LI-RADS Version 2018 Treatment Response Algorithm: Diagnostic Performance after Transarterial Radioembolization for Hepatocellular Carcinoma

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.

Four-dimensional flow MR imaging for evaluating treatment response after transcatheter arterial chemoembolization in cirrhotic patients with hepatocellular carcinoma

PURPOSE

To prospectively evaluate the potential of four-dimensional (4D) flow magnetic resonance imaging (MRI) in predicting treatment responses after transcatheter arterial chemoembolization (TACE) in cirrhotic patients with hepatocellular carcinoma (HCC).

METHODS

A total of 195 patients were classified into four groups (A-D): A, cirrhotic patients without HCC (n = 30); B, cirrhotic patients with HCC before TACE (n = 75); C, cirrhotic patients with HCC showing an incomplete response following TACE (n = 56); and D, cirrhotic patients with HCC achieving a complete response (CR) following TACE (n = 34). The patients were subjected to routine laboratory tests and 4D flow MRI using a 3-T MRI system to measure the quantitative parameters of blood flow in the portal vein (PV), splenic vein (SV), and superior mesenteric vein. The data collected by 4D flow MRI were compared among the groups using one-way analysis of variance. A multivariate analysis was performed to verify the association of clinical characteristics and 4D flow parameters with CR after TACE treatment.

RESULTS

The average through-plane velocity, peak velocity magnitude, average net flow, peak flow, and net forward volume in the PV and SV were significantly lower in groups B and C (P < 0.05) compared to those in group A. Moreover, average through-plane velocity and peak velocity magnitude in the PV in groups B and C were significantly lower than those in group D (P < 0.05). The multivariate analysis demonstrated that the average through-plane velocity and peak velocity magnitude in the PV were independently associated with CR in HCC patients after TACE (P < 0.05).

CONCLUSION

The quantitative flow data obtained by 4D flow MRI may be useful for predicting CR after TACE in cirrhotic patients with HCC.

Complications Related to Transarterial Treatment of Hepatocellular Carcinoma: A Comprehensive Review

Currently, various types of transarterial treatments are performed for hepatocellular carcinoma from the early to advanced stages. Its indications and efficacy have been widely investigated. However, procedure-related complications have not been updated in the literature, although new types of transarterial treatments, such as drug-eluting bead transarterial chemoembolization and transarterial radioembolization, are common in daily practice. Herein, a comprehensive literature review was carried out, and complications were organized according to the organs affected and treatment modalities.

[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.

Application of Intravoxel Incoherent Motion in the Evaluation of Hepatocellular Carcinoma after Transarterial Chemoembolization

(1) Background: To assess the efficacy of the quantitative parameters of intravoxel incoherent motion (IVIM) diffusion-weighted imaging for hepatocellular carcinoma (HCC) diagnosis after transarterial chemoembolization (TACE). (2) Methods: Fifty HCC patients after TACE were included and underwent MRI. All of the patients were scanned with the IVIM-DWI sequence and underwent TACE retreatment within 1 week. Referring to digital subtraction angiography (DSA) and MR enhanced images, two readers measured the f, D, and D* values of the tumor active area (TAA), tumor necrotic area (TNA), and adjacent normal hepatic parenchyma (ANHP). Then, the distinctions of the TAA, TNA, and ANHP were compared and we analyzed the differential diagnosis of the parameters in three tissues. (3) Results: For values of f and D, there were significant differences between any of the TAA, TNA, and ANHP (p < 0.05). The values of f and D were the best indicators for identifying the TAA and TNA, with AUC values of 0.959 and 0.955, respectively. The values of f and D performed well for distinguishing TAA from ANHP, with AUC values of 0.835 and 0.753, respectively. (4) Conclusions: Quantitative IVIM-DWI was effective for evaluating tumor viability in HCC patients treated with TACE and may be helpful for non-invasive monitoring of the tumor viability.

Incorporation of Ancillary MRI Features into the LI-RADS Treatment Response Algorithm: Impact on Diagnostic Performance After Locoregional Treatment for Hepatocellular Carcinoma

Background: The LI-RADS treatment response algorithm may lack sufficient sensitivity for viable tumor after locoregional treatment (LRT) for hepatocellular carcinoma (HCC). Objective: To evaluate the impact of incorporation of ancillary MRI features on the diagnostic performance of the LI-RADS treatment response algorithm after LRT for HCC. Methods: This retrospective study included 141 patients (114 men, 27 women; median age, 56 years) who underwent gadoxetic acid-enhanced MRI following LRT for HCC between October 2005 and January 2020 and subsequent liver surgery. Two readers assessed lesions for LI-RADS features of viability and for ancillary features [transitional phase (TP) hypointensity, hepatobiliary phase (HBP) hypointensity, DWI hyperintensity or low ADC, mild-to-moderate T2 hyperintensity]. Interobserver agreement was assessed before reaching consensus. Significant ancillary features were identified using random forest analysis. Impact of incorporation of significant ancillary features on diagnostic performance for incomplete pathologic necrosis (IPN, pathologically viable tumor >0 mm) was assessed using McNemar tests. Results: Complete pathologic necrosis (CPN) was observed in 88/181 (48.6%) lesions. Inter-reader agreement was almost perfect (κ=0.92-0.97) for LI-RADS features of viability and substantial to almost perfect (κ=0.73-0.94) for ancillary features. Random forest analysis identified TP hypointensity (present in 8.0%, 25.0%, and 75.3% of lesions with CPN, viable tumor <10 mm, and viable tumor ≥10 mm, respectively) and HBP hypointensity (9.2%, 25.0%, and 74.0%, respectively) as significant ancillary features. For detecting IPN, LR-TR Viable OR LR-TR Equivocal had higher sensitivity (71.0% vs 57.0%, P = .001), but lower specificity (86.4% vs 94.3%, P = .02) than LR-TR Viable. However, LR-TR Viable OR LR-TR Equivocal and TP hypointensity showed higher sensitivity (64.5% vs 57.0%, P = .02) than LR-TR Viable, without significantly different specificity (90.9% vs 94.3%, P = .25). LR-TR Viable OR LR-TR Equivocal and HBP hypointensity also showed higher sensitivity (65.6% vs 57.0%, P = .01) than LR-TR Viable, without significantly different specificity (90.8% vs. 94.3%, P = .25). Conclusion: TP hypointensity and HBP hypointensity increase sensitivity of LI-RADS treatment response algorithm for viable tumor without lowering specificity. Clinical Impact: The two identified ancillary features may improve tumor viability assessment and planning of additional therapies after LRT for HCC.

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.