LI-RADS Treatment Response Algorithm: Performance and Diagnostic Accuracy

CT perfusion and MRI: A combined approach for hepatocellular carcinoma diagnosis and follow-up after locoregional treatment

OBJECTIVE

CT liver perfusion (CTLP) has been well validated for hepatocellular carcinoma (HCC) detection, characterization, and treatment response evaluation. However, its role in HCC management algorithms remains unclear. This study aims to assess the diagnostic performance of CTLP alone or as an adjunct to MRI in patients considered for- or undergoing locoregional treatment for HCC.

MATERIAL AND METHODS

Thirty-nine patients under HCC surveillance (36 male, 31 cirrhotic, 16 pretreatment, 19 post-transarterial chemoembolization, 2 post-ablation) underwent MRI and CTLP in a single center within a 45-day interval. Two readers identified and characterized all observations on MRI using Liver Imaging Reporting and Data System (LI-RADS) v2018 criteria. CTLP assessment was based on Mean Slope of Increase (MSI), Time To Peak (TTP), Hepatic arterial Blood Flow (HaBF) and Hepatic Arterial Fraction (HAF) maps and established cut-offs. Diagnostic performance of MRI, CTLP, and their combination was evaluated for treated and untreated lesions using imaging or pathology as reference standard.

RESULTS

Of the total 33 treated and 61 untreated lesions, 13 and 41 were considered viable HCCs. CTLP demonstrated 75.9 % sensitivity and 95 % specificity compared to 72.2 % and 100 % for MRI (p > 0.05). Combining both modalities increased sensitivity to 85.2 % (p < 0.05) and maintained specificity at 97.5 % (p > 0.05). The combined approach led to an LR category change in 5 treated and 19 untreated lesions and affected management in 5 cases.

CONCLUSION

CTLP and MRI have comparable diagnostic performance for HCC. A combined approach improves sensitivity, without sacrificing specificity. This approach might enable more efficient patient selection for early and individualized loco-regional treatment.

LI-RADS Nonradiation Treatment Response Algorithm Version 2024: Diagnostic Performance and Impact of Ancillary Features

BACKGROUND. LI-RADS Treatment Response Algorithm (TRA) version 2024 (v2024) introduced separate algorithms for detecting hepatocellular carcinoma (HCC) viability after radiation and nonradiation locoregional therapies (LRTs). The nonradiation algorithm incorporated MRI-based ancillary features to optionally upgrade lesions from LR-TR Equivocal to LR-TR Viable. OBJECTIVE. The purpose of this study was to compare the diagnostic performance of LI-RADS Nonradiation TRA v2024 with that of LI-RADS TRA version 2017 (v2017) and modified RECIST (mRECIST) for evaluating HCC response to LRT on MRI, with attention given to the impact of ancillary features. METHODS. This retrospective study included 231 patients (198 men and 33 women; median age, 56 years) who underwent LRT for HCC followed by liver resection or transplant between January 2017 and December 2022. Two radiologists (reader 1 and reader 2) independently evaluated treated lesions (n = 306) using LI-RADS Nonradiation TRA v2024, LI-RADS TRA v2017, and mRECIST. Lesions were classified as showing pathologic viability (n = 249) or complete pathologic necrosis (n = 57) based on curative surgery pathology. The diagnostic performance for pathologic viability was compared using Bonferroni-adjusted McNemar tests, with LR-TR Equivocal assessments classified as test negative. RESULTS. The sensitivity, specificity, and accuracy for LI-RADS Nonradiation TRA v2024 with ancillary features were 85.5%, 75.4%, and 83.7%, respectively, for reader 1 and 87.2%, 63.2%, and 82.7%, respectively, for reader 2; for LI-RADS Nonradiation TRA v2024 without ancillary features, they were 81.1%, 78.9%, and 80.7%, respectively, for reader 1 and 80.3%, 78.9%, and 80.1%, respectively, for reader 2; for LI-RADS TRA v2017, they were 79.9%, 82.5%, and 80.4%, respectively, for reader 1 and 79.1%, 79.0%, and 79.1%, respectively, for reader 2; and for mRECIST, they were 83.9%, 54.4%, and 78.4%, respectively, for reader 1 and 87.2%, 40.4%, and 78.4%, respectively, for reader 2. LI-RADS Nonradiation TRA v2024 with ancillary features showed higher sensitivity and accuracy than LI-RADS Nonradiation v2024 without ancillary features (both readers), higher sensitivity than LI-RADS TRA v2017 (both readers), higher specificity than mRECIST (both readers), and higher accuracy than LI-RADS TRA v2017 (reader 2) (p < .008); remaining comparisons between LI-RADS Nonradiation TRA v2024 with ancillary features and other systems were not significant (p > .008). CONCLUSION. LI-RADS Nonradiation TRA v2024 showed good diagnostic performance in detecting pathologic viability. Ancillary features yielded improved sensitivity and accuracy without a significant change in specificity. CLINICAL IMPACT. Use of LI-RADS Nonradiation TRA v2024 with ancillary features is recommended for guiding prognostic assessments and treatment decisions after LRT.

Inter-Reader Agreement in LR-TRA Application and NLR Association in HCC Patients Treated with Endovascular vs. Ablative Procedures

OBJECTIVES

This study aimed to assess the performance of the LI-RADS tumor response algorithm in analyzing inter-reader agreement in patients with hepatocellular carcinoma (HCC) treated with Microwave Ablation (MWA) and Transarterial Embolization (TAE) and the relationship between inter-reader agreement and Neutrophils to Lymphocytes ratio dynamic variations at different time points to explore how inflammation influences tumor response and its interpretation on imaging.

METHODS

A retrospective analysis was conducted on 78 HCC patients treated with MWA or TAE. Two independent radiologists evaluated pre- and post-treatment imaging and assigned categories according to the LR-TRA. Inter-reader agreement was assessed with a focus on subgroup analysis considering the different locoregional treatments. NLR values, measured at baseline (T0), 72 h (T1), and 30 days post-procedure (T2), were compared with patients with concordant and discordant LR-TRA assessments. This analysis aimed to identify any association between NLR dynamics and inter-reader agreement on treatment response.

RESULTS

The inter-reader agreement in the LR-TRA application was "substantial" in the cases of MWA treatment evaluation (κ = 0.65), and "moderate" in the cases of TAE treatment evaluation (κ = 0.51). The differences in inter-reader agreement were found to be expressions of different levels of NLR mean values in the different time frames evaluated. Three days after treatment, NLR increased significantly in TAE groups. At 30 days, NLR had returned close to baseline levels but with NLR persisting higher in the TAE group. There was a statistically significant difference in NLR between the "mismatch" group (those with discrepant LR-TRA readings) and the "match" group at 3 days (p = 0.004) and late evaluation (30+ days).

CONCLUSIONS

This study has shown that NLR levels can predict inter-reader discrepancies in LR-TRA assessment and may be translated into different levels of difficult imaging interpretation. Combining LR-TRA and NLR is promising for a more comprehensive assessment of tumor response and inflammatory dynamics.

Radiological Assessment and Therapeutic Evaluation in Hepatocellular Carcinoma: Differentiation and Treatment Response with Japanese Guidelines

The liver is supplied by a dual blood flow system consisting of the portal vein and hepatic artery. Imaging techniques for diagnosing hepatocellular carcinoma (HCC) have been developed along with blood flow imaging, which visualizes the amount of arterial and portal blood flow. The diagnosis of HCC differentiation is important for early-stage liver cancer screening and determination of treatment strategies. Dynamic computed tomography/magnetic resonance imaging (MRI) includes blood flow imaging and MRI with contrast-enhanced ultrasound and liver-specific contrast agents are used in combination. In addition, unlike the Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1), which is the standard for determining treatment efficacy for solid tumors in general, tumor necrosis is generally considered a treatment effect in HCC, and the modified RECIST and Liver Cancer Direct Effectiveness Criteria (RECICL) are widely used. Familiarity with the definitions, criteria, and potential challenges of the mRECIST and RECICL is essential for their effective application in clinical practice. This review integrates the latest advancements in systemic treatments and imaging techniques, including the role of LI-RADS and updates on molecular-targeted therapies such as regorafenib, supported by some systematic review and meta-analysis.

Inter-reader agreement of LI-RADS treatment response algorithm among three readers with different seniorities for hepatocellular carcinoma after locoregional therapy

BACKGROUND

The accurate evaluation of tumor response after locoregional therapy is crucial for adjusting therapeutic strategy and guiding individualized follow-up.

PURPOSE

To determine the inter-reader agreement of the LR-TR algorithm for hepatocellular carcinoma treated with locoregional therapy among radiologists with different seniority.

MATERIAL AND METHODS

A total of 275 treated observations on 249 MRI scans from 99 patients were retrospectively collected. Three readers of different seniorities (senior, intermediate, and junior with 10, 6, and 2 years of experience in hepatic imaging, respectively) analyzed the presence or absence of features (arterial-phase hyperenhancement and washout) and evaluated LR-TR category.

RESULTS

There were substantial inter-reader agreements for overall LR-TR categorization (kappa = 0.704), LR-TR viable (kappa = 0.715), and LR-TR non-viable (kappa = 0.737), but fair inter-reader agreement for LR-TR equivocal (kappa = 0.231) among three readers. The inter-reader agreement was substantial for arterial-phase hyperenhancement (kappa = 0.725), but moderate for washout (kappa = 0.443) among three readers. The inter-reader agreements between two readers were substantial for overall LR-TR categorization (kappa = 0.734, 0.727, 0.652), LR-TR viable (kappa = 0.719, 0.752, 0.678), and LR-TR non-viable (kappa = 0.758, 0.760, 0.694), which were at the same level as the inter-reader agreements among three readers. In addition, the inter-reader agreements between two readers were substantial for arterial-phase hyperenhancement (kappa = 0.733, 0.766, 0.678), but moderate for washout (kappa = 0.473, 0.422, 0.446), which were at the same level as the inter-reader agreements among three readers.

CONCLUSION

LR-TR algorithm demonstrated overall substantial inter-reader agreement among radiologists with different seniority.

CT/MRI LI-RADS 2024 Update: Treatment Response Assessment

With the rising incidence of hepatocellular carcinoma, there has been increasing use of local-regional therapy (LRT) to downstage or bridge to transplant, for definitive treatment, and for palliation. The CT/MRI Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Assessment (TRA) algorithm provides guidance for step-by-step tumor assessment after LRT and standardized reporting. Current evidence suggests that the algorithm performs well in the assessment of tumor response to arterial embolic and loco-ablative therapies and fair when assessing response to radiation-based therapies, with limited data to validate the latter. Both evidence-based and expert-based refinements of the algorithm are needed to improve its diagnostic accuracy after varying types of LRT. This review provides an overview of the challenges and limitations of the LI-RADS TRA algorithm version 2017 and discusses the refinements introduced in the updated 2024 LI-RADS algorithm for CT/MRI.

Deep learning-based arterial subtraction images improve the detection of LR-TR algorithm for viable HCC on extracellular agents-enhanced MRI

PURPOSE

To determine the role of deep learning-based arterial subtraction images in viability assessment on extracellular agents-enhanced MRI using LR-TR algorithm.

METHODS

Patients diagnosed with HCC who underwent locoregional therapy were retrospectively collected. We constructed a deep learning-based subtraction model and automatically generated arterial subtraction images. Two radiologists evaluated LR-TR category on ordinary images and then evaluated again on ordinary images plus arterial subtraction images after a 2-month washout period. The reference standard for viability was tumor stain on the digital subtraction hepatic angiography within 1 month after MRI.

RESULTS

286 observations of 105 patients were ultimately enrolled. 157 observations were viable and 129 observations were nonviable according to the reference standard. The sensitivity and accuracy of LR-TR algorithm for detecting viable HCC significantly increased with the application of arterial subtraction images (87.9% vs. 67.5%, p < 0.001; 86.4% vs. 75.9%, p < 0.001). And the specificity slightly decreased without significant difference when the arterial subtraction images were added (84.5% vs. 86.0%, p = 0.687). The AUC of LR-TR algorithm significantly increased with the addition of arterial subtraction images (0.862 vs. 0.768, p < 0.001). The arterial subtraction images also improved inter-reader agreement (0.857 vs. 0.727).

CONCLUSION

Extended application of deep learning-based arterial subtraction images on extracellular agents-enhanced MRI can increase the sensitivity of LR-TR algorithm for detecting viable HCC without significant change in specificity.

LI-RADS version 2018 treatment response algorithm on extracellular contrast-enhanced MRI in patients treated with transarterial chemoembolization for hepatocellular carcinoma: diagnostic performance and the added value of ancillary features

BACKGROUND

The Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm (TRA) (LI-RADS TRA) is used for assessing response of HCC to locoregional therapy (LRT), however, the value of ancillary features (AFs) for TACE-treated HCCs has not been extensively investigated on extracellular agent MRI (ECA-MRI).

PURPOSE

To evaluate the diagnostic performance of LI-RADS v2018 TRA on ECA-MRI for HCC treated with transarterial chemoembolization (TACE) and the value of ancillary features.

METHODS

This retrospective study included patients who underwent TACE for HCC and then followed by hepatic surgery between January 2019 and June 2023 with both pre- and post-TACE contrast-enhanced MRI available. Two radiologists independently evaluated the post-treated lesions on MRI using LI-RADS treatment response (TR) (LR-TR) algorithm and modified LR-TR (mLR-TR) algorithm in which ancillary features (restricted diffusion and intermediate T2-weighted hyperintensity) were added, respectively. Lesions were categorized as complete pathologic necrosis (100%, CPN) and non-complete pathologic necrosis (< 100%, non-CPN) on the basis of surgical pathology. The diagnostic performance in predicting viable and non-viable tumors based on LR-TR and mLR-TR algorithms was compared using the McNemar test. Interreader agreement was calculated by using Cohen's weighted and unweighted κ.

RESULTS

A total of 61 patients [mean age 59 years ± 10 (standard deviation); 47 men] with 79 lesions (57 pathologically viable) were included. For non-CPN prediction, the sensitivity, specificity of LR-TR viable and mLR-TR viable category were 75% (43 of 57), 82% (18 of 22) and 88% (50 of 57), 77% (17 of 22), respectively, the sensitivity of mLR-TR was significantly higher than that of LR-TR (P = 0.016) without difference in specificity (P = 1.000). Interreader agreement for LR-TR and mLR-TR category was moderate (k = 0.50, 95% confidence interval 0.33, 0.67, k = 0.42, 95% confidence interval 0.20, 0.63). The sensitivity of both LR-TR and mLR-TR algorithms in predicting viable tumors between conventional TACE (cTACE) and drug-eluting beads TACE (DEB-TACE) did not have significant difference (cTACE: 76%, 89% vs. DEB-TACE: 73%, 82%).

CONCLUSIONS

On ECA-MRI, applying ancillary features to LI-RADS v2018 TRA can improve the sensitivity in predicting pathologic tumor viability in patients treated with TACE for hepatocellular carcinoma with no significant difference in specificity.

Radiomics and liver: Where we are and where we are headed?

Hepatic diffuse conditions and focal liver lesions represent two of the most common scenarios to face in everyday radiological clinical practice. Thanks to the advances in technology, radiology has gained a central role in the management of patients with liver disease, especially due to its high sensitivity and specificity. Since the introduction of computed tomography (CT) and magnetic resonance imaging (MRI), radiology has been considered the non-invasive reference modality to assess and characterize liver pathologies. In recent years, clinical practice has moved forward to a quantitative approach to better evaluate and manage each patient with a more fitted approach. In this setting, radiomics has gained an important role in helping radiologists and clinicians characterize hepatic pathological entities, in managing patients, and in determining prognosis. Radiomics can extract a large amount of data from radiological images, which can be associated with different liver scenarios. Thanks to its wide applications in ultrasonography (US), CT, and MRI, different studies were focused on specific aspects related to liver diseases. Even if broadly applied, radiomics has some advantages and different pitfalls. This review aims to summarize the most important and robust studies published in the field of liver radiomics, underlying their main limitations and issues, and what they can add to the current and future clinical practice and literature.

Contrast-enhanced ultrasonography-CT/MRI fusion guidance for percutaneous ablation of inconspicuous, small liver tumors: improving feasibility and therapeutic outcome

BACKGROUND

Percutaneous radiofrequency ablation (RFA) is pivotal for treating small malignant liver tumors, but tumors often remain inconspicuous on B-mode ultrasound (US). This study evaluates the potential of CEUS-CT/MRI fusion imaging (FI) to improve tumor visibility and the associated RFA outcomes for small (≤ 3 cm) malignant liver tumors that were inconspicuous on US.

METHODS

Between January 2019 and April 2021, a prospective study enrolled 248 patients with liver malignancies (≤ 3 cm) that were poorly visible on B-mode US. Tumor visibility and ablation feasibility were assessed using B-mode US, US-CT/MRI FI, and CEUS-CT/MRI FI, and graded on a 4-point scale. CEUS was employed post-registration of US and CT/MRI images, utilizing either SonoVue or Sonazoid. Comparisons between US-based and CEUS-based fusion visibility and feasibility scores were undertaken using the Friedman test. Moreover, rates of technical success, technique efficacy, local tumor progression (LTP), and major complications were assessed.

RESULTS

The cohort included 223 hepatocellular carcinomas (HCCs) (89.9%) and 23 metastases (9.3%), with an average tumor size of 1.6 cm. CEUS-CT/MRI FI demonstrated a significant advantage in tumor visibility (3.4 ± 0.7 vs. 1.9 ± 0.6, P < 0.001) and technical feasibility (3.6 ± 0.6 vs. 2.9 ± 0.8, P < 0.001) compared to US-FI. In 85.5% of patients, CEUS addition to US-FI ameliorated tumor visibility. Technical success was achieved in 99.6% of cases. No severe complications were reported. One and two-year post CEUS-CT/MRI FI-guided RFA estimates for LTP were 9.3% and 10.9%, respectively.

CONCLUSIONS

CEUS-CT/MRI FI significantly improves the visualization of tumors not discernible on B-mode US, thus augmenting percutaneous RFA success and delivering improved therapeutic outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05445973. Registered 17 June 2022 - Retrospectively registered, http://clinicaltrials.gov/study/NCT05445973?id=NCT05445973&rank=1 .

Early post-treatment MRI predicts long-term hepatocellular carcinoma response to radiation segmentectomy

OBJECTIVES

Radiation segmentectomy using yttrium-90 plays an emerging role in the management of early-stage HCC. However, the value of early post-treatment MRI for response assessment is uncertain. We assessed the value of response criteria obtained early after radiation segmentectomy in predicting long-term response in patients with HCC.

MATERIALS AND METHODS

Patients with HCC who underwent contrast-enhanced MRI before, early, and 12 months after radiation segmentectomy were included in this retrospective single-center study. Three independent radiologists reviewed images at baseline and 1st follow-up after radiation segmentectomy and assessed lesion-based response according to mRECIST, LI-RADS treatment response algorithm (TRA), and image subtraction. The endpoint was response at 12 months based on consensus readout of two separate radiologists. Diagnostic accuracy for predicting complete response (CR) at 12 months based on the 1st post-treatment MRI was calculated.

RESULTS

Eighty patients (M/F 60/20, mean age 67.7 years) with 80 HCCs were assessed (median size baseline, 1.8 cm [IQR, 1.4-2.9 cm]). At 12 months, 74 patients were classified as CR (92.5%), 5 as partial response (6.3%), and 1 as progressive disease (1.2%). Diagnostic accuracy for predicting CR was fair to good for all readers with excellent positive predictive value (PPV): mRECIST (range between 3 readers, accuracy: 0.763-0.825, PPV: 0.966-1), LI-RADS TRA (accuracy: 0.700-0.825, PPV: 0.983-1), and subtraction (accuracy: 0.775-0.825, PPV: 0.967-1), with no difference in accuracy between criteria (p range 0.053 to > 0.9).

CONCLUSION

mRECIST, LI-RADS TRA, and subtraction obtained on early post-treatment MRI show similar performance for predicting long-term response in patients with HCC treated with radiation segmentectomy.

CLINICAL RELEVANCE STATEMENT

Response assessment extracted from early post-treatment MRI after radiation segmentectomy predicts complete response in patients with HCC with high PPV (≥ 0.96).

KEY POINTS

• Early post-treatment response assessment on MRI predicts response in patients with HCC treated with radiation segmentectomy with fair to good accuracy and excellent positive predictive value. • There was no difference in diagnostic accuracy between mRECIST, LI-RADS, and subtraction for predicting HCC response to radiation segmentectomy.

Clinical-radiomics predictors to identify the suitability of transarterial chemoembolization treatment in intermediate-stage hepatocellular carcinoma: A multicenter study

BACKGROUND

Although transarterial chemoembolization (TACE) is the first-line therapy for intermediate-stage hepatocellular carcinoma (HCC), it is not suitable for all patients. This study aimed to determine how to select patients who are not suitable for TACE as the first treatment choice.

METHODS

A total of 243 intermediate-stage HCC patients treated with TACE at three centers were retrospectively enrolled, of which 171 were used for model training and 72 for testing. Radiomics features were screened using the Spearman correlation analysis and the least absolute shrinkage and selection operator (LASSO) algorithm. Subsequently, a radiomics model was established using extreme gradient boosting (XGBoost) with 5-fold cross-validation. The Shapley additive explanations (SHAP) method was used to visualize the radiomics model. A clinical model was constructed using univariate and multivariate logistic regression. The combined model comprising the radiomics signature and clinical factors was then established. This model's performance was evaluated by discrimination, calibration, and clinical application. Generalization ability was evaluated by the testing cohort. Finally, the model was used to analyze overall and progression-free survival of different groups.

RESULTS

A third of the patients (81/243) were unsuitable for TACE treatment. The combined model had a high degree of accuracy as it identified TACE-unsuitable cases, at a sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of 0.759, 0.885, 0.906 [95% confidence interval (CI): 0.859-0.953] in the training cohort and 0.826, 0.776, and 0.894 (95% CI: 0.815-0.972) in the testing cohort, respectively.

CONCLUSIONS

The high degree of accuracy of our clinical-radiomics model makes it clinically useful in identifying intermediate-stage HCC patients who are unsuitable for TACE treatment.

Per-patient Negative Predictive Value of the CT and MRI Liver Imaging Reporting and Data System Version 2018 Treatment Response Algorithm for Hepatocellular Carcinoma

Background The Liver Imaging Reporting and Data System version 2018 (LI-RADS) treatment response algorithm (TRA) is a high-specificity, lower-sensitivity grading system to diagnose hepatocellular carcinoma (HCC) and recurrence after local-regional therapy. However, the emphasis on specificity can result in disease understaging, potentially leading to poorer posttransplant outcomes. Purpose To determine the negative predictive value (NPV) of pretransplant CT and MRI assessment for viable HCC on a per-patient basis using the LI-RADS TRA, considering explant pathology as the reference standard. Materials and Methods Patient records from 218 consecutive adult patients from a single institution with HCC who underwent liver transplant from January 2011 to November 2017 were retrospectively reviewed. Two readers blinded to the original report reviewed immediate (within 90 days) pretransplant imaging and characterized observations according to the LI-RADS TRA. Based on this, patients with LR-4, LR-5, or LR-TR (treatment response) viable tumors were designated as viable tumor; patients with solely LR-3 or LR-TR equivocal tumors were designated as equivocal; and patients with only LR-TR nonviable lesions were designated as no viable disease. Patients were designated as within or outside the Milan criteria. These per-patient designations were compared with the presence of viable disease at explant pathology. Fisher exact test was used to compare the differences between CT and MRI. Weighted κ values were used to calculate interreader reliability. Results Final study sample consisted of 206 patients (median age, 61 years [IQR, 57-65 years]; 157 male patients and 49 female patients). Per-patient LI-RADS TRA assessment of pretransplant imaging had an NPV of 32% (95% CI: 27, 38) and 26% (95% CI: 20, 33) (readers 1 and 2, respectively) for predicting viable disease. Seventy-five percent (reader 1) and 77% (reader 2) of patients deemed equivocal had residual tumors at explant pathology. Weighted interreader reliability was substantial (κ = 0.62). Conclusion Patient-based stratification of viable, equivocal, and nonviable disease at pretransplant CT or MRI, based on LI-RADS TRA, demonstrated low negative predictive value in excluding HCC at explant pathology. © RSNA, 2023 See also the editorial by Tamir and Tau in this issue.

Society of abdominal radiology survey of practice patterns in using LI-RADS treatment response criteria in the evaluation of hepatocellular carcinoma post-locoregional treatment

PURPOSE

To examine national trends in the adoption and use of the LI-RADS Treatment Response Algorithm.

METHODS

Members of the Society of Abdominal Radiology (SAR) Disease-Focused Panel (DFP) on LI-RADS Treatment Response (LR-TR) of hepatocellular carcinoma (HCC) developed a 15-question survey which was distributed to radiologists at academic and private practice institutions around the USA and Canada. The survey focused on HCC-related practice patterns as well as the adoption and use of the LR-TR algorithm.

RESULTS

Of 122 surveys distributed, a total of 76 radiologists responded (62%). Responders were predominantly from academic centers (85%). Nearly all (96%) participate in multidisciplinary hepatic tumor boards and most (67%) have an active liver transplant program. All responders' institutions perform locoregional therapy for HCC, including radiation-based therapy (TARE and SBRT). There was a preference for use of MRI over CT for follow-up after locoregional therapy. All responders were aware of the LR-TR algorithm and nearly all (92%) used the system in routine practice. Radiologists expressed a need for more visual aids related to the LR-TR system. Multiple respondents requested additional clarity within the LR-TR algorithm regarding the evolution of post-treatment radiation changes over time.

CONCLUSION

Most survey participants use the LR-TR algorithm after locoregional therapy for HCC. Future iterations of the algorithm may benefit from increased clarity regarding response after radiation-based therapies. Educational materials should include more visual aids to improve reader understanding.

Contrast-enhanced US Evaluation of Hepatocellular Carcinoma Response to Chemoembolization: A Prospective Multicenter Trial

Background Contrast-enhanced (CE) US has been studied for use in the detection of residual viable hepatocellular carcinoma (HCC) after locoregional therapy, but multicenter data are lacking. Purpose To compare two-dimensional (2D) and three-dimensional (3D) CE US diagnostic performance with that of CE MRI or CT, the current clinical standard, in the detection of residual viable HCC after transarterial chemoembolization (TACE) in a prospective multicenter trial. Materials and Methods Participants aged at least 21 years with US-visible HCC scheduled for TACE were consecutively enrolled at one of three participating academic medical centers from May 2016 to March 2022. Each underwent baseline 2D and 3D CE US before TACE, 2D and 3D CE US 1-2 weeks and/or 4-6 weeks after TACE, and CE MRI or CT 4-6 weeks after TACE. CE US and CE MRI or CT were evaluated by three fellowship-trained radiologists for the presence or absence of viable tumors and were compared with reference standards of pathology (18%), angiography on re-treatment after identification of residual disease at 1-2-month follow-up imaging (31%), 4-8-month CE MRI or CT (42%), or short-term (approximately 1-2 months) CE MRI or CT if clinically decompensated and estimated viability was greater than 50% at imaging (9%). Diagnostic performance criteria, including sensitivity and specificity, were obtained for each modality and time point with generalized estimating equation analysis. Results A total of 132 participants were included (mean age, 64 years ± 7 [SD], 87 male). Sensitivity of 2D CE US 4-6 weeks after TACE was 91% (95% CI: 84, 95), which was higher than that of CE MRI or CT (68%; 95% CI: 58, 76; P < .001). Sensitivity of 3D CE US 4-6 weeks after TACE was 89% (95% CI: 81, 94), which was higher than that of CE MRI or CT (P < .001), with no evidence of a difference from 2D CE US (P = .22). CE MRI or CT had 85% (95% CI: 76, 91) specificity, higher than that of 4-6-week 2D and 3D CE US (70% [95% CI: 56, 80] and 67% [95% CI: 53, 78], respectively; P = .046 and P = .023, respectively). No evidence of differences in any diagnostic criteria were observed between 1-2-week and 4-6-week 2D CE US (P > .21). Conclusion The 2D and 3D CE US examinations 4-6 weeks after TACE revealed higher sensitivity in the detection of residual HCC than CE MRI or CT, albeit with lower specificity. Importantly, CE US performance was independent of follow-up time. Clinical trial registration no. NCT02764801 © RSNA, 2023 Supplemental material is available for this article.

C-Arm Computed Tomographic Image Fusion for Repetitive Transarterial Chemoembolization of Hepatocellular Carcinoma

OBJECTIVE

The aim of this study was to evaluate the potential implications of fusion imaging with C-arm computed tomography (CACT) scans for repetitive conventional transarterial chemoembolization (cTACE) for hepatocellular carcinoma.

MATERIALS AND METHODS

Fifty-six cTACE sessions were performed using fusion CACT images from September 2020 to June 2021 in a tertiary referral center, and the data were retrospectively analyzed. Fusion of unenhanced and enhanced CACT images was considered when previously accumulated iodized oil hampered the identification of local tumor progression or intrahepatic distant metastasis (indication A), when a tumor was supplied by multiple arteries with different origins from the aorta and missing tumor enhancement was suspected (indication B), or when iodized oil distribution on immediate post-cTACE CACT images needed to be precisely compared with the pre-cTACE images (indication C). Fusion image quality, initial tumor response, time to local progression (TTLP) of index tumors, and time to progression (TTP) were evaluated.

RESULTS

The fusion quality was satisfactory with a mean misregistration distance of 1.4 mm. For the 40 patients with indication A, the initial tumor responses at 3 months were nonviable, equivocal, and viable in 27 (67.5%), 4 (10.0%), and 9 (22.5%) index tumors, respectively. The median TTLP and TTP were 14.8 months and 4.5 months, respectively. For 10 patients with indication B, the median TTLP and TTP were 8.3 months and 2.6 months, respectively. Among the 6 patients with indication C, 2 patients were additionally treated at the same cTACE session after confirming incomplete iodized oil uptake on fusion imaging.

CONCLUSIONS

Fusion CACT images are useful in patients with hepatocellular carcinoma undergoing repetitive cTACE.

Updates on LI-RADS Treatment Response Criteria for Hepatocellular Carcinoma: Focusing on MRI

As the incidence of hepatocellular carcinoma (HCC) and subsequent treatments with liver-directed therapies rise, the complexity of assessing lesion response has also increased. The Liver Imaging Reporting and Data Systems (LI-RADS) treatment response algorithm (LI-RADS TRA) was created to standardize the assessment of response after locoregional therapy (LRT) on contrast-enhanced CT or MRI. Originally created based on expert opinion, these guidelines are currently undergoing revision based on emerging evidence. While many studies support the use of LR-TRA for evaluation of HCC response after thermal ablation and intra-arterial embolic therapy, data suggest a need for refinements to improve assessment after radiation therapy. In this manuscript, we review expected MR imaging findings after different forms of LRT, clarify how to apply the current LI-RADS TRA by type of LRT, explore emerging literature on LI-RADS TRA, and highlight future updates to the algorithm. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2.

Computed tomography texture analysis combined with preoperative clinical factors serve as a predictor of early efficacy of transcatheter arterial chemoembolization in hepatocellular carcinoma

AIM

To investigate a pre-therapeutic radiomics nomogram to accurately predict hepatocellular carcinoma (HCC) lesion responses to transcatheter arterial chemoembolization (TACE).

METHODS

This retrospective study from January 2012 to 2022 included 92 TACE-treated patients who underwent liver contrast-enhanced CT scan 7 days before treatment, having complete clinical information. We extracted quantitative texture parameters and clinical factors for the largest tumors on the baseline arterial and portal venous phase CT images. An adaptive least absolute shrinkage and selection operator (LASSO)-penalized logistic regression identified independent predictors of tumor activity after TACE.

RESULTS

We fitted an adaptive LASSO regression model to narrow down the texture features and clinical risk factors of the tumor activity status. The selected texture features were used to construct radiomic scores (RadScore), which demonstrated superior performance in predicting tumor activity on both the training (area under the curve (AUC): 0.881, 95% CI: 0.799-0.963) and testing sets (AUC: 0.88, 95% CI: 0.726-1). A logistic regression-based nomogram was developed using RadScore and four selected clinical features. In the testing set, nomogram total points were significant predictors (P = 0.034), and the training set showed no departure from perfect fit (P = 0.833). Internal validation of the nomogram was obtained for the training (AUC: 0.91, 95% CI: 0.837-0.984) and testing (AUC: 0.889, 95% CI: 0.746-1) sets.

CONCLUSION

We propose a nomogram to predict the early response of HCC lesions to TACE treatment with high accuracy, which may serve as an additional criterion in multidisciplinary decision-making treatment.

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

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

Clinical feasibility of radiofrequency ablation using novel adjustable separable electrodes with a multipurpose needle for treating small hepatocellular carcinomas: a prospective single center study

BACKGROUND

The novel separable clustered electrode system with two adjustable active tips (ICAEs) and a fine multipurpose needle (MPN) for in situ temperature monitoring and adjuvant agent injection was developed and validated in an animal study. The purpose of this study was to evaluate the technical efficacy and complication of the novel electrode system for patients who have small HCC.

METHODS

In this prospective, single-center clinical trial, ten participants with 14 small (≤ 2 cm, BCLC 0-A) HCCs referred for RFA were enrolled. A novel electrode system consisting of two ICAEs and one MPN with a thermometer and side holes was used for RFA. The RF energy was delivered using a multichannel RF system combining bipolar and switching monopolar modes. Technical success, efficacy, and complications were evaluated on immediate and one-month follow-up CT.

RESULTS

Technical success was achieved in 92.9% (13/14) of tumors. One participant withdrew consent after RFA, and technical efficacy was achieved in 91.7% (11/12) of tumors. None showed thermal injury to nontarget organs. All patients were discharged the day after RFA without major complications. The active electrode lengths were adjusted in 60% (6/10) of patients during the procedure to tailor the ablation zone (83.3%, n = 5) or treat two tumors with different sizes (16.7%, n = 1). MPN was capable of continuous temperature monitoring during all ablations (100%, 14/14).

CONCLUSIONS

RFA using a novel electrode system showed acceptable technical efficacy and safety in patients with small HCCs. Further comparative studies are needed for the investigation of the system's potential benefits compared to conventional electrodes.

Radiomics: a primer on high-throughput image phenotyping

Radiomics is a high-throughput approach to image phenotyping. It uses computer algorithms to extract and analyze a large number of quantitative features from radiological images. These radiomic features collectively describe unique patterns that can serve as digital fingerprints of disease. They may also capture imaging characteristics that are difficult or impossible to characterize by the human eye. The rapid development of this field is motivated by systems biology, facilitated by data analytics, and powered by artificial intelligence. Here, as part of Abdominal Radiology's special issue on Quantitative Imaging, we provide an introduction to the field of radiomics. The technique is formally introduced as an advanced application of data analytics, with illustrating examples in abdominal radiology. Artificial intelligence is then presented as the main driving force of radiomics, and common techniques are defined and briefly compared. The complete step-by-step process of radiomic phenotyping is then broken down into five key phases. Potential pitfalls of each phase are highlighted, and recommendations are provided to reduce sources of variation, non-reproducibility, and error associated with radiomics.

A Narrative Review on LI-RADS Algorithm in Liver Tumors: Prospects and Pitfalls

Liver cancer is the sixth most detected tumor and the third leading cause of tumor death worldwide. Hepatocellular carcinoma (HCC) is the most common primary liver malignancy with specific risk factors and a targeted population. Imaging plays a major role in the management of HCC from screening to post-therapy follow-up. In order to optimize the diagnostic-therapeutic management and using a universal report, which allows more effective communication among the multidisciplinary team, several classification systems have been proposed over time, and LI-RADS is the most utilized. Currently, LI-RADS comprises four algorithms addressing screening and surveillance, diagnosis on computed tomography (CT)/magnetic resonance imaging (MRI), diagnosis on contrast-enhanced ultrasound (CEUS) and treatment response on CT/MRI. The algorithm allows guiding the radiologist through a stepwise process of assigning a category to a liver observation, recognizing both major and ancillary features. This process allows for characterizing liver lesions and assessing treatment. In this review, we highlighted both major and ancillary features that could define HCC. The distinctive dynamic vascular pattern of arterial hyperenhancement followed by washout in the portal-venous phase is the key hallmark of HCC, with a specificity value close to 100%. However, the sensitivity value of these combined criteria is inadequate. Recent evidence has proven that liver-specific contrast could be an important tool not only in increasing sensitivity but also in diagnosis as a major criterion. Although LI-RADS emerges as an essential instrument to support the management of liver tumors, still many improvements are needed to overcome the current limitations. In particular, features that may clearly distinguish HCC from cholangiocarcinoma (CCA) and combined HCC-CCA lesions and the assessment after locoregional radiation-based therapy are still fields of research.

Liver imaging reporting and data system (LI-RADS) v2018: Reliability and agreement for assessing hepatocellular carcinoma locoregional treatment response

PURPOSE

The purpose of this study was to determine the reliability and interobserver agreement of the liver imaging reporting and data system (LI-RADS) treatment response algorithm (LR-TR) v2018 using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and the added value of diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

A total of 54 patients who underwent DCE-MRI and DWI after locoregional treatment of 81 hepatocellular carcinoma (HCC) lesions from September 2020 to July 2021 were included. There were 47 men and 7 women, with a mean age of 63.9 ± 9.2 (SD) years (age range: 23-77 years). Locoregional treatments included transarterial chemoembolization (TACE) (53/81; 65.4%), radiofrequency ablation (RFA) (25/81; 30.9%) and microwave ablation (MWA) (3/81; 3.7%). Two independent radiologists retrospectively evaluated DCE-MRI examinations obtained after locoregional treatment using LR-TR, and then three months later both radiologists reevaluated DCE-MRI examinations with DWI. Interobserver agreement was assessed using intraclass correlation coefficient (ICC) and Kappa test. Diagnostic performances were evaluated in term of sensitivity, specificity, and area under ROC curve (AUC) using a composite standard of reference that included results of histopathological examinations and follow-up findings.

RESULTS

Using DCE-MRI alone, observer 1 had 83.9% sensitivity (26/31; 95% confidence interval [CI]: 66-95%), 88% specificity (44/50; 95% CI: 76-95%) and 86.4% accuracy (70/81; 95%CI: 77-93%), and observer 2 had 71% sensitivity (22/31; 95% CI: 52-86%), 92% specificity (46/50; 95% CI: 81-98%) and 83.9% accuracy (68/81; 95% CI: 74-91%). For the diagnosis of viable tumors using DCE-MRI with DWI, observer 1 and observer 2 had 87.1% (27/31; 95% CI: 70-96%) and 74.2% (23/31; 95% CI: 55-88%) sensitivity, respectively. The diagnostic performance of DCE-MRI with DWI yielded an AUC (0.875; 95% CI: 0.789-0.962) not different from that of DCE-MRI without DWI (0.859; 95% CI: 0.768-0.951) (P = 0.317). Interobserver agreement for arterial phase hyperenhancement, washout, enhancement similar to pretreatment and DWI findings in all treated HCCs was almost perfect (kappa = 0.815, 0.837, 0.826 and 0.81 respectively). Agreement between observers for LR-TR category was substantial (kappa = 0.795; 95% CI: 0.665-0.924). Interobserver agreement for size of viable HCC was excellent (ICC = 0.938; 95% CI: 0.904-0.960).

CONCLUSION

LR-TR using DCE-MRI alone or DCE-MRI with DWI are both accurate for detecting viable HCC lesions after locoregional treatment, with no differences in diagnostic performance and excellent interobserver agreement.

Application of the CT/MRI LI-RADS Treatment Response Algorithm to Contrast-Enhanced Ultrasound: A Feasibility Study

Purpose

The contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (TRA) is still in development. The aim of this study was to explore whether the CT/MRI LI-RADS TRA features were applicable to CEUS in evaluating the liver locoregional therapy (LRT) response.

Patients and Methods

This study was a retrospective review of a prospectively maintained database of patients with hepatocellular carcinoma undergoing ablation between July 2017 and December 2018. The standard criteria for a viable lesion were a histopathologically confirmed or typical viable appearance in the follow-up CT/MRI. Performance of the LI-RADS TRA assessing tumor viability was then compared between CEUS and CT/MRI. Inter-reader association was calculated.

Results

A total of 244 patients with 389 treated observations (118 viable) were evaluated. The sensitivity and specificity of the CEUS TRA and CT/MRI LI-RADS TRA viable categories for predicting viable lesions were 55.0% (65/118) versus 56.8% (67/118) (P = 0.480) and 99.3% (269/271) versus 96.3% (261/271) (P = 0.013), respectively. The PPV of CEUS was higher than that of CT/MRI (97.0% vs 87.0%). Subgroup analysis showed that the sensitivity was low in the 1-month assessment for both CEUS (38.1%, 16/42) and CT/MR (47.6%, 20/42) and higher in the 2–6-month assessment for both CEUS (65.7%, 23/35) and CT/MR (62.9%, 22/35). Interobserver agreements were substantial for both CEUS TRA and CT/MRI LI-RADS TRA (κ, 0.74 for both).

Conclusion

The CT/MRI LI-RADS TRA features were applicable to CEUS TRA for liver locoregional therapy. The CEUS TRA for liver locoregional therapy has sufficiently high specificity and PPV to diagnose the viability of lesions after ablation.

LI-RADS Treatment Response Algorithm: Performance and Diagnostic Accuracy With Radiologic-Pathologic Explant Correlation in Patients With SBRT-Treated Hepatocellular Carcinoma

PURPOSE

Our purpose was to evaluate the accuracy of LI-RADS Treatment Response Algorithm (LR-TRA) for assessing the viability of hepatocellular carcinoma (HCC) treated with stereotactic body radiation therapy (SBRT), using explant pathology as the gold standard.

METHODS AND MATERIALS

This retrospective study included patients who underwent SBRT for locoregional treatment of HCC between 2008 and 2019 with subsequent liver transplantation. Five radiologists independently assessed all treated lesions by using the LR-TRA. Imaging and posttransplant histopathology were compared. Lesions were categorized as either completely (100%) or incompletely (<100%) necrotic, and performance characteristics and predictive values for the LR-TR viable and nonviable categories were calculated for each reader. Interreader reliability was calculated using the Fleiss kappa test.

RESULTS

A total of 40 treated lesions in 26 patients (median age, 63 years [interquartile range, 59.4-65.5]; 23 men) were included. For lesions treated with SBRT, sensitivity for incomplete tumor necrosis across readers ranged between 71% and 86%, specificity between 85% and 96%, and positive predictive value between 86% and 92%, when the LR-TR equivocal category was treated as nonviable, accounting for subject clustering. When the LR-TR equivocal category was treated as viable, sensitivity of complete tumor necrosis for lesions treated with SBRT ranged from 88% to 96%, specificity from 71% to 93%, and negative predictive value from 85% to 96%. Interreader reliability was fair (k = 0.22; 95% confidence interval, 0.13-0.33). Although a loss of arterial phase hyperenhancement (APHE) was highly correlated with pathologically nonviable tumor on explant, almost half of the patients with APHE had pathologically nonviable tumor on explant.

CONCLUSIONS

LR-TRA v2018 performs well for predicting complete and incomplete necrosis in HCC treated with SBRT. In contrast to other locoregional therapies, the presence of APHE after SBRT does not always indicate viable tumor and suggests that observation may be an appropriate strategy for these patients.

A new proposal for secondary surveillance following potentially curative therapy of HCC: alternating MRI and CEUS

Purpose

A high recurrence rate following ablative therapy of hepatocellular carcinoma (HCC) necessitates routine follow-up imaging (secondary surveillance) to facilitate early re-treatment. We evaluate our unique secondary surveillance algorithm (with use of alternating MRI and CEUS) by assessment of the relative diagnostic accuracy of MRI and CEUS in detection of residual/recurrent tumor. Potential benefits of alternating surveillance are compared to the use of MRI alone.

Materials and methods

This prospective observational IRB approved study included 231 patients with 354 treated tumors between January 2017 and June 2020. Treated lesions underwent secondary surveillance for a minimum of 7 months and up to 3 years, median follow-up 14 months. Secondary surveillance involved MRI performed at 1 month after treatment, followed by CEUS and MRI at alternate 3-month intervals (i.e., CEUS at month 4, MRI at month 7, etc.), for a total of 2 years. An equivocal finding on one imaging modality triggered expeditious evaluation with the alternate modality. Arterial phase hyperenhancement and washout comprise the classic features of recurrent tumor on both modalities.

Results

A total of 746 MRI and 712 CEUS examinations were performed, and a total of 184 tumor recurrences detected, MRI (n = 82) and CEUS (n = 102) (p = 0.19). There was no difference in the sensitivity (71.0–85.0% and 80.9–92.0%), specificity (97.4–99.2% and 98.5–99.9%), and area under the ROC curve (0.85–0.92 and 0.91–0.96) between MRI and CEUS, respectively. 23 of 82 recurrent tumors identified on MRI were equivocal and confirmed with expedited CEUS. 9 equivocal cases on MRI were disproved by expedited CEUS. On CEUS, 1 of the 102 recurrent tumors was equivocal and confirmed on MRI, and 2 equivocal CEUS cases were disproved by MRI.

Conclusion

MRI and CEUS performed similarly in our secondary surveillance algorithm for HCC in their ability to detect tumor recurrence, and showed no significant difference in their relative diagnostic test accuracy measures. Of greater interest, equivocal results on MRI (typically due to difficulty in distinguishing tumor recurrence from post-treatment change/shunting) were either confirmed or disproven by CEUS in all cases. Secondary surveillance of treated HCC with alternating MRI and CEUS shows equivalent performance of each modality. CEUS resolves equivocal MRI and optimally demonstrates APHE and washout in tumor recurrence.

Graphic abstract

Inter-observer agreement using the LI-RADS version 2018 CT treatment response algorithm in patients with hepatocellular carcinoma treated with conventional transarterial chemoembolization

Aim

To determine inter-reader agreement in categorization of imaging features using the Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) algorithm in patients with hepatocellular carcinoma (HCC) treated with conventional transarterial chemoembolization (cTACE).

Methods

Two radiologists used the LR-TR algorithm to assess 112 computed tomography (CT) examinations of 102 patients treated with cTACE. The inter-observer agreement in categorization of LR-TR features was assessed using kappa (κ) statistics.

Results

There was substantial inter-observer agreement between the two reviewers using the LR-TR algorithm (κ = 0.70; 95% CI 0.58–0.81). The two reviewers categorized tumors as non-viable in 37 (33.0%) and 39 (34.8%) of 112 examinations, viable in 58 (51.8%) and 62 (55.4%) examinations, and equivocal in 18 (16.1%) and 11 (9.8%) examinations, respectively. There was almost perfect inter-observer agreement for the LR-TR non-viable category (κ = 0.80; 95% CI 0.68–0.92), substantial agreement for the viable category (κ = 0.78 95% CI 0.67–0.90), and fair agreement for the equivocal category (κ = 0.25; 95% CI 0.02–0.49).

Conclusion

The LR-TR algorithm conveys high degrees of inter-observer agreement for the assessment of CT imaging features in the viable and non-viable categories. Further refinement of indeterminate features may be necessary to improve the correct categorization of equivocal lesions.

Graphic abstract

Evaluation of response in patients with hepatocellular carcinoma treated with intratumoral dendritic cell vaccination using intravoxel incoherent motion (IVIM) MRI and histogram analysis

BACKGROUND

Immunotherapy of hepatocellular carcinoma (HCC) is an emerging method with promising results. Immunotherapy can have an antitumor effect without affecting tumor size, calling for functional imaging methods for response evaluation.

PURPOSE

To evaluate the response to intratumoral injections with the immune primer ilixadencel in HCCs with diffusion-weighted magnetic resonance imaging (DW-MRI) using intravoxel incoherent motion (IVIM) and histogram analysis.

MATERIAL AND METHODS

A total of 17 patients with advanced HCC were treated with intratumoral injections with ilixadencel on three occasions 2-5 weeks apart. The patients were examined with IVIM before each injection as well as approximately three months after the first injection.

RESULTS

The 10th percentile of perfusion-related parameter D* decreased significantly after the first and second intratumoral injections of ilixadencel compared to baseline (P < 0.05). There was a non-significant trend of lower median region of interest f (perfusion fraction) before injection 2 compared to baseline (P = 0.07). There were significant correlations between the 10th percentile and median of D at baseline and change in tumor size after three months (r = 0.79, P < 0.01 and r = 0.72, P < 0.05, respectively).

CONCLUSION

DW-MRI with IVIM and histogram analysis revealed significant reductions of D* early after treatment as well as an association between D at baseline and smaller tumor growth at three months. The lower percentiles (10th and 50th) were found more important. Further research is needed to confirm our preliminary findings of reduced perfusion after ilixadencel vaccinations, suggesting a treatment effect on HCC.

Hepatocellular Carcinoma Staging: Differences Between Radiologic and Pathologic Systems and Relevance to Patient Selection and Outcomes in Liver Transplantation

Liver transplant is indicated with curative intent for patients with early-stage hepatocellular carcinoma (HCC). The radiologic T category is used to determine candidacy and priority of patients on the waiting list. After transplant, the explant liver pathologic TNM stage is used as a predictor of postoperative outcomes and overall prognosis. Although the comparison of radiologic and pathologic T categories for concordance is often considered to be straightforward, the staging conventions significantly differ. Not accounting for these differences is in part the reason for the high rates of radiologic-pathologic discordance reported in the literature, with inconsistent terminology being an additional source of confusion when evaluating concordance. These factors may affect the understanding of important radiopathologic phenotypes of disease and the adequate investigation of their prognostic capabilities. The aims of this article are to provide an overview of the pathologic and radiologic TNM staging systems for HCC while describing staging procedures, emphasize the differences between these staging systems to highlight the limitations of radiologic-pathologic stage correlation, present a review of the literature on the prognostic value of individual features used for HCC staging; and signal significant aspects of preoperative risk stratification that could be improved to positively impact posttransplant outcomes.

No-Touch vs. Conventional Radiofrequency Ablation Using Twin Internally Cooled Wet Electrodes for Small Hepatocellular Carcinomas: A Randomized Prospective Comparative Study

Objective

This study aimed to compare the efficacy between no-touch (NT) radiofrequency ablation (RFA) and conventional RFA using twin internally cooled wet (TICW) electrodes in the bipolar mode for the treatment of small hepatocellular carcinomas (HCC).

Materials and Methods

In this single-center, two-arm, parallel-group, prospective randomized controlled study, we performed a 1:1 random allocation of eligible patients with HCCs to receive NT-RFA or conventional RFA between October 2016 and September 2018. The primary endpoint was the cumulative local tumor progression (LTP) rate after RFA. Secondary endpoints included technical conversion rates of NT-RFA, intrahepatic distance recurrence, extrahepatic metastasis, technical parameters, technical efficacy, and rates of complications. Cumulative LTP rates were analyzed using Kaplan-Meier analysis and the Cox proportional hazard regression model. Considering conversion cases from NT-RFA to conventional RFA, intention-to-treat and as-treated analyses were performed.

Results

Enrolled patients were randomly assigned to the NT-RFA group (37 patients with 38 HCCs) or the conventional RFA group (36 patients with 38 HCCs). Among the NT-RFA group patients, conversion to conventional RFA occurred in four patients (10.8%, 4/37). According to intention-to-treat analysis, both 1- and 3-year cumulative LTP rates were 5.6%, in the NT-RFA group, and they were 11.8% and 21.3%, respectively, in the conventional RFA group (p = 0.073, log-rank). In the as-treated analysis, LTP rates at 1 year and 3 years were 0% and 0%, respectively, in the NT-RFA group sand 15.6% and 24.5%, respectively, in the conventional RFA group (p = 0.004, log-rank). In as-treated analysis using multivariable Cox regression analysis, RFA type was the only significant predictive factor for LTP (hazard ratio = 0.061 with conventional RFA as the reference, 95% confidence interval = 0.000–0.497; p = 0.004). There were no significant differences in the procedure characteristics between the two groups. No procedure-related deaths or major complications were observed.

Conclusion

NT-RFA using TICW electrodes in bipolar mode demonstrated significantly lower cumulative LTP rates than conventional RFA for small HCCs, which warrants a larger study for further confirmation.

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

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

Per-Feature Accuracy of Liver Imaging Reporting and Data System Locoregional Treatment Response Algorithm: A Systematic Review and Meta-Analysis

We aimed to investigate the accuracy of each imaging feature of LI-RADS treatment response (LR-TR) viable category for diagnosing tumor viability of locoregional therapy (LRT)-treated HCC. Studies evaluating the per feature accuracy of the LR-TR viable category on dynamic contrast-enhanced CT or MRI were identified in databases. A bivariate random-effects model was used to calculate the pooled sensitivity, specificity, and diagnostic odds ratio (DOR) of LR-TR viable features. Ten studies assessing the accuracies of LR-TR viable features (1153 treated observations in 971 patients) were included. The pooled sensitivities and specificities for diagnosing viable HCC were 81% (95% confidence interval [CI], 63-92%) and 95% (95% CI, 88-98%) for nodular, mass-like, or irregular thick tissue (NMLIT) with arterial phase hyperenhancement (APHE), 55% (95% CI, 34-75%) and 96% (95% CI, 94-98%) for NMLIT with washout appearance, and 21% (95% CI, 6-53%) and 98% (95% CI, 92-100%) for NMLIT with enhancement similar to pretreatment, respectively. Of these features, APHE showed the highest pooled DOR (81 [95% CI, 25-261]), followed by washout appearance (32 [95% CI, 13-82]) and enhancement similar to pretreatment (14 [95% CI, 5-39]). In conclusion, APHE provided the highest sensitivity and DOR for diagnosing viable HCC following LRT, while enhancement similar to pretreatment showed suboptimal performance.

LI-RADS treatment response algorithm after first-line DEB-TACE: reproducibility and prognostic value at initial post-treatment CT/MRI

PURPOSE

To evaluate the inter-reader reproducibility and prognostic accuracy of the Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (LR-TR) at the time of initial post-treatment evaluation following drug-eluting beads transarterial chemoembolization (DEB-TACE) for hepatocellular carcinoma (HCC).

METHODS

This retrospective study included patients with HCC who underwent first-line DEB-TACE between January 2011 and December 2015. Six readers (three fellowship-trained radiologists and three radiology trainees) independently assessed lesion-level response in up to two treated lesions per LR-TR and modified Response Evaluation Criteria in Solid Tumors (mRECIST)-target criteria, as well as patient-level response per mRECIST-overall criteria, on the initial post-treatment CT/MRI. Inter-reader agreement was calculated by Fleiss' multi-reader κ. We tested whether LR-TR, mRECIST-target, and mRECIST-overall response were associated with overall survival using Kaplan-Meier and Cox proportional hazard model analyses.

RESULTS

A total of 82 patients with 113 treated target lesions were included. Inter-reader agreement was moderate for LR-TR and mRECIST-overall (κ range 0.42-0.57), and substantial for mRECIST-target (κ range 0.62-0.66), among all three reader-groups: all readers, experienced readers, and less-experienced readers. LR-TR and mRECIST-target response were not significantly associated with overall survival regardless of reader experience (P > 0.05). In contrast, mRECIST-overall response was significantly associated with overall survival when assessed by all readers (P = 0.02) and experienced readers (P = 0.03), but not by the less-experienced readers (P = 0.35).

CONCLUSION

Although LR-TR algorithm has moderate inter-reader reproducibility, it alone may not predict overall survival on the initial post-treatment CT/MRI after first-line DEB-TACE for HCC.

LI-RADS treatment response algorithm for detecting incomplete necrosis in hepatocellular carcinoma after locoregional treatment: a systematic review and meta-analysis using individual patient data

PURPOSE

To perform a systematic review and meta-analysis using individual patient data to investigate the diagnostic performance of Liver Imaging Reporting and Data System (LI-RADS) Treatment Response (TR) algorithm for detecting incomplete necrosis on pathology.

METHODS

PubMed and EMBASE were searched from Jan 1, 2017 until October 14, 2020. Studies reporting diagnostic accuracy of LI-RADS TR algorithm on CT or MRI for detecting incomplete necrosis on pathology as a reference standard were included. Sensitivity and specificity were pooled using random-effects model. Subgroup analyses were performed for locoregional treatment (LRT) type and imaging modality.

RESULTS

Six studies (393 patients, 534 lesions) were included. Pooled sensitivity was 0.56 (95% confidence interval [CI] 0.43-0.69) and specificity was 0.91 (95%CI 0.84-0.96). Pooled sensitivity was highest using arterial phase hyperenhancement (APHE) (0.67 [95%CI 0.51-0.81]), followed by washout (0.43 [95%CI 0.26-0.62]) and enhancement similar to pretreatment (0.24 [95%CI 0.15-0.36]). Among lesions with incomplete necrosis, 2% (95%CI 0.00-0.05) manifested as washout but no APHE; 0% (95% CI 0.00-0.02) as enhancement similar to pretreatment without both APHE and washout. Pooled sensitivity was lower after ablation than embolization (0.42 [95%CI, 0.28-0.57] vs. 0.65 [95%CI, 0.53-0.77], p = 0.033). MRI and CT were comparable (p = 0.783 and 0.290 for sensitivity and specificity).

CONCLUSIONS

LI-RADS TR algorithm shows moderate sensitivity and high specificity for detecting incomplete necrosis after LRT. APHE is the dominant criterion, a washout contributes to small but meaningful extent, while the contribution of enhancement similar to pretreatment may be negligible. LRT type may affect performance of the algorithm.

LI-RADS treatment response assessment of combination locoregional therapy for HCC

HCC incidence continues to increase worldwide and is most frequently discovered at an advanced stage when limited curative options are available. Combination locoregional therapies have emerged to improve patient survival and quality of life or downstage patients to curative options. The increasing options for locoregional therapy combinations require an understanding of the expected post-treatment imaging appearance in order to assess treatment response. This review aims to describe the synergy between TACE combined with thermal ablation and TACE combined with SBRT. We will also illustrate expected imaging findings that determine treatment efficacy based on the mechanism of tissue injury using the LI-RADS Treatment Response Algorithm.

Post-treatment CT LI-RADS categories: predictors of overall survival in hepatocellular carcinoma post bland transarterial embolization

PURPOSE

The LI-RADS Treatment Response (LR-TR) algorithm was introduced in 2017 to assist radiologists in assessing hepatocellular carcinoma (HCC) response following locoregional therapy. The objective of this study was to evaluate the associations between pre-treatment LI-RADS diagnostic categories, post-treatment LR-TR categories, and mRECIST response categories with overall survival (OS) of patients with HCC.

METHODS

This retrospective study included untreated patients with one or two lesions who underwent transarterial embolization with or without concomitant ablation from December 2003 to December 2017. Two radiologists (R1 and R2) reviewed pre- and post-treatment CT imaging. Associations between pre- and post-treatment variables, including post-treatment LR-TR categories (Viable, Equivocal, Nonviable), with OS were assessed using the Kaplan-Meier method and Cox proportional hazards regression.

RESULTS

Eighty-five patients were included (median age = 71 years, range 50-87; 17 women). The median OS from first embolization was 43.92 months. Pre- and post-treatment tumor size, pre-treatment LR-TIV (compared with LR-5), and post-treatment LR-TR Viable (compared with LR-TR Nonviable) were associated with OS (p < 0.05 for all). Median OS was shorter for LR-TR Viable patients (R1, 25.64 months, 95% CI 18.58-35.70; R2, 26.43 months 95% CI 20.68-43.92) than for LR-TR Nonviable patients (64.21 months R1 and R2, 95% CI 42.71-92.45 and 36.30-94.09, respectively). mRECIST categories showed similar associations with OS. Inter-reader agreement was moderate for LI-RADS categories (κ = 0.57, 95% CI 0.35-0.78) and substantial for LR-TR categories (κ = 0.68, 95% CI 0.55-0.81).

CONCLUSIONS

LR-TR categories show a strong association with OS in HCC patients treated with transarterial embolization.

LI-RADS treatment response lexicon: review, refresh and resolve with emerging data

The imaging findings after loco regional treatment of hepatocellular carcinoma are variable based on the type of treatment used, the timing interval of imaging after treatment, and the cross-sectional modality used for treatment response assessment. Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm (TRA) is a relatively new standardized method of evaluating treatment response after loco regional therapy to hepatocellular carcinoma. In this article, we provide an overview of the evolution of the treatment response algorithm, its current applicability and its outlook for the future. We will review current guidelines and discuss proposed changes to the algorithm as a means to continually improve LI-RADS TRA as an assessment tool post-loco regional treatment of hepatocellular carcinoma.

Role of the radiologist at HCC multidisciplinary conference and use of the LR-TR algorithm for improving workflow

Multidisciplinary conferences (MDCs) play a major role in management and care of oncology patients. Hepatocellular carcinoma (HCC) is a complex disease benefiting from multidisciplinary discussions to determine optimal patient management. A multitude of liver-directed locoregional therapies have emerged allowing for more options for treatment of HCC. A radiologist dedicated to HCC-MDC is an important member of the team contributing to patient care in multiple ways. The radiologist plays a key role in image interpretation guiding initial therapy discussions as well as interpreting post-treatment imaging following liver-directed therapy. Standardization of image interpretation can lead to more consistent treatment received by the patient as well as accurate assessment of transplant eligibility. The radiologist can facilitate this process using structured reporting that is also supported by stakeholders involved in interdisciplinary management of liver diseases. The Liver Imaging Reporting and Data System (LI-RADS), is a living document which offers a standardized reporting algorithm for consistent communication of radiologic findings for HCC screening and characterization of liver observations in patients at risk for HCC. The LI-RADS post-treatment algorithm (LR-TR algorithm) has been developed to standardize liver observations following liver-directed locoregional therapy. This review article focuses on the role of the radiologist at HCC-MDC and implementation of the LR-TR algorithm for improving workflow.

Evaluation of Hepatocellular Carcinoma Treatment Response After Locoregional Therapy

Locoregional therapy (LRT) for hepatocellular carcinoma can be used alone or with other treatment modalities to reduce rates of progression, improve survival, or act as a bridge to cure. As the use of LRT expands, so too has the need for systems to evaluate treatment response, such as the World Health Organization and modified Response Evaluation Criteria In Solid Tumors systems and more recently, the Liver Imaging Reporting and Data System (LI-RADS) treatment response algorithm (TRA). Early validation results for LI-RADS TRA have been promising, and as research accrues, the TRA is expected to evolve in the near future.

Artificial intelligence in assessment of hepatocellular carcinoma treatment response

Artificial Intelligence (AI) continues to shape the practice of radiology, with imaging of hepatocellular carcinoma (HCC) being of no exception. This article prepared by members of the LI-RADS Treatment Response (TR LI-RADS) work group and associates, presents recent trends in the utility of AI applications for the volumetric evaluation and assessment of HCC treatment response. Various topics including radiomics, prognostic imaging findings, and locoregional therapy (LRT) specific issues will be discussed in the framework of HCC treatment response classification systems with focus on the Liver Reporting and Data System treatment response algorithm (LI-RADS TRA).

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

PURPOSE

To evaluate the diagnostic performance of LI-RADS treatment response algorithm (LR-TRA) and modified RECIST (mRECIST) for the detection of viable hepatocellular carcinoma (HCC) on MRI after trans-arterial chemoembolization (TACE).

MATERIALS AND METHODS

This retrospective study includes cirrhotic patients that underwent trans-arterial chemoembolization prior to liver transplantation from 2013 to 2017 with a pre- and post-treatment MRI available. Three blinded readers assigned a LR-TRA and mRECIST category to each lesion. Lesions on MRI and explant pathology were matched and characterized as complete (100% necrosis) or incomplete necrosis (≤99% necrosis). Diagnostic performance of LR-TRA and mRECIST were calculated with a generalized estimating equation.

RESULTS

A total of 52 patients with 71 lesions were included, 47 with incomplete and 24 with complete necrosis. In consensus, 45 lesions were categorized as LR-TR Nonviable, of which 62.2% (28/45) had incomplete and 37.8% (17/45) had complete necrosis. Six lesions were categorized as LR-TR Equivocal, of which 33.3% (2/6) had incomplete and 66.7% (4/6) had complete necrosis. Twenty lesions were categorized as LR-TR Viable of which 85.0% (17/20) had incomplete and 15.0% (3/20) had complete necrosis. The sensitivity of LR-TR Viable for detecting incompletely necrotic tumor when LR-TR Equivocal was considered as viable, in consensus was 40.4%; specificity 70.8%; accuracy 50.7%. The sensitivity of mRECIST for detecting incompletely necrotic tumor was 37.0%; specificity 79.2%; accuracy 51.4%. There was no significant difference in diagnostic performance between mRECIST and LR-TRA (p = 0.14-0.33). Agreement for LR-TRA category was moderate (k = 0.53 [95% CI: 0.45, 0.67]).

CONCLUSION

LI-RADS treatment response algorithm demonstrates high specificity and low to moderate sensitivity for the detection of viable HCC after TACE in a North American cirrhotic cohort, without significant difference in diagnostic performance between LR-TRA and mRECIST.

Imaging After Locoregional Therapy for Hepatocellular Carcinoma With Emphasis on LIRADS Treatment Response Assessment Criteria

The Liver Imaging Reporting and Data System (LI-RADS) is a set of algorithms designed to provide a standardized, comprehensive framework for the interpretation of surveillance and diagnostic imaging in patients at high risk for hepatocellular carcinoma. LI-RADS is the result of a multidisciplinary collaboration between radiologists, hepatologists, hepatobiliary surgeons and pathologists and has recently been incorporated into the practice guidelines for the American Association for the Study of Liver Diseases (AASLD) and made congruent with the Organ Procurement and Transplantation Network (OPTN) criteria. This manuscript illustrates the common ultrasound, computed tomography, and magnetic resonance imaging appearances of hepatocellular carcinoma and describes how these findings can be properly categorized using the LI-RADS system.

Up-to-Date Role of CT/MRI LI-RADS in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of mortality worldwide and a major healthcare burden in most societies. Computed tomography (CT) and magnetic resonance imaging (MRI) play a pivotal role in the medical care of patients with or at risk for hepatocellular carcinoma (HCC). When stringent imaging criteria are fulfilled, CT and MRI allow for diagnosis, staging, and assessment of response to treatment, without the need for invasive workup, and can inform clinical decision making. Owing to the central role of these imaging modalities in HCC management, standardization is essential to facilitate proper imaging technique, accurate interpretation, and clear communication among all stakeholders in both the clinical practice and research settings. The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system that provides standardization across the continuum of HCC imaging, including ordinal probabilistic approach for reporting that directs individualized management. This review discusses the up-to-date role of CT and MRI in HCC imaging from the LI-RADS perspective. It also provides a glimpse into the future by discussing how advances in knowledge and technology are likely to enrich the LI-RADS approach.

Usefulness of Arterial Subtraction in Applying Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm to Gadoxetic Acid-Enhanced MRI

Objective

We aimed to evaluate the usefulness of arterial subtraction images for predicting the viability of hepatocellular carcinoma (HCC) after locoregional therapy (LRT) using gadoxetic acid-enhanced MRI and the Liver Imaging Reporting and Data System treatment response (LR-TR) algorithm.

Materials and Methods

This study included 90 patients (mean age ± standard deviation, 57 ± 9 years) who underwent liver transplantation or resection after LRT and had 73 viable and 32 nonviable HCCs. All patients underwent gadoxetic acid-enhanced MRI before surgery. Two radiologists assessed the presence of LR-TR features, including arterial phase hyperenhancement (APHE) and LR-TR categories (viable, nonviable, or equivocal), using ordinary arterial-phase and arterial subtraction images. The reference standard for tumor viability was surgical pathology. The sensitivity of APHE for diagnosing viable HCC was compared between ordinary arterial-phase and arterial subtraction images. The sensitivity and specificity of the LR-TR algorithm for diagnosing viable HCC was compared between the use of ordinary arterial-phase and the use of arterial subtraction images. Subgroup analysis was performed on lesions treated with transarterial chemoembolization (TACE) only.

Results

The sensitivity of APHE for viable HCCs was higher for arterial subtraction images than ordinary arterial-phase images (71.2% vs. 47.9%; p < 0.001). LR-TR viable category with the use of arterial subtraction images compared with ordinary arterial-phase images showed a significant increase in sensitivity (76.7% [56/73] vs. 63.0% [46/73]; p = 0.002) without significant decrease in specificity (90.6% [29/32] vs. 93.8% [30/32]; p > 0.999). In a subgroup of 63 lesions treated with TACE only, the use of arterial subtraction images showed a significant increase in sensitivity (81.4% [35/43] vs. 67.4% [29/43]; p = 0.031) without significant decrease in specificity (85.0% [17/20] vs. 90.0% [18/20]; p > 0.999).

Conclusion

Use of arterial subtraction images compared with ordinary arterial-phase images improved the sensitivity while maintaining specificity for diagnosing viable HCC after LRT using gadoxetic acid-enhanced MRI and the LR-TR algorithm.

Does Training in LI-RADS Version 2018 Improve Readers' Agreement with the Expert Consensus and Inter-reader Agreement in MRI Interpretation?

BACKGROUND

The Liver Imaging Reporting and Data System (LI-RADS) was established for noninvasive diagnosis for hepatocellular carcinoma (HCC). However, whether training can improve readers' agreement with the expert consensus and inter-reader agreement for final categories is still unclear.

PURPOSE

To explore training effectiveness on readers' agreement with the expert consensus and inter-reader agreement.

STUDY TYPE

Prospective.

SUBJECTS

Seventy lesions in 61 patients at risk of HCC undergoing liver MRI; 20 visiting scholars.

FIELD STRENGTH/SEQUENCE

1.5 T or 3 T, Dual-echo T₁ WI, Fast spin-echo T₂ WI, SE-EPI DWI, and Dynamic multiphase fast gradient-echo T₁ WI.

ASSESSMENT

Seventy lesions assigned LI-RADS categories of LR1-LR5, LR-M, and LR-TIV by three radiologists in consensus were randomly selected, with 10 cases for each category. The consensus opinion was the standard reference. The third radiologist delivered the training. Twenty readers reviewed images independently and assigned each an LI-RADS category both before and after the training.

STATISTICAL TESTS

Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, receiver operating characteristic (ROC) analysis, simple and weighted kappa statistics, and Fleiss kappa statistics.

RESULTS

Before and after training: readers' AUC (areas under ROC) for LR-1-LR-5, LR-M, and LR-TIV were 0.898 vs. 0.913, 0.711 vs. 0.876, 0.747 vs. 0.860, 0.724 vs. 0.815, 0.844 vs. 0.895, 0.688 vs. 0.873, and 0.720 vs. 0.948, respectively, and all improved significantly (P < 0.05), except LR-1(P = 0.25). Inter-reader agreement between readers for LR-1-LR-5, LR-M, LR-TIV were 0.725 vs. 0.751, 0.325 vs. 0.607, 0.330 vs. 0.559, 0.284 vs. 0.488, 0.447 vs. 0.648, 0.229 vs. 0.589, and 0.362 vs. 0.852, respectively, and all increased significantly (P < 0.05). For training effectiveness on both AUC and inter-reader agreement, LR-TIV, LR-M, and LR-2 improved most, and LR-1 made the least.

DATA CONCLUSION

This study shows LI-RADS training could improve reader agreement with the expert consensus and inter-reader agreement for final categories.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.