LI-RADS CT and MRI Ancillary Feature Association with Hepatocellular Carcinoma and Malignancy: An Individual Participant Data Meta-Analysis.

Background The independent contribution of each Liver Imaging Reporting and Data System (LI-RADS) CT or MRI ancillary feature (AF) has not been established. Purpose To evaluate the association of LI-RADS AFs with hepatocellular carcinoma (HCC) and malignancy while adjusting for LI-RADS major features through an individual participant data (IPD) meta-analysis. Materials and Methods Medline, Embase, Cochrane Central Register of Controlled Trials, and Scopus were searched from January 2014 to January 2022 for studies evaluating the diagnostic accuracy of CT and MRI for HCC using LI-RADS version 2014, 2017, or 2018. Using a one-step approach, IPD across studies were pooled. Adjusted odds ratios (ORs) and 95% CIs were derived from multivariable logistic regression models of each AF combined with major features except threshold growth (excluded because of infrequent reporting). Liver observation clustering was addressed at the study and participant levels through random intercepts. Risk of bias was assessed using a composite reference standard and Quality Assessment of Diagnostic Accuracy Studies 2. Results Twenty studies comprising 3091 observations (2456 adult participants; mean age, 59 years ± 11 [SD]; 1849 [75.3%] men) were included. In total, 89% (eight of nine) of AFs favoring malignancy were associated with malignancy and/or HCC, 80% (four of five) of AFs favoring HCC were associated with HCC, and 57% (four of seven) of AFs favoring benignity were negatively associated with HCC and/or malignancy. Nonenhancing capsule (OR = 3.50 [95% CI: 1.53, 8.01]) had the strongest association with HCC. Diffusion restriction (OR = 14.45 [95% CI: 9.82, 21.27]) and mild-moderate T2 hyperintensity (OR = 10.18 [95% CI: 7.17, 14.44]) had the strongest association with malignancy. The strongest negative associations with HCC were parallels blood pool enhancement (OR = 0.07 [95% CI: 0.01, 0.49]) and marked T2 hyperintensity (OR = 0.18 [95% CI: 0.07, 0.45]). Seventeen studies (85%) had a high risk of bias. Conclusion Most LI-RADS AFs were independently associated with HCC, malignancy, or benignity as intended when adjusting for major features. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Crivellaro in this issue.

Comparative Performance of 2018 LI-RADS versus Modified LIRADS (mLI-RADS): An Individual Participant Data Meta-Analysis.

BACKGROUND: LI-RADS version 2018 (v2018) is used for non-invasive diagnosis of hepatocellular carcinoma (HCC). A recently proposed modification (known as mLI-RADS) demonstrated improved sensitivity while maintaining specificity and positive predictive value (PPV) of LI-RADS category 5 (definite HCC) for HCC. However, mLI-RADS requires multicenter validation. PURPOSE: To evaluate the performance of v2018 and mLI-RADS for liver lesions in a large, heterogeneous, multi-national cohort of patients at risk for HCC. STUDY TYPE: Systematic review and meta-analysis using individual participant data (IPD) [Study Protocol: https://osf.io/duys4]. POPULATION: 2223 observations from 1817 patients (includes all LI-RADS categories; females = 448, males = 1361, not reported = 8) at elevated risk for developing HCC (based on LI-RADS population criteria) from 12 retrospective studies. FIELD STRENGTH/SEQUENCE: 1.5T and 3T; complete liver MRI with gadoxetate disodium, including axial T2w images and dynamic axial fat-suppressed T1w images precontrast and in the arterial, portal venous, transitional, and hepatobiliary phases. Diffusion-weighted imaging was used when available. ASSESSMENT: Liver observations were categorized using v2018 and mLI-RADS. The diagnostic performance of each system's category 5 (LR-5 and mLR-5) for HCC were compared. STATISTICAL TESTS: The Quality Assessment of Diagnostic Accuracy Studies version 2 (QUADAS-2 was applied to determine risk of bias and applicability. Diagnostic performances were assessed using the likelihood ratio test for sensitivity and specificity and the Wald test for PPV. The significance level was P < 0.05. RESULTS: 17% (2/12) of the studies were considered low risk of bias (244 liver observations; 164 patients). When compared to v2018, mLR-5 demonstrated higher sensitivity (61.3% vs. 46.5%, P < 0.001), similar PPV (85.3% vs. 86.3%, P = 0.89), and similar specificity (85.8% vs. 90.8%, P = 0.16) for HCC. DATA CONCLUSION: This study confirms mLR-5 has higher sensitivity than LR-5 for HCC identification, while maintaining similar PPV and specificity, validating the mLI-RADS proposal in a heterogeneous, international cohort. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Individual Participant Data Meta-Analysis of LR-5 in LI-RADS Version 2018 versus Revised LI-RADS for Hepatocellular Carcinoma Diagnosis.

Background A simplification of the Liver Imaging Reporting and Data System (LI-RADS) version 2018 (v2018), revised LI-RADS (rLI-RADS), has been proposed for imaging-based diagnosis of hepatocellular carcinoma (HCC). Single-site data suggest that rLI-RADS category 5 (rLR-5) improves sensitivity while maintaining positive predictive value (PPV) of the LI-RADS v2018 category 5 (LR-5), which indicates definite HCC. Purpose To compare the diagnostic performance of LI-RADS v2018 and rLI-RADS in a multicenter data set of patients at risk for HCC by performing an individual patient data meta-analysis. Materials and Methods Multiple databases were searched for studies published from January 2014 to January 2022 that evaluated the diagnostic performance of any version of LI-RADS at CT or MRI for diagnosing HCC. An individual patient data meta-analysis method was applied to observations from the identified studies. Quality Assessment of Diagnostic Accuracy Studies version 2 was applied to determine study risk of bias. Observations were categorized according to major features and either LI-RADS v2018 or rLI-RADS assignments. Diagnostic accuracies of category 5 for each system were calculated using generalized linear mixed models and compared using the likelihood ratio test for sensitivity and the Wald test for PPV. Results Twenty-four studies, including 3840 patients and 4727 observations, were analyzed. The median observation size was 19 mm (IQR, 11-30 mm). rLR-5 showed higher sensitivity compared with LR-5 (70.6% [95% CI: 60.7, 78.9] vs 61.3% [95% CI: 45.9, 74.7]; P < .001), with similar PPV (90.7% vs 92.3%; P = .55). In studies with low risk of bias (n = 4; 1031 observations), rLR-5 also achieved a higher sensitivity than LR-5 (72.3% [95% CI: 63.9, 80.1] vs 66.9% [95% CI: 58.2, 74.5]; P = .02), with similar PPV (83.1% vs 88.7%; P = .47). Conclusion rLR-5 achieved a higher sensitivity for identifying HCC than LR-5 while maintaining a comparable PPV at 90% or more, matching the results presented in the original rLI-RADS study. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Sirlin and Chernyak in this issue.

Comparing Survival Outcomes of Patients With LI-RADS-M Hepatocellular Carcinomas and Intrahepatic Cholangiocarcinomas.

BACKGROUND: There is a sparsity of data evaluating outcomes of patients with Liver Imaging Reporting and Data System (LI-RADS) (LR)-M lesions. PURPOSE: To compare overall survival (OS) and progression free survival (PFS) between hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA) meeting LR-M criteria and to evaluate factors associated with prognosis. STUDY TYPE: Retrospective. SUBJECTS: Patients at risk for HCC with at least one LR-M lesion with histologic diagnosis, from 8 academic centers, yielding 120 patients with 120 LR-M lesions (84 men [mean age 62 years] and 36 women [mean age 66 years]). FIELD STRENGTH/SEQUENCE: A 1.5 and 3.0 T/3D T1 -weighted gradient echo, T2 -weighted fast spin-echo. ASSESSMENT: The imaging categorization of each lesion as LR-M was made clinically by a single radiologist at each site and patient outcome measures were collected. STATISTICAL TESTS: OS, PFS, and potential independent predictors were evaluated by Kaplan-Meier method, log-rank test, and Cox proportional hazard model. A P value of <0.05 was considered significant. RESULTS: A total of 120 patients with 120 LR-M lesions were included; on histology 65 were HCC and 55 were iCCA. There was similar median OS for patients with LR-M HCC compared to patients with iCCA (738 days vs. 769 days, P = 0.576). There were no significant differences between patients with HCC and iCCA in terms of sex (47:18 vs. 37:18, P = 0.549), age (63.0 ± 8.4 vs. 63.4 ± 7.8, P = 0.847), etiology of liver disease (P = 0.202), presence of cirrhosis (100% vs. 100%, P = 1.000), tumor size (4.73 ± 3.28 vs. 4.75 ± 2.58, P = 0.980), method of lesion histologic diagnosis (P = 0.646), and proportion of patients who underwent locoregional therapy (60.0% vs. 38.2%, P = 0.100) or surgery (134.8 ± 165.5 vs. 142.5 ± 205.6, P = 0.913). Using multivariable analysis, nonsurgical compared to surgical management (HR, 4.58), larger tumor size (HR, 1.19), and higher MELD score (HR, 1.12) were independently associated with worse OS. DATA CONCLUSION: There was similar OS in patients with LR-M HCC and LR-M iCCA, suggesting that LR-M imaging features may more closely reflect patient outcomes than histology. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 5.

The Organ Procurement and Transplantation Network hepatocellular carcinoma classification: Alignment with Liver Imaging Reporting and Data System, current gaps, and future direction.

The Organ Procurement and Transplantation Network (OPTN) updated its allocation policy for liver transplantation to align with the Liver Imaging Reporting and Data System (LI-RADS) for the diagnosis of hepatocellular carcinoma (HCC). LI-RADS computed tomography/magnetic resonance imaging algorithm had achieved congruency with the American Association for the Study of Liver Diseases (AASLD) HCC Practice Guidance in 2018, and therefore, alignment of OPTN, LI-RADS, and AASLD unifies HCC diagnostic approaches. The two changes to the OPTN HCC classification are adoption of LI-RADS terminology or lexicon for HCC major imaging features as well as the modification of OPTN Class-5A through the adoption of LI-RADS-5 criteria. However, despite this significant milestone, the OPTN allocation policy may benefit from further refinements such as adoption of treatment response assessment criteria after locoregional therapy and categorization criteria for lesions with atypical imaging appearances that are not specific for HCC. In this review, we detail the changes to the OPTN HCC classification to achieve alignment with LI-RADS, discuss current limitations of the OPTN classification, and explore future directions.

Liver Transplant for Nonhepatocellular Malignancies: A Review for Radiologists.

Although liver transplant is traditionally only performed for hepatocellular carcinoma (HCC), the last decade has seen a resurgence in its use for non-HCC malignancies, likely due to improvements in neoadjuvant treatment regimens and the establishment of well-defined eligibility criteria. Given promising survival results, patients with perihilar cholangiocarcinoma, neuroendocrine liver metastases, and hepatic hemangioendothelioma are eligible to receive Model for End-Stage Liver Disease (MELD) exception points for tumors that meet well-defined criteria. Patients with additional tumors such as colorectal cancer liver metastases, intrahepatic cholangiocarcinoma, and hepatocellular cholangiocarcinoma may undergo transplant at specialized centers with well-defined protocols, although these patients are not yet eligible for MELD exception. Transplant eligibility criteria commonly incorporate imaging findings; however, because of the relatively novel and evolving nature of liver transplant for non-HCC malignancies, radiologists may be unaware of relevant criteria or the implications of their imaging interpretations. Knowledge of the allocation process, previous studies, and liver transplant selection criteria facilitates radiologists' active participation in multidisciplinary discussion, leading to better and more equitable care for transplant candidates with non-HCC malignancy. This review provides an overview of transplant allocation and selection criteria in patients with non-HCC malignancy, with an emphasis on imaging features and the role of the radiologist.

Utility of gadolinium for identifying the malignant potential of pancreatic cystic lesions.

PURPOSE: To determine if gadolinium is necessary for the diagnosis of a pancreatic cystic lesion (PCL) as benign or malignant by assessing inter- and intra-observer agreement and diagnostic accuracy for the presence of worrisome features/high-risk stigmata on non-contrast MRI compared to MRI with and without contrast, with cytopathology as a reference standard. METHODS: The institutional database was searched to identify consecutive patients that underwent EUS/FNA or surgical resection of an asymptomatic PCL performed from 01/01/2015 to 01/01/2019. Two abdominal radiologists independently evaluated PCLs on MRI with all sequences except for contrast-enhanced sequences followed by a second reading with data from the entire MRI including pre- and post-contrast sequences. Cyst size, growth, and the presence of worrisome features/high-risk stigmata were assessed for each cyst on both datasets. RESULTS: There were 87 patients with 87 pancreatic cysts; 76(87.4%) were benign and 11 (12.7%) were malignant. The presence of any worrisome features/high-risk stigmata for reader 1 was concordant on both MRIs in 95.4% (83/87; k = 0.874) of cases and for reader 2 was concordant in 96.6% (84/87; k = 0.920) of cases. The diagnostic accuracy of the two datasets when the presence of any worrisome feature/high-risk stigmata was predictive of malignancy was identical for reader 1 (AUC = 0.622 for both; p = 1.0) and similar for reader 2 (AUC 0.569 and 0.589; p = 0.08) for both MRI datasets. CONCLUSION: The addition of gadolinium had no significant impact in the diagnosis of a benign versus malignant PCL, with similar intra-observer agreement and diagnostic accuracy for both readers when using contrast-enhanced and unenhanced MRI datasets.

CT/MRI and CEUS LI-RADS Major Features Association with Hepatocellular Carcinoma: Individual Patient Data Meta-Analysis.

Background The Liver Imaging Reporting and Data System (LI-RADS) assigns a risk category for hepatocellular carcinoma (HCC) to imaging observations. Establishing the contributions of major features can inform the diagnostic algorithm. Purpose To perform a systematic review and individual patient data meta-analysis to establish the probability of HCC for each LI-RADS major feature using CT/MRI and contrast-enhanced US (CEUS) LI-RADS in patients at high risk for HCC. Materials and Methods Multiple databases (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus) were searched for studies from January 2014 to September 2019 that evaluated the accuracy of CT, MRI, and CEUS for HCC detection using LI-RADS (CT/MRI LI-RADS, versions 2014, 2017, and 2018; CEUS LI-RADS, versions 2016 and 2017). Data were centralized. Clustering was addressed at the study and patient levels using mixed models. Adjusted odds ratios (ORs) with 95% CIs were determined for each major feature using multivariable stepwise logistic regression. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) (PROSPERO protocol: CRD42020164486). Results A total of 32 studies were included, with 1170 CT observations, 3341 MRI observations, and 853 CEUS observations. At multivariable analysis of CT/MRI LI-RADS, all major features were associated with HCC, except threshold growth (OR, 1.6; 95% CI: 0.7, 3.6; P = .07). Nonperipheral washout (OR, 13.2; 95% CI: 9.0, 19.2; P = .01) and nonrim arterial phase hyperenhancement (APHE) (OR, 10.3; 95% CI: 6.7, 15.6; P = .01) had stronger associations with HCC than enhancing capsule (OR, 2.4; 95% CI: 1.7, 3.5; P = .03). On CEUS images, APHE (OR, 7.3; 95% CI: 4.6, 11.5; P = .01), late and mild washout (OR, 4.1; 95% CI: 2.6, 6.6; P = .01), and size of at least 20 mm (OR, 1.6; 95% CI: 1.04, 2.5; P = .04) were associated with HCC. Twenty-five studies (78%) had high risk of bias due to reporting ambiguity or study design flaws. Conclusion Most Liver Imaging Reporting and Data System major features had different independent associations with hepatocellular carcinoma; for CT/MRI, arterial phase hyperenhancement and washout had the strongest associations, whereas threshold growth had no association. © RSNA, 2021 Online supplemental material is available for this article.

Imaging Evaluation of Living Liver Donor Candidates: Techniques, Protocols, and Anatomy.

The need for liver transplants is increasing because the prevalence of liver diseases and the indications for transplants are growing. In response to the shortage of grafts from deceased donors, more transplants are being performed worldwide with grafts from living donors. Radiologic evaluation is an integral component in the assessment of donor candidates to ensure their eligibility and to choose the most appropriate surgical approach. MRI is the preferred modality for evaluation of the liver parenchyma and biliary tree. In most centers, a combination of MRI and CT is used to take advantage of the higher spatial resolution of CT for evaluation of arteries. However, MRI-only assessment is feasible. In addition to assessment of the liver parenchyma for abnormalities such as steatosis, a detailed evaluation of the hepatic vascular and biliary system for pertinent anatomic variants is crucial, because these variants can affect surgical techniques and outcomes in both recipients and donors. In this pictorial article, after a brief review of the most common surgical techniques and postsurgical liver anatomy, the biliary and vascular anatomy are discussed, with specific attention paid to the variants that are pertinent to this surgical procedure. The roles of liver segmentation and volumetric assessment and current imaging techniques and protocols are also discussed. Online supplemental material is available for this article. ©RSNA, 2021.

Evaluation of the LI-RADS treatment response algorithm in hepatocellular carcinoma after trans-arterial chemoembolization.

PURPOSE: To evaluate the diagnostic performance of LI-RADS treatment response algorithm (LR-TRA) and modified RECIST (mRECIST) for the detection of viable hepatocellular carcinoma (HCC) on MRI after trans-arterial chemoembolization (TACE). MATERIALS AND METHODS: This retrospective study includes cirrhotic patients that underwent trans-arterial chemoembolization prior to liver transplantation from 2013 to 2017 with a pre- and post-treatment MRI available. Three blinded readers assigned a LR-TRA and mRECIST category to each lesion. Lesions on MRI and explant pathology were matched and characterized as complete (100% necrosis) or incomplete necrosis (≤99% necrosis). Diagnostic performance of LR-TRA and mRECIST were calculated with a generalized estimating equation. RESULTS: A total of 52 patients with 71 lesions were included, 47 with incomplete and 24 with complete necrosis. In consensus, 45 lesions were categorized as LR-TR Nonviable, of which 62.2% (28/45) had incomplete and 37.8% (17/45) had complete necrosis. Six lesions were categorized as LR-TR Equivocal, of which 33.3% (2/6) had incomplete and 66.7% (4/6) had complete necrosis. Twenty lesions were categorized as LR-TR Viable of which 85.0% (17/20) had incomplete and 15.0% (3/20) had complete necrosis. The sensitivity of LR-TR Viable for detecting incompletely necrotic tumor when LR-TR Equivocal was considered as viable, in consensus was 40.4%; specificity 70.8%; accuracy 50.7%. The sensitivity of mRECIST for detecting incompletely necrotic tumor was 37.0%; specificity 79.2%; accuracy 51.4%. There was no significant difference in diagnostic performance between mRECIST and LR-TRA (p = 0.14-0.33). Agreement for LR-TRA category was moderate (k = 0.53 [95% CI: 0.45, 0.67]). CONCLUSION: LI-RADS treatment response algorithm demonstrates high specificity and low to moderate sensitivity for the detection of viable HCC after TACE in a North American cirrhotic cohort, without significant difference in diagnostic performance between LR-TRA and mRECIST.

PET/MRI of the hepatobiliary system: Review of techniques and applications.

Simultaneous positron emission tomography and MRI (PET/MRI) is an emerging technology that offers the benefits of MRI, including excellent soft tissue contrast, lack of ionizing radiation, and functional MRI techniques, with the physiologic information provided by PET. Although most PET/MRI systems are currently installed in tertiary care centers, PET/MRI technology is becoming increasingly widespread. The usefulness of PET/MRI varies by tumor type and organ system and has been shown to have utility in evaluation of primary and secondary hepatic neoplasms. Understanding the appropriate applications, techniques and relevant imaging findings is important for practicing radiologists considering or currently utilizing PET/MR for the evaluation of primary liver neoplasms, including hepatocellular carcinoma (HCC), as well as staging of biliary neoplasms including cholangiocarcinoma and gallbladder cancer, identification of liver metastases, and staging of neuroendocrine tumor.

Diagnostic Performance of LI-RADS Version 2018, LI-RADS Version 2017, and OPTN Criteria for Hepatocellular Carcinoma.

OBJECTIVE. Liver Imaging Reporting and Data System (LI-RADS) was updated in 2018 (LI-RADS version 2018 [LI-RADSv2018]) to facilitate integration into the American Association for the Study of Liver Diseases 2018 clinical practice guidelines and involved changes in LR-5 categorization and threshold growth definitions. There are also differences between the criteria for LI-RADSv2018 LR-5 category and the criteria for Organ Procurement and Transplantation Network (OPTN) class 5. The objective of our study was to compare the diagnostic performances of LI-RADSv2018, LI-RADS version 2017 (LI-RADSv2017), and OPTN criteria for diagnosing hepatocellular carcinoma (HCC) on MRI. MATERIALS AND METHODS. In this retrospective study, 122 patients with 159 observations were included who met LI-RADS criteria for at risk for HCC and had at least one hepatic observation on MRI performed between January 1, 2015, and January 1, 2018 and who had histopathology results (n = 104) or follow-up imaging (n = 55) as reference standards. Three abdominal radiologists assigned categories independently and in consensus using LI-RADSv2017, LI-RADSv2018, and OPTN criteria. Diagnostic performance was compared among the guidelines with a generalized estimating equation. RESULTS. Fourteen of 159 (8.8%) observations were assigned a different category according to LI-RADSv2018 compared with LI-RADSv2017. Eight of 31 (25.8%) LR-4 observations using v2017 were recategorized as LR-5 using v2018, and all eight were HCC. Six of 31 (19.4%) LR-4 observations based on v2017 were recategorized as LR-3 using v2018, and all six were non-HCCs. Seven of 114 (6.1%) observations not meeting OPTN class 5 criteria were LR-5 using v2018, and all seven were HCC. Sensitivity for HCC of LR-5 and LR-TIV+5 (i.e., LR-TIV [tumor in vein] definitely due to HCC) categories based on v2018 was significantly higher than that based on v2017 (63.9% vs 55.2%, respectively; p = 0.008) without a difference in specificity (97.3% vs 97.3%; p = 1.00). Sensitivity of LR-5 and LR-TIV+5 in LI-RADSv2018 was significantly higher than the sensitivity of class 5 in OPTN criteria (63.9% vs 53.6%; p = 0.004) without a difference in specificity (97.3% vs 97.3%; p = 1.00). Reader agreement was moderate for overall LIRADSv2017 and LI-RADSv2018 categories (κ = 0.504 and 0.561, respectively); substantial for LR-5 and LR-TIV+5 categories as diagnostic of HCC versus other categories for both v2017 and v2018 (κ = 0.758 and 0.802, respectively); and substantial for OPTN class 5 criteria (κ = 0.756). CONCLUSION. The diagnostic performance of LI-RADSv2018 is higher, with higher sensitivity and similar specificity, than the diagnostic performance of LI-RADSv2017 and OPTN criteria for HCC.

Imaging and Treatment of Complications of Abdominal and Pelvic Mesh Repair.

Surgical mesh is used most frequently for tension-free repair of abdominal wall hernias in adults, because the rate of hernia recurrence is lower with mesh than with primary soft-tissue repair. Since the introduction of polypropylene mesh in the middle of the 20th century, many mesh materials and configurations for specific surgical procedures have been developed. In addition to abdominal wall hernia repair, mesh may be used for repair of diaphragmatic hernias, urinary incontinence in women (female slings), genitourinary prolapse (vaginal mesh and sacrocolpopexy), rectal prolapse (rectopexy), and postprostatectomy male urinary incontinence (male slings). General mesh repair complications include chronic pain; fluid collections such as seromas, hematomas, and abscesses; adhesions that may lead to intestinal blockage; erosion into solid or hollow viscera including enterocutaneous fistulizing disease; and mesh failure characterized by mesh shrinkage, detachment, and migration with repair malfunction. Several mesh complications are often diagnosed with imaging, primarily with CT and less frequently with MRI and US, despite variable mesh visibility at imaging. This article reviews the common surgical mesh applications in the abdomen and pelvis, discusses imaging of mesh repair complications, and provides complication treatment highlights.©RSNA, 2020.

Advanced Endoscopic Procedures: An Update for Radiologists.

OBJECTIVE. The purposes of this article are to familiarize radiologists with endoscopic techniques currently in use and to improve identification of clinically relevant imaging findings and procedural complications related to common endoscopic interventions. CONCLUSION. The frequency of performance of therapeutic endoscopic ultrasound-guided procedures has risen precipitously in the last decade. These procedures are replacing surgical and percutaneous approaches to a variety of disease entities. Recent advances include endoscopic bariatric procedures, endoscopic myotomies, and endoscopic ultrasound-guided drainage procedures.

Rapid automated liver quantitative susceptibility mapping.

BACKGROUND: Accurate measurement of the liver iron concentration (LIC) is needed to guide iron-chelating therapy for patients with transfusional iron overload. In this work, we investigate the feasibility of automated quantitative susceptibility mapping (QSM) to measure the LIC. PURPOSE: To develop a rapid, robust, and automated liver QSM for clinical practice. STUDY TYPE: Prospective. POPULATION: 13 healthy subjects and 22 patients. FIELD STRENGTH/SEQUENCES: 1.5 T and 3 T/3D multiecho gradient-recalled echo (GRE) sequence. ASSESSMENT: Data were acquired using a 3D GRE sequence with an out-of-phase echo spacing with respect to each other. All odd echoes that were in-phase (IP) were used to initialize the fat-water separation and field estimation (T2 *-IDEAL) before performing QSM. Liver QSM was generated through an automated pipeline without manual intervention. This IP echo-based initialization method was compared with an existing graph cuts initialization method (simultaneous phase unwrapping and removal of chemical shift, SPURS) in healthy subjects (n = 5). Reproducibility was assessed over four scanners at two field strengths from two manufacturers using healthy subjects (n = 8). Clinical feasibility was evaluated in patients (n = 22). STATISTICAL TESTS: IP and SPURS initialization methods in both healthy subjects and patients were compared using paired t-test and linear regression analysis to assess processing time and region of interest (ROI) measurements. Reproducibility of QSM, R2 *, and proton density fat fraction (PDFF) among the four different scanners was assessed using linear regression, Bland-Altman analysis, and the intraclass correlation coefficient (ICC). RESULTS: Liver QSM using the IP method was found to be ~5.5 times faster than SPURS (P < 0.05) in initializing T2 *-IDEAL with similar outputs. Liver QSM using the IP method were reproducibly generated in all four scanners (average coefficient of determination 0.95, average slope 0.90, average bias 0.002 ppm, 95% limits of agreement between -0.06 to 0.07 ppm, ICC 0.97). DATA CONCLUSION: Use of IP echo-based initialization enables robust water/fat separation and field estimation for automated, rapid, and reproducible liver QSM for clinical applications. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:725-732.

Validation of Liver Imaging Reporting and Data System 2017 (LI-RADS) Criteria for Imaging Diagnosis of Hepatocellular Carcinoma.

BACKGROUND: The Liver Imaging Reporting and Data System (LI-RADS) is being adapted by many clinical practices. To support continuation of its use, LI-RADS (LR) is in need of multicenter validation studies of recent LI-RADS iterations. Furthermore, while both gadoxetate and extracellular agents have been incorporated into LI-RADS, comparison of the diagnostic performance between the two has yet to be determined. PURPOSE/HYPOTHESIS: To evaluate the rate, diagnostic performance, and interreader reliability (IRR) of LI-RADS 2017 for hepatocellular carcinoma, including LR major and ancillary features, with both gadoxetate and extracellular agent-enhanced MRI against a reference standard of histopathology or imaging follow-up. STUDY TYPE: Retrospective. POPULATION: In all, 114 patients with 144 observations were included who met LR 2017 criteria for at risk and had at least one hepatic observation on liver MRI performed with either gadoxetate (n = 52) or an extracellular agent (n = 92) between 2010-2016, with histopathology (n = 103) or follow-up imaging (n = 41). FIELD STRENGTH/SEQUENCE: 1.5 and 3.0T/T1 -T2 WI, diffusion-weighted imaging. ASSESSMENT: Three radiologists independently assessed major/ancillary features and assigned overall LI-RADS category for every observation. STATISTICAL TESTS: Diagnostic performance of LR5/TIV+LR5 for identifying hepatocellular carcinoma (HCC) was compared between contrast agents with a generalized estimating equation. Weighted kappa was performed for interrater reliability. RESULTS: The frequency of HCCs among LR1, LR2, LR3, L4, LR5, LRTIV+LR5, and LRM observations were: 0% (all readers), 0-12.5%, 11.4-26.9%, 50-76%, 83.0-95.1%, 83.3-100.0%, and 45.0-65.0%, respectively. Sensitivity of LR5/LRTIV+LR5 for HCC was 59.7-71.4% and specificity 85.0-96.8%. LI-RADS specificity and positive predictive value for observations imaged with gadoxetate was higher than extracellular agent for the most inexperienced reader (R3) (P = 0.009-0.034). IRR for LI-RADS categorization was substantial (k = 0.661). DATA CONCLUSION: Increasing numerical LI-RADS 2017 categories demonstrate a greater percentage of HCCs. LR5/TIV+LR5 demonstrates excellent specificity and fair sensitivity for HCC. MRI with gadoxetate in liver transplant candidates may be beneficial for less experienced readers, although further large-scale prospective studies are needed. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:e205-e215.

Portal Cavernoma Cholangiopathy: Histologic Features and Differential Diagnosis.

Objectives: Portal cavernoma cholangiopathy (formerly portal biliopathy) is a type of biliary injury that occurs in association with a portal vein thrombus or cavernoma. Although the radiographic features of portal cavernoma cholangiopathy have been enumerated in the literature, its histologic features have not been described in detail. Methods: We describe the histologic findings in liver specimens from three patients with radiologically confirmed portal cavernoma cholangiopathy. Results: Of the three patients, one underwent surgical resection due to a clinical suspicion for cholangiocarcinoma, one had a liver biopsy sample obtained for evaluation of possible cirrhosis, and one had a clinically suspicious "hilar mass" at the time of orthotopic liver transplant. Histologic features common among the three liver specimens included portal venous abnormalities, where the portal veins were obliterated or small relative to the portal tract size, and obstructive biliary changes, such as ductular reaction and reactive epithelial atypia accompanied by a mixed inflammatory cell infiltrate with neutrophils. Conclusions: This case series provides clinicopathologic characteristics of portal cavernoma cholangiopathy. Histologic changes are reminiscent of hepatoportal sclerosis and/or bile duct obstruction. Attention to portal veins can provide helpful diagnostic clues, especially when biopsy samples are obtained from patients with a known portal vein thrombus or cavernoma.