Reappraising imaging features of pancreatic acinar cystic transformation: be aware of differential diagnoses.

OBJECTIVES: Imaging features of pancreatic acinar cystic transformation (ACT) have been published. We aimed to describe the clinical and radiological characteristics of patients with a presumed pancreatic ACT diagnosis, reappraising the value of these published imaging criteria. MATERIALS AND METHODS: Single-center retrospective study (2003-2021) of consecutive patients with a presumed diagnosis of ACT as suggested by the local expert multidisciplinary case review board. Patients without available imaging (CT or MRI) for review were excluded. Patients were classified into "certain" ACT (if ≥ 2 imaging criteria and no differential diagnosis) or "uncertain" ACT (if ≥ 1 imaging criteria and suggested differential diagnoses). RESULTS: Sixty-four patients (35 males, [55%]) were included. ACT was considered "certain" for 34 patients (53%) and "uncertain" for 30 patients (47%). The number of ACT criteria did not differ between groups, with 91.2% of patients with ≥ 3 ACT imaging criteria in the "certain" group vs 93.3% in the "uncertain" group (p = 0.88). In the "uncertain" group, the main suggested differentials were branch-duct intraductal papillary mucinous neoplasm (18/30 patients, 60%), calcifying chronic pancreatitis (8/30 patients, 27%), both (three patients, 10%) and serous cystadenoma (one patient, 3%). Calcifications were significantly more frequent in the "uncertain" group (89% vs 63% in the "certain" group, p = 0.02). CONCLUSION: Published ACT imaging criteria are frequently associated with features suggesting differential diagnoses. They appear insufficient to reach a final diagnosis in a subset of patients. CLINICAL RELEVANCE STATEMENT: ACT displays a heterogeneous morphological imaging presentation challenging the non-invasive diagnostic work-up. Physicians' and radiologists' awareness of this entity is important to better understand its natural history and improve non-invasive diagnostic criteria. KEY POINTS: The criteria to help diagnose ACT are frequently associated with features suggestive of differentials. The main alternatives suggested when ACT diagnosis was "uncertain" were branch-duct intraductal papillary mucinous neoplasm and calcifying chronic pancreatitis. Published ACT diagnostic imaging criteria can be insufficient for a definite non-invasive diagnosis.

Predictors of Survival Without Intestinal Resection after First-Line Endovascular Revascularization in Patients with Acute Arterial Mesenteric Ischemia.

Background Acute arterial mesenteric ischemia requires emergency treatment and is associated with high mortality rate and poor quality of life. Identifying factors associated with survival without intestinal resection (hereafter, intestinal resection-free [IRF] survival) could help in treatment decision-making after first-line endovascular revascularization. Purpose To identify factors associated with 30-day IRF survival in patients with acute arterial mesenteric ischemia whose first-line treatment was endovascular revascularization. Materials and Methods Patients with acute arterial mesenteric ischemia whose first-line treatment was endovascular revascularization because of a low probability of bowel necrosis were included in this single-center retrospective cohort (May 2014 to August 2022). Patient demographics, laboratory values, clinical characteristics at admission, CT scans, angiograms, and endovascular revascularization-related variables were included. The primary end point was 30-day IRF survival, and secondary end points were 3-month, 1-year, and 3-year overall survival. Factors independently associated with 30-day IRF survival were identified with binary logistic regression. Results A total of 117 patients (median age, 70 years [IQR, 60-77]; 53 female, 64 male) were included. Within 30 days after revascularization, 73 of 117 patients (62%) survived without resection, 28 of 117 (24%) survived after resection, 14 of 117 (12%) died without resection, and two of 117 (2%) underwent resection but died. The 30-day IRF survival was 63% (74 of 117). The 3-month, 1-year, and 3-year mortality rate was 18% (21 of 117), 21% (25 of 117), and 27% (32 of 117), respectively. Independent predictors of 30-day IRF survival were persistent bowel enhancement at initial CT (odds ratio [OR], 0.3; 95% CI: 0.2, 0.8; P = .013) and C-reactive protein (CRP) level less than 100 mg/L (OR, 0.3; 95% CI: 0.1, 0.8; P = .002). The 30-day IRF survival was 86%, 61%, 47%, and 23% in patients with both favorable features, persistent bowel enhancement but CRP level greater than 100 mg/L, no bowel enhancement but CRP level less than 100 mg/L, and both unfavorable features, respectively. Conclusion Independent predictors associated with 30-day IRF survival in patients with acute arterial mesenteric ischemia whose first-line treatment was endovascular revascularization were persistent bowel wall enhancement at initial CT and CRP level less than 100 mg/L. © RSNA, 2024 Supplemental material is available for this article.

Clinical management of liver cyst infections: an international, modified Delphi-based clinical decision framework.

Liver cyst infections often necessitate long-term hospital admission and are associated with considerable morbidity and mortality. We conducted a modified Delphi study to reach expert consensus for a clinical decision framework. The expert panel consisted of 24 medical specialists, including 12 hepatologists, from nine countries across Europe, North America, and Asia. The Delphi had three rounds. The first round (response rate 21/24 [88%]) was an online survey with questions constructed from literature review and expert opinion, in which experts were asked about their management preferences and rated possible management strategies for seven clinical scenarios. Experts also rated 14 clinical decision-making items for relevancy and defined treatment outcomes. During the second round (response rate 13/24 [54%]), items that did not reach consensus and newly suggested themes were discussed in an online panel meeting. In the third round (response rate 16/24 [67%]), experts voted on definitions and management strategies using an online survey based on previous answers. Consensus was predefined as a vote threshold of at least 75%. We identified five subclassifications of liver cyst infection according to cyst phenotypes and patient immune status and consensus on episode definitions (new, persistent, and recurrent) and criteria for treatment success or failure was reached. The experts agreed that fever and elevated C-reactive protein are pivotal decision-making items for initiating and evaluating the management of liver cyst infections. Consensus was reached on 26 management statements for patients with liver cyst infections across multiple clinical scenarios, including two treatment algorithms, which were merged into one after comments. We provide a clinical decision framework for physicians managing patients with liver cyst infections. This framework will facilitate uniformity in the management of liver cyst infections and can constitute the basis for the development of future guidelines.

Integration of new technologies in the multidisciplinary approach to primary liver tumours: The next-generation tumour board.

Primary liver tumours, including benign liver tumours, hepatocellular carcinoma and cholangiocarcinoma, present a multifaceted challenge, necessitating a collaborative approach, as evidenced by the role of the multidisciplinary tumour board (MDTB). The approach to managing primary liver tumours gathers specialized teams, including surgeons, radiologists, oncologists, pathologists, hepatologists, and radiation oncologists, to propose individualized treatment plans. The evolving landscape of primary liver cancer treatment introduces complexities, particularly with the expanding array of systemic and locoregional therapies, alongside the potential integration of molecular biology and artificial intelligence (AI) into MDTB in the future. Precision medicine demands collaboration across disciplines, challenging traditional frameworks. The next decade anticipates the convergence of AI, molecular biology, pathology, and advanced imaging, requiring adaptability in MDTB structure to incorporate these cutting-edge technologies. Navigating this evolution also requires a focus on enhancing basic, translational, and clinical research, as well as boosting clinical trials through an upgraded use of MDTBs as hubs for scientific collaboration and raising literacy about AI and new technologies. In this review, we will delineate the current unmet needs in the clinical management of primary liver cancers, discuss our perspective on the future role of MDTBs in primary liver cancers ("next generation" MDTBs), and unravel the potential power and limitations of novel technologies that may shape the multidisciplinary care landscape for primary liver cancers in the coming decade.

Hepatic compartment syndrome, a rare complication after any liver insult or liver transplantation: Three case reports and literature review.

Hepatic compartment syndrome (HCS) is a rare but life-threatening entity that consists of a decreased portal flow due to intraparenchymal hypertension secondary to subcapsular liver hematoma. Lethal liver failure can be observed. We report three cases, and review the literature. A 54-year-old male was admitted for extensive hepatic subcapsular hematoma after blunt abdominal trauma. Initially, he underwent embolization of the hepatic artery's right branch, after which he presented clinical deterioration, major cytolysis (310 times the upper limit of normal [ULN]), and liver failure with a prothrombin time (PT) at 31.0%. A 56-year-old male underwent liver transplantation for acute alcoholic hepatitis. On postoperative day 2, he presented a hemorrhagic shock associated with deterioration of liver function (cytolysis 21 ULN, PT 39.0%) due to extensive hepatic subcapsular hematoma. A 59-year-old male presented a hepatic subcapsular hematoma five days after a cholecystectomy, revealed by abdominal pain with liver dysfunction (cytolysis 10 ULN, PT 63.0%). All patients ultimately underwent urgent surgery for liver capsule excision, hematoma evacuation, and liver packing, if needed. The international literature was screened for this entity. These three patients' outcomes were favorable, and all were alive at postoperative day 90. The literature review found 15 reported cases. HCS can occur after any direct or indirect liver trauma. Surgical decompression is the main treatment, and there is probably no place for arterial embolization, which may increase the risk of liver necrosis. A 13.3% mortality rate is reported. HCS is a rare complication of subcapsular liver hematoma that compresses the liver parenchyma, and leads to liver failure. Urgent surgical decompression is needed.

Adding Short to Left Gastric Artery Embolization for the Treatment of Obesity: Safety and Effectiveness.

PURPOSE: This study assessed the safety and effectiveness of a technical modification that involves adding short gastric artery (SGA) embolization to left gastric artery (LGA) embolization. MATERIAL AND METHODS: This retrospective single-center study analyzed twenty obese patients (median age of 53.5 (30-73)) who were not eligible for bariatric surgery and underwent bariatric embolization with 300-500-µm microspheres in addition to a lifestyle counseling program between March 2021 and July 2022. Eight patients had LGA + SGA embolization, and twelve had LGA embolization alone. The primary outcome measure was total body weight loss (TBWL) at 6 months in the SGA + LGA and the LGA-only cohorts. Safety was assessed, defined as the 30-day adverse events rate according to the SIR classification. RESULTS: The mean 6-month post-embolization TBWL in the SGA + LGA cohort was 7.3 kg (95%CI 2.1-12.4; p = .01) and 4.1 kg (95%CI 0.4-8.6; p = 0.034) in the LGA-only cohort (mean difference - 3.1 kg ± 2.8; 95%CI (- 9.1-2.8); p = .28). The mean 6-month post-embolization TBWL in the entire cohort was 5.3 kg (p < .01). The rate of complications was similar between the two groups. CONCLUSION: Combined SGA and LGA embolization is safe and effective to treat obesity. Larger studies are needed to determine whether SGA + LGA embolization results in more significant weight loss than LGA embolization alone.

Ultrasound-based steatosis grading system using 2D-attenuation imaging: An individual patient data meta-analysis with external validation.

BACKGROUND AND AIMS: Noninvasive tools assessing steatosis, such as ultrasonography-based 2D-attenuation imaging (ATI), are needed to tackle the worldwide burden of steatotic liver disease. This one-stage individual patient data (IPD) meta-analysis aimed to create an ATI-based steatosis grading system. APPROACH AND RESULTS: A systematic review (EMBASE + MEDLINE, 2018-2022) identified studies, including patients with histologically or magnetic resonance imaging proton-density fat fraction (MRI-PDFF)-verified ATI for grading steatosis (S0 to S3). One-stage IPD meta-analyses were conducted using generalized mixed models with a random study-specific intercept. Created ATI-based steatosis grading system (aS0 to aS3) was externally validated on a prospective cohort of patients with type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (n=174, histologically and MRI-PDFF-verified steatosis). Eleven enrolled studies included 1374 patients, classified into S0, S1, S2, and S3 in 45.4%, 35.0%, 9.3%, and 10.3% of the cases. ATI was correlated with histological steatosis ( r = 0.60; 95% CI: 0.52, 0.67; p < 0.001) and MRI-PDFF ( r = 0.70; 95% CI: 0.66, 0.73; p < 0.001) but not with liver stiffness ( r = 0.03; 95% CI: -0.04, 0.11, p = 0.343). Steatosis grade was an independent factor associated with ATI (coefficient: 0.24; 95% CI: [0.22, 0.26]; p < 0.001). ATI marginal means within S0, S1, S2, and S3 subpopulations were 0.59 (95% CI: [0.58, 0.61]), 0.69 (95% CI [0.67, 0.71]), 0.78 (95% CI: [0.76, 0.81]), and 0.85 (95% CI: [0.83, 0.88]) dB/cm/MHz; all contrasts between grades were significant ( p < 0.0001). Three ATI thresholds were calibrated to create a new ATI-based steatosis grading system (aS0 to aS3, cutoffs: 0.66, 0.73, and 0.81 dB/cm/MHz). Its external validation showed Obuchowski measures of 0.84 ± 0.02 and 0.82 ± 0.02 with histologically based and MRI-PDFF-based references. CONCLUSIONS: ATI is a reliable, noninvasive marker of steatosis. This validated ATI-based steatosis grading system could be valuable in assessing patients with metabolic dysfunction-associated steatotic liver disease.

Biliary tract cancers: French national clinical practice guidelines for diagnosis, treatments and follow-up (TNCD, SNFGE, FFCD, UNICANCER, GERCOR, SFCD, SFED, AFEF, SFRO, SFP, SFR, ACABi, ACHBPT).

INTRODUCTION: This document is a summary of the French intergroup guidelines of the management of biliary tract cancers (BTC) (intrahepatic, perihilar and distal cholangiocarcinomas, and gallbladder carcinomas) published in September 2023, available on the website of the French Society of Gastroenterology (SNFGE) (www.tncd.org). METHODS: This collaborative work was conducted under the auspices of French medical and surgical societies involved in the management of BTC. Recommendations were graded in three categories (A, B and C) according to the level of scientific evidence until August 2023. RESULTS: BTC diagnosis and staging is mainly based on enhanced computed tomography, magnetic resonance imaging and (endoscopic) ultrasound-guided biopsy. Treatment strategy depends on BTC subtype and disease stage. Surgery followed by adjuvant capecitabine is recommended for localised disease. No neoadjuvant treatment is validated to date. Cisplatin-gemcitabine chemotherapy combined to the anti-PD-L1 inhibitor durvalumab is the first-line standard of care for advanced disease. Early systematic tumour molecular profiling is recommended to screen for actionable alterations (IDH1 mutations, FGFR2 rearrangements, HER2 amplification, BRAFV600E mutation, MSI/dMMR status, etc.) and guide subsequent lines of treatment. In the absence of actionable alterations, FOLFOX chemotherapy is the only second-line standard-of-care. No third-line chemotherapy standard is validated to date. CONCLUSION: These guidelines are intended to provide a personalised therapeutic strategy for daily clinical practice. Each individual BTC case should be discussed by a multidisciplinary team.

Imaging and prognostic characterization of fat-containing hepatocellular carcinoma subtypes.

PURPOSE: Steatohepatitic hepatocellular carcinoma (SH-HCC) is characterized by intratumoral fat with > 50% inflammatory changes. However, intratumoral fat (with or without inflammation) can also be found in not-otherwise specified HCC (NOS-HCC). We compared the imaging features and outcome of resected HCC containing fat on pathology including SH-HCC (> 50% steatohepatitic component), NOS-HCC with < 50% steatohepatitic component (SH-NOS-HCC), and fatty NOS-HCC (no steatohepatitic component). MATERIAL AND METHODS: From September 2012 to June 2021, 94 patients underwent hepatic resection for fat-containing HCC on pathology. Imaging features and categories were assessed using LIRADS v2018. Fat quantification was performed on chemical-shift MRI. Recurrence-free and overall survival were estimated. RESULTS: Twenty-one patients (26%) had nonalcoholic steatohepatitis (NASH). The median intra-tumoral fat fraction was 8%, with differences between SH-HCC and SH-NOS-HCC (9.5% vs. 5% p = 0.03). There was no difference in major LI-RADS features between all groups; most tumors were classified as LR-4/5. A mosaic architecture on MRI was rare (7%) in SH-HCC, a fat in mass on CT was more frequently depicted (48%) in SH-HCC. A combination of NASH with no mosaic architecture on MRI or NASH with fat in mass on CT yielded excellent specificity for diagnosing SH-HCC (97.6% and 97.7%, respectively). The median recurrence-free and overall survival were 58 and 87 months, with no difference between groups (p = 0.18 and p = 0.69). CONCLUSION: In patients with NASH, an SH-HCC may be suspected in L4/LR-5 observations with no mosaic architecture at MRI or with fat in mass on CT. Oncological outcomes appear similar between fat-containing HCC subtypes.

Study protocol for FASTRAK: a randomised controlled trial evaluating the cost impact and effectiveness of FAST-MRI for HCC suRveillance in pAtients with high risK of liver cancer.

INTRODUCTION: The surveillance of hepatocellular carcinoma (HCC) using semi-annual liver ultrasound (US) is justified in patients with cirrhosis. In this context, US has a low sensitivity (<30%) for the detection of HCC at the very early stage (ie, Barcelona clinic liver cancer (BCLC) 0, uninodular tumour <2 cm). The sensitivity of abbreviated liver MRI (AMRI) is reported to exceed 80%, but its use is hampered by costs and availability. Our hypothesis is that AMRI used as a screening examination in patients at high risk of HCC (>3% per year) could increase the rates of patients with a tumour detected at an early stage accessible to curative-intent treatment, and demonstrate its cost-effectiveness in this population. METHODS AND ANALYSIS: The FASTRAK trial is a multicentre, randomised controlled trial with two parallel arms, aiming for superiority and conducted on patients at high risk for HCC (yearly HCC incidence >3%). Randomisation will be conducted on an individual basis with a centralised approach and stratification by centre. After inclusion in the trial, each patient will be randomly assigned to the experimental group (semi-annual US and AMRI) or the control group (semi-annual US alone). The main objective is to assess the cost/quality-adjusted life year and cost/patient detected with a BCLC 0 HCC in both arms. A total of 944 patients will be recruited in 37 tertiary French centres during a 36-month period and will be followed-up during 36 months. ETHICS AND DISSEMINATION: The FASTRAK trial received ethical approval on 4 April 2022. Results will be disseminated via publication in peer-reviewed journals as well as presentation at international conferences. TRIAL REGISTRATION NUMBER: Clinical trial number (ClinicaTrials.gov) NCT05095714.

Association of LI-RADS and Histopathologic Features with Survival in Patients with Solitary Resected Hepatocellular Carcinoma.

Background Both Liver Imaging Reporting and Data System (LI-RADS) and histopathologic features provide prognostic information in patients with hepatocellular carcinoma (HCC), but whether LI-RADS is independently associated with survival is uncertain. Purpose To assess the association of LI-RADS categories and features with survival outcomes in patients with solitary resected HCC. Materials and Methods This retrospective study included patients with solitary resected HCC from three institutions examined with preoperative contrast-enhanced CT and/or MRI between January 2008 and December 2019. Three independent readers evaluated the LI-RADS version 2018 categories and features. Histopathologic features including World Health Organization tumor grade, microvascular and macrovascular invasion, satellite nodules, and tumor capsule were recorded. Overall survival and disease-free survival were assessed with Cox regression models. Marginal effects of nontargetoid features on survival were estimated using propensity score matching. Results A total of 360 patients (median age, 64 years [IQR, 56-70 years]; 280 male patients) were included. At CT and MRI, the LI-RADS LR-M category was associated with increased risk of recurrence (CT: hazard ratio [HR] = 1.83 [95% CI: 1.26, 2.66], P = .001; MRI: HR = 2.22 [95% CI: 1.56, 3.16], P < .001) and death (CT: HR = 2.47 [95% CI: 1.72, 3.55], P < .001; MRI: HR = 1.80 [95% CI: 1.32, 2.46], P < .001) independently of histopathologic features. The presence of at least one nontargetoid feature was associated with an increased risk of recurrence (CT: HR = 1.80 [95% CI: 1.36, 2.38], P < .001; MRI: HR = 1.93 [95% CI: 1.81, 2.06], P < .001) and death (CT: HR = 1.51 [95% CI: 1.10, 2.07], P < .010) independently of histopathologic features. In matched samples, recurrence was associated with the presence of at least one nontargetoid feature at CT (HR = 2.06 [95% CI: 1.15, 3.66]; P = .02) or MRI (HR = 1.79 [95% CI: 1.01, 3.20]; P = .048). Conclusion In patients with solitary resected HCC, LR-M category and nontargetoid features were negatively associated with survival independently of histopathologic characteristics. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Kartalis and Grigoriadis in this issue.

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.

Factors Impacting Survival After Transarterial Radioembolization in Patients with Unresectable Intrahepatic Cholangiocarcinoma: A Combined Analysis of the Prospective CIRT Studies.

PURPOSE: Transarterial radioembolization (TARE) with Yttrium-90 resin microspheres is a treatment option for patients with intrahepatic cholangiocarcinoma (ICC). However, optimising the timing of TARE in relation to systemic therapies and patient selection remains challenging. We report here on the effectiveness, safety, and prognostic factors associated with TARE for ICC in a combined analysis of the prospective observational CIRT studies (NCT02305459 and NCT03256994). METHODS: A combined analysis of 174 unresectable ICC patients enrolled between 2015 and 2020 was performed. Patient characteristics and treatment-related data were collected at baseline; adverse events and time-to-event data (overall survival [OS], progression-free survival [PFS] and hepatic PFS) were collected at every follow-up visit. Log-rank tests and a multivariable Cox proportional hazard model were used to identify prognostic factors. RESULTS: Patients receiving a first-line strategy of TARE in addition to any systemic treatment had a median OS and PFS of 32.5 months and 11.3 months. Patients selected for first-line TARE alone showed a median OS and PFS of 16.2 months and 7.4 months, whereas TARE as 2nd or further treatment-line resulted in a median OS and PFS of 12 and 9.3 months (p = 0.0028), and 5.1 and 3.5 months (p = 0.0012), respectively. Partition model dosimetry was an independent predictor for better OS (HR 0.59 [95% CI 0.37-0.94], p = 0.0259). No extrahepatic disease, no ascites, and < 6.1 months from diagnosis to treatment were independent predictors for longer PFS. CONCLUSION: This combined analysis indicates that in unresectable ICC, TARE in combination with any systemic treatment is a promising treatment option. LEVEL OF EVIDENCE: level 3, Prospective observational.

Automated MRI liver segmentation for anatomical segmentation, liver volumetry, and the extraction of radiomics.

OBJECTIVES: To develop and evaluate a deep convolutional neural network (DCNN) for automated liver segmentation, volumetry, and radiomic feature extraction on contrast-enhanced portal venous phase magnetic resonance imaging (MRI). MATERIALS AND METHODS: This retrospective study included hepatocellular carcinoma patients from an institutional database with portal venous MRI. After manual segmentation, the data was randomly split into independent training, validation, and internal testing sets. From a collaborating institution, de-identified scans were used for external testing. The public LiverHccSeg dataset was used for further external validation. A 3D DCNN was trained to automatically segment the liver. Segmentation accuracy was quantified by the Dice similarity coefficient (DSC) with respect to manual segmentation. A Mann-Whitney U test was used to compare the internal and external test sets. Agreement of volumetry and radiomic features was assessed using the intraclass correlation coefficient (ICC). RESULTS: In total, 470 patients met the inclusion criteria (63.9±8.2 years; 376 males) and 20 patients were used for external validation (41±12 years; 13 males). DSC segmentation accuracy of the DCNN was similarly high between the internal (0.97±0.01) and external (0.96±0.03) test sets (p=0.28) and demonstrated robust segmentation performance on public testing (0.93±0.03). Agreement of liver volumetry was satisfactory in the internal (ICC, 0.99), external (ICC, 0.97), and public (ICC, 0.85) test sets. Radiomic features demonstrated excellent agreement in the internal (mean ICC, 0.98±0.04), external (mean ICC, 0.94±0.10), and public (mean ICC, 0.91±0.09) datasets. CONCLUSION: Automated liver segmentation yields robust and generalizable segmentation performance on MRI data and can be used for volumetry and radiomic feature extraction. CLINICAL RELEVANCE STATEMENT: Liver volumetry, anatomic localization, and extraction of quantitative imaging biomarkers require accurate segmentation, but manual segmentation is time-consuming. A deep convolutional neural network demonstrates fast and accurate segmentation performance on T1-weighted portal venous MRI. KEY POINTS: • This deep convolutional neural network yields robust and generalizable liver segmentation performance on internal, external, and public testing data. • Automated liver volumetry demonstrated excellent agreement with manual volumetry. • Automated liver segmentations can be used for robust and reproducible radiomic feature extraction.

Automated Assessment of T2-Weighted MRI to Differentiate Malignant and Benign Primary Solid Liver Lesions in Noncirrhotic Livers Using Radiomics.

RATIONALE AND OBJECTIVES: Distinguishing malignant from benign liver lesions based on magnetic resonance imaging (MRI) is an important but often challenging task, especially in noncirrhotic livers. We developed and externally validated a radiomics model to quantitatively assess T2-weighted MRI to distinguish the most common malignant and benign primary solid liver lesions in noncirrhotic livers. MATERIALS AND METHODS: Data sets were retrospectively collected from three tertiary referral centers (A, B, and C) between 2002 and 2018. Patients with malignant (hepatocellular carcinoma and intrahepatic cholangiocarcinoma) and benign (hepatocellular adenoma and focal nodular hyperplasia) lesions were included. A radiomics model based on T2-weighted MRI was developed in data set A using a combination of machine learning approaches. The model was internally evaluated on data set A through cross-validation, externally validated on data sets B and C, and compared to visual scoring of two experienced abdominal radiologists on data set C. RESULTS: The overall data set included 486 patients (A: 187, B: 98, and C: 201). The radiomics model had a mean area under the curve (AUC) of 0.78 upon internal validation on data set A and a similar AUC in external validation (B: 0.74 and C: 0.76). In data set C, the two radiologists showed moderate agreement (Cohen's κ: 0.61) and achieved AUCs of 0.86 and 0.82. CONCLUSION: Our T2-weighted MRI radiomics model shows potential for distinguishing malignant from benign primary solid liver lesions. External validation indicated that the model is generalizable despite substantial MRI acquisition protocol differences. Pending further optimization and generalization, this model may aid radiologists in improving the diagnostic workup of patients with liver lesions.