesions.

Cirrhosis is the end stage of chronic liver disease and causes architectural distortion and perfusional anomalies. It is a major risk factor for developing hepatocellular carcinoma (HCC). Common disease entities in noncirrhotic livers, such as hemangiomas, can be rare in cirrhotic livers, and benign entities such as confluent hepatic fibrosis and focal nodular hyperplasia-like lesions may mimic the appearance of malignancies,. HCC usually has typical imaging characteristics, such as the major features established by the Liver Imaging Reporting and Data System. However, HCC can also have a spectrum of atypical or uncommon appearances, such as cystic HCC, hypovascular HCC, or macroscopic fat-containing HCC. HCCs with certain genetic mutations such as CTNNB-1-mutated HCC can harbor unique imaging features not seen in other types of HCC. In addition, malignancies that are less common than HCC, such as cholangiocarcinoma and metastases, which can be difficult to differentiate, can still occur in cirrhotic livers. Atypical imaging features of benign and malignant lesions can be challenging to accurately diagnose. Therefore, familiarity with these features and an understanding of the prevalence of disease entities in cirrhotic livers are key in the daily practice of radiologists for evaluation of cirrhotic livers. The authors illustrate the typical and atypical features of benign and malignant lesions in cirrhosis and discuss the technical pitfalls and unique advantages associated with various imaging modalities in assessing cirrhotic livers, including noncontrast and contrast-enhanced US, CT, and MRI. Work of the U.S. Government published under an exclusive license with the RSNA. Quiz questions for this article are available in the supplemental material.

Universal Liver Imaging Lexicon: Imaging Atlas for Research and Clinical Practice.

The use of standardized terms in assessing and reporting disease processes has well-established benefits, such as clear communication between radiologists and other health care providers, improved diagnostic accuracy and reproducibility, and the enhancement and facilitation of research. Recently, the Liver Imaging Reporting and Data System (LI-RADS) Steering Committee released a universal liver imaging lexicon. The current version of the lexicon includes 81 vetted and precisely defined terms that are relevant to acquisition of images using all major liver imaging modalities and contrast agents, as well as lesion- and organ-level features. Most terms in the lexicon are applicable to all patients undergoing imaging of the liver, and only a minority of the terms are strictly intended to be used for patients with high risk factors for hepatocellular carcinoma. This pictorial atlas familiarizes readers with the liver imaging lexicon and includes discussion of general concepts, providing sample definitions, schematics, and clinical examples for a subset of the terms in the liver imaging lexicon. The authors discuss general, technical, and imaging feature terms used commonly in liver imaging, with the goal of illustrating their use for clinical and research applications. Work of the U.S. Government published under an exclusive license with the RSNA. Online supplemental material is available for this article.

LI-RADS: Past, Present, and Future, From the AJR Special Series on Radiology Reporting and Data Systems.

The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing the terminology, interpretation, reporting, and data collection of liver imaging. Over the past 10 years, LI-RADS has undergone a substantial expansion in scope, building on and refining its initial CT and MRI algorithm for hepatocellular carcinoma (HCC) diagnosis and developing three new algorithms: ultrasound (US) LI-RADS for HCC screening and surveillance, contrast-enhanced US (CEUS) LI-RADS for HCC diagnosis, and LI-RADS CT/MRI treatment response. As of 2018, LI-RADS and the American Association for the Study of Liver Diseases (AASLD) guidance share LR-5 (definitely HCC) criteria for the image-based diagnosis of HCC, and LI-RADS diagnostic criteria and management recommendations were integrated into the AALSD clinical practice guidance for HCC diagnosis, staging, and management. LI-RADS is updated in response to new knowledge, technology, and user feedback every 3-5 years. This article details the origins and growth of LI-RADS, reviews its current state, and articulates its short- and long-term objectives.

Imaging Features at the Periphery: Hemodynamics, Pathophysiology, and Effect on LI-RADS Categorization.

Liver lesions have different enhancement patterns at dynamic contrast-enhanced imaging. The Liver Imaging Reporting and Data System (LI-RADS) applies the enhancement kinetic of liver observations in its algorithms for imaging-based diagnosis of hepatocellular carcinoma (HCC) in at-risk populations. Therefore, careful analysis of the spatial and temporal features of these enhancement patterns is necessary to increase the accuracy of liver mass characterization. The authors focus on enhancement patterns that are found at or around the margins of liver observations-many of which are recognized and defined by LI-RADS, such as targetoid appearance, rim arterial phase hyperenhancement, peripheral washout, peripheral discontinuous nodular enhancement, enhancing capsule appearance, nonenhancing capsule appearance, corona enhancement, and periobservational arterioportal shunts-as well as peripheral and periobservational enhancement in the setting of posttreatment changes. Many of these are considered major or ancillary features of HCC, ancillary features of malignancy in general, features of non-HCC malignancy, features associated with benign entities, or features related to treatment response. Distinction between these different patterns of enhancement can help with achieving a more specific diagnosis of HCC and better assessment of response to local-regional therapy. ©RSNA, 2021.

How to Use LI-RADS to Report Liver CT and MRI Observations.

Primary liver cancer is the fourth leading cause of cancer-related deaths worldwide, with hepatocellular carcinoma (HCC) comprising the vast majority of primary liver malignancies. Imaging plays a central role in HCC diagnosis and management. As a result, the content and structure of radiology reports are of utmost importance in guiding clinical management. The Liver Imaging Reporting and Data System (LI-RADS) provides guidance for standardized reporting of liver observations in patients who are at risk for HCC. LI-RADS standardized reporting intends to inform patient treatment and facilitate multidisciplinary communication and decisions, taking into consideration individual clinical factors. Depending on the context, observations may be reported individually, in aggregate, or as a combination of both. LI-RADS provides two templates for reporting liver observations: in a single continuous paragraph or in a structured format with keywords and imaging findings. The authors clarify terminology that is pertinent to reporting, highlight the benefits of structured reports, discuss the applicability of LI-RADS for liver CT and MRI, review the elements of a standardized LI-RADS report, provide guidance on the description of LI-RADS observations exemplified with two case-based reporting templates, illustrate relevant imaging findings and components to be included when reporting specific clinical scenarios, and discuss future directions. An invited commentary by Yano is available online. Online supplemental material is available for this article. Work of the U.S. Government published under an exclusive license with the RSNA.

The Safety of Maternal and Fetal MRI at 3 T.

OBJECTIVE. The purpose of this study was to evaluate the effects of clinical 3-T MRI during pregnancy on fetal growth and neonatal hearing in neonates at low risk of congenital hearing impairment or of brain or chromosomal abnormalities. MATERIALS AND METHODS. This single-center retrospective case-control study included consecutively born healthy neonates exposed in utero to 3-T MR during MRI for maternal or fetal indications and born between January 2008 and March 2015. Each exposed neonate was randomly matched 1:2 by birth date to healthy control neonates who had not been exposed to MR. Infant birth weights were compared by unpaired t test. Hearing impairment between groups was compared by Fisher exact test. RESULTS. There was no significant difference in mean birth weight between the MR-exposed (3398 g) and control (3510 g) neonates (p = 0.06). There was no significant difference in prevalence of hearing impairment (p = 0.55) between the MR-exposed (0% [0/81]) and control (1.8% [3/162]) groups. CONCLUSION. This study showed no adverse effects with regard to neonatal hearing or fetal growth in healthy neonates who were variably exposed to 3-T MR in utero during MRI for various clinical maternal or fetal indications at any gestational age.

Evidence Supporting LI-RADS Major Features for CT- and MR Imaging-based Diagnosis of Hepatocellular Carcinoma: A Systematic Review.

The Liver Imaging Reporting and Data System (LI-RADS) standardizes the interpretation, reporting, and data collection for imaging examinations in patients at risk for hepatocellular carcinoma (HCC). It assigns category codes reflecting relative probability of HCC to imaging-detected liver observations based on major and ancillary imaging features. LI-RADS also includes imaging features suggesting malignancy other than HCC. Supported and endorsed by the American College of Radiology (ACR), the system has been developed by a committee of radiologists, hepatologists, pathologists, surgeons, lexicon experts, and ACR staff, with input from the American Association for the Study of Liver Diseases and the Organ Procurement Transplantation Network/United Network for Organ Sharing. Development of LI-RADS has been based on literature review, expert opinion, rounds of testing and iteration, and feedback from users. This article summarizes and assesses the quality of evidence supporting each LI-RADS major feature for diagnosis of HCC, as well as of the LI-RADS imaging features suggesting malignancy other than HCC. Based on the evidence, recommendations are provided for or against their continued inclusion in LI-RADS. © RSNA, 2017 Online supplemental material is available for this article.

Diagnostic Accuracy of Preoperative Gadoxetic Acid-enhanced 3-T MR Imaging for Malignant Liver Lesions by Using Ex Vivo MR Imaging-matched Pathologic Findings as the Reference Standard.

PURPOSE: To determine per-lesion sensitivity and positive predictive value (PPV) of gadoxetic acid-enhanced 3-T magnetic resonance (MR) imaging for the diagnosis of malignant lesions by using matched (spatially correlated) hepatectomy pathologic findings as the reference standard. Materials and METHODS: In this prospective, institutional review board-approved, HIPAA-compliant study, 20 patients (nine men, 11 women; mean age, 59 years) with malignant liver lesions who gave written informed consent underwent preoperative gadoxetic acid-enhanced 3-T MR imaging for surgical planning. Two image sets were independently analyzed by three readers to detect liver lesions (set 1 without and set 2 with hepatobiliary phase [HBP] images). Hepatectomy specimen ex vivo MR imaging assisted in matching gadoxetic acid-enhanced 3-T MR imaging findings with pathologic findings. Interreader agreement was assessed by using the Cohen κ coefficient. Per-lesion sensitivity and PPV were calculated. RESULTS: Cohen κ values were 0.64-0.76 and 0.57-0.84, and overall per-lesion sensitivity was 45% (42 of 94 lesions) to 56% (53 of 94 lesions) and 58% (55 of 94 lesions) to 64% (60 of 94 lesions) for sets 1 and 2, respectively. The addition of HBP imaging did not affect interreader agreement but significantly improved overall sensitivity for one reader (P < .05) and almost for another (P = .05). Sensitivity for 0.2-0.5-cm lesions was 0% (0 of 26 lesions) to 8% (two of 26 lesions) for set 1 and 4% (one of 26 lesions) to 12% (three of 26 lesions) for set 2. Sensitivity for 0.6-1.0-cm lesions was 28% (nine of 32 lesions) to 59% (19 of 32 lesions) for set 1 and 66% (21 of 32 lesions) to 69% (22 of 32 lesions) for set 2. Sensitivity for lesions at least 1.0 cm in diameter was at least 81% (13 of 16 lesions) for set 1 and was not improved for set 2. PPV was 98% (56 of 57 lesions) to 100% (60 of 60 lesions) for all readers without differences between image sets or lesion size. CONCLUSION: Gadoxetic acid-enhanced 3-T MR imaging provides high per-lesion sensitivity and PPV for preoperative malignant liver lesion detection overall, although sensitivity for 0.2-0.5-cm malignant lesions is poor.

Diagnostic per-patient accuracy of an abbreviated hepatobiliary phase gadoxetic acid-enhanced MRI for hepatocellular carcinoma surveillance.

OBJECTIVE. The purpose of this study is to evaluate the per-patient diagnostic performance of an abbreviated gadoxetic acid-enhanced MRI protocol for hepatocellular carcinoma (HCC) surveillance. MATERIALS AND METHODS. A retrospective review identified 298 consecutive patients at risk for HCC enrolled in a gadoxetic acid-enhanced MRI-based HCC surveillance program. For each patient, the first gadoxetic acid-enhanced MRI was analyzed. To simulate an abbreviated protocol, two readers independently read two image sets per patient: set 1 consisted of T1-weighted 20-minute hepatobiliary phase and T2-weighted single-shot fast spin-echo (SSFSE) images; set 2 included diffusion-weighted imaging (DWI) and images from set 1. Image sets were scored as positive or negative according to the presence of at least one nodule 10 mm or larger that met the predetermined criteria. Agreement was assessed using Cohen kappa statistics. A composite reference standard was used to determine the diagnostic performance of each image set for each reader. RESULTS. Interreader agreement was substantial for both image sets (κ = 0.72 for both) and intrareader agreement was excellent (κ = 0.97-0.99). Reader performance for image set 1 was sensitivity of 85.7% for reader A and 79.6% for reader B, specificity of 91.2% for reader A and 95.2% for reader B, and negative predictive value of 97.0% for reader A and 96.0% for reader B. Reader performance for image set 2 was nearly identical, with only one of 298 examinations scored differently on image set 2 compared with set 1. CONCLUSION. An abbreviated MRI protocol consisting of T2-weighted SSFSE and gadoxetic acid-enhanced hepatobiliary phase has high negative predictive value and may be an acceptable method for HCC surveillance. The inclusion of a DWI sequence did not significantly alter the diagnostic performance of the abbreviated protocol.

Imaging cholangiocarcinoma: CT and MRI techniques.

Cross-sectional imaging plays a crucial role in the detection, diagnosis, staging, and resectability assessment of intra- and extrahepatic cholangiocarcinoma. Despite this vital function, there is a lack of standardized CT and MRI protocol recommendations for imaging cholangiocarcinoma, with substantial differences in image acquisition across institutions and vendor platforms. In this review, we present standardized strategies for the optimal imaging assessment of cholangiocarcinoma including contrast media considerations, patient preparation recommendations, optimal contrast timing, and representative CT and MRI protocols with individual sequence optimization recommendations. Our recommendations are supported by expert opinion from members of the Society of Abdominal Radiology's Disease-Focused Panel (DFP) on Cholangiocarcinoma, encompassing a broad array of institutions and practice patterns.

The adoption of LI-RADS: a survey of non-academic radiologists.

PURPOSE: To understand the practice and determinants of non-academic radiologists regarding LI-RADS and the four current LI-RADS algorithms: CT/MRI, contrast-enhanced ultrasound (CEUS), ultrasound (US), and CT/MRI Treatment Response. MATERIALS AND METHODS: Seven themes were covered in this international survey, as follows: (1) demographics of participants and sub-specialty, (2) HCC practice and interpretation, (3) reporting practice, (4) screening and surveillance, (5) HCC imaging diagnosis, (6) treatment response, and (7) CT and MRI technique. RESULTS: Of the 232 participants, 69.4% were from the United States, 25.0% from Canada, and 5.6% from other countries and 45.9% were abdominal/body imagers. During their radiology training or fellowship, no formal HCC diagnostic system was used by 48.7% and LI-RADS was used by 44.4% of participants. In their current practice, 73.6% used LI-RADS, 24.7% no formal system, 6.5% UNOS-OPTN, and 1.3% AASLD. Barriers to LI-RADS adoption included lack of familiarity (25.1%), not used by referring clinicians (21.6%), perceived complexity (14.5%), and personal preference (5.3%). The US LI-RADS algorithm was used routinely by 9.9% of respondents and CEUS LI-RADS was used by 3.9% of the respondents. The LI-RADS treatment response algorithm was used by 43.5% of the respondents. 60.9% of respondents thought that webinars/workshops on LI-RADS Technical Recommendations would help them implement these recommendations in their practice. CONCLUSION: A majority of the non-academic radiologists surveyed use the LI-RADS CT/MR algorithm for HCC diagnosis, while nearly half use the LI-RADS TR algorithm for assessment of treatment response. Less than 10% of the participants routinely use the LI-RADS US and CEUS algorithms.

Comparative efficacy of an optimal exam between ultrasound versus abbreviated MRI for HCC screening in NAFLD cirrhosis: A prospective study.

BACKGROUND: Retrospective studies report that visualisation of the liver may be severely limited using ultrasound (US), potentially contributing to diminished sensitivity for detection of hepatocellular carcinoma (HCC) among patients with nonalcoholic fatty liver disease (NAFLD) and cirrhosis, but there are limited prospective data. AIMS: To compare liver visualisation scores prospectively for US and abbreviated hepatobiliary phase (HBP) magnetic resonance imaging (AMRI) in a cohort of participants with NAFLD cirrhosis and a clinical indication for HCC surveillance. METHODS: This prospective multicenter study included 54 consecutive participants (67% women) with NAFLD cirrhosis who underwent contemporaneous US as well as HBP-AMRI with gadoxetic acid. Primary outcome was the proportion of imaging examinations with severe limitations in liver visualisation (visualisation score C) compared head-to-head between US and AMRI. RESULTS: The mean (± standard deviation) age was 63.3 years (±8.4) and body mass index was 32.0 kg/m2 (±6.0). Nineteen participants (35%) had severe visualisation limitations on US, compared with 10 (19%) with AMRI, p < 0.0001. Nine (17%) participants had <90% of the liver visualised on US, compared with only 1 (2%) participant with AMRI, p < 0.0001. Obesity was a strong and independent predictor for severe visualisation limitation on US (OR 5.1, CI 1.1-23.1, p = 0.03), after adjustment for age, sex and ethnicity. CONCLUSION: More than one-third of participants with NAFLD cirrhosis had severe visualisation limitations on US for HCC screening, compared with one-sixth on AMRI. US adequacy should be reported in all clinical studies and when suboptimal then AMRI may be considered for HCC screening.

MR Imaging of Diffuse Liver Disease.

The liver performs many vital functions for the human body. It stores essential vitamins and minerals, such as iron and vitamins A, D, K, and B12. It synthesizes proteins, such as blood clotting factors, albumin, and glycogen, as well as cholesterol, carbohydrates, and triglycerides. Additionally, it acts as a detoxifier, metabolizing and helping to clear alcohol, drugs, and ammonia. Typical MR imaging protocols for liver imaging include T2-weighted, chemical shift imaging, and precontrast and postcontrast T1-weighted sequences. This article discussed MR imaging of diffuse liver diseases and their typical imaging findings.

Online Liver Imaging Course; Pivoting to Transform Radiology Education During the SARS-CoV-2 Pandemic.

PURPOSE: The SARS-CoV-2 pandemic has drastically disrupted radiology in-person education. The purpose of this study was to assess the implementation of a virtual teaching method using available technology and its role in the continuity of education of practicing radiologists and trainees during the pandemic. METHODS: The authors created the Online Liver Imaging Course (OLIC) that comprised 28 online comprehensive lectures delivered in real-time and on-demand over six weeks. Radiologists and radiology trainees were asked to register to attend the live sessions. At the end of the course, we conducted a 46-question survey among registrants addressing their training level, perception of virtual conferencing, and evaluation of the course content. RESULTS: One thousand four hundred and thirty four radiologists and trainees completed interest sign up forms before the start of the course with the first webinar having the highest number of live attendees (343 people). On average, there were 89 live participants per session and 750 YouTube views per recording (as of July 9, 2020). After the end of the course, 487 attendees from 37 countries responded to the postcourse survey for an overall response rate of (33%). Approximately (63%) of participants were practicing radiologists while (37%) were either fellows or residents and rarely medical students. The overwhelming majority (97%) found the OLIC webinar series to be beneficial. Essentially all attendees felt that the webinar sessions met (43%) or exceeded (57%) their expectations. When asked about their perception of virtual conferences after attending OLIC lectures, almost all attendees (99%) enjoyed the virtual conference with a majority (61%) of the respondents who enjoyed the virtual format more than in-person conferences, while (38%) enjoyed the webinar format but preferred in-person conferences. When asked about the willingness to attend virtual webinars in the future, (84%) said that they would attend future virtual conferences even if in-person conferences resume while (15%) were unsure. CONCLUSION: The success of the OLIC, attributed to many factors, indicates that videoconferencing technology provides an inexpensive alternative to in-person radiology conferences. The positive responses to our postcourse survey suggest that virtual education will remain to stay. Educational institutions and scientific societies should foster such models.

Alternative approach of hepatocellular carcinoma surveillance: abbreviated MRI.

This review focuses on emerging abbreviated magnetic resonance imaging (AMRI) surveillance of patients with chronic liver disease for hepatocellular carcinoma (HCC). This surveillance strategy has been proposed as a high-sensitivity alternative to ultrasound for identification of patients with early-stage HCC, particularly in patients with cirrhosis or obesity, in whom sonographic visualization of small tumors may be compromised. Three general AMRI approaches have been developed and studied in the literature - non-contrast AMRI, dynamic contrast-enhanced AMRI, and hepatobiliary phase contrast-enhanced AMRI - each comprising a small number of selected sequences specifically tailored for HCC detection. The rationale, general technique, advantages and disadvantages, and diagnostic performance of each AMRI approach is explained. Additionally, current gaps in knowledge and future directions are discussed. Based on emerging evidence, we cautiously recommend the use of AMRI for HCC surveillance in situations where ultrasound is compromised.

Clinicians and surgeon survey regarding current and future versions of CT/MRI LI-RADS.

PURPOSE: To determine preferences of clinicians and surgeons regarding radiology reporting of liver observations in patients at risk for hepatocellular carcinoma (HCC). METHODS: Members of the American College of Radiology Liver Imaging and Data Reporting System (LI-RADS) Outreach & Education Group (30 members) as well as Society of Abdominal Radiology Disease-Focused Panel on HCC diagnosis (27 members) created and distributed an 18-question survey to clinicians and surgeons, with focus on preferences regarding radiology reporting of liver observations in patients. The survey questions were directed to physician demographics, current use of LI-RADS by their local radiologists, their opinions about current LI-RADS and potential improvements. RESULTS: A total of 152 physicians responded, 66.4% (101/152) from North America, including 42 surgeons, 81 physicians and 29 interventional radiologists. Participants were predominantly from academic centers 83% (126/152), while 13.8% (21/152) worked in private/community centers and 3.2% (5/152) worked in a hybrid practice. Almost 90% (136/152) of participants preferred the use of LI-RADS (compared to nothing or other standardized reporting systems; OPTN and AASLD) to communicate liver-related observations. However, only 28.5% (43/152) of participants input was sought at the time of implementing LI-RADS in their institutions. Fifty-eight percent (88/152) of all participants found standardized LI-RADS management recommendations in radiology reports to be clinically helpful. However, a subgroup analysis of surgeons in academic centers showed that 61.8% (21/34) prefer not to receive standardized LI-RADS recommendations. CONCLUSIONS: Most participants preferred the use LI-RADS in reporting CT and MRI examination. When considering inclusion of management recommendations, radiologists should consult with their referring physicians, as preference may differ.