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The suppression of fat signals in abdominal magnetic resonance imaging has become a basic and routine practice in the diagnosis of pathologic conditions of abdominal organs in clinical settings. Many fat-suppression techniques have been developed in the past several decades, with fat-quantification methods introduced in response in more recent years. Fat-suppression techniques can be divided into two categories. Chemical shift–based techniques include chemical shift selective (CHESS), water excitation, and the Dixon method. CHESS is the most commonly used fat-suppression method, nulling the fat signal using a fat-selective radiofrequency pulse with a spoiler gradient. Water excitation employs a binomial pulse that excites only the water protons. Finally, the Dixon method involves using the in-phase/out-of-phase cycling of fat and water. An inversionbased technique, known as short tau inversion recovery (STIR), uses a pre-excitation inversion pulse that inverts the spin of all tissues. By selecting the appropriate MRI inversion time such that the longitudinal magnetization of fat is zero, fat protons will not contribute to the MRI signal. Also, spectral attenuated inversion recovery (SPAIR) is a hybrid technique that combines the characteristics of both CHESS and STIR. The most precise fat-quantification technique known to date is a complex-based multipoint Dixon method, with which the protondensity fat fraction (PDFF) can be obtained. Multiple confounding factors must be well-corrected for accurate fat quantification. Radiologists should be familiar with the various fat suppression and measurement methods during MRI and be able to apply them to enhance patient care.

In HCC, locoregional therapy (LRT) is performed as a bridging or downstaging treatment before curative surgery. The impact of the LI-RADS Treatment Response (LR-TR) algorithm on surgical outcomes remains unknown. We aimed to evaluate radiologic and clinical factors predicting recurrence-free survival (RFS) and overall survival (OS) after curative surgery for LRT-treated HCC.Consecutive HCC patients who underwent liver transplantation or curative resection after LRT from 2010 to 2016 and had baseline and follow-up post-LRT CT/MRI up to the point of surgery were included. The LR-TR category at the time of surgery and other features were assessed using Cox proportional hazard models. RFS was estimated and compared using the Kaplan-Meier method with log-rank tests.We evaluated 73 patients with 115 lesions. The LR-TR viable category at the time of surgery (hazard ratio [HR], 3.84; 95% confidence interval [CI]: 1.04, 14.16), preoperative AFP200 ng/mL (HR, 3.63; 95% CI: 1.63, 8.10), LRT sessions3 (HR, 4.99; 95% CI: 1.73, 14.38), and resection (HR, 3.35; 95% CI: 1.39, 8.09) independently predicted recurrence. The risk score categorized the patients into poor, intermediate, and favorable-risk groups with 1-year RFS rates of 35.0%, 78.3%, and 97.0%, respectively (p0.001). Outside Milan at the time of surgery (HR, 5.79; 95% CI: 1.94, 17.07) and recurrence within the first postoperative year (HR, 17.66; 95% CI: 6.42, 48.56) predicted death.In LRT-treated HCC, non-LR-TR viable disease achieved within fewer LRT sessions and removed by liver transplantation recurred less.• The Liver Imaging Reporting and Data System treatment response (LR-TR) viable disease (hazard ratio [HR], 3.84; p = 0.043), preoperative serum AFP level200 ng/mL (HR, 3.63; p = 0.002), more than three locoregional treatment (LRT) sessions (HR, 4.99; p = 0.003), and resection compared to liver transplantation (HR, 3.35; p = 0.001) were the independent predictors for postsurgical recurrence in LRT-treated HCCs. • A scoring system combining LR-TR categories and key clinical factors stratifies the patients into poor, intermediate, and favorable recurrence risk groups, with 1-year RFS rates of 35.0%, 78.3%, and 97.0%, respectively (p0.001). • Outside Milan at the time of surgery (HR, 5.79; p = 0.001) and recurrence within the first postoperative year (HR, 17.66; p0.001) were associated with poor overall survival.

BACKGROUND: Lowering kVp affects the image contrast and computed tomography (CT) attenuation values of low kVp CT is different from those of conventional 120-kVp scans. The purpose of this study is to determine the diagnostic performance and to establish the reference range of low-kVp unenhanced CT for the assessment of hepatic steatosis in liver transplantation donors using magnetic resonance (MR) spectroscopy as a reference standard. METHODS: This retrospective study included 165 potential donors (male:female =114:51, 36.5±12.0 years old) who underwent 100-kVp single-slice unenhanced CT scan and MR spectroscopy. The difference between hepatic and splenic attenuation (CT(L-S)) and liver-to-spleen attenuation ratio (CT(L/S)) were calculated. Reference standard was the fat signal fraction measured by MR spectroscopy. Limits of agreement between CT measurements and the reference standard were calculated. Areas under receiver operating characteristic curves (AUROCs) of CT(L-S) and CT(L/S) were compared for the diagnosis of moderate to severe steatosis. Cut-off values of CT(L-S) and CT(L/S) that provided a balance between sensitivity and specificity and the highest specificity using the lower limit of the reference range were calculated. RESULTS: Eighty-seven subjects had a non-steatotic liver. Sixty-one subjects had mild steatosis and 17 subjects had moderate to severe steatosis based on MR spectroscopy. CT(L-S) and CT(L/S) values were negatively correlated with the fat signal fraction (P

Background: Interest in health insurance coverage for artificial intelligence (AI)–based medical technologies is growing. This article provides a review of the current developments in the sphere and provides future perspectives, focusing on AI application in radiology.Current Concepts: In December 2019, the Health Insurance Review and Assessment Service under the Korean Ministry of Health and Welfare released its first guidelines for determining the National Health Insurance coverage for AI–based medical technologies. Additionally, in 2020, the largest US health insurance provider, the Centers for Medicare and Medicaid Services, approved payment for AI technologies using two different systems. First, in September 2020, it granted New Technology Add-on Payments for AI algorithms that facilitate the diagnosis and treatment of large vessel occlusion strokes. Second, in December 2020, the Centers for Medicare and Medicaid Services finalized the provision of reimbursements for IDx-DR through a Current Procedural Terminology code. The AI system screens for more than mild diabetic retinopathy, which requires further evaluation by an ophthalmologist.Discussion and Conclusion: An in-depth look at the three events suggests the importance of demonstrating the added clinical value of AI technologies through improved patient outcomes in enabling insurance coverage. Therefore, it is critical to create clinically meaningful collaboration between healthcare professionals and AI by understanding and combining their unique strengths, thus actualizing new forms of patient care instead of having AI merely copy the professionals. Furthermore, if National Health Insurance coverage is granted for AI technologies in radiology, add-on payments would be the most appropriate method.

Preamble The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing rapidly worldwide as the obese and diabetic populations increase, and it has been estimated to be 20–30% in Korea. Considering the increased popularity of a westernized diet and lifestyle, lack of exercise, and the resulting increase in obesity and diabetes, NAFLD is predicted to become more prevalent in the future and to become a major cause of chronic liver disease. In some patients, NAFLD progresses to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC), and it is an independent cardiovascular risk factor. In 2013, the Korean Association for the Study of the Liver (KASL) enacted a clinical practice guideline for the diagnosis and treatment of NAFLD to improve understanding of the disease and provide useful clinical information and direction for healthcare providers. The research results that have accumulated since then necessitate a revision. Accordingly, the clinical practice guidelines committee began revising the guidelines to reflect the results of Korean and international research and develop new recommendations based on a systematic approach that reflects evidencebased medicine and expert opinions. However, evidence remains insufficient, and many studies are currently being conducted. As medical evidence and new findings accumulate in the future, these guidelines will require ongoing supplementation and revision.

Hepatic surface nodularity quantified on CT images has shown promising results in staging hepatic fibrosis in chronic hepatitis C. The aim of this study was to evaluate hepatic surface nodularity, serum fibrosis indices, and a linear combination of them for staging fibrosis in chronic liver disease, mainly chronic hepatitis B. We developed a semiautomated software quantifying hepatic surface nodularity on CT images. Hepatic surface nodularity and serum fibrosis indices were assessed in the development group of 125 patients to generate 3 linear models combining hepatic surface nodularity with the aspartate aminotransferase to platelet ratio index, fibrosis-4 index, or platelet count in reference to the METAVIR scoring system. The models were validated in 183 patients. Hepatic surface nodularity and serum fibrosis indices all significantly correlated with fibrosis stages. For binary classifications into cirrhosis (F4), advanced fibrosis (≥ F3), and significant fibrosis (≥ F2), hepatic surface nodularity was significantly different across categories. The areas under the curve (AUCs) of the best model were 0.901, 0.872, and 0.794 for cirrhosis, advanced fibrosis, and significant fibrosis, respectively, higher than serum fibrosis indices alone (0.797–0.802, 0.799–0.818, and 0.761–0.773). In the validation group, the same model likewise showed higher AUCs (0.872, 0.831, and 0.850) compared to serum fibrosis indices (0.722–0.776, 0.692–0.768, and 0.695–0.769; p

We aimed to systematically determine the etiology of the Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) on contrast-enhanced CT or MRI and to determine the sources of heterogeneity between reported results. Original studies reporting the etiology of LR-TIV were identified in MEDLINE and EMBASE up until July 7, 2020. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were calculated. Subgroup analyses were performed according to the type of reference standard and the most common underlying liver disease. Meta-regression analysis was performed to explore study heterogeneity. Sixteen studies reported the etiology of a total of 150 LR-TIV, of which 98 (65%) were HCC and 52 (35%) were non-HCC. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were 70.9% (95% confidence interval [CI], 55.7–82.5%; I2 = 59%) and 29.2% (95% CI, 17.5–44.4%; I2 = 59%), respectively. The meta-analytic pooled percentage of HCC was lower in studies using only pathology as a reference standard (67.1%; 95% CI, 49.3–81.1%), but higher in studies in which hepatitis C was the most common underlying liver disease (81.9%; 95% CI, 11.3–99.4%) than that in the total 16 studies. Study type (cohort study versus case-control study) was significantly associated with study heterogeneity (p = 0.04). The most common etiology of LR-TIV was HCC. It might be important to understand the percentage of HCC and non-HCC in LR-TIV in consideration of the type of reference standard, geographic differences, and study design. • The most common etiology of Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) was hepatocellular carcinoma (HCC). • The percentage of HCC in LR-TIV was relatively low in studies using only pathology as a reference standard, but high in studies in which hepatitis C was the most common underlying liver disease. • Study type was a factor significantly influencing study heterogeneity.

Background Hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE) at gadoxetic acid-enhanced MRI may indicate hepatocellular carcinoma (HCC) or nonmalignant cirrhosis-associated nodules. Purpose To assess the distribution of pathologic diagnoses of HBP hypointense nodules without APHE at gadoxetic acid-enhanced MRI and to evaluate clinical and imaging features in differentiating their histologic grades. Materials and Methods This retrospective multicenter study included pathologic analysis-confirmed HBP hypointense nodules without APHE (≤30 mm) in patients with chronic liver disease or cirrhosis screened between January 2008 and June 2016. Central pathologic review by 10 pathologists determined final histologic grades as progressed HCC, early HCC, high-grade dysplastic nodule (DN), and low-grade DN or regenerative nodule. Gadoxetic acid-enhanced MRI features were analyzed by three radiologists. Multivariable logistic regression analyses with elastic net regularization were performed to identify clinical and imaging features for differentiating histologic grades. Results There were 298 patients (mean age, 59 years ± 10; 226 men) with 334 nodules evaluated, and progressed HCCs were diagnosed in 44.0% (147 of 334), early HCCs in 20.4% (68 of 334), high-grade DNs in 27.5% (92 of 334), and low-grade DNs or regenerative nodules in 8.1% (27 of 334). Serum α-fetoprotein level 100 ng/mL or greater (odds ratio, 2.7; P = .01) and MRI features including well-defined margin (odds ratio, 5.5; P = .003), hypointensity at precontrast T1-weighted imaging (odds ratio, 3.2; P < .001), intermediate hyperintensity at T2-weighted imaging (odds ratio, 3.4; P < .001), and restricted diffusion (odds ratio, 1.9; P = .04) were independent predictors for progressed HCC at multivariable analysis. Conclusion In patients at high risk for hepatocellular carcinoma (HCC), hepatobiliary phase hypointense nodules without arterial phase hyperenhancement at gadoxetic acid-enhanced MRI corresponded mainly to progressed HCCs, early HCCs, and high-grade dysplastic nodules. High α-fetoprotein level and some imaging features at MRI helped to differentiate progressed HCC from lower grade nodules. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Motosugi in this issue.

Although the overall prognosis of patients with hepatocellular carcinoma (HCC) remains poor, curative treatment may improve the survival of patients diagnosed at an early stage through surveillance. Accordingly, ultrasonography (US)-based HCC surveillance programs proposed in international society guidelines are now being implemented and regularly updated based on the latest evidence to improve their efficacy. Recently, other imaging modalities such as magnetic resonance imaging have shown potential as alternative surveillance tools based on individualized risk stratification. In this review article, we describe the current status of US-based surveillance for HCC and summarize the supporting evidence. We also discuss alternative surveillance imaging modalities that are currently being studied to validate their diagnostic performance and cost-effectiveness.

Our meta-analysis aimed to evaluate the diagnostic performance of surveillance magnetic resonance imaging (sMRI) for detecting hepatocellular carcinoma (HCC), and to compare the diagnostic performance of sMRI between different protocols. Original articles about the diagnostic accuracy of sMRI for detecting HCC were found in major databases. The meta-analytic pooled sensitivity and specificity of sMRI for detecting HCC were determined using a bivariate random effects model. The pooled sensitivity and specificity of full MRI and abbreviated MRI protocols were compared using bivariate meta-regression. In the total seven included studies (1830 patients), the pooled sensitivity of sMRI for any-stage HCC and very early-stage HCC were 85% (95% confidence interval, 79–90%; I2 = 0%) and 77% (66–85%; I2 = 32%), respectively. The pooled specificity for any-stage HCC and very early-stage HCC were 94% (90–97%; I2 = 94%) and 94% (88–97%; I2 = 96%), respectively. The pooled sensitivity and specificity of abbreviated MRI protocols were 87% (80–94%) and 94% (90–98%), values that were comparable with those of full MRI protocols (84% [76–91%] and 94% [89–99%]; p = 0.83). In conclusion, sMRI had good sensitivity for detecting HCC, particularly very early-stage HCC. Abbreviated MRI protocols for HCC surveillance had comparable diagnostic performance to full MRI protocols.

Simple Summary Locoregional therapy (LRT) is widely performed as a nonsurgical treatment for hepatocellular carcinoma (HCC). Following LRT, precise assessment of post-treatment imaging can play an important role in determining residual tumor viability and future treatment for patients with HCC. Owing to the need to provide a more standardized image interpretation, Liver Imaging Reporting and Data Systems (LI-RADS) treatment response (TR) algorithm was developed. We conducted a systematic review and meta-analysis to assess the accuracy of each imaging feature of LI-RADS TR (LR-TR) viable category for diagnosing viable HCC after LRT. This meta-analysis of 10 studies comprising 971 patients found that the pooled sensitivity and diagnostic odds ratio were the highest for arterial phase hyperenhancement (APHE), followed by washout appearance and enhancement similar to pretreatment. The diagnostic performance of APHE was significantly different depending on the type of reference standard and MRI contrast agent. The results of this meta-analysis represent the currently available evidence regarding the performance of LR-TR algorithm. Abstract 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.

Several imaging-based systems have been proposed for the diagnosis of hepatocellular carcinoma (HCC) using magnetic resonance imaging (MRI), reflecting geographical differences in the clinical environment for HCC. We conducted a systematic review and meta-analysis to determine the performance of the Korean Liver Cancer Association-National Cancer Center (KLCA-NCC) 2018 criteria for the MRI diagnosis of HCC. Original studies reporting the performance of the KLCA-NCC 2018 criteria for the diagnosis of HCC using MRI were identified in MEDLINE and EMBASE until 29 March 2021. The meta-analytic pooled sensitivity and specificity of the KLCA-NCC 2018 criteria for diagnosing HCC were calculated using a bivariate random-effects model. A meta-regression analysis was performed to explore study heterogeneity further. Eight studies involving 1690 HCCs reported the accuracy of the KLCA-NCC 2018 imaging criteria. The pooled sensitivity and specificity of the definite HCC criteria for diagnosing HCC were 81% (95% confidence interval, 76–85%; I2 = 86%) and 90% (86–93%; I2 = 23%), respectively. For five available studies, the pooled sensitivity and specificity of the definite HCC criteria for diagnosing HCCs smaller than 20 mm were 80% (72–86%; I2 = 76%) and 91% (86–94%; I2 = 0%), respectively. A considerable threshold effect with a correlation coefficient of 0.667 was observed. The results of the meta-regression analysis revealed that the accuracy of the definite HCC criteria differed significantly depending on the type of MRI contrast agent (p = 0.01). In conclusion, the KLCA-NCC 2018 criteria had good overall diagnostic performance in diagnosing HCC. Substantial study heterogeneity was observed for sensitivity, which was significantly influenced by the type of contrast agent and by a threshold effect.

We aimed to determine the histopathological characteristics and prognosis of curatively resected pancreatic ductal adenocarcinoma (PDAC) showing intratumoral necrosis on preoperative CT or MRI. This study consecutively included 102 patients who underwent upfront surgery with margin-negative resection from 2012 to 2020. All patients underwent both pancreatic CT and MRI within 1 month before surgery. Two radiologists independently assessed CT/MRI findings, including the presence of CT- and MRI-detected necrosis. Histopathological characteristics of PDACs according to CT or MRI detection of necrosis were evaluated. Disease-free survival (DFS) and overall survival (OS) were assessed by the Kaplan–Meier method and the Cox proportional hazards model. Among the 102 PDAC patients, 14 patients (13.7%) had CT-detected necrosis, and 16 patients (15.7%) had MRI-detected necrosis, of which 9 showed both CT- and MRI-detected necrosis. PDACs with CT- or MRI-detected necrosis demonstrated a significantly higher degree of histopathological necrosis than those without (p < 0.001). Multivariable analysis revealed that tumor size (hazard ratio [HR], 1.19; p = 0.040), tumor location (HR, 0.46; p = 0.009), and MRI-detected necrosis (HR, 2.64; p = 0.002) had independent associations with DFS. Only MRI-detected necrosis was significantly associated with OS (HR, 2.59; p = 0.004). Therefore, MRI-detected necrosis might be a potential imaging predictor of poor survival after curative resection of PDAC.

We aimed to systematically evaluate the incidence of inadequate US in hepatocellular carcinoma (HCC) surveillance and determine the risk factors. Original studies reporting the incidence or risk factors for inadequate US were identified in MEDLINE, EMBASE, and the Cochrane database. The pooled incidence of inadequate US was calculated using a random effects model, and subgroup analyses were performed. The pooled odds ratio (OR) was calculated for each risk factor for inadequate US. Six eligible articles were identified from 756 screened articles (4250 patients). The pooled incidence of inadequate US was 21.5%. Significantly higher rates of inadequate US were noted in studies including patients with and without hepatic observations compared with those evaluating only patients with hepatic observations (23.2% vs. 18.8%), studies using US alone compared with US plus alpha-fetoprotein (28.0% vs. 20.8%), and those using pathology and imaging as a reference standard compared with imaging only (23.2% vs. 17.9%). Nonalcoholic steatohepatitis (OR = 2.3 (1.07–4.84)), Child–Pugh B cirrhosis (OR = 2.2 (1.10–4.37)), and high body mass index (OR = 2.2 (1.12–4.24)) were significant risk factors for inadequate US (p ≤ 0.04). In patients at risk of HCC, 21.5% of US surveillance was inadequate. An alternative surveillance modality might be considered in patients with risk factors.

To determine the inter-reader agreement of abbreviated magnetic resonance imaging (AMRI) for the detection of hepatocellular carcinoma (HCC) and explore the causes of heterogeneity between the reported results. Original studies reporting the inter-reader agreement of AMRI for detecting HCC were identified in MEDLINE, EMBASE, and Cochrane databases. The pooled kappa coefficient (κ) was calculated using the DerSimonian–Laird random-effects model. Subgroup analyses were performed according to the AMRI protocol (non-contrast [NC]-AMRI, dynamic contrast-enhanced [DCE]-AMRI, and hepatobiliary phase [HBP]-AMRI). Meta-regression analyses were performed to further explore study heterogeneity. In the eight included studies (1182 patients), the overall pooled κ was 0.76 (95% confidence interval [CI], 0.70–0.82; I2 = 74.4%). The κ of NC-AMRI, DCE-AMRI, and HBP-AMRI were 0.72 (95% CI, 0.62–0.82), 0.80 (95% CI, 0.78–0.82), and 0.98 (95% CI, 0.95–1.00), respectively. In the NC-AMRI, the pooled κ of NC-AMRI using only diffusion-weighted imaging (DWI) was 0.64, which was lower than the values using two or more imaging sequences (κ = 0.74–0.77). In subgroup analysis, no study heterogeneity was noted in studies using DCE-AMRI (I2 = 0%), whereas high heterogeneity was noted with NC-AMRI (I2 = 80.5%). Especially, NC-AMRI including more than two imaging sequences showed high residual heterogeneity (I2 = 87.6%). Meta-regression analysis found that difference in reader experience was significantly associated with study heterogeneity (p = .02). AMRI for detecting HCC showed substantial inter-reader agreement across all examined protocols. NC-AMRI, notably NC-AMRI using only DWI, had relatively low inter-reader agreement. Therefore, DCE-AMRI or HBP-AMRI may be more reliable than NC-AMRI using only DWI.

Simple Summary Ultrasonography is recommended as a standard surveillance modality, but the performance of surveillance ultrasound for detecting early-stage hepatocellular carcinoma (HCC) is limited. Motivated to provide a more sensitive method, abbreviated magnetic resonance imaging (AMRI) protocols have been introduced for HCC surveillance. We aimed to systematically determine the diagnostic performance of surveillance AMRI for detecting HCC. This meta-analysis of 10 studies comprising 1547 patients found that the pooled sensitivity and specificity of surveillance AMRI for detecting HCC were 86% and 96%, respectively. Hepatobiliary phase contrast-enhanced AMRI showed significantly higher sensitivities for detecting HCC than non-contrast AMRI (87% vs. 82%), but significantly lower specificities (93% vs. 98%). Therefore, surveillance AMRI had overall good diagnostic performance for detecting HCC and might be clinically useful for HCC surveillance. In addition, AMRI protocol should be selected with consideration of the advantages and disadvantages of each protocol. Abstract We aimed to determine the performance of surveillance abbreviated magnetic resonance imaging (AMRI) for detecting hepatocellular carcinoma (HCC), and to compare the performance of surveillance AMRI according to different protocols. Original research studies reporting the performance of surveillance AMRI for the detection of HCC were identified in MEDLINE, EMBASE, and Cochrane databases. The pooled sensitivity and specificity of surveillance AMRI were calculated using a hierarchical model. The pooled sensitivity and specificity of contrast-enhanced hepatobiliary phase (HBP)-AMRI and non-contrast (NC)-AMRI were calculated and compared using bivariate meta-regression. Ten studies, including 1547 patients, reported the accuracy of surveillance AMRI. The pooled sensitivity and specificity of surveillance AMRI for detecting any-stage HCC were 86% (95% confidence interval (CI), 80–90%; I2 = 0%) and 96% (95% CI, 93–98%; I2 = 80.5%), respectively. HBP-AMRI showed a significantly higher sensitivity for detecting HCC than NC-AMRI (87% vs. 82%), but significantly lower specificity (93% vs. 98%) (p = 0.03). Study quality and MRI magnet field strength were factors significantly associated with study heterogeneity (p ≤ 0.01). In conclusion, surveillance AMRI showed good overall diagnostic performance for detecting HCC. HBP-AMRI had significantly higher sensitivity for detecting HCC than NC-AMRI, but lower specificity.

To compare the prognosis of pancreatic ductal adenocarcinoma (PDAC) after curative resection according to the type of intratumoral fluid–containing area identified on MRI. This retrospective study included 112 consecutive patients who underwent upfront surgery with margin-negative resection between 2012 and 2019. All patients underwent MRI within 1 month before surgery. Three radiologists independently assessed the MRI findings, determined whether intratumoral fluid–containing areas were present, and classified all intratumoral fluid-containing areas by type (i.e., imaging necrosis or neoplastic mucin cysts). Recurrence-free survival (RFS) and overall survival (OS) were evaluated by the Kaplan–Meier method and the Cox proportional hazards model. Histopathological differences according to the type of intratumoral fluid–containing area were assessed. Of the 112 PDAC patients, intratumoral fluid–containing areas were identified on MRI in 33 (29.5%), among which 18 were classified as imaging necrosis and 15 as neoplastic mucin cysts. PDAC patients with imaging necrosis demonstrated significantly shorter RFS (mean 6.1 months versus 47.3 months; p

Hepatic surface nodularity quantified on CT images has shown promising results in staging hepatic fibrosis in chronic hepatitis C. The aim of this study was to evaluate hepatic surface nodularity, serum fibrosis indices, and a linear combination of them for staging fibrosis in chronic liver disease, mainly chronic hepatitis B.We developed a semiautomated software quantifying hepatic surface nodularity on CT images. Hepatic surface nodularity and serum fibrosis indices were assessed in the development group of 125 patients to generate 3 linear models combining hepatic surface nodularity with the aspartate aminotransferase to platelet ratio index, fibrosis-4 index, or platelet count in reference to the METAVIR scoring system. The models were validated in 183 patients.Hepatic surface nodularity and serum fibrosis indices all significantly correlated with fibrosis stages. For binary classifications into cirrhosis (F4), advanced fibrosis (≥ F3), and significant fibrosis (≥ F2), hepatic surface nodularity was significantly different across categories. The areas under the curve (AUCs) of the best model were 0.901, 0.872, and 0.794 for cirrhosis, advanced fibrosis, and significant fibrosis, respectively, higher than serum fibrosis indices alone (0.797-0.802, 0.799-0.818, and 0.761-0.773). In the validation group, the same model likewise showed higher AUCs (0.872, 0.831, and 0.850) compared to serum fibrosis indices (0.722-0.776, 0.692-0.768, and 0.695-0.769; p 0.001 for F4).Hepatic surface nodularity combined with serum blood test could be a practical method to predict cirrhosis, advanced fibrosis, and significant fibrosis in chronic liver disease patients, providing higher accuracy than using serum fibrosis indices alone.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterized by focal or diffuse organ infiltration of IgG4-bearing plasma cells. The diagnosis of IgG4-RD is based on a combination of clinical, serologic, radiologic, and histopathologic findings. IgG4-RD has been reported to affect almost all organ systems. The kidney is the most frequently involved of the genitourinary organs. The most common renal manifestation of IgG4-RD is IgG4-RD tubulointerstitial nephritis, followed by membranous glomerulonephropathy and, less frequently, obstructive nephropathy involving the renal pelvis, ureter, or retroperitoneum. Renal parenchymal lesions may appear as multiple nodular lesions, diffuse patchy infiltrative lesions, or a single nodular lesion. Multiple small nodular cortical lesions are the most common imaging findings of IgG4-RD involving the kidney. Renal pelvic, sinus, or perinephric lesions can also occur. IgG4-RD involvement of other genitourinary organs including the ureter, bladder, urethra, and male and female reproductive organs is rare compared with kidney involvement but may show variable imaging findings such as a localized mass within or surrounding the involved organ or diffuse enlargement of the involved organ. Imaging findings of IgG4-RD involving the genitourinary system are nonspecific but should be differentiated from inflammatory and neoplastic lesions that mimic IgG4-RD.

To systematically determine the accuracy of Liver Imaging Reporting and Data System treatment response (LR-TR) algorithm for diagnosing the viability of hepatocellular carcinoma (HCC) treated with locoregional therapy (LRT). Original studies reporting the diagnostic accuracy of LR-TR algorithm on dynamic contrast-enhanced computed tomography or magnetic resonance imaging (MRI) were identified in MEDLINE and EMBASE up to June 1, 2020. The meta-analytic summary sensitivity and specificity of LR-TR algorithm were calculated using a bivariate random-effects model. Subgroup analyses and meta-regression analysis were performed to explore study heterogeneity. We found six studies reporting the accuracy of LR-TR viable category (601 observations in 453 patients). The meta-analytic pooled sensitivity and specificity of LR-TR viable category were 63% (95% confidence interval [CI], 39–81%; I2 = 88%) and 96% (95% CI, 91–99%; I2 = 76%), respectively. The meta-analytic pooled sensitivity and specificity of LR-TR viable or equivocal category combined were 71% (95% CI, 55–84%; I2 = 89%) and 87% (95% CI, 73–94% I2 = 80%), respectively. Studies which used only MRI showed a trend towards higher sensitivity (71% [95% CI, 46–88%]) with a comparable specificity (95% [95% CI, 86–99%]) of LR-TR viable category compared to the whole group. The type of reference standard and study design were significantly associated with study heterogeneity (p ≤ 0.01). The LR-TR viable category had high specificity but suboptimal sensitivity for diagnosing the viability of HCC after LRT. Substantial study heterogeneity was noted, and it was significantly associated with the type of reference standard and study design. • The meta-analytic pooled sensitivity and specificity of LR-TR viable category were 63% (95% CI, 39–81%) and 96% (95% CI, 91–99%), respectively. • The meta-analytic pooled sensitivity and specificity of LR-TR viable or equivocal category combined were 71% (95% CI, 55–84%) and 87% (95% CI, 73–94%), respectively. • The type of reference standard and study design were the factors significantly influencing study heterogeneity (p ≤ 0.01).

We aimed to systematically determine the etiology of the Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) on contrast-enhanced CT or MRI and to determine the sources of heterogeneity between reported results.Original studies reporting the etiology of LR-TIV were identified in MEDLINE and EMBASE up until July 7, 2020. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were calculated. Subgroup analyses were performed according to the type of reference standard and the most common underlying liver disease. Meta-regression analysis was performed to explore study heterogeneity.Sixteen studies reported the etiology of a total of 150 LR-TIV, of which 98 (65%) were HCC and 52 (35%) were non-HCC. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were 70.9% (95% confidence interval [CI], 55.7-82.5%; IThe most common etiology of LR-TIV was HCC. It might be important to understand the percentage of HCC and non-HCC in LR-TIV in consideration of the type of reference standard, geographic differences, and study design.• The most common etiology of Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) was hepatocellular carcinoma (HCC). • The percentage of HCC in LR-TIV was relatively low in studies using only pathology as a reference standard, but high in studies in which hepatitis C was the most common underlying liver disease. • Study type was a factor significantly influencing study heterogeneity.

Purpose This study compared the technical parameters and clinical outcomes of manual and automatic image fusion techniques of ultrasonography and magnetic resonance imaging/computed tomography for radiofrequency ablation (RFA) of hepatic tumors. Methods Seventy consecutive patients (male:female=47:23, 67.1±10.9 years old) who underwent RFA for hepatic tumors were prospectively enrolled and randomly assigned to the manual or automatic registration group. Two operators performed RFA with one of two imaging fusion techniques. Technical parameters (the registration error, time required for image registration, number of point registrations) and clinical outcomes (technical success, technical effectiveness, local tumor progression [LTP]-free survival, and progression-free survival [PFS]) were compared. Results The automatic group contained 35 patients with hepatocellular carcinoma, while the manual group included 34 hepatocellular carcinoma patients and a patient with colon cancer liver metastasis. The registration error, time required for registration, and number of point registrations were 5.7±4.3 mm, 147.8±78.2 seconds, and 3.26±1.20 in the automatic group, and 6.3±5.0 mm, 150.3±89.7 seconds, and 3.20±1.13 in the manual group, respectively. The technical success and effectiveness rates were both 97.1% in the automatic group and both 100.0% in the manual group. The above differences were not significant. The LTP-free survival and PFS (28.3 and 21.2 months in the automatic group, and 29.0 and 24.9 months in the manual group, respectively) showed no significant between-group differences during a median 20.1-month follow-up period. Conclusion The technical parameters and clinical outcomes of automatic image fusion were not significantly different from those of manual image fusion for RFA of hepatic tumors.

The objective of our study was to identify whether quantitative measurements from gadoxetic acid-enhanced MRI are useful for predicting posthepatectomy liver failure (PHLF) in patients with hepatocellular carcinoma (HCC) compared with and in combination with future remnant liver volume (FRLV) and an indocyanine green (ICG) clearance test.Preoperative gadoxetic acid-enhanced MR images were retrospectively evaluated in 73 patients who underwent anatomic liver resection for HCC between 2011 and 2013. For quantitative measurement of hepatocyte function, relative liver enhancement (RLE) and remnant hepatocyte uptake index (rHUI) were measured using hepatobiliary phase MR images. FRLV was determined using measurements from preoperative CT scans. Univariate and multivariate analyses of measurements from gadoxetic acid-enhanced MRI, ICG clearance tests, and FRLV for finding predictors of PHLF were performed. To compare the diagnostic performance of predictors, ROC analyses were also performed.Eighteen (25%) of 73 patients met the criteria for PHLF. Univariate analysis revealed that all measurements related to MRI including RLE, rHUI, ICG clearance, and FRLV were significantly associated with PHLF. Multivariate analysis showed that RLE, FRLV, ICG-plasma disappearance rate (ICG-PDR), rHUI, and rHUI corrected for body weight (rHUI-BW) were independent predictors of PHLF (p = 0.011, p = 0.034, p = 0.003, p0.001, and p = 0.001, respectively). In ROC analyses, AUCs of rHUI and rHUI-BW were larger than those of other independent predictors; the differences were statistically significant (for rHUI-BW vs RLE, ICG-PDR, and FRLV, p = 0.016, 0.007, and 0.046, respectively; for rHUI vs RLE and ICG-PDR, p = 0.045 and 0.016, respectively).Measurements from gadoxetic acid-enhanced MRI predicted PHLF better than the ICG clearance test in patients with HCC who underwent hepatectomy.

This study was conducted in order to compare the diagnostic performance of noncontrast and abbreviated MRI using gadoxetic acid for detecting hepatocellular carcinoma (HCC) in initially diagnosed HCC patients. We identified 140 consecutive patients with newly diagnosed HCC (173 HCCs) within the Milan criteria, who underwent liver MRI using gadoxetic acid between 2015 and 2016. One hundred twenty-three consecutive patients without HCC who underwent liver MRI in the same period for HCC surveillance were enrolled for the control group. Two radiologists independently reviewed two MRI sets: a noncontrast set and an abbreviated set. The noncontrast set consists of T2 FSE/ssFSE, T1 in- and out-of-phase image, DWI, and the ADC map. The abbreviated set consists of T2 FSE/ssFSE, hepatobiliary phase image 20 min after gadoxetic acid injection, DWI, and the ADC map. In a per-patient analysis, sensitivity of reviewer 1 for noncontrast and abbreviated sets was 85.7 and 90.0%, respectively. The specificity for both noncontrast and abbreviated sets was 92.7%. For reviewer 2, sensitivity of noncontrast and abbreviated sets was 86.4 and 89.3%, respectively. Per-patient specificity of reviewer 2 was 92.7% for both noncontrast and abbreviated sets. The sensitivity and specificity of two image sets were not significantly different for both reviewers. The per-tumor sensitivity of noncontrast and abbreviated sets was 81.5 and 84.4% for reviewer 1, respectively, and 79.8 and 84.4% for reviewer 2, respectively. There was no significant difference. Noncontrast and abbreviated MRI using gadoxetic acid showed comparable diagnostic performance for detecting patients with HCCs in the early stage. • Diagnostic performance of noncontrast MRI and abbreviated MRI using gadoxetic acid for detecting HCCs is comparable in patients with HCCs in the early stage. • Noncontrast MRI and abbreviated MRI showed high sensitivity and specificity for detecting HCCs in the early stage. • Outcomes of surveillance for HCC in high-risk patients can be improved by adopting these simplified and focused MRI protocols.

Summary Background & aim The relationship between obesity and hepatic steatosis is well known, and there are many methods to measure obesity and severity of hepatic steatosis. Because of advances in radiologic techniques, the areas of certain body components can be measured on computed tomography (CT) while the severity of hepatic steatosis can be measured by magnetic resonance spectroscopy (MRS) with high accuracy. The aim of this study is to investigate the relationship between degree of fatty infiltration of the liver measured by MRS and body composition measured from CT images. Materials and methods We evaluated 95 potential liver donors who underwent abdomen CT and liver MRI (including MRS) between February 2014 and September 2015 in a tertiary university hospital. Body composition analysis was performed on CT images using commercial software. The areas of subcutaneous fat, visceral fat and abdominal circumference were measured automatically and the area of muscle was measured semi-automatically. The degree of hepatic steatosis was measured by MRS. Results The degree of hepatic steatosis showed a significant correlation with total fat area, visceral fat area, subcutaneous fat area, muscle area, abdominal circumference, BMI, and ratio of visceral fat to total fat. The strongest correlation was between hepatic steatosis and the area of visceral fat in all subjects ( r =0.569). Multivariate regression analysis showed that male gender and visceral fat area were significantly associated with hepatic steatosis ( P = 0.031, Conclusions The area of visceral fat has the most intimate correlation to the severity of hepatic steatosis among all significantly correlated parameters associated with body habitus. Accurate and quantitative body composition measurement and degree of hepatic steatosis can be noninvasively performed using advanced radiological techniques.