Pancreas CT assessment for pancreatic ductal adenocarcinoma resectability: effect of tube voltage and slice thickness on image quality and diagnostic performance.

OBJECTIVES: To assess the resectability of pancreatic ductal adenocarcinoma (PDAC), the evaluation of tumor vascular contact holds paramount significance. This study aimed to compare the image quality and diagnostic performance of high-resolution (HR) pancreas computed tomography (CT) using an 80 kVp tube voltage and a thin slice (1 mm) for assessing PDAC resectability, in comparison with the standard protocol CT using 120 kVp. METHODS: This research constitutes a secondary analysis originating from a multicenter prospective study. All participants underwent both the standard protocol pancreas CT using 120 kVp with 3 mm slice thickness (ST) and HR-CT utilizing an 80 kVp tube voltage and 1 mm ST. The contrast-to-noise ratio (CNR) between parenchyma and tumor, along with the degree of enhancement of the abdominal aorta and main portal vein (MPV), were measured and subsequently compared. Additionally, the likelihood of margin-negative resection (R0) was evaluated using a five-point scale. The diagnostic performance of both CT protocols in predicting R0 resection was assessed through the area under the receiver operating characteristic curve (AUC). RESULTS: A total of 69 patients (37 males and 32 females; median age, 66.5 years) were included in the study. The median CNR of PDAC was 10.4 in HR-CT, which was significantly higher than the 7.1 in the standard CT (P=0.006). Furthermore, HR-CT demonstrated notably higher median attenuation values for both the abdominal aorta (579.5 HU vs. 327.2 HU; P=0.002) and the MPV (263.0 HU vs. 175.6 HU; P=0.004) in comparison with standard CT. Following surgery, R0 resection was achieved in 51 patients. The pooled AUC for HR-CT in predicting R0 resection was 0.727, slightly exceeding the 0.699 of standard CT, albeit lacking a significant statistical distinction (P=0.128). CONCLUSION: While HR pancreas CT using 80 kVp offered a notably greater degree of contrast enhancement in vessels and a higher CNR for PDAC compared to standard CT, its diagnostic performance in predicting R0 resection remained statistically comparable.

Comparison Between Contrast-Enhanced Computed Tomography and Contrast-Enhanced Magnetic Resonance Imaging With Magnetic Resonance Cholangiopancreatography for Resectability Assessment in Extrahepatic Cholangiocarcinoma.

OBJECTIVE: To compare the diagnostic performance and interobserver agreement between contrast-enhanced computed tomography (CECT) and contrast-enhanced magnetic resonance imaging (CE-MRI) with magnetic resonance cholangiopancreatography (MRCP) for evaluating the resectability in patients with extrahepatic cholangiocarcinoma (eCCA). MATERIALS AND METHODS: This retrospective study included treatment-naïve patients with pathologically confirmed eCCA, who underwent both CECT and CE-MRI with MRCP using extracellular contrast media between January 2015 and December 2020. Among the 214 patients (146 males; mean age ± standard deviation, 68 ± 9 years) included, 121 (56.5%) had perihilar cholangiocarcinoma. R0 resection was achieved in 108 of the 153 (70.6%) patients who underwent curative-intent surgery. Four fellowship-trained radiologists independently reviewed the findings of both CECT and CE-MRI with MRCP to assess the local tumor extent and distant metastasis for determining resectability. The pooled area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of CECT and CE-MRI with MRCP were compared using clinical, surgical, and pathological findings as reference standards. The interobserver agreement of resectability was evaluated using Fleiss kappa (κ). RESULTS: No significant differences were observed between CECT and CE-MRI with MRCP in the pooled AUC (0.753 vs. 0.767), sensitivity (84.7% [366/432] vs. 90.3% [390/432]), and specificity (52.6% [223/424] vs. 51.4% [218/424]) (P > 0.05 for all). The AUC for determining resectability was higher when CECT and CE-MRI with MRCP were reviewed together than when CECT was reviewed alone in patients with discrepancies between the imaging modalities or with indeterminate resectability (0.798 [0.754-0.841] vs. 0.753 [0.697-0.808], P = 0.014). The interobserver agreement for overall resectability was fair for both CECT (κ = 0.323) and CE-MRI with MRCP (κ = 0.320), without a significant difference (P = 0.884). CONCLUSION: CECT and CE-MRI with MRCP showed no significant differences in the diagnostic performance and interobserver agreement in determining the resectability in patients with eCCA.

Consensus report from the 10th Global Forum for Liver Magnetic Resonance Imaging: developments in HCC management.

The 10th Global Forum for Liver Magnetic Resonance Imaging (MRI) was held as a virtual 2-day meeting in October 2021, attended by delegates from North and South America, Asia, Australia, and Europe. Most delegates were radiologists with experience in liver MRI, with representation also from specialists in liver surgery, oncology, and hepatology. Presentations, discussions, and working groups at the Forum focused on the following themes: • Gadoxetic acid in clinical practice: Eastern and Western perspectives on current uses and challenges in hepatocellular carcinoma (HCC) screening/surveillance, diagnosis, and management • Economics and outcomes of HCC imaging • Radiomics, artificial intelligence (AI) and deep learning (DL) applications of MRI in HCC. These themes are the subject of the current manuscript. A second manuscript discusses multidisciplinary tumor board perspectives: how to approach early-, mid-, and late-stage HCC management from the perspectives of a liver surgeon, interventional radiologist, and oncologist (Taouli et al, 2023). Delegates voted on consensus statements that were developed by working groups on these meeting themes. A consensus was considered to be reached if at least 80% of the voting delegates agreed on the statements. CLINICAL RELEVANCE STATEMENT: This review highlights the clinical applications of gadoxetic acid-enhanced MRI for liver cancer screening and diagnosis, as well as its cost-effectiveness and the applications of radiomics and AI in patients with liver cancer. KEY POINTS: • Interpretation of gadoxetic acid-enhanced MRI differs slightly between Eastern and Western guidelines, reflecting different regional requirements for sensitivity vs specificity. • Emerging data are encouraging for the cost-effectiveness of gadoxetic acid-enhanced MRI in HCC screening and diagnosis, but more studies are required. • Radiomics and artificial intelligence are likely, in the future, to contribute to the detection, staging, assessment of treatment response and prediction of prognosis of HCC-reducing the burden on radiologists and other specialists and supporting timely and targeted treatment for patients.

Two-dimensional Convolutional Neural Network Using Quantitative US for Noninvasive Assessment of Hepatic Steatosis in NAFLD.

Background Quantitative US (QUS) using radiofrequency data analysis has been recently introduced for noninvasive evaluation of hepatic steatosis. Deep learning algorithms may improve the diagnostic performance of QUS for hepatic steatosis. Purpose To evaluate a two-dimensional (2D) convolutional neural network (CNN) algorithm using QUS parametric maps and B-mode images for diagnosis of hepatic steatosis, with the MRI-derived proton density fat fraction (PDFF) as the reference standard, in patients with nonalcoholic fatty liver disease (NAFLD). Materials and Methods: Consecutive adult participants with suspected NAFLD were prospectively enrolled at a single academic medical center from July 2020 to June 2021. Using radiofrequency data analysis, two QUS parameters (tissue attenuation imaging [TAI] and tissue scatter-distribution imaging [TSI]) were measured. On B-mode images, hepatic steatosis was graded using visual scoring (none, mild, moderate, or severe). Using B-mode images and two QUS parametric maps (TAI and TSI) as input data, the algorithm estimated the US fat fraction (USFF) as a percentage. The correlation between the USFF and MRI PDFF was evaluated using the Pearson correlation coefficient. The diagnostic performance of the USFF for hepatic steatosis (MRI PDFF ≥5%) was evaluated using receiver operating characteristic curve analysis and compared with that of TAI, TSI, and visual scoring. Results Overall, 173 participants (mean age, 51 years ± 14 [SD]; 96 men) were included, with 126 (73%) having hepatic steatosis (MRI PDFF ≥5%). USFF correlated strongly with MRI PDFF (Pearson r = 0.86, 95% CI: 0.82, 0.90; P < .001). For diagnosing hepatic steatosis (MRI PDFF ≥5%), the USFF yielded an area under the receiver operating characteristic curve of 0.97 (95% CI: 0.93, 0.99), higher than those of TAI, TSI, and visual scoring (P = .015, .006, and < .001, respectively), with a sensitivity of 90% (95% CI: 84, 95 [114 of 126]) and a specificity of 91% (95% CI: 80, 98 [43 of 47]) at a cutoff value of 5.7%. Conclusion A deep learning algorithm using quantitative US parametric maps and B-mode images accurately estimated the hepatic fat fraction and diagnosed hepatic steatosis in participants with nonalcoholic fatty liver disease. ClinicalTrials.gov registration nos. NCT04462562, NCT04180631 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Sidhu and Fang in this issue.

Deep learning-based image reconstruction of 40-keV virtual monoenergetic images of dual-energy CT for the assessment of hypoenhancing hepatic metastasis.

OBJECTIVES: To evaluate the diagnostic value of deep learning model (DLM) reconstructed dual-energy CT (DECT) low-keV virtual monoenergetic imaging (VMI) for assessing hypoenhancing hepatic metastases. METHODS: This retrospective study included 131 patients who underwent contrast-enhanced DECT (80-kVp and 150-kVp with a tin filter) in the portal venous phase for hepatic metastasis surveillance. Linearly blended images simulating 100-kVp images (100-kVp), standard 40-keV VMI images (40-keV VMI), and post-processed 40-keV VMI using a vendor-agnostic DLM (i.e., DLM 40-keV VMI) were reconstructed. Lesion conspicuity and diagnostic acceptability were assessed by three independent reviewers and compared using the Wilcoxon signed-rank test. The contrast-to-noise ratios (CNRs) were also measured placing ROIs in metastatic lesions and liver parenchyma. The detection performance of hepatic metastases was assessed by using a jackknife alternative free-response ROC method. The consensus by two independent radiologists was used as the reference standard. RESULTS: DLM 40-keV VMI, compared to 40-keV VMI and 100-kVp, showed a higher lesion-to-liver CNR (8.25 ± 3.23 vs. 6.05 ± 2.38 vs. 5.99 ± 2.00), better lesion conspicuity (4.3 (4.0-4.7) vs. 3.7 (3.7-4.0) vs. 3.7 (3.3-4.0)), and better diagnostic acceptability (4.3 (4.0-4.3) vs. 3.0 (2.7-3.3) vs. 4.0 (4.0-4.3)) (p < 0.001 for all). For lesion detection (246 hepatic metastases in 68 patients), the figure of merit was significantly higher with DLM 40-keV VMI than with 40-keV VMI (0.852 vs. 0.822, p = 0.012), whereas no significant difference existed between DLM 40-keV VMI and 100-kVp (0.852 vs. 0.842, p = 0.31). CONCLUSIONS: DLM 40-keV VMI provided better image quality and comparable diagnostic performance for detecting hypoenhancing hepatic metastases compared to linearly blended images. KEY POINTS: • DLM 40-keV VMI provides a superior image quality compared with 40-keV or 100-kVp for assessing hypoenhancing hepatic metastasis. • DLM 40-keV VMI has the highest CNR and lesion conspicuity score for hypoenhancing hepatic metastasis due to noise reduction and structural preservation. • DLM 40-keV VMI provides higher lesion detectability than standard 40-keV VMI (p = 0.012).

Diagnostic Performance of Spin-Echo Echo-Planar Imaging Magnetic Resonance Elastography in 3T System for Noninvasive Assessment of Hepatic Fibrosis.

OBJECTIVE: To validate the performance of 3T spin-echo echo-planar imaging (SE-EPI) magnetic resonance elastography (MRE) for staging hepatic fibrosis in a large population, using surgical specimens as the reference standard. MATERIALS AND METHODS: This retrospective study initially included 310 adults (155 undergoing hepatic resection and 155 undergoing donor hepatectomy) with histopathologic results from surgical liver specimens. They underwent 3T SE-EPI MRE ≤ 3 months prior to surgery. Demographic findings, underlying liver disease, and hepatic fibrosis pathologic stage according to METAVIR were recorded. Liver stiffness (LS) was measured by two radiologists, and inter-reader reproducibility was evaluated using the intraclass correlation coefficient (ICC). The mean LS of each fibrosis stage (F0-F4) was calculated in total and for each etiologic subgroup. Comparisons among subgroups were performed using the Kruskal-Wallis test and Conover post-hoc test. The cutoff values for fibrosis staging were estimated using receiver operating characteristic (ROC) curve analysis. RESULTS: Inter-reader reproducibility was excellent (ICC, 0.98; 95% confidence interval, 0.97-0.99). The mean LS values were 1.91, 2.41, 3.24, and 5.41 kPa in F0-F1 (n = 171), F2 (n = 26), F3 (n = 38), and F4 (n = 72), respectively. The discriminating cutoff values for diagnosing ≥ F2, ≥ F3, and F4 were 2.18, 2.71, and 3.15 kPa, respectively, with the ROC curve areas of 0.97-0.98 (sensitivity 91.2%-95.9%, specificity 90.7%-99.0%). The mean LS was significantly higher in patients with cirrhosis (F4) of nonviral causes, such as primary biliary cirrhosis (9.56 kPa) and alcoholic liver disease (7.17 kPa) than in those with hepatitis B or C cirrhosis (4.28 and 4.92 kPa, respectively). There were no statistically significant differences in LS among the different etiologic subgroups in the F0-F3 stages. CONCLUSION: The 3T SE-EPI MRE demonstrated high interobserver reproducibility, and our criteria for staging hepatic fibrosis showed high diagnostic performance. LS was significantly higher in patients with non-viral cirrhosis than in those with viral cirrhosis.

How to approach pancreatic cancer after neoadjuvant treatment: assessment of resectability using multidetector CT and tumor markers.

OBJECTIVES: To investigate clinical and CT factors associated with local resectability in patients with nonmetastatic pancreatic cancers after neoadjuvant chemotherapy ± radiation therapy (CRT). METHODS: This retrospective study included consecutive patients with nonmetastatic pancreatic cancers who underwent neoadjuvant CRT between June 2009 and June 2019. Tumor size, tumor-vascular contact with artery/vein, and local resectability categories (resectable, borderline resectable, or locally advanced) were assessed at baseline and post-CRT CT. Baseline and post-CRT carbohydrate antigen (CA) 19-9 levels were also assessed. Clinical or imaging features related to R0 resection were determined using logistic regression analysis. RESULTS: A total of 179 patients (mean age, 62.4 ± 9.3 years; 92 men) were included. After neoadjuvant CRT, 105 (58.7%) patients received R0 resection, while 74 (41.3%) did not. R0 resection rates were significantly different according to post-CRT CT resectability categories (p < 0.001): 82.8% (48/58), 70.1% (47/67), and 18.5% (10/54) for resectable, borderline resectable, and locally advanced disease, respectively. For post-CRT borderline resectable disease, ≥ 50% decrease in CA 19-9 was significantly associated with R0 resection (odds ratio (OR), 3.160; p = 0.02). For post-CRT locally advanced disease, small post-CRT tumor size ≤ 2 cm (OR, 9.668; p = 0.026) and decreased tumor-arterial contact (OR, 24.213; p = 0.022) were significantly associated with R0 resection. CONCLUSION: Post-CRT CT resectability categorization may be useful for the assessment of R0 resectability in patients with pancreatic cancer following neoadjuvant CRT. Additionally, ≥ 50% decrease in CA 19-9 was associated with R0 resection in post-CRT borderline resectable disease, while small post-CRT tumor size and decreased tumor-arterial contact were with locally advanced disease. KEY POINTS: • R0 resection rates following neoadjuvant chemotherapy ± radiation therapy (CRT) were 82.8%, 70.1%, and 18.5% in resectable, borderline resectable, and locally advanced disease, respectively, at post-CRT CT (p < 0.001). • For post-CRT borderline resectable disease, ≥ 50% decrease in carbohydrate antigen (CA) 19-9 was significantly associated with R0 resection. • For post-CRT locally advanced disease, small post-CRT tumor size ≤ 2 cm and decreased tumor-arterial contact were significantly associated with R0 resection.

Assessment of the inter-platform reproducibility of ultrasound attenuation examination in nonalcoholic fatty liver disease.

PURPOSE: This study aimed to assess the inter-platform reproducibility of ultrasound attenuation examination in patients with nonalcoholic fatty liver disease (NAFLD). METHODS: Between March 2021 and April 2021, patients with clinically suspected or known NAFLD were prospectively enrolled; each patient underwent ultrasound attenuation examinations with three different platforms (Attenuation Imaging [ATI], Canon Medical System; Tissue Attenuation Imaging [TAI], Samsung Medison; and Ultrasound-Guided Attenuation Parameter [UGAP], GE Healthcare) on the same day. The mean attenuation coefficient (AC) values of the three platforms were compared using repeated-measures analysis of variance with the Bonferroni correction. To evaluate inter-platform reproducibility, the AC values obtained for each platform were compared using Bland-Altman analysis with the calculation of 95% limits of agreement (LOA), intraclass correlation coefficients (ICCs), and coefficients of variation (CVs). RESULTS: Forty-six patients (23 men; mean age±standard deviation, 52.3±12.4 years) were enrolled. The mean AC values showed significant differences among the three platforms (0.75±0.12, 0.80±0.11, and 0.74±0.09 dB/cm/MHz for ATI, TAI, and UGAP, respectively; P<0.001). For inter-platform reproducibility, the 95% LOAs were -0.22 to 0.11 dB/cm/MHz between ATI and TAI, -0.17 to 0.18 dB/cm/MHz between ATI and UGAP, and -0.08 to 0.20 dB/cm/MHz between TAI and UGAP, respectively. The pairwise ICCs were 0.790-0.797 in terms of absolute agreement among the three platforms; the CVs were 8.23%-9.47%. CONCLUSION: The AC values obtained from different ultrasound attenuation examination platforms showed significant differences, with significant inter-platform variability. Therefore, the AC values measured using different ultrasound attenuation examination techniques should not be used interchangeably for longitudinal follow-up of patients with NAFLD.

Quantitative Ultrasound Radiofrequency Data Analysis for the Assessment of Hepatic Steatosis in Nonalcoholic Fatty Liver Disease Using Magnetic Resonance Imaging Proton Density Fat Fraction as the Reference Standard.

OBJECTIVE: To investigate the diagnostic performance of quantitative ultrasound (US) parameters for the assessment of hepatic steatosis in patients with nonalcoholic fatty liver disease (NAFLD) using magnetic resonance imaging proton density fat fraction (MRI-PDFF) as the reference standard. MATERIALS AND METHODS: In this single-center prospective study, 120 patients with clinically suspected NAFLD were enrolled between March 2019 and January 2020. The participants underwent US examination for radiofrequency (RF) data acquisition and chemical shift-encoded liver MRI for PDFF measurement. Using the RF data analysis, the attenuation coefficient (AC) based on tissue attenuation imaging (TAI) (AC-TAI) and scatter-distribution coefficient (SC) based on tissue scatter-distribution imaging (TSI) (SC-TSI) were measured. The correlations between the quantitative US parameters (AC and SC) and MRI-PDFF were evaluated using Pearson correlation coefficients. The diagnostic performance of AC-TAI and SC-TSI for detecting hepatic fat contents of ≥ 5% (MRI-PDFF ≥ 5%) and ≥ 10% (MRI-PDFF ≥ 10%) were assessed using receiver operating characteristic (ROC) analysis. The significant clinical or imaging factors associated with AC and SC were analyzed using linear regression analysis. RESULTS: The participants were classified based on MRI-PDFF: < 5% (n = 38), 5-10% (n = 23), and ≥ 10% (n = 59). AC-TAI and SC-TSI were significantly correlated with MRI-PDFF (r = 0.659 and 0.727, p < 0.001 for both). For detecting hepatic fat contents of ≥ 5% and ≥ 10%, the areas under the ROC curves of AC-TAI were 0.861 (95% confidence interval [CI]: 0.786-0.918) and 0.835 (95% CI: 0.757-0.897), and those of SC-TSI were 0.964 (95% CI: 0.913-0.989) and 0.935 (95% CI: 0.875-0.972), respectively. Multivariable linear regression analysis showed that MRI-PDFF was an independent determinant of AC-TAI and SC-TSI. CONCLUSION: AC-TAI and SC-TSI derived from quantitative US RF data analysis yielded a good correlation with MRI-PDFF and provided good performance for detecting hepatic steatosis and assessing its severity in NAFLD.

Quantitative ultrasound radiofrequency data analysis for the assessment of hepatic steatosis using the controlled attenuation parameter as a reference standard.

PURPOSE: This study was aimed to investigate the value of quantitative ultrasound (US) parameters from radiofrequency (RF) data analysis for assessing hepatic steatosis, using controlled attenuation parameter (CAP)-based steatosis grades as the reference standard. METHODS: We analyzed 243 participants with both B-mode liver US with RF data acquisition and CAP measurements. On B-mode US images, hepatic steatosis was visually scored (0/1/2/3, none/mild/moderate/severe), and the hepatorenal index (HRI) was calculated. From the RF data analysis, the tissue scatter-distribution imaging parameter (TSI-p) and tissue attenuation imaging parameter (TAI-p) of the liver parenchyma were measured. US parameters were correlated with CAP-based steatosis grades (S0/1/2/3, none/mild/moderate/severe) and their diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. Multivariate linear regression analysis was performed to identify determinants of TSI-p and TAI-p. RESULTS: Participants were classified as having S0 (n=152), S1 (n=54), S2 (n=14), and S3 (n=23) on CAP measurements. TSI-p and TAI-p were significantly correlated with steatosis grades (ρ =0.593 and ρ=-0.617, P<0.001 for both). For predicting ≥S1, ≥S2, and S3, the areas under the ROC curves (AUCs) of TSI-p were 0.827/0.914/0.917; TAI-p, 0.844/0.914/0.909; visual scores, 0.659/0.778/0.794; and HRI, 0.629/0.751/0.759, respectively. TSI-p and TAI-p had significantly higher AUCs than did visual scores or HRI for ≥S1 or ≥S2 (P≤0.003). In the multivariate analysis, the transient elastography-based fibrosis grade (P=0.034) and steatosis grade (P<0.001) were independent determinants of TSI-p, while steatosis grade (P<0.001) was an independent determinant of TAI-p. CONCLUSION: TSI-p and TAI-p derived from US RF data may be useful for detecting hepatic steatosis and assessing its severity.

Ultrasound-guided transient elastography and two-dimensional shear wave elastography for assessment of liver fibrosis: emphasis on technical success and reliable measurements.

PURPOSE: This study investigated whether the use of ultrasound (US) guidance in transient elastography (TE) improved the technical success and reliability of liver stiffness (LS) measurements and whether 2-dimensional (2D) shear wave elastography (SWE) provided reliable LS measurements if TE measurements failed. METHODS: In this prospective study, 292 participants (male:female, 189:103; median age, 60 years) with chronic liver disease (CLD) were enrolled. LS was measured via the consecutive use of conventional TE, 2D-SWE, and US-guided TE. The technical success rates and reliable LS measurement rates of the three elastography techniques were compared. The risk factors for TE failure were assessed through univariate and multivariate logistic regression models. RESULTS: US-guided TE was associated with a higher technical success rate (281 of 292, 96.2%) and a higher reliable measurement rate (266 of 292, 91.1%) than conventional TE (technical success: 256 of 292, 87.7%; reliable measurements: 231 of 292, 79.1%; P<0.001 for both). In participants for whom conventional TE failed, 2D-SWE provided high rates of technical success (36 of 36, 100%) and reliable measurements (30 of 36, 83.3%). TE failure was associated with female sex (odds ratio [OR], 5.85; 95% confidence interval [CI], 1.30 to 26.40), severe reverberation artifacts (OR, 8.79; 95% CI, 3.93 to 19.69), and high skin-to-liver capsule depth (OR, 1.23; 95% CI, 1.09 to 1.39). CONCLUSION: US guidance in TE improved the technical success and reliable measurement rates in the assessment of LS in patients with CLD. In participants for whom TE failed, subsequent 2D-SWE successfully delivered reliable LS measurements.

A differential risk assessment and decision model for Transarterial chemoembolization in hepatocellular carcinoma based on hepatic function.

BACKGROUND: The decision of transarterial chemoembolization (TACE) initiation and/or repetition remains challenging in patients with unresectable hepatocellular carcinoma (HCC). The aim was to develop a prognostic scoring system to guide TACE initiation/repetition. METHODS: A total of 597 consecutive patients who underwent TACE as their initial treatment for unresectable HCC were included. We derived a prediction model using independent risk factors for overall survival (OS), which was externally validated in an independent cohort (n = 739). RESULTS: Independent risk factors of OS included Albumin-bilirubin (ALBI) grade, maximal tumor size, alpha-fetoprotein, and tumor response to initial TACE, which were used to develop a scoring system ("ASAR"). C-index values for OS were 0.733 (95% confidence interval [CI] = 0.570-0.871) in the derivation, 0.700 (95% CI = 0.445-0.905) in the internal validation, and 0.680 (95% CI = 0.652-0.707) in the external validation, respectively. Patients with ASAR< 4 showed significantly longer OS than patients with ASAR≥4 in all three datasets (all P < 0.001). Among Child-Pugh class B patients, a modified model without TACE response, i.e., "ASA(R)", discriminated OS with a c-index of 0.788 (95% CI, 0.703-0.876) in the derivation, and 0.745 (95% CI, 0.646-0.862) in the internal validation, and 0.670 (95% CI, 0.605-0.725) in the external validation, respectively. Child-Pugh B patients with ASA(R) < 4 showed significantly longer OS than patients with ASA(R) ≥ 4 in all three datasets (all P < 0.001). CONCLUSIONS: ASAR provides refined prognostication for repetition of TACE in patients with unresectable HCC. For Child-Pugh class B patients, a modified model with baseline factors might guide TACE initiation.

LI-RADS M (LR-M) criteria and reporting algorithm of v2018: diagnostic values in the assessment of primary liver cancers on gadoxetic acid-enhanced MRI.

PURPOSE: To evaluate diagnostic values of the liver imaging reporting and data system (LI-RADS) M (LR-M) category based on novel explicit criteria that accept both targetoid and nontargetoid LR-M features and the suggested reporting algorithm of LI-RADS v2018 to assess primary liver cancers (PLCs) on gadoxetic acid-enhanced MRI (Gd-EOB-MRI). METHODS: This retrospective study included 165 patients at high risk for hepatocellular carcinoma (HCC) with pathologically confirmed PLCs (HCC, n = 113; intrahepatic cholangiocarcinoma [iCCA], n = 23; and combined hepatocellular cholangiocarcinoma [cHCC-CCA], n = 29). Two radiologists independently analyzed Gd-EOB-MRI features and determined LI-RADS category for each tumor and categorized the likely etiology either as HCC or non-HCC malignancy if LR-M was assigned. Diagnostic performances for HCC or those for malignancy were compared according to imaging criteria. RESULTS: LR-M was assigned in 95.7%/91.3% of iCCAs; 55.2%/58.6% of cHCC-CCAs; and 21.2%/17.7% of HCCs in reviewers 1/2. Combination of LR-5 plus LR-M resulted in sensitivity of 95.2%/97.6% to diagnose PLCs as malignant, which were significantly higher than that of LR-5 plus "LR-M with ≥ 1 targetoid appearances" (84.8%/91.5%, Ps < 0.01). In comparison to LR-5, LR-5 plus "LR-M of HCC as likely etiology" resulted in significant increase in sensitivity (73.5%/79.6% versus 87.6%/92.9%, Ps < 0.001) but significant decrease in specificity (76.9%/75.0% versus 57.7%/50.0%, P = 0.002 and < 0.001) in the diagnosis of HCC. CONCLUSION: The LR-M criteria v2018 are useful to differentiate non-HCC malignancies from HCCs and to accurately diagnose PLCs as a malignancy. Reporting the likely etiology in LR-M may facilitate a more sensitive detection of HCC, but along with a considerable decrease in specificity.

Two-dimensional Shear Wave Elastography with Propagation Maps for the Assessment of Liver Fibrosis and Clinically Significant Portal Hypertension in Patients with Chronic Liver Disease: A Prospective Study.

OBJECTIVES: To investigate the diagnostic performance of liver stiffness (LS) measurements on two-dimensional (2D) shear wave elastography (SWE) for the assessment of hepatic fibrosis using LS measurements on MR elastography (MRE) as the reference standard and the prediction of clinically significant portal hypertension (CSPH). METHODS: In this prospective study, 101 patients with chronic liver disease or cirrhosis underwent both MRE and SWE. After exclusion of technical failure on MRE (n = 5), technical failure/unreliable measurement on SWE (n = 4), LS measurements obtained on SWE with the aid of propagation maps were correlated with those of the MRE using Pearson's correlation analysis. Diagnostic performances for significant fibrosis (≥F2: MRE of ≥2.99 kPa) or cirrhosis (F4: MRE of ≥3.63 kPa) and for the prediction of CSPH were assessed using receiver operating characteristics (ROC) curve analysis. RESULTS: LS values on SWE showed a strong correlation with those on MRE (r = 0.846, P < 0.001). For the diagnosis of significant fibrosis or cirrhosis in patients with hepatitis B virus-related liver disease (n = 75), SWE showed areas under the ROC curves (AUC) of 0.975 and 0.912, respectively (95% confidence interval [CI], 0.910-997, and 0.824-0.965). For the prediction of CSPH, the AUC of SWE was 0.818 (95% CI, 0.712-0.898), and when an LS value of 11.5 kPa was applied as a cut-off, SWE showed a sensitivity of 81.5% and a specificity of 72.9%. CONCLUSION: LS measurements on 2D SWE were demonstrated to be well correlated with those obtained with MRE, and thus, may provide good diagnostic performance for the prediction of hepatic fibrosis and the presence of CSPH.

Assessment of liver fibrosis using 2-dimensional shear wave elastography: a prospective study of intra- and inter-observer repeatability and comparison with point shear wave elastography.

PURPOSE: The purpose of this study was to prospectively investigate the intra- and interobserver repeatability of a new 2-dimensional (2D) shear wave elastography (SWE) technique (S-Shearwave Imaging) for assessing liver fibrosis in chronic liver disease patients, and to compare liver stiffness measurements (LSMs) made using 2D-SWE with those made using point SWE (pSWE). METHODS: This prospective study received institutional review board approval and informed consent was obtained from all patients. Fifty-three chronic liver disease patients were randomly allocated to group 1 (for intra-observer repeatability [n=33]) or group 2 (for inter-observer repeatability [n=20]). In group 1, two 2D-SWE sessions and one pSWE sessions were performed by one radiologist. In group 2, one 2D-SWE session and one pSWE session were performed by the aforementioned radiologist, and a second 2D-SWE session was performed by another radiologist. The intraclass correlation coefficient (ICC) was used to assess intra- and interobserver reliability. LSMs obtained using 2D-SWE and pSWE were compared and correlated using the paired t test and Pearson correlation coefficient, respectively. RESULTS: LSMs made using 2D-SWE demonstrated excellent intra- and inter-observer repeatability (ICC, 0.997 [95% confidence interval, 0.994 to 0.999]) and 0.995 [0.988 to 0.998], respectively). LSMs made using 2D-SWE were significantly different from those made using pSWE (2.1±0.6 m/sec vs. 1.9±0.6 m/sec, P<0.001), although a significant correlation existed between the 2D-SWE and pSWE LSMs (rho=0.836, P<0.001). CONCLUSION: S-Shearwave Imaging demonstrated excellent intra- and inter-observer repeatability, and a strong correlation with pSWE measurements of liver stiffness. However, because of the significant difference between LSMs obtained using 2D-SWE and pSWE, these methods should not be used interchangeably.

Validation of a New Point Shear-Wave Elastography Method for Noninvasive Assessment of Liver Fibrosis: A Prospective Multicenter Study.

OBJECTIVE: To validate the diagnostic value of a new point shear-wave elastography method, S-shearwave elastography (S-SWE; Samsung Medison Co., Ltd.), in noninvasive assessment of liver fibrosis. MATERIALS AND METHODS: In this prospective multicenter study, liver stiffness (LS) measurements for 600 participants were obtained with both S-SWE and transient elastography (TE). The rates of unsuccessful LS measurements in S-SWE and TE were compared, and correlations between S-SWE and TE measurements were assessed. In 107 patients with histologic reference data, the optimal LS cut-off values for predicting severe fibrosis and cirrhosis on S-SWE were determined using receiver operating characteristic (ROC) curve analysis. The LS cut-off values in S-SWE were then validated in 463 patients without histologic reference data by using TE values as the reference standard, and the sensitivity and specificity of the cut-off values for predicting severe fibrosis and cirrhosis were calculated. RESULTS: The frequency of unsuccessful LS measurements on TE (4.5%, 27/600) was significantly higher than that (0.7%, 4/600) on S-SWE (p < 0.001). LS measurements on S-SWE showed a significant correlation with TE values (r = 0.880, p < 0.001). In 107 patients with histological reference data, the areas under the ROC curves on S-SWE were 0.845 and 0.850, with optimal cut-offs of 7.0 kilopascals (kPa) and 9.7 kPa, for the diagnosis of severe fibrosis and cirrhosis, respectively. Using these cut-off values, S-SWE showed sensitivities of 92.9% and 97.4% and specificities of 89.5% and 83.1% in TE-based evaluations of severe fibrosis and cirrhosis, respectively. CONCLUSION: LS measurements on S-SWE were well correlated with those on TE. In addition, S-SWE provided good diagnostic performance for staging of hepatic fibrosis, with a lower rate of unsuccessful LS measurements compared with TE.

Quantitative Assessment of Liver Function by Using Gadoxetic Acid-enhanced MRI: Hepatocyte Uptake Ratio.

Purpose To determine whether hepatocyte uptake ratios derived at gadoxetic acid-enhanced MRI correlate with quantitative measures of liver function and can help to identify contraindication to major hepatectomy. Materials and Methods Between August 2016 and October 2016, 50 study participants with chronic liver disease or cirrhosis underwent liver MRI at 3.0 T including T1 mapping and elastography. Liver function was quantitatively assessed by using the indocyanine green retention test (ICG R15). T1 maps were obtained by using the Look-Locker sequence before and 10 minutes after gadoxetic acid administration (0.025 mmol/kg). The relationship between ICG R15 and the following MRI parameters was evaluated: pre- and postcontrast T1 values of the liver, hepatocyte uptake ratio representing the amount of contrast media solely taken into hepatocytes, liver volume, and degree of enhancement at the common bile duct. Diagnostic performance of the hepatocyte uptake ratio to identify patients with ICG R15 greater than 20% (ie, contraindication to hepatectomy) was compared with other parameters by using areas under the receiver operating characteristic curve. Results Hepatocyte uptake ratio showed a negative correlation with ICG R15 r of -0.78 (P < .001). In participants with chronic liver disease or Child-Pugh class A, those with ICG R15 of 20% or less showed higher hepatocyte uptake ratio than those with ICG R15 greater than 20% (P < .001). Hepatocyte uptake ratios demonstrated better performance for helping to detect ICG R15 greater than 20% than did liver volume (area under the curve, 0.96 vs 0.70; P = .01). Conclusion Hepatocyte uptake ratios are negatively correlated with liver function as measured by indocyanine green retention test and provide acceptable diagnostic performance for helping to identify participants who have contraindications to major hepatectomy. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Reeder in this issue.

Prediction of Local Tumor Progression after Radiofrequency Ablation (RFA) of Hepatocellular Carcinoma by Assessment of Ablative Margin Using Pre-RFA MRI and Post-RFA CT Registration.

Objective: To evaluate the clinical impact of using registration software for ablative margin assessment on pre-radiofrequency ablation (RFA) magnetic resonance imaging (MRI) and post-RFA computed tomography (CT) compared with the conventional side-by-side MR-CT visual comparison. Materials and Methods: In this Institutional Review Board-approved prospective study, 68 patients with 88 hepatocellulcar carcinomas (HCCs) who had undergone pre-RFA MRI were enrolled. Informed consent was obtained from all patients. Pre-RFA MRI and post-RFA CT images were analyzed to evaluate the presence of a sufficient safety margin (≥ 3 mm) in two separate sessions using either side-by-side visual comparison or non-rigid registration software. Patients with an insufficient ablative margin on either one or both methods underwent additional treatment depending on the technical feasibility and patient's condition. Then, ablative margins were re-assessed using both methods. Local tumor progression (LTP) rates were compared between the sufficient and insufficient margin groups in each method. Results: The two methods showed 14.8% (13/88) discordance in estimating sufficient ablative margins. On registration software-assisted inspection, patients with insufficient ablative margins showed a significantly higher 5-year LTP rate than those with sufficient ablative margins (66.7% vs. 27.0%, p = 0.004). However, classification by visual inspection alone did not reveal a significant difference in 5-year LTP between the two groups (28.6% vs. 30.5%, p = 0.79). Conclusion: Registration software provided better ablative margin assessment than did visual inspection in patients with HCCs who had undergone pre-RFA MRI and post-RFA CT for prediction of LTP after RFA and may provide more precise risk stratification of those who are treated with RFA.

Assessment of the Surveillance Interval at 1 Year after Curative Treatment in Hepatocellular Carcinoma: Risk Stratification.

Background/Aims: Guidelines recommend surveillance for hepatocellular carcinoma (HCC) recurrence at 3-month intervals during the first year after curative treatment and 6-month intervals thereafter in all patients. This strategy does not reflect individual risk of recurrence. We aimed to stratify risk of recurrence to optimize surveillance intervals 1 year after treatment. Methods: We retrospectively analyzed 1,316 HCC patients treated with resection/radiofrequency ablation at Barcelona Clinic Liver Cancer stage 0/A. In patients without 1-year recurrence under 3-monthly surveillance, a new model for recurrence was developed using backward elimination methods: training (n=582)/validation cohorts (n=291). Overall survival (OS) according to risk stratified by the new model was compared according to surveillance intervals: 3-monthly versus 6-monthly (n=401) after lead time bias correction and propensity-score matching analyses. Results: Among patients without 1-year recurrence, age and international normalized ratio values were significant factors for recurrence (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.00 to 1.03; p=0.009 and HR, 5.63; 95% CI, 2.24 to 14.18; p<0.001; respectively). High-risk patients stratified by the new model showed significantly higher recurrence rates than low-risk patients in the validation cohort (HR, 1.73; 95% CI, 1.18 to 2.53; p=0.005). After propensity-score matching between the 3-monthly and 6-monthly surveillance groups, OS in high-risk patients under 3-monthly surveillance was significantly higher than that under 6-monthly surveillance (p=0.04); however, OS in low-risk patients under 3-monthly surveillance was not significantly different from that under 6-monthly surveillance (p=0.17). Conclusions: In high-risk patients, 3-monthly surveillance can prolong survival compared to 6-monthly surveillance. However, in low-risk patients, 3-monthly surveillance might not be beneficial for survival compared to 6-monthly surveillance.