Risk of Bias in Liver Imaging Reporting and Data System Studies Using QUADAS-2

Purpose: Use a tailored version of the Quality Assessment of Diagnostic Accuracy Studies tool to evaluate risk of bias and applicability across LIRADS related publications. Method: A tailored QUADAS-2 tool was created through consensus approach to assess risk of bias and applicability across 37 LI-RADS related publications. Studies were selected from 2017 to 2022 using the assistance of experienced hospital librarians to search for studies evaluating the diagnostic accuracy of CT, MRI, or contrast-enhanced ultrasound for HCC using LI-RADS through multiple different databases. QUADAS-2 assessments were performed in duplicate and independently by 2 authors with experience using the QUADAS-2 tool. Disagreements were resolved with a third expert reviewer. Consensus QUADAS-2 assessments were tabulated for each domain. Results: Using the tailored QUADAS-2 tool, 31 of the 37 included LI-RADS studies were assessed as high risk of bias, and 9 out of 37 studies demonstrated concerns for applicability. Patient selection (21 out of 37 studies) and flow/timing (24 out of 37 studies) domains demonstrated the highest risk of bias. 6 out of 37 studies in the index domain demonstrated high risk of bias. 2 out of 37 studies showed high risk of bias in the reference standard domain. Conclusion: A significant proportion of LI-RADS research is at risk of bias with concerns for applicability. Identifying risk of bias in such research is essential to recognize limitations of a study that may affect the validity of the results. Areas for improvement in LI-RADS research include reducing selection bias, avoiding inappropriate exclusions, and decreasing verification bias.

Performance of LI-RADS category 5 vs combined categories 4 and 5: a systemic review and meta-analysis

OBJECTIVE

Computed tomography (CT)/magnetic resonance imaging (MRI) Liver Imaging Reporting and Data System (LI-RADS, LR) category 5 has high specificity and modest sensitivity for diagnosis of hepatocellular carcinoma (HCC). The purpose of this study was to compare the diagnostic performance of LR-5 vs combined LR-4 and LR-5 (LR-4/5) for HCC diagnosis.

METHODS

MEDLINE and EMBASE databases through January 03, 2023 were searched for studies reporting the performance of LR-5 and combined LR-4/5 for HCC diagnosis, using CT/MRI LI-RADS version 2014, 2017, or 2018. A bivariate random-effects model was used to calculate the pooled per-observation diagnostic performance. Subgroup analysis was performed based on imaging modalities and type of MRI contrast material.

RESULTS

Sixty-nine studies (15,108 observations, 9928 (65.7%) HCCs) were included. Compared to LR-5, combined LR-4/5 showed significantly higher pooled sensitivity (83.0% (95% CI [80.3-85.8%]) vs 65.7% (95% CI [62.4-69.1%]); p < 0.001), lower pooled specificity (75.0% (95% CI [70.5-79.6%]) vs 91.7% (95% CI [90.2-93.1%]); p < 0.001), lower pooled positive likelihood ratio (3.60 (95% CI [3.06-4.23]) vs 6.18 (95% CI [5.35-7.14]); p < 0.001), and lower pooled negative likelihood ratio (0.22 (95% CI [0.19-0.25]) vs 0.38 (95% CI [0.35-0.41]) vs; p < 0.001). Similar results were seen in all subgroups.

CONCLUSIONS

Our meta-analysis showed that combining LR-4 and LR-5 would increase sensitivity but decrease specificity, positive likelihood ratio, and negative likelihood ratio. These findings may inform management guidelines and individualized management.

CLINICAL RELEVANCE STATEMENT

This meta-analysis estimated the magnitude of changes in the sensitivity and specificity of imaging criteria when LI-RADS categories 4 and 5 were combined; these findings can inform management guidelines and individualized management.

KEY POINTS

There is no single worldwide reporting system for liver imaging, partly due to regional needs. Combining LI-RADS categories 4 and 5 increased sensitivity and decreased specificity and positive and negative likelihood ratios. Changes in the sensitivity and specificity of imaging criteria can inform management guidelines and individualized management.

Best Practice for MRI Diagnostic Accuracy Research With Lessons and Examples from the LI-RADS Individual Participant Data Group

Medical imaging diagnostic test accuracy research is strengthened by adhering to best practices for study design, data collection, data documentation, and study reporting. In this review, key elements of such research are discussed, and specific recommendations provided for optimizing diagnostic accuracy study execution to improve uniformity, minimize common sources of bias and avoid potential pitfalls. Examples are provided regarding study methodology and data collection practices based on insights gained by the liver imaging reporting and data system (LI-RADS) individual participant data group, who have evaluated raw data from numerous MRI diagnostic accuracy studies for risk of bias and data integrity. The goal of this review is to outline strategies for investigators to improve research practices, and to help reviewers and readers better contextualize a study's findings while understanding its limitations. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Magnetic resonance elastography as a preoperative assessment for predicting intrahepatic recurrence in patients with hepatocellular carcinoma

PURPOSE

Magnetic resonance elastography (MRE) is a noninvasive tool for diagnosing hepatic fibrosis with high accuracy. We investigated the preoperative clinical and imaging predictors of intrahepatic recurrence after curative resection of hepatocellular carcinoma (HCC), and evaluated MRE as a predictor of intrahepatic recurrence.

METHODS

We retrospectively evaluated 80 patients who underwent preoperative contrast-enhanced magnetic resonance imaging (MRI) with two-dimensional MRE and curative resection for treatment-naïve HCC between May 2019 and December 2021. Liver stiffness (LS) was measured on the elastograms, and the optimal cutoff of LS for predicting intrahepatic recurrence was obtained using receiver operating characteristic (ROC) analysis. An LS above this cutoff was defined as MRE-recurrence. Preoperative imaging features of the tumor were assessed on MRI, including features in the Liver Imaging Reporting and Data System and microvascular invasion (MVI). Recurrence-free survival (RFS) rates were estimated using the Kaplan-Meier method, and differences were compared using the log-rank test. Using a Cox proportional hazards model, we conducted a multivariable analysis to investigate the factors affecting recurrence-free survival.

RESULTS

During a median follow-up period of 32 months (range, 4-52 months), thirteen patients (16.3%) developed intrahepatic recurrence. ROC analysis determined an LS cutoff of ≥4.35 kPa to define MRE-recurrence. The 4-year RFS rate was significantly higher in patients without MRE-recurrence than in those with MRE-recurrence (93.4% vs. 48.9%; p = 0.001). In multivariable analysis, MRE-recurrence (Hazard ratio [HR], 5.9; 95% confidence interval [CI], 1.5-23.1) and MVI (HR, 3.4; 95% CI, 1.0-11.3) were independent predictors of intrahepatic recurrence.

CONCLUSIONS

Patients without MRE-recurrence had significantly higher RFS rates than those with MRE-recurrence. MRE-recurrence and MVI were independent predictors of intrahepatic recurrence in patients after curative resection for HCC.

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.

Proliferative hepatocellular carcinomas in cirrhosis: patient outcomes of LI-RADS category 4/5 and category M

OBJECTIVES

We aimed to compare Liver Imaging Reporting and Data System (LI-RADS) category 4/5 and category M (LR-M) of proliferative hepatocellular carcinomas (HCCs) in cirrhotic patients and evaluate their impacts on prognosis.

METHODS

This retrospective multi-reader study included cirrhotic patients with single treatment-naïve HCC ≤ 5.0 cm who underwent contrast-enhanced CT, MRI, and subsequent hepatic resection within 2 months. The percentages of CT/MRI LR-4/5 and LR-M in proliferative and non-proliferative HCCs were compared. Univariable and multivariable Cox proportional hazards regression analyses were performed to assess the association of LI-RADS categories (LR-4/5 vs. LR-M) and pathologic classification (proliferative vs. non-proliferative) with overall survival (OS) and recurrence-free survival (RFS). Subgroups of patients with proliferative and non-proliferative HCCs were analyzed to compare OS and RFS between LR-4/5 and LR-M.

RESULTS

Of the 204 included patients, 38 were classified as having proliferative HCC. The percentages of LR-M were higher in proliferative than non-proliferative HCC on both CT (15.8% vs. 3.0%, p = 0.007) and MRI (26.3% vs. 9.6%, p = 0.016). Independent of pathologic classification, CT and MRI LR-M were significantly associated with poorer OS (hazard ratio (HR) = 4.58, p = 0.013, and HR = 6.45, p < 0.001) and RFS (HR = 3.66, p = 0.005, and HR = 6.44, p < 0.001) than LR-4/5. MRI LR-M was associated with significantly poorer OS (p ≤ 0.003) and RFS (p < 0.001) than MRI LR-4/5 in both proliferative and non-proliferative HCCs.

CONCLUSIONS

This multi-reader study showed that the percentages of LR-M were significantly higher in proliferative than non-proliferative HCCs. CT/MRI LR-M was significantly associated with poor OS and RFS, independent of the pathologic classification of proliferative versus non-proliferative HCCs.

CLINICAL RELEVANCE STATEMENT

CT and MRI LI-RADS category M can be clinically useful in predicting poor outcomes in patients with proliferative and non-proliferative hepatocellular carcinomas.

KEY POINTS

• The percentages of LR-M tumors on both CT and MRI were significantly higher in proliferative than non-proliferative hepatocellular carcinomas. • Independent of pathologic classification, CT/MRI LR-M categories were correlated with poor overall survival and recurrence-free survival. • Patients with both proliferative and non-proliferative hepatocellular carcinomas categorized as MRI LR-M had significantly poorer overall survival and recurrence-free survival than those categorized as MRI LR-4/5.

A Modified Targetoid Feature Emphasizing Thin-Rim APHE to Improve the Diagnostic Performance of LI-RADS for Malignant Hepatic Tumors

Objective

To identify imaging features that help distinguish between HCCs and non-HCC malignancies assigned to LI-RADS M (LR-M) and evaluate the diagnostic performance of a LI-RADS with targetoid criteria using thin-rim arterial phase hyperenhancement (APHE).

Materials and Methods

This retrospective study included 381 patients (387 observations) at high-risk for HCC who underwent enhanced-MRI before surgery. Three radiologists reviewed images for LI-RADS categorization of hepatic observations. Univariate and multivariate analysis was conducted to determine reliable features to differentiate between HCC and non-HCC malignancies among the LR-M lesions. The thin-rim (<30%) APHE was defined based on the thickest thickness of rim APHE compared with the tumor radius, and a modified LI-RADS emphasizing thin-rim APHE as a specific feature of LR-M was established. We compared the diagnostic performance of modified LR-M and LI-RADS 5 (LR-5) with the conventional one.

Results

Thin-rim APHE and targetoid diffusion-weighted imaging (DWI) were found as independent predictive factors of non-HCC malignancies, while enhancing capsule, thick-rim APHE and peripheral washout were noted as independent variables significantly associated with HCC of LR-M (P<0.05). The noticeable diagnostic performance of thin-rim APHE in distinguishing non-HCC malignancies from HCCs using the ROC curve. Emphasizing thin-rim APHE on targetoid features, the modified LR-M revealed significantly superior specificity and accuracy (89.4% vs 81.1%, P=0.004; and 87.9% vs 82.2%, P=0.027, respectively) while maintaining high sensitivity (82.2% vs 86.0%; P=0.529) compared with the LR-M. Meanwhile, the modified LR-5 achieved greater sensitivity and accuracy (88.6% vs 79.7%, P=0.004; and 85.8% vs 80.1%, P=0.036, respectively) for diagnosing HCC, without compromising specificity (78.3% vs.81.1%; P=0.608) compared with the LR-5.

Conclusion

Thin-rim APHE may be the specific imaging feature for differentiating non-HCC malignancies from HCCs within LR-M. The modified targetoid criteria emphasizing thin-rim APHE can improve the diagnostic performance of LI-RADS for hepatic malignancies.

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 category is associated with treatment outcomes of small single HCC: surgical resection vs. radiofrequency ablation

OBJECTIVES

To assess whether the Liver Imaging Reporting and Data System (LI-RADS) category is associated with the treatment outcomes of small single hepatocellular carcinoma (HCC) after surgical resection (SR) and radiofrequency ablation (RFA).

METHODS

This retrospective study included 357 patients who underwent SR (n = 209) or RFA (n = 148) for a single HCC of ≤ 3 cm between 2014 and 2016. LI-RADS categories were assigned. Overall survival (OS), recurrence-free survival (RFS), and local tumor progression (LTP) rates after treatment were compared according to the LI-RADS category (LR-4/5 vs. LR-M) before and after propensity score matching (PSM). Prognostic factors for treatment outcomes were assessed.

RESULTS

In total, 357 patients (mean age, 59 years; men, 272) with 357 HCCs (294 LR-4/5 and 63 LR-M) were included. After PSM (n = 78 in each treatment group), there were 10 and 11 LR-M HCCs in the SR and RFA group, respectively. There were no significant differences in OS or RFS. However, SR provided a lower 5-year LTP rate than RFA (1.4% vs. 14.9%, p = 0.001). SR provided a lower 5-year LTP rate than RFA for LR-M HCCs (0% vs. 34.4%, p = 0.062) and LR-4/5 HCCs (1.5% vs. 12.0%, p = 0.008). The LI-RADS category was the sole risk factor associated with poor OS (hazard ratio [HR] 3.79, p = 0.004), RFS (HR 2.12; p = 0.001), and LTP (HR 2.89; p = 0.032).

CONCLUSION

LI-RADS classification is associated with the treatment outcome of HCC, supporting favorable outcomes of SR over RFA for LTP, especially for HCCs categorized as LR-M.

CLINICAL RELEVANCE STATEMENT

Liver Imaging Reporting and Data System category has a potential prognostic role, supporting favorable outcomes of surgical resection over radiofrequency ablation for local tumor progression, especially for hepatocellular carcinoma categorized as LR-M.

KEY POINTS

• SR provided a lower 5-year LTP rate than RFA for HCCs categorized as LR-M (0% vs. 34.4%, p = 0.062) and HCCs categorized as LR-4/5 (1.5% vs. 12.0%, p = 0.008). • There is a steeply increased risk of LTP within 1 year after RFA for LR-M HCCs, compared to SR. • The LI-RADS category was the sole risk factor associated with poor OS (HR 3.79, p = 0.004), RFS (HR 2.12; p = 0.001), and LTP (HR 2.89; p = 0.032) in patients with HCC of ≤ 3 cm treated with SR or RFA.

Prognostic value of LI-RADS category on MRI in patients with primary hepatic lymphoepithelioma-like carcinoma

OBJECTIVES

To compare the clinical and MRI features of primary hepatic lymphoepithelioma-like carcinoma (LELC) categorized as LR-M or LR-4/5 using the Liver Imaging Reporting and Data System (LI-RADS) version 2018 and to determine the prognostic factors for recurrence-free survival (RFS).

METHODS

In this retrospective study, 37 patients with surgically confirmed LELC were included. Two independent observers evaluated preoperative MRI features according to the LI-RADS version 2018. Clinical and imaging features were compared between two groups. RFS and the associated factors were evaluated using Cox proportional hazards regression analysis, Kaplan-Meier analysis, and log-rank test.

RESULTS

In total, 37 patients (mean age, 58.5 ± 10.3 years) were evaluated. Sixteen (43.2%) LELCs were categorized as LR-M and twenty-one (56.8%) LELCs were categorized as LR-4/5. In the multivariate analysis, the LR-M category was an independent factor for RFS (HR 7.908, 95% CI 1.170-53.437; p = 0.033). RFS rates were significantly lower in patients with LR-M LELCs than in patients with LR-4/5 LELCs (5-year RFS rate, 43.8% vs.85.7%; p = 0.002).

CONCLUSION

The LI-RADS category was significantly associated with postsurgical prognosis of LELC, with tumor categorized as LR-M having a worse RFS than those categorized as LR-4/5.

KEY POINTS

• Lymphoepithelioma-like carcinoma patients categorized as LR-M have worse recurrence-free survival than those categorized as LR-4/5. • MRI-based LI-RADS categorization was an independent factor for postoperative prognosis of primary hepatic lymphoepithelioma-like carcinoma.

Estimating postsurgical outcomes of patients with a single hepatocellular carcinoma using gadoxetic acid-enhanced MRI: risk scoring system development and validation

OBJECTIVES

To develop and validate risk scoring systems using gadoxetic acid-enhanced liver MRI features and clinical factors that predict recurrence-free survival (RFS) of a single hepatocellular carcinoma (HCC).

METHODS

Consecutive 295 patients with treatment-naïve single HCC who underwent curative surgery were retrospectively enrolled from two centers. Cox proportional hazard models developed risk scoring systems whose discriminatory powers were validated using external data and compared to the Barcelona Clinic Liver Cancer (BCLC) or American Joint Committee on Cancer (AJCC) staging systems using Harrell's C-index.

RESULTS

Independent variables-tumor size (per cm; hazard ratio [HR], 1.07; 95% confidence interval [CI]: 1.02-1.13; p = 0.005), targetoid appearance (HR, 1.74; 95% CI: 1.07-2.83; p = 0.025), radiologic tumor in vein or tumor vascular invasion (HR, 2.59; 95% CI: 1.69-3.97; p < 0.001), the presence of a nonhypervascular hypointense nodule on the hepatobiliary phase (HR, 4.65; 95% CI: 3.03-7.14; p < 0.001), and pathologic macrovascular invasion (HR, 2.60; 95% CI: 1.51-4.48; p = 0.001)-with tumor markers (AFP ≥ 206 ng/mL or PIVKA-II ≥ 419 mAU/mL) derived pre- and postoperative risk scoring systems. The risk scores showed comparably good discriminatory powers in the validation set (C-index, 0.75-0.82) and outperformed the BCLC (C-index, 0.61) and AJCC staging systems (C-index, 0.58; ps < 0.05). The preoperative scoring system stratified the patients into low-, intermediate-, and high-risk for recurrence, whose 2-year recurrence rate was 3.3%, 31.8%, and 85.7%, respectively.

CONCLUSION

The developed and validated pre- and postoperative risk scoring systems can estimate RFS after surgery for a single HCC.

KEY POINTS

• The risk scoring systems predicted RFS better than the BCLC and AJCC staging systems (C-index, 0.75-0.82 vs. 0.58-0.61; ps < 0.05). • Five variables-tumor size, targetoid appearance, radiologic tumor in vein or vascular invasion, the presence of a nonhypervascular hypointense nodule on the hepatobiliary phase, and pathologic macrovascular invasion-combined with tumor markers derived risk scoring systems predicting postsurgical RFS for a single HCC. • In the risk scoring system using preoperatively-available factors, patients were classified into three distinct risk groups, with 2-year recurrence rates in the low-, intermediate-, and high-risk groups being 3.3%, 31.8%, and 85.7% in the validation set.

Radiologic features of hepatocellular carcinoma related to prognosis

The cross-sectional imaging findings play a crucial role in the diagnosis of hepatocellular carcinoma (HCC). Recent studies have shown that imaging findings of HCC are not only relevant for the diagnosis of HCC, but also for identifying genetic and pathologic characteristics and determining prognosis. Imaging findings such as rim arterial phase hyperenhancement, arterial phase peritumoral hyperenhancement, hepatobiliary phase peritumoral hypointensity, non-smooth tumor margin, low apparent diffusion coefficient, and the LR-M category of the Liver Imaging-Reporting and Data System have been reported to be associated with poor prognosis. In contrast, imaging findings such as enhancing capsule appearance, hepatobiliary phase hyperintensity, and fat in mass have been reported to be associated with a favorable prognosis. Most of these imaging findings were examined in retrospective, single-center studies that were not adequately validated. However, the imaging findings can be applied for deciding the treatment strategy for HCC, if their significance can be confirmed by a large multicenter study. In this literature, we would like to review imaging findings related to the prognosis of HCC as well as their associated clinicopathological characteristics.

Targetoid Primary Liver Malignancy in Chronic Liver Disease: Prediction of Postoperative Survival Using Preoperative MRI Findings and Clinical Factors

OBJECTIVE

We aimed to assess and validate the radiologic and clinical factors that were associated with recurrence and survival after curative surgery for heterogeneous targetoid primary liver malignancies in patients with chronic liver disease and to develop scoring systems for risk stratification.

MATERIALS AND METHODS

This multicenter retrospective study included 197 consecutive patients with chronic liver disease who had a single targetoid primary liver malignancy (142 hepatocellular carcinomas, 37 cholangiocarcinomas, 17 combined hepatocellular carcinoma-cholangiocarcinomas, and one neuroendocrine carcinoma) identified on preoperative gadoxetic acid-enhanced MRI and subsequently surgically removed between 2010 and 2017. Of these, 120 patients constituted the development cohort, and 77 patients from separate institution served as an external validation cohort. Factors associated with recurrence-free survival (RFS) and overall survival (OS) were identified using a Cox proportional hazards analysis, and risk scores were developed. The discriminatory power of the risk scores in the external validation cohort was evaluated using the Harrell C-index. The Kaplan-Meier curves were used to estimate RFS and OS for the different risk-score groups.

RESULTS

In RFS model 1, which eliminated features exclusively accessible on the hepatobiliary phase (HBP), tumor size of 2-5 cm or > 5 cm, and thin-rim arterial phase hyperenhancement (APHE) were included. In RFS model 2, tumors with a size of > 5 cm, tumor in vein (TIV), and HBP hypointense nodules without APHE were included. The OS model included a tumor size of > 5 cm, thin-rim APHE, TIV, and tumor vascular involvement other than TIV. The risk scores of the models showed good discriminatory performance in the external validation set (C-index, 0.62-0.76). The scoring system categorized the patients into three risk groups: favorable, intermediate, and poor, each with a distinct survival outcome (all log-rank p < 0.05).

CONCLUSION

Risk scores based on rim arterial enhancement pattern, tumor size, HBP findings, and radiologic vascular invasion status may help predict postoperative RFS and OS in patients with targetoid primary liver malignancies.

LI-RADS Category on MRI Is Associated With Recurrence of Intrahepatic Cholangiocarcinoma After Surgery: A Multicenter Study

BACKGROUND

The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing the terminology and interpretation of liver imaging. The association between the LI-RADS category and tumor recurrence in patients with intrahepatic cholangiocarcinomas (iCCAs) has not yet been evaluated in a multicenter study.

PURPOSE

To retrospectively investigate the preoperative clinical and imaging features associated with recurrence-free survival (RFS) after curative resection of iCCAs and to identify the role of the LI-RADS category in at-risk patients.

STUDY TYPE

Retrospective, multicenter.

SUBJECTS

A total of 113 patients (mean age: 61.1 years; 74 men, 39 women) who underwent preoperative contrast-enhanced MRI and curative surgical resection for a single treatment-naive iCCA between 2008 and 2021.

FILED STRENGTH/SEQUENCE

A 3 T dual gradient-echo T₁ WI with in- and opposed-phase, turbo spin-echo T₂ WI, diffusion-weighted echo-planar images, and three-dimensional gradient-echo T₁ WI before and after administration of contrast agent.

ASSESSMENT

MR imaging features were evaluated and assigned for each lesion using LI-RADS version 2018. RFS was calculated from the date of surgery to tumor recurrence or the last imaging date without evidence of recurrence. Factors affecting RFS were evaluated using clinical and imaging features.

STATISTICAL TESTS

Cox proportional hazards model, Kaplan-Meier method, and log-rank test. A P-value of <0.05 was considered statistically significant.

RESULTS

A total of 93 (82.3%) were categorized as LR-M and 20 (17.7%) were categorized as LR-4 or 5. In the multivariable analysis, LR-M category (hazard ratio [HR], 8.035; 95% confidence interval [CI], 1.096-58.931) and a tumor size >3 cm on MRI (HR, 2.690; 95% CI, 1.319-5.487) were independent factors for poor RFS. The 5-year RFS rate was significantly higher in patients with iCCA categorized as LR-4 or 5 than in those categorized as LR-M (94.4% vs. 51.9%, respectively).

DATA CONCLUSION

Patients with iCCA categorized as LR-4 or 5 may have a better RFS than those categorized as LR-M.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Percentages of Hepatocellular Carcinoma in LI-RADS Categories with CT and MRI: A Systematic Review and Meta-Analysis

Background The Liver Imaging Reporting and Data System (LI-RADS) CT and MRI algorithm applies equally to CT, MRI with extracellular contrast agents (ECA-MRI), and MRI with gadoxetate (Gx-MRI). Purpose To estimate pooled percentages of hepatocellular carcinoma (HCC) and overall malignancy for each LI-RADS category with CT and MRI. Materials and Methods MEDLINE and EMBASE databases were searched for research articles (January 2014-April 2021) reporting the percentages of observations in each LI-RADS category with use of versions 2014, 2017, or 2018. Study design, population characteristics, imaging modality, reference standard, and numbers of HCC and non-HCC malignancies in each category were recorded. A random-effects model evaluated the pooled percentage of HCC and overall malignancy for each category. Results There were 49 studies with 9620 patients and a total 11 562 observations, comprising 7921 HCCs, 1132 non-HCC malignancies, and 2509 benign entities. No HCC or non-HCC malignancies were reported with any modality in the LR-1 category. The pooled percentages of HCC for CT, ECA-MRI, and Gx-MRI, respectively, were 10%, 6%, and 1% for LR-2 (P = .16); 48%, 31%, and 38% for LR-3 (P = .42); 76%, 64%, and 77% for LR-4 (P = .62); 96%, 95%, and 96% for LR-5 (P = .76); 88%, 76%, and 78% for LR-5V or LR-TIV (tumor in vein) (P = .42); and 20%, 30%, and 35% for LR-M (P = .32). Most LR-M (93%-100%) and LR-5V or LR-TIV (99%-100%) observations were malignant, regardless of modality. Conclusion There was no difference in percentages of hepatocellular carcinoma and overall malignancy between CT, MRI with extracellular contrast agents, and MRI with gadoxetate for any Liver Imaging Reporting and Data System categories. © RSNA, 2023 Supplemental material is available for this article See also the editorial by Ronot in this issue.

Predicting histologic differentiation of solitary hepatocellular carcinoma up to 5 cm on gadoxetate disodium-enhanced MRI

BACKGROUND

To establish a preoperative score based on gadoxetate disodium-enhanced magnetic resonance imaging (EOB-MRI) and clinical indicators for predicting histologic differentiation of solitary HCC up to 5 cm.

METHODS

From July 2015 to January 2022, consecutive patients with surgically proven solitary HCC measuring ≤ 5 cm at preoperative EOB-MRI were retrospectively enrolled. All MR images were independently evaluated by two radiologists who were blinded to all clinical and pathologic information. Univariate and multivariate logistic regression analyses were performed to identify significant clinicoradiological features associated with poorly differentiated (PD) HCC, which were then incorporated into the predictive score. The predictive score was validated in an independent validation set by area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy.

RESULTS

A total of 182 patients were included, 42 (23%) with PD HCC. According to the multivariate analysis, marked hepatobiliary phase hypointensity (odds ratio [OR], 9.98), LR-M category (OR, 5.60), and serum alpha-fetoprotein (AFP) level > 400 ng/mL (OR, 3.58) were incorporated into the predictive model; the predictive score achieved an AUC of 0.802 and 0.830 on the training and validation sets, respectively. The sensitivity, specificity, and accuracy of the predictive score were 66.7%, 85.7%, and 81.3%, respectively, on the training set and 66.7%, 81.0%, and 77.8%, respectively, on the validation set.

CONCLUSION

The proposed score integrating two EOB-MRI features and AFP level can accurately predict PD HCC in the preoperative setting.

[CT/MRI Liver Imaging Reporting and Data System (LI-RADS): Standardization, Evidence, and Future Direction]

The liver imaging reporting and data system (LI-RADS) has been developed with the support of the American College of Radiology to standardize the diagnosis and evaluation of treatment response of hepatocellular carcinoma (HCC). The CT/MRI LI-RADS version 2018 has been incorporated in the American Association for the Study of Liver Diseases guidance. This review examines the effect of CT/MRI LI-RADS on the standardized reporting of liver imaging, and the evidence in diagnosing HCC and evaluating treatment response after locoregional treatment using CT/MRI LI-RADS. The results are compared with other HCC diagnosis guidelines, and future directions are described.

LI-RADS Version 2018 Targetoid Appearances on Gadoxetic Acid-Enhanced MRI: Interobserver Agreement and Diagnostic Performance for the Differentiation of HCC and Non-HCC Malignancy

BACKGROUND. In LI-RADS version 2018, observations showing at least one of five targetoid appearances in different sequences or postcontrast phases are categorized LR-M, indicating likely non-hepatocellular carcinoma (HCC) malignancy. OBJECTIVE. The purpose of this study was to evaluate interobserver agreement for LI-RADS targetoid appearances among a large number of radiologists of varying experience and the diagnostic performance of targetoid appearances for differentiating HCC from non-HCC malignancy. METHODS. This retrospective study included 100 patients (76 men, 24 women; mean age, 58 ± 9 [SD] years) at high risk of HCC who underwent gadoxetic acid-enhanced MRI within 30 days before hepatic tumor resection (25 randomly included patients with non-HCC malignancy [13, intrahepatic cholangiocarcinoma; 12, combined HCC-cholangiocarcinoma]; 75 matched patients with HCC). Eight radiologists (four more experienced [8-15 years]; four less experienced [1-5 years]) from seven institutions independently assessed observations for the five targetoid appearances and LI-RADS categorization. Interobserver agreement and diagnostic performance for non-HCC malignancy were evaluated. RESULTS. Interobserver agreement was poor for peripheral washout (κ = 0.20); moderate for targetoid transitional phase or hepatobiliary phase appearance (κ = 0.33), delayed central enhancement (κ = 0.37), and targetoid restriction (κ = 0.43); and substantial for rim arterial phase hyperenhancement (κ = 0.61). Agreement was fair for at least one targetoid appearance (κ = 0.36) and moderate for at least two, three, or four targetoid appearances (κ = 0.43-0.51). Agreement for individual targetoid appearances was not significantly different between more experienced and less experienced readers other than for targetoid restriction (κ = 0.63 vs 0.43; p = .001). Agreement for at least one targetoid appearance was fair among more experienced (κ = 0.29) and less experienced (κ = 0.37) reviewers. Agreement for at least two, three, or four targetoid appearances was moderate to substantial among more experienced reviewers (κ = 0.45-0.63) and moderate among less experienced reviewers (κ = 0.42-0.56). Existing LR-M criteria of at least one targetoid appearance had median accuracy for non-HCC malignancy of 62%, sensitivity of 84%, and specificity of 54%. For all reviewers, accuracy was highest when at least three (median accuracy, 79%; sensitivity, 68%; specificity, 82%) or four (median accuracy, 80%; sensitivity, 54%; specificity, 88%) targetoid appearances were required. CONCLUSION. Targetoid appearances and LR-M categorization exhibited considerable interobserver variation among both more and less experienced reviewers. CLINICAL IMPACT. Requiring multiple targetoid appearances for LR-M categorization improved interobserver agreement and diagnostic accuracy for non-HCC malignancy.

HCC or Something Else? Frequency of Various Benign and Malignant Etiologies in Cirrhotic Patients with Newly Detected Focal Liver Lesions in Relation to Different Clinical and Sonographic Parameters

Background and Aims: To investigate the frequency of different benign and malignant focal liver lesions (FLLs) in relation to clinical and sonographic features among patients with liver cirrhosis (LC) and newly detected FLLs. Methods: This study was a retrospective analysis of 225 cirrhotic patients with newly detected FLLs who underwent hepatic ultrasound (US) examinations at our university hospital from 2011 to 2022. The diagnosis of FLLs was based on histology and/or consensus radiological criteria, in accordance with the current diagnostic guidelines. The FLLs were classified into benign (bFLLs) or malignant (mFLLs) lesions and the latter group was subclassified into HCC and non-HCC mFLLs. The frequency, clinical parameters, and sonographic features of the different groups were examined and compared. Results: Of the 225 FLLs, 154 (68.4%) were mFLLs and 71 (31.6%) bFLLs. HCC was the most frequent subcategory of FLLs (132; 58.7%). There were (22; 9.8%) non-HCC mFLLs with 11 (4.9%) metastases and 11 (4.9%) non-HCC primary liver tumors. Regenerative nodules (RNs) were the most frequent form of bFLLs (25; 11.1%), followed by simple cysts (22; 9.8%) and hemangiomas (14; 6.2%). The other bFLLs (10; 14.1%) were fat deposition/sparing (5), hematomas (2), abscesses (2), and echinococcal cysts (1). The distribution of bFLLs and HCC and non-HCC mFLLs varied significantly according to the clinical scenarios. HCC mFLLs were more frequent in males (p = 0.001), in those with no history of active non-hepatic primary malignant disease (NHPMD) (p < 0.001), in those with a hepatitis B or C etiology of LC (p = 0.002), when located in the right lobe (p = 0.008), and when portal vein thrombosis was present (p = 0.03). Conclusion: In cirrhotic patients with newly detected FLLs, the non-HCC etiology was more frequently diagnosed in lesions that were located in the left lobe, in females, and in patients with a history of active NHPMD. Thus, the lower frequency of HCC in the abovementioned groups demonstrated that a cautious implementation of the current consensus radiological criteria would be required for these groups, particularly in patients with an active NHPMD, given the fact that the consensus criteria were not validated in these populations. A more active diagnostic approach may ultimately be needed for these patients. Large prospective studies are needed to validate these findings.

Radiomics Analysis on Gadoxetate Disodium-Enhanced MRI Predicts Response to Transarterial Embolization in Patients with HCC

Objectives: To explore the potential of radiomics on gadoxetate disodium-enhanced MRI for predicting hepatocellular carcinoma (HCC) response after transarterial embolization (TAE). Methods: This retrospective study included cirrhotic patients treated with TAE for unifocal HCC naïve to treatments. Each patient underwent gadoxetate disodium-enhanced MRI. Radiomics analysis was performed by segmenting the lesions on portal venous (PVP), 3-min transitional, and 20-min hepatobiliary (HBP) phases. Clinical data, laboratory variables, and qualitative features based on LI-RADSv2018 were assessed. Reference standard was based on mRECIST response criteria. Two different radiomics models were constructed, a statistical model based on logistic regression with elastic net penalty (model 1) and a computational model based on a hybrid descriptive-inferential feature extraction method (model 2). Areas under the ROC curves (AUC) were calculated. Results: The final population included 51 patients with HCC (median size 20 mm). Complete and objective responses were obtained in 14 (27.4%) and 29 (56.9%) patients, respectively. Model 1 showed the highest performance on PVP for predicting objective response with an AUC of 0.733, sensitivity of 100%, and specificity of 40.0% in the test set. Model 2 demonstrated similar performances on PVP and HBP for predicting objective response, with an AUC of 0.791, sensitivity of 71.3%, specificity of 61.7% on PVP, and AUC of 0.790, sensitivity of 58.8%, and specificity of 90.1% on HBP. Conclusions: Radiomics models based on gadoxetate disodium-enhanced MRI can achieve good performance for predicting response of HCCs treated with TAE.

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 features of histological subtypes of hepatocellular carcinoma: Implication for LI-RADS

BACKGROUND & AIMS

The histopathological subtypes of hepatocellular carcinoma (HCC) are associated with distinct clinical features and prognoses. This study aims to report Liver Imaging Reporting and Data System (LI-RADS)-defined imaging features of different HCC subtypes in a cohort of resected tumours and to assess the influence of HCC subtypes on computed tomography (CT)/magnetic resonance imaging (MRI) LI-RADS categorisation in the subgroup of high-risk patients.

METHODS

This retrospective institutional review board-approved study included patients with resected HCCs and available histopathological classification. Three radiologists independently reviewed preoperative CT and MRI exams. The readers evaluated the presence of imaging features according to LI-RADS v2018 definitions and provided a LI-RADS category in patients at high risk of HCC. Differences in LI-RADS features and categorisations were assessed for not otherwise specified (NOS-HCC), steatohepatitic (SH-HCC), and macrotrabecular-massive (MTM-HCC) types of HCCs.

RESULTS

Two hundred and seventy-seven patients (median age 64.0 years, 215 [77.6%] men) were analysed, which involved 295 HCCs. There were 197 (66.7%) NOS-HCCs, 62 (21.0%) SH-HCCs, 23 (7.8%) MTM-HCCs, and 13 (4.5%) other rare subtypes. The following features were more frequent in MTM-HCC: elevated α-foetoprotein serum levels (p <0.001), tumour-in-vein (p <0.001 on CT, p ≤0.052 on MRI), presence of at least 1 LR-M feature (p ≤0.010 on CT), infiltrative appearance (p ≤0.032 on CT), necrosis or severe ischaemia (p ≤0.038 on CT), and larger size (p ≤0.006 on CT, p ≤0.011 on MRI). SH-HCC was associated with fat in mass (p <0.001 on CT, p ≤0.002 on MRI). The distribution of the LI-RADS major features and categories in high-risk patients did not significantly differ among the 3 main HCC subtypes.

CONCLUSIONS

The distribution of LI-RADS major features and categories is not different among the HCC subtypes. Nevertheless, careful analysis of tumour-in-vein, LR-M, and ancillary features as well as clinico-biological data can provide information for the non-invasive diagnosis of HCC subtypes.

LAY SUMMARY

In high-risk patients, the overall distribution of LI-RADS major features and categories is not different among the histological subtypes of hepatocellular carcinoma, but tumour-in-vein, presence of LR-M features, and ancillary features can provide information for the non-invasive diagnosis of hepatocellular carcinoma subtypes.

A modified LI-RADS: targetoid tumors with enhancing capsule can be diagnosed as HCC instead of LR-M lesions

OBJECTIVE

To elucidate whether the presence of enhancing capsule can be applied to establish a modified Liver Imaging Reporting and Data System (LI-RADS) to differentiate hepatocellular carcinoma (HCC) from non-HCC malignancies in extracellular contrast agent (ECA)-enhanced and hepatobiliary agent (HBA)-enhanced MRI.

METHODS

We enrolled 198 participants (161 men; mean age, 56.3 years) with chronic liver disease who underwent ECA-MRI and HBA-MRI before surgery for de novo hepatic nodule(s). Two reviewers assigned LI-RADS categories (v2018). We defined a "modified LR-5 category, which emphasizes enhancing capsule (mLR-5C)" over targetoid features and classifies tumors with both targetoid appearance and enhancing capsule as HCC instead of LR-M. We compared the diagnostic performance of conventional LI-RADS and modified LI-RADS criteria for both MRIs.

RESULTS

A total of 258 hepatic nodules (194 HCCs, 43 benign lesions, and 21 non-HCC malignancies; median size, 19 mm) were analyzed. By conventional LI-RADS, 47 (18.2%) nodules (31 HCCs and 16 non-HCC malignancies) were categorized as LR-M. The mLR-5C criterion showed superior sensitivity (ECA-MRI, 76.6% vs. 67.0%; HBA-MRI, 60.4% vs. 56.3%; both p < 0.05) while maintaining high specificity (ECA-MRI, 93.8% vs. 98.4%; HBA-MRI, 95.3% vs. 98.4%; both p > 0.05) compared with the LR-5 criterion. Using the mLR-5C criterion, ECA-MRI exhibited higher sensitivity than HBA-MRI (76.6% vs. 60.4%, p < 0.001) and similar specificity (93.8% vs. 95.3%, p > 0.99).

CONCLUSION

Our modified LI-RADS achieved superior sensitivity for diagnosing HCC, without compromising specificity compared with LR-5. ECA-MRI showed higher sensitivity in diagnosing HCC than HBA-MRI by applying the mLR-5C for LR-M lesions.

KEY POINTS

• By conventional LI-RADS, 31 (16.0%) of 194 HCCs were categorized as LR-M. • Among 31 HCCs categorized as LR-M, 19 HCCs or 8 HCCs were recategorized as HCC on ECA-MRI or HBA-MRI, respectively, after applying the modified LR-5 category, which allocates targetoid lesions with enhancing capsule as mLR-5C instead of LR-M. • The mLR-5C showed superior sensitivity compared with the LR-5 in both MRIs (ECA-MRI, 76.6% vs. 67.0%; HBA-MRI, 60.4% vs. 56.3%, both p < 0.05), while maintaining high specificity (ECA-MRI, 93.8% vs. 98.4%; HBA-MRI, 95.3% vs. 98.4%; both p > 0.05).

Magnetic Resonance Imaging of Nonhepatocellular Malignancies in Chronic Liver Disease

Hepatocellular carcinoma (HCC) is the most common liver malignancy associated with chronic liver disease. Nonhepatocellular malignancies may also arise in the setting of chronic liver disease. The imaging diagnosis of non-HCC malignancies may be challenging. Non-HCC malignancies in patients with chronic liver disease most commonly include intrahepatic cholangiocarcinoma and combined hepatocellular-cholangiocarcinoma, and less commonly hepatic lymphomas and metastases. On MR imaging, non-HCC malignancies often demonstrate a targetoid appearance, manifesting as rim arterial phase hyperenhancement, peripheral washout, central delayed enhancement, and peripheral restricted diffusion. When applying the Liver Imaging Reporting and Data System algorithm, observations with targetoid appearance are categorized as LR-M.

Combined hepatocellular-cholangiocarcinoma: can we use contrast-enhanced ultrasound Liver Imaging Reporting and Data System (LI-RADS) to predict the patient's survival?

OBJECTIVES

To evaluate the relationship between contrast-enhanced (CE) ultrasound Liver Reporting and Data System (LI-RADS) classification of combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and their histopathological component predominance, and to determine if the CEUS LI-RADS category can be used to predict the patient's survival after surgical resection.

METHODS

Between January 2011 and December 2018, medical records and CEUS of patients with pathologically proven cHCC-CCA were studied. The predominance of hepatocellular carcinoma (HCC)/intrahepatic cholangiocarcinoma (ICC) component of cHCC-CCA was analyzed by histopathology. The proportion of HCC-predominant cHCC-CCA in different LI-RADS category was compared by using Fisher's exact test. Factors affecting tumor recurrence were analyzed by Cox proportional hazard model. Disease-free survival (DFS) was estimated by using Kaplan-Meier survival curve and compared by log-rank test.

RESULTS

The study included 37 cHCC-CCA patients (33 men, 4 women; average age, 50.4 ± 11.0 years) and 37 nodules (mean diameter, 6.1 ± 3.9 cm). According to CEUS LI-RADS, 62.2% (23/37), 18.9% (7/37), and 18.9% (7/37) of cHCC-CCA were classified as LR-M, LR-5, and LR-TIV, respectively. The ratio of HCC predominance in LR-5 was 100% (10/10) vs 81.5% (22/27) in the LR-M group (p = 0.591). In our population, LR-5 patients had longer DFS than LR-M and LR-TIV patients combined (median DFS: 18.0 vs 6.4 months, p = 0.016). Multiple lesions (hazard ratio, 3.1; p = 0.007), tumor size (≥ 5 cm, hazard ratio, 4.1; p = 0.003), and CEUS LI-RADS category (LR-M and LR-TIV, hazard ratio, 4.7; p = 0.011) showed independent association with shorter DFS.

CONCLUSION

cHCC-CCA characterized as LR-5 on CEUS tend to represent HCC-predominant tumors with significantly longer disease-free survival compared to cHCC-CCA categorized as LR-M and LR-TIV.

KEY POINTS

• By using the American College of Radiology contrast-enhanced ultrasound Liver Imaging Reporting and Data System (CEUS LI-RADS), majority (30/37, 81.1%) of cHCC-CCA tumors were classified as LR-M or LR-TIV and only 18.9% (7/30) of cHCC-CCA were categorized as LR-5. • Patients with CEUS LR-5 cHCC-CCA had statistically significant longer disease-free time than those with LR-M and TIV cHCC-CCA (median DFS: 18.0 vs 6.4 months, p = 0.016). • Multiple lesions (hazard ratio, 3.1; p = 0.007), tumor size (≥ 5 cm, hazard ratio, 4.1; p = 0.003), and CEUS LI-RADS category (LR-M and LR-TIV, hazard ratio, 4.7; p = 0.011) showed independent association with shorter DFS.

Prognosis after Curative Resection of Single Hepatocellular Carcinoma with A Focus on LI-RADS Targetoid Appearance on Preoperative Gadoxetic Acid-Enhanced MRI

Objective

To evaluate the prognostic implications of preoperative magnetic resonance imaging (MRI) features of hepatocellular carcinoma (HCC) with a focus on those with targetoid appearance based on the Liver Imaging Reporting and Data System (LI-RADS), as well as known microvascular invasion (MVI) features.

Materials and Methods

This retrospective study included 242 patients (190 male; mean age, 57.1 years) who underwent surgical resection of a single HCC (≤ 5 cm) as well as preoperative gadoxetic acid-enhanced MRI between January 2012 and March 2015. LI-RADS category was assigned, and the LR-M category was further classified into two groups according to rim arterial-phase hyperenhancement (APHE). The imaging features associated with MVI were also assessed. The overall survival (OS), recurrence-free survival (RFS), and their associated factors were evaluated.

Results

Among the 242 HCCs, 190 (78.5%), 25 (10.3%), and 27 (11.2%) were classified as LR-4/5, LR-M with rim APHE, and LR-M without rim APHE, respectively. LR-M with rim APHE (vs. LR-4/5; hazard ratio [HR] for OS, 5.48 [p = 0.002]; HR for RFS, 2.09 [p = 0.042]) and tumor size (per cm increase; HR for OS, 6.04 [p = 0.009]; HR for RFS, 1.77 [p = 0.014]) but not MVI imaging features (p > 0.05) were independent factors associated with OS and RFS. Compared to the 5-year OS and RFS rates in the LR-4/5 group (93.9% and 66.8%, respectively), the LR-M with rim APHE group had significantly lower rates (68.0% and 45.8%, respectively, both p < 0.05), while the LR-M without rim APHE group did not significantly differ in the survival rates (91.3% and 80.2%, respectively, both p > 0.05).

Conclusion

Further classification of LR-M according to the presence of rim APHE may help predict the postoperative prognosis of patients with a single HCC.

Gadoxetate-enhanced MRI Features of Proliferative Hepatocellular Carcinoma Are Prognostic after Surgery

Background Hepatocellular carcinomas (HCCs) are heterogeneous neoplasms, and the prognosis varies based on the subtype. Two broad molecular classes of HCC have been proposed: a proliferative and a nonproliferative class. Purpose To evaluate the gadoxetate-enhanced MRI findings of the proliferative class HCC and its prognostic significance after surgery. Materials and Methods This retrospective cohort study evaluated patients with surgically resected treatment-naive single HCC (≤5 cm) who underwent hepatic resection from January 2010 through February 2013 and preoperative gadoxetate-enhanced MRI. A Cox proportional hazards model was used to determine the predictive factors for overall survival (OS), intrahepatic distant recurrence, and extrahepatic metastasis (EM). The mean follow-up period was 75.5 months ± 30.2 (standard deviation). Multivariable logistic regression was performed to determine factors associated with proliferative class HCC. Results A total of 158 patients (mean age, 57 years ± 11; 128 men and 30 women) were evaluated. Forty-two of the 158 HCCs (26.6%) were proliferative class HCCs (17 macrotrabecular-massive HCCs, 14 keratin 19-positive HCCs, 10 scirrhous HCCs, and one sarcomatoid HCC). The proliferative class was associated with worse OS (hazard ratio [HR], 3.1; 95% CI: 1.5, 6.0; P = .01) and higher rates of intrahepatic distant recurrence (HR, 1.83; 95% CI: 1.1, 2.9; P = .01) and EM (HR, 9.97; 95% CI: 3.2, 31.4; P < .001). Rim arterial phase hyperenhancement (APHE) at gadoxetate-enhanced MRI (odds ratio [OR], 6.35; 95% CI: 1.9, 21.7; P = .01) and high serum α-fetoprotein (>100 ng/mL) (OR, 4.18; 95% CI: 1.64, 10.7; P = .01) were independent predictors for proliferative HCC. The presence of rim APHE was associated with poor OS (HR, 2.4; 95% CI: 1.2, 4.9; P = .02) and higher rates of EM (HR, 7.4; 95% CI: 2.5, 21.7; P < .01). Conclusion The proliferative class of hepatocellular carcinoma (HCC) is an independent factor for poor overall survival with increased rates of intrahepatic and extrahepatic metastasis. Rim arterial phase hyperenhancement at gadoxetate-enhanced MRI may help to identify proliferative class HCC and predict poor overall survival and an increased incidence of extrahepatic metastasis. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Krinsky and Shanbhogue in this issue.

Characteristics and Early Recurrence of Hepatocellular Carcinomas Categorized as LR-M: Comparison with Those Categorized as LR-4 or 5

BACKGROUND

According to the Liver Imaging Reporting and Data System (LI-RADS), the LI-RADS category M (LR-M), which are probably or definitely malignant but are not specific for hepatocellular carcinomas (HCCs), does not exclude HCCs. A gap in knowledge remains, including their characteristics and recurrence of HCCs categorized as LR-M.

PURPOSE

To compare the characteristics of HCCs categorized as LR-M with HCCs categorized as LR-4 or LR-5 (LR-4/5) using the LI-RADS version 2018 and evaluate the relationship of these categories with the risk of early recurrence after curative resections of single HCCs.

STUDY TYPE

Retrospective.

SUBJECTS

Two hundred and eighty-one patients (mean age, 57 years; 191 men and 90 women) who underwent curative resections for single HCCs and preoperative contrast-enhanced MRI between 2015 and 2017.

FIELD STRENGTH/SEQUENCE

3T Dual gradient-echo T₁ WI with in- and opposed-phase, turbo spin-echo T₂ WI, diffusion-weighted echo-planar images, and three-dimensional gradient-echo T₁ WI before and after administration of contrast agent.

ASSESSMENT

MRI features according to the LI-RADS version 2018 were evaluated and LI-RADS category were assigned for each observation. Clinical, imaging, and histopathological features were compared based on LI-RADS categorization. Early recurrence rates (<2 years) and associated factors were also evaluated.

STATISTICAL TESTS

Fisher's exact test, two-sample t test after satisfying assumption of normality through Shapiro-Wilk test, Fleiss κ coefficient, Cox proportional hazards regression analysis, Kaplan-Meier method, and log-rank test.

RESULTS

Forty-one HCCs (14.6%) were categorized as LR-M and 240 HCCs (85.4%) were categorized as LR-4/5. LR-M HCCs showed poorer differentiation than LR-4/5 HCCs. In the multivariate analysis, the LR-M category was an independent predictor for early recurrence (hazard ratio, 1.904; 95% confidence interval, 1.024-3.542; P < 0.05). Early recurrence rates were significantly higher in patients with LR-M HCCs than in patients with LR-4/5 HCCs (32.0% vs. 18.4%, respectively, P < 0 05).

DATA CONCLUSION

Compared to LR-4/5 HCCs, LR-M HCCs were associated with poorer tumor differentiation and higher early recurrence rates after curative resections of single HCCs.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 2.

Liver Imaging Reporting and Data System Category on Magnetic Resonance Imaging Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation Within the Milan Criteria: A Multicenter Study

BACKGROUND

This study was designed to investigate the association between Liver Imaging Reporting and Data System (LI-RADS) category and recurrence of hepatocellular carcinoma (HCC) after primary liver transplantation (LT) within the Milan criteria.

METHODS

This multicenter, retrospective study included 140 recipients who underwent living donor LT (LDLT) for treatment-naïve HCC and pretransplant contrast-enhanced magnetic resonance imaging (MRI) between 2009 and 2013. LI-RADS categories were assigned using LI-RADS version 2018. Recurrence-free survival (RFS) and associated factors were evaluated using Cox proportional hazards regression analysis, Kaplan-Meier analysis, and log-rank test. Histological grading and microvascular invasion (MVI) were analyzed on the pathologic examinations of explanted livers.

RESULTS

The overall 1-, 3-, 5-, and 7-year RFS rates were 95.6%, 92.6%, 90.2%, and 89.3%, respectively. In the multivariable analysis, independent predictors of recurrence included HCCs categorized as LR-M (hazard ratio [HR], 18.68; 95% confidence interval [CI], 5.79-60.23; P < 0.001) and the largest tumor size of ≥ 3 cm on MRI (HR, 4.18; 95% CI, 1.42-12.37; P = 0.010). The 5-year RFS rate was significantly lower in patients with HCCs categorized as LR-M than in those with HCCs categorized as LR-5 or 4 (LR-5/4) (36.9% vs. 95.8%, respectively; P < 0.001). HCCs categorized as LR-M exhibited significantly more MVI than HCCs categorized as LR-5/4 (57.1% vs. 17.5%, respectively; P = 0.002).

CONCLUSIONS

Patients with HCCs categorized as LR-M using LI-RADS version 2018 may have a worse prognosis after primary LT within the Milan criteria than those with HCCs categorized as LR-5/4.

Hepatocellular Carcinoma With Atypical Imaging Features: Review of the Morphologic Hepatocellular Carcinoma Subtypes With Radiology-Pathology Correlation

Hepatocellular carcinoma (HCC) is the fastest growing cause of cancer death in the United States with the incidence rate more than doubling in 20 years. HCC is unique since a noninvasive diagnosis can be achieved with imaging alone when specific clinical criteria and imaging characteristics are met, obviating the need for tissue sampling. However, HCC is a highly heterogeneous neoplasm. Atypical HCC subtypes vary significantly in their morphology, which can be attributed to specific histologic and molecular features, and can cause deviations from the classic imaging characteristics. The different morphologic subtypes of HCC frequently present a diagnostic challenge for radiologists and pathologists since their imaging and pathologic features can overlap with those of non-HCC malignancies. Identifying an atypical subtype can have important clinical implications. Liver transplant, albeit a scarce and limited resource, is the optimal treatment for conventional HCC, potentially curing both the tumor and the underlying pre-malignant condition. Some HCC subtypes as well as mimickers are associated with unacceptably high recurrence and poor outcome after transplant, and there remains limited data on the role and prognosis of liver transplantation for treatment of rare HCC subtypes. Other subtypes tend to recur later than classic HCC, potentially requiring a different follow-up scheme. This review will discuss the appearance of different HCC subtypes in relation to their histopathologic features. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Update on Pathologic and Radiologic Diagnosis of Combined Hepatocellular-Cholangiocarcinoma

Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) is a malignant primary liver carcinoma characterized by the unequivocal presence of both hepatocytic and cholangiocytic differentiation within the same tumor. Recent research has highlighted that cHCC-CCAs are more heterogeneous than previously expected. In the updated consensus terminology and WHO 2019 classification, "classical type" and "subtypes with stem-cell features" of the WHO 2010 classification are no longer recommended. Instead, it is recommended that the presence and percentages of various histopathologic components and stem-cell features be mentioned in the pathologic report. The new terminology and classification enable the exchange of clearer and more objective information about cHCC-CCAs, facilitating multi-center and multi-national research. However, there are limitations to the diagnosis of cHCC-CCA by imaging and biopsy. cHCC-CCAs showing typical imaging findings of HCC could be misdiagnosed as HCC and subjected to inappropriate treatment, if other clinical findings are not sufficiently considered. cHCC-CCAs showing at least one of the CCA-like imaging features or unusual clinical features should be subjected to biopsy. There may be a sampling error for the biopsy diagnosis of cHCC-CCA. An optimized diagnostic algorithm integrating clinical, radiological, and histopathologic information of biopsy is required to resolve these diagnostic pitfalls.

Combined Hepatocellular-Cholangiocarcinoma: Magnetic Resonance Imaging Features and Prognosis According to Risk Factors for Hepatocellular Carcinoma

BACKGROUND

Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) can develop in patients with and without risk factors for hepatocellular carcinoma (HCC).

PURPOSE

To compare the clinical and magnetic resonance imaging (MRI) characteristics of cHCC-CCA in patients with and without risk factors for HCC, and to assess the influence of risk factors on patient prognosis.

STUDY TYPE

Retrospective.

POPULATION

A total of 152 patients with surgically confirmed cHCC-CCA.

FIELD STRENGTH/SEQUENCE

1.5-T and 3-T/T1-weighted dual gradient-echo in- and opposed-phase, T2-weighted turbo-spin-echo, diffusion-weighted single-shot spin-echo echo-planar, and T1-weighted three-dimensional gradient-echo contrast-enhanced sequences.

ASSESSMENT

MRI features according to the Liver Imaging Reporting and Data System (LI-RADS) and pathologic findings based on revised classification were compared between patients with and without risk factors for HCC. Overall survival (OS) and recurrence-free survival (RFS) were also compared between the two groups, and factors associated with survival were evaluated.

STATISTICAL TESTS

The clinico-pathologic and MRI features of the two groups were compared using Student's t-tests, Mann-Whitney U-tests, and chi-square tests. OS and RFS were evaluated by the Kaplan-Meier method, and factors associated with survival were evaluated by Cox proportional hazard model.

RESULTS

cHCC-CCA in patients with risk factors were more frequently classified as LI-RADS category 4 or 5 (LR-4/5; probably or definitely HCC) (48.7%), whereas those without risk factors were more frequently classified as category M (LR-M; probably malignant, not specific for HCC) (63.6%). RFS and OS did not differ significantly according to risk factors (P = 0.63 and 0.83). Multivariable analysis showed that pathologic tumor type (hazard ratio 2.02; P < 0.05) and LI-RADS category (hazard ratio 2.19; P < 0.05) were significantly associated with RFS and OS, respectively.

DATA CONCLUSION

Although MRI features of cHCC-CCA differed significantly between patients with and without risk factors for HCC, postsurgical prognosis did not. LI-RADS category and pathologic tumor type were independently correlated with postsurgical prognosis in patients with cHCC-CCA.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

LI-RADS and transplantation: challenges and controversies

Patients with early stage hepatocellular carcinoma (HCC) can be cured by liver transplantation. HCC imaging features on CT or MRI are specific enough to allow for definitive diagnosis and treatment without the need of confirmatory biopsy. When applied to the appropriate at-risk population the Liver Imaging Reporting and Data System (LI-RADS) imaging criteria achieve high specificity and positive predictive value for the diagnosis of HCC. The Organ Procurement and Transplantation Network (OPTN) is the United States organization that aims to assure the adequate and fair distribution of livers across candidates. Given the importance of fair organ allocation, OPTN also provides stringent imaging criteria for the diagnosis of HCC aiming to avoid false positive diagnosis. Although most imaging criteria are identical for both systems, discrepancies between LI-RADS and the current OPTN classification system for HCC diagnosis exists. Main differences include, but are not limited to, the binary approach of OPTN to classify lesions as HCC or not, versus the probabilistic algorithmic approach of LI-RADS, technical and interpretation considerations, and the approach towards treated lesions. The purpose of this article is to highlight the similarities and discrepancies between LI-RADS and the current OPTN criteria for HCC diagnosis and the implications that these differences may have on the management of patients who are transplant candidates.

Diagnostic performance of LI-RADS for MRI and CT detection of HCC: A systematic review and diagnostic meta-analysis

PURPOSE

To perform a meta-analysis evaluating the diagnostic accuracy of the Liver Imaging Reporting and Data System (LI-RADS) category ≥ 3 (LI-RADS 3-5v) for detecting hepatocellular carcinoma (HCC).

METHOD

A systematic PubMed, Embase, and Web of Science electronic database search was performed for original diagnostic studies published through July 31, 2018. Statistical analysis included data pooling, forest plot construction, heterogeneity testing, meta-regression, and subgroup analyses.

RESULTS

Eighteen studies (v2011, v2014 and v2017) involving 3386 patients were included in the meta-analysis. The pooled sensitivity and specificity of LI-RADS ≥ 3 for diagnosing HCC were 0.86 (95 % confidence interval (CI): 0.78-0.91) and 0.85 (95 % CI: 0.78-0.90), respectively. The area under the curve (AUC) was 0.92 (95 % CI: 0.89-0.94). Meta-regression analysis showed that the publication year, blinding to the reference standard and the number of readers were significant factors affecting heterogeneity. In subgroup analyses, magnetic resonance imaging (MRI) demonstrated higher sensitivity (0.82 vs. 0.73) and comparable specificity (0.79 vs. 0.78) than computed tomography (CT). For HCCs ≤30 mm, LI-RADS showed lower sensitivity of 0.72 and specificity of 0.80 compared with HCC of all sizes. LR-5 showed higher sensitivity and specificity than LR-3 (sensitivity: 0.67 vs. 0.07, P = 0.02; specificity: 0.93 vs. 0.75, p < 0.001) and higher sensitivity than LR-4 (sensitivity: 0.67 vs. 0.29, P = 0.02; specificity: 0.93 vs. 0.80, p = 0.75). LR ≥ 5 had higher specificity at the cost of decreased sensitivity than LR ≥ 3 (specificity: 0.94 vs. 0.68, p < 0.001; sensitivity: 0.66 vs. 0.74, P = 0.70) and LR ≥ 4 (specificity: 0.94 vs. 0.84, p < 0.001; sensitivity: 0.66 vs. 0.74, P = 0.77).

CONCLUSIONS

LI-RADS ≥ 3 shows high diagnostic accuracy for HCCs, with a pooled sensitivity of 0.86 and specificity of 0.85. The specificity is higher for LR-5 and LR ≥ 5. However, further prospective studies on LI-RADS ≥ 3 are needed to elucidate its value for diagnosing small HCCs (≤20 mm).

Prognostic value of LI-RADS category on gadoxetic acid-enhanced MRI and 18F-FDG PET-CT in patients with primary liver carcinomas

OBJECTIVES

To evaluate the postoperative prognostic value of the Liver Imaging Reporting and Data System (LI-RADS) category on gadoxetic acid-enhanced MRI and 18F-fluorodeoxyglucose PET-CT in patients with primary liver carcinomas (PLCs).

METHODS

A total of 189 patients with chronic liver disease and surgically proven single PLC (42 intrahepatic cholangiocarcinomas and 21 combined hepatocellular-cholangiocarcinomas and 126 hepatocellular carcinomas [2:1 matching to non-HCC malignancies]) were retrospectively evaluated with gadoxetic acid-enhanced MRI and PET-CT. Two independent reviewers assigned an LI-RADS category for each observation. The tumor-to-liver standardized uptake value ratio (TLR) was calculated. The overall survival (OS), recurrence-free survival (RFS), and the associated factors were evaluated.

RESULTS

In multivariable analysis, LI-RADS category (LR-4 or LR-5 [LR-4/5] vs. LR-M; OS, hazard ratio [HR] 2.24, p = 0.006; RFS, HR 1.61, p = 0.028) and TLR (low, < 2.3 vs. high, ≥ 2.3; OS, HR 2.09, p = 0.014; RFS, HR 2.17, p < 0.001) were the independent factors for OS and RFS. For the LR-M group, the high TLR group showed lower OS and RFS rates than the low TLR group (OS, p = 0.008; RFS, p < 0.001). For the LR-4/5 group, the OS and RFS rates were not significantly different between the high TLR and low TLR groups (both p > 0.05).

CONCLUSIONS

Both LI-RADS category on MRI and TLR on PET-CT are associated with the postoperative prognosis of PLCs. The prognosis of PLCs classified as LR-M can be further stratified according to the TLR group, but not for the PLCs classified as LR-4/5.

KEY POINTS

• The LI-RADS category (LR-4/5 vs. LR-M) and tumor-to-liver standardized uptake value ratio (TLR, low vs. high) were independent factors for postoperative prognosis of primary liver carcinomas (PLCs). • For PLCs classified as LR-M, the TLR group helps stratify the postoperative prognosis of PLCs, with the high TLR group having a poor prognosis and the low TLR group having a better prognosis (p = 0.008 for OS and p < 0.001 for RFS). • For PLCs classified as LR-4/5, the OS and RFS rates were not significantly different between the high TLR and low TLR groups (both p > 0.05).

Prognostic factors of gadoxetic acid-enhanced MRI for postsurgical outcomes in multicentric hepatocellular carcinoma

OBJECTIVES

The primary aim of this study was to determine the clinical and histopathological prognostic factors for patients who underwent surgical resection of multiple hepatocellular carcinomas (HCCs) of multicentric occurrence. The secondary aim of this study was to evaluate whether specific imaging-related factors, including arterial phase hyperenhancement (APHE) and the LI-RADS category of each lesion on gadoxetic acid-enhanced MRI, would provide additional prognostic information about multicentric HCCs.

METHODS

In this retrospective study, 54 patients with 120 multicentric HCCs were diagnosed by surgical resection at a single tertiary hospital between 2009 and 2014. Two independent readers evaluated patients' preoperative gadoxetic acid-enhanced MR images and recorded APHE and LI-RADS category for each HCC, with discrepancies resolved through consensus sessions if necessary. Potential clinicopathologic and imaging parameters for predicting disease-free survival (DFS) and overall survival (OS) were analyzed using Cox regression analysis.

RESULTS

Presence of microvascular invasion (MVI) (p = 0.003) and of three or more HCCs (p = 0.013) were both independent predictors of a shorter DFS. Patients with concurrent MVI and three or more HCCs had the shortest DFS. MVI was the only statistically significant parameter (p = 0.023) predicting OS. The number of HCCs with APHE or LR-5/M category was not associated with survival.

CONCLUSIONS

Presence of MVI and of three or more HCCs were associated with poorer outcomes after surgical resection of multicentric HCCs. Imaging parameters on gadoxetic acid-enhanced MRI such as APHE or LI-RADS category were not associated with postsurgical outcomes.

KEY POINTS

• Patients with three or more hepatocellular carcinomas showed worse disease-free survival than those with two hepatocellular carcinomas after surgical resection. • Microvascular invasion was the only significant factor to affect both the disease-free and overall survivals of patients after surgical resection of multicentric hepatocellular carcinomas. • Preoperative MRI findings related to multicentric hepatocellular carcinomas such as arterial phase hyperenhancement and LI-RADS category of lesions did not provide significant prognostic information.

Evaluation of Primary Liver Cancers Using Hepatocyte-Specific Contrast-Enhanced MRI: Pitfalls and Potential Tips

When radiologists interpret hepatic focal lesions seen on dynamic magnetic resonance imaging (MRI) scans, it is important not only to distinguish malignant lesions from benign ones but also to distinguish nonhepatocellular carcinoma (HCC) malignancies from HCCs. In addition, most major guidelines, including those of the American Association for the Study of Liver Disease, European Association for the Study of the Liver, and Korean Liver Cancer Association and National Cancer Center, allow for the noninvasive imaging diagnosis of HCC in at-risk patients. However, ~40% of HCC cases show atypical imaging features mimicking non-HCC malignancies. Furthermore, several benign and malignant lesions, such as flash-filling hemangioma and intrahepatic mass-forming cholangiocarcinoma, frequently look like HCC. In contrast, although multiparametric MRI options, including hepatobiliary phase and diffusion-weighted imaging, provide useful information that could help address these challenges, there remain several unresolved issues with regard to the noninvasive diagnostic criteria characterizing HCC. In this article, we discuss the typical imaging features and challenging situations related to primary liver cancers in MRI, while considering how to make a correct diagnosis. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

Liver imaging reporting and data system category M: A systematic review and meta-analysis

BACKGROUND AND AIMS

The Liver Imaging Reporting and Data System (LI-RADS) category M (LR-M) was introduced to preserve the high specificity of LI-RADS algorithm for diagnosing hepatocellular carcinoma (HCC). We aimed to systematically determine the probability of the LR-M for HCC and non-HCC malignancy, and to determine the sources of heterogeneity between reported results.

METHODS

Original studies reporting the probability of LR-M for HCC and non-HCC malignancy on magnetic resonance imaging (MRI) were identified in MEDLINE and EMBASE. The meta-analytic pooled percentages of HCC and non-HCC in LR-M were calculated. Meta-regression analysis was performed to explore study heterogeneity. The meta-analytic frequency of each LR-M imaging feature was determined.

RESULTS

We found 10 studies reporting the diagnostic performance of LR-M (1819 lesions in 1631 patients), and six reporting the frequency of LR-M imaging features. The pooled percentages of HCC and non-HCC malignancy for LR-M were 28.2% (95% confidence interval [CI], 23.8%-33.1%; I²  = 83%) and 69.6% (95% CI, 64.6%-74.1%; I²  = 83%) respectively. The study type and MRI scanner field strength were significantly associated with study heterogeneity (P ≤ .04). Of the seven imaging features, rim arterial phase hyperenhancement showed the highest frequency in both non-HCC (48.9%; 95% CI, 43.0%-54.8%) and HCC groups (9.8%; 95% CI, 6.9%-13.6%).

CONCLUSIONS

The LR-M category most commonly included non-HCC malignancy but also included 28.2% of HCC. Substantial study heterogeneity was noted, and it was significantly associated with study type and MRI scanner field strength. In addition, the frequency of LR-M imaging features was variable.

The Role of Preoperative Dynamic Contrast-enhanced 3.0-T MR Imaging in Predicting Early Recurrence in Patients With Early-Stage Hepatocellular Carcinomas After Curative Resection

Objectives: Liver resection is potentially curative for early-stage hepatocellular carcinoma (eHCC) in patients with well-preserved liver function. The prognosis of these patients after resection is still unsatisfactory because of frequent early recurrence (ER). Therefore, we investigated the role of preoperative dynamic contrast-enhanced 3.0-T MR imaging in predicting ER of eHCC after curative resection. Methods From May 2014 to October 2017, we retrospectively analyzed 82 patients with eHCC who underwent dynamic MR imaging and subsequently underwent curative resection. Liver Imaging Reporting and Data System (LI-RADS) v2018 major and ancillary imaging features, as well as two non-LI-RADS MR imaging features (irregular tumor margin and tumor number), were evaluated. A multivariate Cox regression analysis was used to identify independent predictors, and two models (preoperative and postoperative prediction models) were developed. Results ER was observed in 25 patients (25/82, 30.5%). In the univariate analyses, preoperative alpha-fetoprotein (AFP) level >200 ng/ml, three MR imaging features (multifocal tumors, corona enhancement, and irregular tumor margin), and microvascular invasion (MVI) were associated with ER. In the multivariate analysis, corona enhancement (hazard ratio [HR]: 2.970; p = 0.013) and irregular tumor margin (HR: 2.377; p = 0.048) were independent predictors in the preoperative prediction model, and preoperative AFP level >200 ng/ml (HR: 2.493; p = 0.044) plus corona enhancement (HR: 3.046; p = 0.014) were independent predictors in the postoperative prediction model (microvascular invasion [MVI] was not; p = 0.061). When combined with both predictors, the specificity for ER in the preoperative prediction model was 98.2% (56/57), which was comparable to that of the postoperative prediction model [96.7% (55/57)]. Conclusions Our results demonstrated that preoperative MR imaging features (corona enhancement and irregular tumor margin) have the potential to preoperatively identify high-risk ER patients with eHCC, with a specificity >90%.

Arterial subtraction images of gadoxetate-enhanced MRI improve diagnosis of early-stage hepatocellular carcinoma

BACKGROUND & AIMS

Although gadoxetate disodium-enhanced magnetic resonance imaging (MRI) shows higher sensitivity for diagnosing hepatocellular carcinoma (HCC), its arterial-phase images may be unsatisfactory because of weak arterial enhancement. We investigated the clinical effectiveness of arterial subtraction images from gadoxetate disodium-enhanced MRI for diagnosing early-stage HCC using the Liver Imaging Reporting and Data System (LI-RADS) v2018.

METHODS

In 258 patients at risk of HCC who underwent gadoxetate disodium-enhanced MRI in 2016, a total of 372 hepatic nodules (273 HCCs, 18 other malignancies, and 81 benign nodules) of 3.0 cm or smaller were retrospectively analyzed. Final diagnosis was assessed histopathologically or clinically (marginal recurrence after treatment or change in lesion size on follow-up imaging). The detection rate for arterial hyperenhancement was compared between ordinary arterial-phase and arterial subtraction images, and the benefit of arterial subtraction images in diagnosing HCC using LI-RADS was assessed.

RESULTS

Arterial subtraction images had a significantly higher detection rate for arterial hyperenhancement than ordinary arterial-phase images, both for all hepatic nodules (72.3% vs. 62.4%, p <0.001) and HCCs (91.9% vs. 80.6%, p <0.001). Compared with ordinary arterial-phase images, arterial subtraction images significantly increased the sensitivity of LI-RADS category 5 for diagnosis of HCC (64.1% [173/270] vs. 55.9% [151/270], p <0.001), without significantly decreasing specificity (92.9% [91/98] vs. 94.9% [93/98], p = 0.155). For histopathologically confirmed lesions, arterial subtraction images significantly increased sensitivity to 68.8% (128/186) from the 61.3% (114/186) of ordinary arterial-phase images (p <0.001), with a minimal decrease in specificity to 84.8% (39/46) from 89.1% (41/46) (p = 0.151).

CONCLUSIONS

Arterial subtraction images of gadoxetate disodium-enhanced MRI can significantly improve the sensitivity of early-stage HCC diagnosis using LI-RADS, without a significant decrease in specificity.

LAY SUMMARY

Gadoxetate disodium-enhanced magnetic resonance imaging is an imaging technique with a high sensitivity for the diagnosis of hepatocellular carcinoma. However, arterial-phase images may be unsatisfactory because of weak arterial enhancement. We found that using arterial subtraction images led to clinically meaningful improvements in the diagnosis of early-stage hepatocellular carcinoma.

User and system pitfalls in liver imaging with LI-RADS

The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing the terminology, technique, interpretation, reporting, and data collection of liver imaging, created specifically for patients at risk for hepatocellular carcinoma. Over the past years, LI-RADS has been progressively implemented into clinical practice, but pitfalls remain related to user error and inherent limitations of the system. User pitfalls include the inappropriate application of LI-RADS to a low-risk patient population, incorrect measurement techniques, inaccurate assumptions about LI-RADS requirements, and improper usage of LI-RADS terminology and categories. System pitfalls include areas of discordance with the Organ Procurement and Transplantation Network (OPTN) as well as pitfalls related to rare ancillary features. This article reviews common user pitfalls in applying LI-RADS v2018 and how to avoid preventable errors and also highlights deficiencies of the current version of LI-RADS and how it might be improved in the future. Level of Evidence:3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2019;50:1673-1686.

Introduction to the Liver Imaging Reporting and Data System for Hepatocellular Carcinoma

The Liver Imaging Reporting And Data System (LI-RADS) was created with the support of the American College of Radiology (ACR) to standardize the acquisition, interpretation, reporting, and data collection for imaging examinations in patients at risk for hepatocellular carcinoma (HCC). A comprehensive and rigorous system developed by radiologists, hepatologists, pathologists, and surgeons, LI-RADS addresses a wide range of imaging contexts. Currently, 4 algorithms are available publicly on the ACR website: ultrasound for HCC surveillance, computed tomography and magnetic resonance imaging for HCC diagnosis and tumor staging, contrast-enhanced ultrasound for HCC diagnosis, and computed tomography/magnetic resonance imaging for treatment response assessment. Each algorithm is supported by a decision tree, categorization table, lexicon, atlas, technical requirements, and reporting and management guidance. Category codes reflecting the relative probability of HCC and malignancy are assigned to imaging-detected liver observations, with emerging evidence suggesting that LI-RADS accurately stratifies HCC and malignancy probabilities. LI-RADS is an evolving system and has been updated and refined iteratively since 2011 based on scientific evidence, expert opinion, and user feedback, with input from the American Association for the Study of Liver Diseases and the Organ Procurement Transplantation Network/United Network for Organ Sharing. Concurrent with its most recent update, LI-RADS was integrated into the American Association for the Study of Liver Diseases HCC guidance released in 2018. We anticipate continued refinement of LI-RADS and progressive adoption by radiologists worldwide, with the eventual goal of culminating in a single unified system for international use.

Liver Imaging Reporting and Data System Category 5: MRI Predictors of Microvascular Invasion and Recurrence After Hepatectomy for Hepatocellular Carcinoma

OBJECTIVE. We investigated in Liver Imaging Reporting and Data System category 5 (LR-5) observations whether imaging features, including LI-RADS imaging features, could predict microvascular invasion (MVI) and posthepatectomy recurrence in high-risk adult patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS. We retrospectively identified 149 high-risk patients who underwent 3-T MRI within 1 month before hepatectomy for HCC; 81 of 149 patients with no HCC recurrence were followed for more than 1 year. Tumors with clear surgical margins were confirmed in each hepatectomy specimen. MVI was evaluated histologically by a histopathologist. Tumor recurrence was determined by clinical and imaging follow-up. Two independent radiologists reviewed the prehepatectomy MR images and assessed LI-RADS v2018 imaging features as well as some non-LI-RADS features in all LR-5 observations in consensus. Alpha-fetoprotein level, tumor number, and imaging features were analyzed as potential predictors for MVI and posthepatectomy recurrence using multivariate logistic regression and Cox proportional hazards models. RESULTS. One hundred forty-nine patients with pathologically confirmed HCC were included; 64 of 149 (43.0%) patients had MVI, whereas 48 of 129 (37.2%) patients had tumor recurrence within 3 years after hepatectomy. Mosaic architecture (odds ratio, 3.420; p < 0.001) and nonsmooth tumor margin (odds ratio, 2.554; p = 0.011) were independent predictors of MVI. Multifocal tumors (hazard ratio, 2.101; p = 0.034), absence of fat in mass (hazard ratio, 2.109; p = 0.015), and nonsmooth tumor margin (hazard ratio, 2.415; p = 0.005) were independent predictors of posthepatectomy recurrence. CONCLUSION. In high-risk patients with LR-5 HCC, mosaic architecture and non-smooth tumor margin independently predicted MVI. Multifocal tumors, absence of fat in mass, and nonsmooth tumor margin independently predicted recurrence.

Accuracy of the Liver Imaging Reporting and Data System in Computed Tomography and Magnetic Resonance Image Analysis of Hepatocellular Carcinoma or Overall Malignancy-A Systematic Review

BACKGROUND & AIMS

The Liver Imaging Reporting and Data System (LI-RADS) categorizes observations from imaging analyses of high-risk patients based on the level of suspicion for hepatocellular carcinoma (HCC) and overall malignancy. The categories range from definitely benign (LR-1) to definitely HCC (LR-5), malignancy (LR-M), or tumor in vein (LR-TIV) based on findings from computed tomography or magnetic resonance imaging. However, the actual percentage of HCC and overall malignancy within each LI-RADS category is not known. We performed a systematic review to determine the percentage of observations in each LI-RADS category for computed tomography and magnetic resonance imaging that are HCCs or malignancies.

METHODS

We searched the MEDLINE, Embase, Cochrane CENTRAL, and Scopus databases from 2014 through 2018 for studies that reported the percentage of observations in each LI-RADS v2014 and v2017 category that were confirmed as HCCs or other malignancies based on pathology, follow-up imaging analyses, or response to treatment (reference standard). Data were assessed on a per-observation basis. Random-effects models were used to determine the pooled percentages of HCC and overall malignancy for each LI-RADS category. Differences between categories were compared by analysis of variance of logit-transformed percentage of HCC and overall malignancy. Risk of bias and concerns about applicability were assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Of 454 studies identified, 17 (all retrospective studies) were included in the final analysis, consisting of 2760 patients, 3556 observations, and 2482 HCCs. The pooled percentages of observations confirmed as HCC and overall malignancy, respectively, were 94% (95% confidence interval [CI] 92%-96%) and 97% (95% CI 95%-99%) for LR-5, 74% (95% CI 67%-80%) and 80% (95% CI 75%-85%) for LR-4, 38% (95% CI 31%-45%) and 40% (95% CI 31%-50%) for LR-3, 13% (95% CI 8%-22%) and 14% (95% CI 9%-21%) for LR-2, 79% (95% CI 63%-89%) and 92% (95% CI 77%-98%) for LR-TIV, and 36% (95% CI 26%-48%) and 93% (95% CI 87%-97%) for LR-M. No malignancies were found in the LR-1 group. The percentage of HCCs and overall malignancies confirmed differed significantly among LR groups 2-5 (P < .00001). Patient selection was the most frequent factor that affected bias risk, because of verification bias and case-control study design.

CONCLUSIONS

In a systematic review, we found that increasing LI-RADS categories contained increasing percentages of HCCs and overall malignancy based on reference standard confirmation. Of observations categorized as LR-M, 93% were malignancies and 36% were confirmed as HCCs. The percentage of HCCs found in the LR-2 and LR-3 categories indicate the need for a more active management strategy than currently recommended. Prospective studies are needed to validate these findings. PROSPERO number CRD42018087441.

Hepatocellular Carcinoma with Irregular Rim-Like Arterial Phase Hyperenhancement: More Aggressive Pathologic Features

BACKGROUND AND AIMS

The purpose of our study was to examine the histopathologic characteristics of hepatocellular carcinoma (HCC) with irregular rim-like arterial phase enhancement (IRE), which has been reported to be associated with more aggressive tumor behavior.

METHODS

We investigated 84 pathologically confirmed HCCs in 84 patients who underwent curative hepatic resection after gadoxetate-enhanced magnetic resonance imaging between January 2008 and February 2013. Two abdominal radiologists independently reviewed these images and classified HCCs into two categories: HCC showing IRE (IRE-HCC) and HCC showing hypoenhancement or diffuse arterial enhancement (non-IRE-HCC). Twenty-two HCCs were classified as IRE-HCCs, and 51 were classified as non-IRE-HCCs concordantly by both reviewers. The remaining 11 HCCs, on whose radiologic classifications the reviewers disagreed, were classified as HCCs with intermediate enhancement patterns. The HCC clinicopathologic characteristics and patient outcomes were then compared.

RESULTS

IRE-HCCs showed more frequent microvascular invasion (91 vs. 35%), lower microvascular density (246.5 vs. 426.5/mm²), higher proportions of sinusoid-like microvascular pattern (55 vs. 0%) and macrotrabecular pattern (45 vs. 0%), and larger areas of tumor necrosis (15 vs. 0%) and fibrous stroma (8.3 vs. 2.1%) than non-IRE-HCCs. IRE-HCCs also expressed higher levels of immunomarkers of hypoxia (carbonic anhydrase IX, 64 vs. 8%) and stemness (EpCAM, 50 vs. 20%). p values were < 0.001 for all comparisons except for EpCAM (p = 0.026). HCCs with intermediate enhancement patterns showed mixed/intermediate pathologic features from both IRE- and non-IRE-HCCs. IRE-HCC patients showed poorer 5-year disease-free survival after curative resection than non-IRE-HCC patients (p = 0.005).

CONCLUSIONS

IRE-HCCs demonstrate aggressive histopathologic features, including more hypoxic and fibrotic tumor microenvironments and increased stemness, compared to non-IRE-HCCs. IRE might therefore serve as a noninvasive imaging biomarker for aggressive HCC.