Magnetic resonance imaging-based risk factors of hepatocellular carcinoma after direct-acting antiviral therapy: A multicenter observational study.

AIM: To determine risk factors associated with hepatocellular carcinoma (HCC) development following direct-acting antiviral (DAA) therapy. METHODS: We enrolled patients with chronic hepatitis C who underwent direct-acting antiviral therapy and achieved sustained virologic response at 12 weeks between 2012 and 2018. Subsequently, patients were followed up. The primary endpoint was the development of HCC or the date of the last follow up when the absence of HCC was confirmed. Uni- and multivariate Cox proportional hazards models were used to identify factors contributing to HCC development, including gadoxetic acid-enhanced magnetic resonance imaging findings. The cumulative incidence rates of HCC development were calculated using the Kaplan-Meier method, and differences between groups were assessed using the log-rank test. RESULTS: The final study cohort comprised 482 patients (median age 70.5 years; 242 men). The median follow-up period was 36.8 months. Among 482 patients, 96 developed HCC (19.9%). The 1-, 3-, and 5-year cumulative rates of HCC development were 4.9%, 18.6%, and 30.5%, respectively. Multivariate analysis revealed that age, male sex, history of HCC, and hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were independent risk factors significantly associated with HCC development (p < 0.001-0.04). The highest risk group included patients with both a history of HCC and the presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement (the 1- and 3-year cumulative HCC development rates were 14.2% and 62.2%, respectively). CONCLUSION: History of HCC and presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were strong risk factors for HCC development following direct-acting antiviral therapy.

Association of the lung immune prognostic index with the survival of patients with idiopathic interstitial pneumonias.

BACKGROUND AND OBJECTIVE: The lung immune prognostic index (LIPI), a simple index calculated from the blood lactate dehydrogenase level and derived neutrophil-to-lymphocyte ratio, is thought to be associated with host immune status. However, the utility of LIPI in patients with idiopathic interstitial pneumonias (IIPs) is unknown. METHODS: In this multicentre, retrospective, observational study, an association between LIPI and the survival of patients with IIPs was evaluated. RESULTS: Exploratory and validation cohorts consisting of 460 and 414 patients with IIPs, respectively, were included (159 and 159 patients had idiopathic pulmonary fibrosis [IPF], and 301 and 255 had non-IPF, respectively). In the exploratory cohort, patients with IPF and a low LIPI had significantly better survival than those with a high LIPI (median of 5.6 years vs. 3.9 years, p = 0.016). The predictive ability of LIPI for the survival of patients with IPF was validated in the validation cohort (median of 8.5 years vs. 4.4 years, p = 0.003). In a multivariate Cox proportional hazard analysis, LIPI was selected as an independent predictive factor for the survival of IPF patients. There was no significant association between LIPI and survival of non-IPF patients in the exploratory and validation cohorts. CONCLUSION: The LIPI was a predictive factor for the survival of patients with IPF and could aid the management of IPF.

Key CT and MRI findings of drug-associated hepatobiliary and pancreatic disorders.

Obtaining an imaging diagnosis of various hepatobiliary and pancreatic disorders caused by certain drugs can often be challenging. Familiarity with these conditions may improve diagnostic accuracy and patient management. This review aimed to describe the imaging findings of drug-associated hepatobiliary and pancreatic disorders and identify suggestions for obtaining a correct diagnosis. We focused on relatively common disorders or those that can present with characteristic imaging findings, such as drug-induced acute hepatitis, sinusoidal obstruction syndrome, focal nodular hyperplasia-like lesions, hepatocellular adenoma, pseudocirrhosis, chemotherapy-associated steatohepatitis, amiodarone deposition in the liver, secondary iron overload, drug-induced pancreatitis, pancreatic enlargement after epoprostenol therapy, ceftriaxone-associated gallbladder pseudolithiasis, immune-related adverse events, and methotrexate-associated lymphoproliferative disorders.

Gadoxetic Acid-Enhanced Liver MRI: Everything You Need to Know.

ABSTRACT: Since its introduction in the worldwide medical market, gadoxetic acid has attracted considerable interest. The year 2023 marks the 15th anniversary of the introduction of gadoxetic acid in Japan. Gadoxetic acid-enhanced magnetic resonance imaging (GA-MRI) is the predominantly performed contrast MRI examination for the liver. Its most essential characteristic, namely, the hepatobiliary phase, revolutionized the clinical management of liver disease. Gadoxetic acid-enhanced MRI is currently the most efficient method for focal liver lesion detection and analysis. Meta-analyses demonstrated its excellent effectiveness for the diagnosis of hepatocellular carcinoma and liver metastases. Owing to the extensive usage of gadoxetic acid, a hepatobiliary phase hypointense nodule without arterial phase hyperenhancement is well documented. The existence of such nodules may be a sign of hypervascular hepatocellular carcinoma in nodules and other areas in the liver. Apart from its role in tumor identification and characterization, GA-MRI can help assess response to therapy and liver fibrosis. Therefore, it is proposed to use gadoxetic acid as the first option for MRI of the liver in the majority of patients. The efficacy of gadoxetic acid surpasses its disadvantages, rendering this contrast agent the preferred choice for routine MRI of the liver. The clinical use of GA-MRI is discussed in this review article.

Six-week oral prednisolone therapy for immune-related pneumonitis: a single-arm phase II study.

BACKGROUND: There has been no prospective trial for treatment of immune-related pneumonitis (irP) occurred after immune checkpoint inhibitors (ICIs). METHODS: In this single-arm phase II study, patients with cancer with grade ≥2 irP received oral prednisolone (1 mg/kg/day), tapered over 6 weeks. The primary endpoint was a pneumonitis control rate at 6 weeks from the start of the study treatment, defined as complete disappearance or partial improvement of irP in high-resolution CT of the chest. RESULTS: Among 57 patients enrolled, 56 were included in the final analysis. The most frequent cause of irP was single ICI therapy (51.8%), followed by combination with chemotherapy plus ICI (39.3%). Thirty-five (62.5%) patients had grade 2 irP and 21 (37.5%) had grade ≥3. Fifty-one (91.1%) patients completed the study treatment while 5 discontinued the study treatment because of relapse of irP (n=1), death from cancer (n=1), occurrence of immune-related hepatitis (n=1), extension of the treatment duration more than 6 weeks (n=1), and attending physician's decision (n=1). Six weeks after the start of the study treatment, 16 (28.5%) patients demonstrated complete recovery from irP, 35 (62.5%) had a partial improvement in irP, 1 (1.8%) had a relapse of irP, and 4 (7.1%) were not evaluable. The pneumonitis control rate at 6 weeks was 91.1% (95% CI, 80.7% to 96.1%). Twelve weeks after the start of the study treatment, 5 (8.9%), 27 (48.2%), and 15 (26.8%) patients demonstrated complete recovery, partial improvement, and relapse, respectively, and 9 (16.1%) were not evaluable. The pneumonitis control rate at 12 weeks was 57.1% (95% CI, 44.1% to 69.2%). During the observation period, 18 (32.1%) patients experienced a relapse of irP, and of those, 17 received re-treatment with corticosteroids. Grade ≥3 adverse events occurred in 10 (17.9%) patients, in which hyperglycemia was most frequent (n=6). There was no treatment-related death. CONCLUSIONS: In this first prospective study for irP, prednisolone at 1 mg/kg/day, tapered over 6 weeks, demonstrated a promising clinical benefit and manageable toxicity, suggesting a potential treatment option for irP. TRIAL REGISTRATION NUMBER: jRCT: 1041190029.

Inter-observer agreement and accuracy of LI-RADS v2018 for differentiating tumor in vein from bland thrombus using gadoxetic acid-enhanced magnetic resonance imaging.

PURPOSE: To assess inter-observer agreement and accuracy of LI-RADS v2018 for differentiating tumor in vein (TIV) from bland thrombus on gadoxetic acid-enhanced magnetic resonance imaging (Gx-MRI). Secondarily, to determine whether a multi-feature model improves accuracy compared to LI-RADS. METHODS: We retrospectively identified consecutive patients at risk for hepatocellular carcinoma with venous occlusion(s) reported on Gx-MRI. Five radiologists independently classified each occlusion as TIV or bland thrombus using the LI-RADS TIV criterion (enhancing soft tissue in vein). They also evaluated imaging features suggestive of TIV or bland thrombus. Intra-class correlation coefficient (ICC) was calculated for individual features. A multi-feature model was developed based on consensus scores of features with > 5% consensus prevalence and > 0.40 ICC. Sensitivity and specificity of the LI-RADS criterion and of the cross-validated multi-feature model were compared. RESULTS: Ninety-eight patients with 103 venous occlusions (58 TIV, 45 bland thrombus) were included. The LI-RADS criterion provided 0.63 ICC and, depending on the reader, 0.62-0.93 sensitivity and 0.87-1.00 specificity. Five other features had > 5% consensus prevalence and > 0.40 ICC, including three LI-RADS suggestive features and two non-LI-RADS features. The optimal multi-feature model incorporated the LI-RADS criterion and one LI-RADS suggestive feature (occluded or obscured vein contiguous with malignant parenchymal mass). After cross-validation, the multi-feature model did not improve sensitivity or specificity compared to the LI-RADS criterion (P = 0.23 and 0.25, respectively). CONCLUSION: Using Gx-MRI, the LI-RADS criterion for TIV provides substantial inter-observer agreement, variable sensitivity, and high specificity for differentiating TIV from bland thrombus. A cross-validated multi-feature model did not improve diagnostic performance.

Clinical Significance of Liver MR Imaging.

MRI is widely used in clinical practice for detecting liver diseases. Since the introduction of gadoxetic acid, MRI has become the most effective modality for the detection and characterization of focal liver lesions. According to previous meta-analyses, the area under the receiver operating characteristic curve (AUROC) was 0.97-0.99 for the diagnosis of small hepatocellular carcinoma (≥ 2 cm) by gadoxetic-acid-enhanced MRI. Moreover, the AUROC for the diagnosis of colorectal liver metastases was significantly high (0.98). Despite gadoxetic acid's drawbacks, its clinical utility outweighs them, making it the contrast agent of choice in routine liver MRIs. Moreover, clinically, liver MRI has become more prevalent for a quantitative assessment. Liver fibrosis can be evaluated using MR elastography; whereas, hepatic steatosis and iron overload can be evaluated using proton density fat fraction, with high accuracy and reproducibility. This article reviewed the usefulness of liver MRI, which can be a comprehensive imaging modality in clinical practice.

A predictive model for acute exacerbation of idiopathic interstitial pneumonias.

BACKGROUND: Acute exacerbation of idiopathic interstitial pneumonias (AE-IIPs) induces permanent pulmonary dysfunction and is potentially lethal. The unpredictable occurrence of AE-IIPs remains an important clinical issue in the management of IIPs. METHODS: In this multicentre, retrospective, observational study, a predictive score for AE-IIPs was designed using clinical factors based on multivariate Fine-Gray analysis in patients with IIPs. RESULTS: Based on multivariate Fine-Gray analysis in an exploratory cohort of 487 patients with IIPs, the predictive score for AE-IIPs was determined as follows: 1 point each was added for honeycombing on high-resolution computed tomography (H), age >75 years (A) and lactate dehydrogenase level >222 U·L-1 (L); the total score ranged from 0 to 3 (HAL score). The HAL score discriminated the risk of AE-IIPs with a C-index of 0.62 (95% CI 0.56-0.67); this discrimination was verified in a validation cohort of 402 patients with IIPs with a C-index of 0.67 (95% CI 0.60-0.73). In a combined cohort, the estimated cumulative risks for AE-IIPs at 1, 2, 3, 5 and 10 years were 1.9%, 3.5%, 5.1%, 7.7% and 12.9%, respectively, in the total score 0 group; 4.7%, 8.3%, 12.0%, 17.7% and 28.4%, respectively, in the total score 1 group; and 8.0%, 14.2%, 19.7%, 28.7% and 43.0%, respectively, in the total score ≥2 group. Subgroup analysis revealed that the HAL score was applicable to patients with and without idiopathic pulmonary fibrosis. CONCLUSIONS: The HAL score discriminated the risk of AE-IIPs and could aid in the management of IIPs.

Diagnostic value of heart-to-mediastinum ratio in 99mTc-pyrophospate SPECT/CT for transthyretin cardiac amyloidosis.

BACKGROUND: In transthyretin cardiac amyloidosis (ATTR-CA), 99mTc-pyrophosphate myocardial scintigraphy (99mTc-PYP) is a diagnostic tool that utilizes visual and quantitative evaluation. However, false positive cases can occur because of tracer accumulation in the blood. We investigated the effectiveness of the heart-to-mediastinum (H/M) ratio of 99mTc-PYP in ATTR-CA diagnosis. METHODS: We retrospectively included 164 patients who underwent 99mTc-PYP single-photon emission computed tomography/computed tomography between March 2019 and January 2022. The diagnostic accuracy of ATTR-CA was examined by the heart-to-contralateral lung (H/CL) and H/M ratio calculated at 3 hours post-tracer administration. RESULTS: After the exclusion of patients who did not undergo endomyocardial biopsy, 30 patients (15 each with ATTR-CA and without ATTR-CA) were included. The receiver operating characteristic curve used to distinguish ATTR-CA from non-ATTR-CA patients revealed an area under the curve of 0.986 and 0.943, respectively. A H/M ratio of > 1.41 identified ATTR-CA patients with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100, 93.3, 93.3, and 100%, respectively. Conversely, an H/CL ratio of > 1.3 identified ATTR-CA patients with 100% sensitivity, 40.0% specificity, 62.5% PPV, and 100% NPV. CONCLUSION: The H/M ratio obtained at 3 hours post-injection has the potential to be a novel indicator for ATTR-CA.

Computed tomography and magnetic resonance imaging findings of gynaecologic emergencies: A pictorial essay.

Gynaecologic emergencies include diseases resulting from adnexal and uterine disorders. Some emergencies are life threatening; however, they often have non-specific symptoms and physical findings. Thus, imaging diagnosis is important for evaluating these conditions. The first-choice modality for obstetrics and gynaecology is ultrasonography; however, some cases require computed tomography (CT) and magnetic resonance imaging (MRI) for correct diagnosis. Treatment options for gynaecologic emergencies vary from conservative therapy to emergency surgery, thus a correct diagnosis is critical. The purpose of this article is to describe notable CT and MRI findings of gynaecologic emergencies, which will help emergency department physicians arrive at the correct diagnosis and thus facilitate optimal treatment for patients.

Distinction Between Hepatocellular Carcinoma and Hypervascular Liver Metastases in Non-cirrhotic Patients Using Gadoxetate Disodium-Enhanced Magnetic Resonance Imaging.

Purpose: This study aims to identify the hallmarks of gadoxetate disodium-enhanced magnetic resonance imaging distinguishing hepatocellular carcinoma (HCC) from hypervascular liver metastases (HLMs). Methods: Between January 2008 and October 2020, among patients who underwent gadoxetate disodium-enhanced MRI, those who met the following criteria were retrospectively included: without chronic hepatitis or liver stiffness ≤ 2.5 kPa on magnetic resonance elastography or F0/F1 on pathological assessment. Two blinded radiologists reviewed the imaging findings to judge the presence or absence of the enhancing capsule, nonperipheral washout, corona enhancement, hypointensity in the transitional/hepatobiliary phase (HBP), hyperintensity on T2-weighted/diffusion-weighted imaging (DWI), mosaic architecture, and blood products/fat in mass. The lesion-to-liver signal intensity ratios in HBP and DWI were also calculated. Univariate and multivariate analyses were performed to identify the imaging hallmarks distinguishing HCC from HLM. Interobserver agreement was calculated using kappa values and intraclass correlation coefficients (ICCs). Results: The final study cohort comprised 72 lesions in 44 patients (mean age, 65.0±11.9 years). Univariate analysis revealed higher frequencies of the following features in HCC than in HLM (P < .10): nonperipheral washout, corona enhancement, transitional phase hypointensity, mosaic architecture, and fat in mass (P = .002-.073). Multivariate analysis revealed that nonperipheral washout and mosaic architecture favored the diagnosis of HCC over that of HLM with odds ratios of 7.66 and 14.6, respectively (P = .038 and .029, respectively). The interobserver agreement for each item was moderate or substantial (kappa or ICC = .447-.792). Conclusion: Peripheral washout and mosaic architecture may be reliable imaging hallmarks for distinguishing HCC from HLM.

MRI-based radiomics analysis for differentiating phyllodes tumors of the breast from fibroadenomas.

OBJECTIVES: To evaluate the diagnostic performance of MRI-based radiomics model for differentiating phyllodes tumors of the breast from fibroadenomas. METHODS: This retrospective study included 88 patients (32 with phyllodes tumors and 56 with fibroadenomas) who underwent MRI. Radiomic features were extracted from T2-weighted image, pre-contrast T1-weighted image, and the first-phase and late-phase dynamic contrast-enhanced MRIs. To create stable machine learning models and balanced classes, data augmentation was performed. A least absolute shrinkage and selection operator (LASSO) regression was performed to select features and build the radiomics model. A radiological model was constructed from conventional MRI features evaluated by radiologists. A combined model was constructed using both radiomics features and radiological features. Machine learning classifications were done using support vector machine, extreme gradient boosting, and random forest. The area under the receiver operating characteristic (ROC) curve (AUC) was computed to assess the performance of each model. RESULTS: Among 1070 features, the LASSO logistic regression selected 35 features. Among three machine learning classifiers, support vector machine had the best performance. Compared to the radiological model (AUC: 0.77 ± 0.11), the radiomics model (AUC: 0.96 ± 0.04) and combined model (0.97 ± 0.03) had significantly improved AUC values (both p < 0.01) in the validation set. The combined model had a relatively higher AUC than that of the radiomics model in the validation set, but this was not significantly different (p = 0.391). CONCLUSIONS: Radiomics analysis based on MRI showed promise for discriminating phyllodes tumors from fibroadenomas. KEY POINTS: • The radiomics model and the combined model were superior to the radiological model for differentiating phyllodes tumors from fibroadenomas. • The SVM classifier performed best in the current study. • MRI-based radiomics model could help accurately differentiate phyllodes tumors from fibroadenomas.

Pathologic, Molecular, and Prognostic Radiologic Features of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a malignancy with variable biologic aggressiveness based on the tumor grade, presence or absence of vascular invasion, and pathologic and molecular classification. Knowledge and understanding of the prognostic implications of different pathologic and molecular phenotypes of HCC are emerging, with therapeutics that promise to provide improved outcomes in what otherwise remains a lethal cancer. Imaging has a central role in diagnosis of HCC. However, to date, the imaging algorithms do not incorporate prognostic features or subclassification of HCC according to its biologic aggressiveness. Emerging data suggest that some imaging features and further radiologic, pathologic, or radiologic-molecular phenotypes may allow prediction of the prognosis of patients with HCC. An invited commentary by Bashir is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Diagnostic performance and image quality of low-tube voltage and low-contrast medium dose protocol with hybrid iterative reconstruction for hepatic dynamic CT.

OBJECTIVE: To evaluate the diagnostic performance and image quality of the low-tube voltage and low-contrast medium dose protocol for hepatic dynamic CT. METHODS: This retrospective study was conducted between January and May 2018. All patients underwent hepatic dynamic CT using one of the two protocols: tube voltage, 80 kVp and contrast dose, 370   mgI/kg with hybrid iterative reconstruction or tube voltage, 120 kVp and contrast dose, 600  mgI/kg with filtered back projection. Two radiologists independently scored lesion conspicuity and image quality. Another radiologist measured the CT numbers of abdominal organs, muscles, and hepatocellular carcinoma (HCC) in each phase. Lesion detectability, HCC diagnostic ability, and image quality of the arterial phase were compared between the two protocols using the non-inferiority test. CT numbers and HCC-to-liver contrast were compared between the protocols using the Mann-Whitney U test. RESULTS: 424 patients (70.5 ± 10.1 years) were evaluated. The 80-kVp protocol showed non-inferiority in lesion detectability and diagnostic ability for HCC (sensitivity, 85.7-89.3%; specificity, 96.3-98.6%) compared with the 120-kVp protocol (sensitivity, 91.0-93.3%; specificity, 93.6-97.3%) (p < 0.001-0.038). The ratio of fair image quality in the 80-kVp protocol also showed non-inferiority compared with that in the 120-kVp protocol in assessments by both readers (p < 0.001). HCC-to-liver contrast showed no significant differences for all phases (p = 0.309-0.705) between the two protocols. CONCLUSION: The 80-kVp protocol with hybrid iterative reconstruction for hepatic dynamic CT can decrease iodine doses while maintaining diagnostic performance and image quality compared with the 120-kVp protocol. ADVANCES IN KNOWLEDGE: The 80- and 120-kVp protocols showed equivalent hepatic lesion detectability, diagnostic ability for HCC, image quality, and HCC-to-liver contrast.The 80-kVp protocol showed a 38.3% reduction in iodine dose compared with the 120-kVp protocol.

Key Imaging Findings for the Prospective Diagnosis of Rare Diseases of the Gallbladder and Cystic Duct.

There are various diseases of the gallbladder and cystic duct, and imaging diagnosis is challenging for the rare among them. However, some rare diseases show characteristic imaging findings or patient history; therefore, familiarity with the imaging presentation of rare diseases may improve diagnostic accuracy and patient management. The purpose of this article is to describe the imaging findings of rare diseases of the gallbladder and cystic duct and identify their pathological correlations with these diseases.

Preoperative CT Findings for Predicting Acute Exacerbation of Interstitial Pneumonia After Lung Cancer Surgery: A Multicenter Case-Control Study.

BACKGROUND. Acute exacerbation (AE) is a life-threatening complication of inter-stitial pneumonia (IP). Thoracic surgery may trigger AE. OBJECTIVE. The purpose of this study is to explore the role of preoperative CT findings in predicting postoperative AE in patients with IP and lung cancer. METHODS. This retrospective case-control study included patients from 22 institutions who had IP and underwent thoracic surgery for lung cancer. AE was diagnosed on the basis of symptoms and imaging findings noted within 30 days after surgery and the absence of alternate causes. For each patient with AE, two control patients without AE were identified. After exclusions, the study included 92 patients (78 men and 14 women; 31 with AE [the AE group] and 61 without AE [the no-AE group]; mean age, 72 years). Two radiologists independently reviewed preoperative thin-slice CT examinations for pulmonary findings and resolved differences by consensus. The AE and no-AE groups were compared using the Fisher exact and Mann-Whitney U tests. Multivariable logistic regression was performed. Interreader agreement was assessed by kappa coefficients. RESULTS. A total of 94% of patients in the AE group underwent segmentectomy or other surgery that was more extensive than wedge resection versus 75% in the no-AE group (p = .046). The usual IP pattern was present in 58% of the AE group versus 74% of the no-AE group (p = .16). According to subjective visual scoring, the mean (± SD) ground-glass opacity (GGO) extent was 6.3 ± 5.4 in the AE group versus 3.9 ± 3.8 in the no-AE group (p = .03), and the mean consolidation extent was 0.5 ± 1.2 in the AE group versus 0.1 ± 0.3 in the no-AE group (p = .009). Mean pulmonary trunk diameter was 28 ± 4 mm in the AE group versus 26 ± 3 mm in the no-AE group (p = .02). In a model of CT features only, independent predictors of AE (p < .05) were GGO extent (odds ratio [OR], 2.8), consolidation extent (OR, 9.4), and pulmonary trunk diameter (OR, 4.2); this model achieved an AUC of 0.75, a PPV of 71%, and an NPV of 77% for AE. When CT and clinical variables were combined, undergoing segmentectomy or more extensive surgery also independently predicted AE (OR, 8.2; p = .02). CONCLUSION. The presence of GGO, consolidation, and pulmonary trunk enlargement on preoperative CT predicts AE in patients with IP who are undergoing lung cancer surgery. CLINICAL IMPACT. Patients with IP and lung cancer should be carefully managed when predictive CT features are present. Wedge resection, if possible, may help reduce the risk of AE in these patients. TRIAL REGISTRATION. University Hospital Medical Information Clinical Trial Registry UMIN000029661.

Multi-arterial phase MRI depicts inconsistent arterial phase hyperenhancement (APHE) subtypes in liver observations of patients at risk for hepatocellular carcinoma.

OBJECTIVES: According to LI-RADS, a major discriminating feature between hepatocellular carcinoma (HCC) and non-HCC malignancies is the subtype of arterial phase hyperenhancement (APHE). The aim of this study was to investigate whether APHE subtypes are consistent across multi-arterial phase (mHAP) MRI acquisitions while evaluating reader agreement. Secondarily, we investigated factors that may affect reader agreement for APHE subtype. METHODS: In this retrospective study, consecutive patients with liver cirrhosis and focal observations who underwent mHAP were included. Five radiologists reviewed MR images in 2 reading sessions. In reading session 1, individual AP series were reviewed and scored for presence of APHE and subtype. In reading session 2, readers scored observations' major and ancillary features and LI-RADS category in the complete MRI examination. Reader agreement was calculated using Fleiss' kappa for binary outcomes and Kendall's coefficient of concordance for LI-RADS categories. Univariate mixed effects logistic regressions were performed to investigate factors affecting agreement. RESULTS: In total, 61 patients with 77 focal observations were analyzed. Of observations unanimously scored as having APHE, 27.7% showed both rim and nonrim subtypes on mHAP. Inter-reader agreement for APHE subtype ranged from 0.49 (95% CI: 0.33, 0.64) to 0.57 (95% CI: 0.40, 0.74) between reading sessions. Observation size had a trend level effect on rim APHE agreement (p = 0.052). CONCLUSION: Approximately 1/3 of observations demonstrated inconsistent APHE subtype during mHAP acquisition. Small lesions were particularly challenging. Further guidance on APHE subtype classification, especially when applied to mHAP, could be a focus of LI-RADS refinement. KEY POINTS: • In a cohort of patients at risk for HCC, 28% of the observations showed inconsistent arterial phase hyperenhancement (APHE) subtypes (rim and nonrim) on multi-arterial phase imaging according to the majority score of 5 independent readers. • Inconsistent APHE subtypes may challenge reliable imaging diagnosis, i.e., LI-RADS categorization, of focal liver observations in patients at risk for HCC.