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Background: Complete resection is the only potentially curative treatment in patients with pancreatic ductal adenocarcinoma (PDA) and is associated with a longer overall survival (OS) than incomplete resection of tumor. Hence, prediction of the resection status after surgery would help predict the prognosis of patients with PDA., Purpose: To predict residual tumor (R) classification and OS in patients who underwent first-line surgery for PDA using preoperative magnetic resonance imaging (MRI)., Material and Methods: In this study, 210 patients with PDA who underwent MRI and first-line surgery were randomly categorized into a test group (n=150) and a validation group (n=60). The R classification was divided into R0 (no residual tumor) and R1/R2 (microscopic/macroscopic residual tumor). Preoperative MRI findings associated with R classification and OS were assessed by using logistic regression and Cox proportional hazard models. In addition, the prediction models for the R classification and OS were validated using calibration plots and C statistics., Results: On preoperative MRI, portal vein encasement (odds ratio 4.755) was an independent predictor for R1/R2 resection ( P =0.040). Tumor size measured on MRI (hazard ratio [HR] per centimeter 1.539) was a predictor of OS, along with pathologic N1 and N2 stage (HR 1.944 and 3.243, respectively), R1/R2 resection (HR 3.273), and adjuvant chemoradiation therapy (HR 0.250) ( P <0.050). Calibration plots demonstrated satisfactory predictive performance., Conclusion: Preoperative MRI was valuable for predicting R1/R2 resection using portal vein encasement. Tumor size measured on MRI was useful for the prediction of OS after first-line surgery for PDA.

Background Diagnostic performance of the Liver Imaging Reporting and Data System tumor in vein (LR-TIV) category at CT and/or MRI has not yet been evaluated, to the knowledge of the authors. Purpose To assess the diagnostic performance of the LR-TIV category in detecting macroscopic tumors in veins (TIVs) at CT and hepatobiliary contrast agent-enhanced (HBA) MRI, with pathologic results used as the reference standard. Materials and Methods Between January 2010 and December 2019, consecutive patients with or without macroscopic TIV who underwent both CT and HBA MRI before hepatic resection or liver transplant were retrospectively included. Three radiologists independently assessed the LR-TIV features of enhancing soft tissue in vein and features suggestive of TIV (FSTIV) and reached a consensus. Macroscopic TIV at pathologic examination was the reference standard. Sensitivities and specificities of the LR-TIV category without and with FSTIV were calculated, and the added value of FSTIV was evaluated by using the McNemar test. Results In the 1322 patients with ( n = 101) or without ( n = 1221) macroscopic TIV (median age, 64 years [interquartile range, 58-70 years]; 1053 men), without consideration of FSTIV, the sensitivity and specificity of enhancing soft tissue in vein for detecting macroscopic TIV at pathologic examination were 64.4% (65 of 101) and 99.8% (1218 of 1221) with CT and 62.4% (63 of 101) and 99.8% (1218 of 1221) with HBA MRI, respectively. With consideration of FSTIV, the sensitivity and specificity of the LR-TIV category became 67.3% (68 of 101 patients) and 99.7% (1217 of 1221 patients) at both CT and HBA MRI. No difference was found between measurements without and with FSTIV (sensitivity, 62% vs 67% for CT [ P = .45] and 64% vs 67% for HBA MRI [ P = .18]; specificity, 99% for both CT and HBA MRI [ P > .99 for both]). Conclusion The Liver Imaging Reporting and Data System tumor in vein category showed moderate sensitivity and high specificity in the detection of macroscopic tumors in veins at both CT and hepatobiliary contrast agent-enhanced MRI, with pathologic examination used as the reference standard. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Morrell in this issue.

Background The Liver Imaging Reporting and Data System (LI-RADS), version 2018, treatment response algorithm (TRA) is used to assess hepatocellular carcinoma (HCC) after local-regional therapy (LRT). However, its diagnostic performance has not yet been fully compared between CT and hepatobiliary agent (HBA)-enhanced MRI in patients who have undergone liver transplant (LT). Purpose To compare the diagnostic performance of LI-RADS TRA when using CT versus using HBA-enhanced MRI in an intraindividual manner according to pathologic results. Materials and Methods Between January 2011 and September 2019, 165 patients with 237 clinically suspected HCCs underwent LRT followed by LT and were retrospectively included. All patients underwent both CT and HBA-enhanced MRI after LRT and before LT. Three radiologists independently assessed tumor viability with both modalities by using LI-RADS TRA and reached a consensus. Pathologic tumor viability categorized as either completely (100%) or incompletely (<100%) necrotic obtained from the explanted liver served as the reference standard. Sensitivity and specificity of the LI-RADS TRA in the consensus reading were then compared between CT and HBA-enhanced MRI by using the ratio estimator approach. Interobserver agreements were calculated by using Fleiss κ statistics. Results There were 165 patients (mean age, 62 years ± 9 [standard deviation]; 135 men) with a total of 237 lesions, of which 107 were viable tumors (45.1%) at pathologic evaluation. With the LI-RADS TRA, sensitivity and specificity of the viable category for detection of viable HCCs at pathologic evaluation were 42.1% (45 of 107 lesions) and 95.4% (124 of 130 lesions) with CT and 52.3% (56 of 107 lesions) and 93.9% (122 of 130 lesions) with HBA-enhanced MRI, with a significant difference in sensitivity but not specificity ( P = .009 and P = .42, respectively). Interobserver agreements for the LI-RADS TRA were substantial for both CT and HBA-enhanced MRI (κ, 0.69 for both). Conclusion In patients who underwent local-regional therapy for hepatocellular carcinoma before liver transplant, hepatobiliary agent-enhanced MRI was more sensitive than CT in evaluating tumor viability with the Liver Imaging Reporting and Data System, version 2018, treatment response algorithm. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Bashir and Mendiratta-Lala in this issue.

Background The Liver Imaging Reporting and Data System Treatment Response (LR-TR) algorithm is used to assess the response of hepatocellular carcinoma (HCC) to local-regional therapy (LRT) based on enhancement patterns. The potential value of adding MRI ancillary features (AFs) needs to be investigated. Purpose To evaluate the potential application of MRI AFs in category adjustment to detect pathologic tumor viability in comparison with the LR-TR algorithm in CT and gadoxetic acid-enhanced MRI. Materials and Methods This retrospective study included patients with HCCs treated with LRT followed by surgical resection or liver transplantation between January 2014 and December 2017 who underwent both post-LRT CT and gadoxetic acid-enhanced MRI. For each treated observation, treatment response (TR) categories were assigned based on a consensus reading of three radiologists according to the LR-TR algorithm in CT and MRI and according to the MRI-modified TR algorithm in which MRI AFs were allowed for category adjustment. The diagnostic performances of CT LR-TR viable, MRI LR-TR viable, and MRI-modified TR viable categories were compared intraindividually with the McNemar test, with pathologic tumor viability used as a reference standard. Results A total of 138 patients (119 men; mean age, 58 years ± 9 [standard deviation]) with 138 treated observations (108 pathologically viable) were evaluated. The sensitivity and specificity of CT LR-TR viable and MRI LR-TR viable categories for predicting tumor viability were 73% (79 of 108 lesions; 95% confidence interval [CI]: 64%, 81%) versus 76% (82 of 108 lesions; 95% CI: 67%, 84%) and 90% (27 of 30 lesions; 95% CI: 74%, 98%) versus 83% (25 of 30 lesions; 95% CI: 65%, 94%), respectively, without differences between CT and MRI ( P = .65 and P = .63, respectively). MRI-modified TR viable category had higher sensitivity (84% [91 of 108 lesions; 95% CI: 76%, 91%]) than CT or MRI LR-TR viable category ( P = .002 and P = .01, respectively), without difference in specificity (80% [24 of 30 lesions]; 95% CI: 61%, 92%) ( P = .38 and P > .99, respectively). Conclusion The application of MRI ancillary features to the Liver Imaging Reporting and Data System Treatment Response algorithm resulted in higher sensitivity and no change in specificity compared with CT or MRI enhancement patterns alone in the prediction of pathologic tumor viability in patients with hepatocellular carcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Do and Mendiratta-Lala in this issue.

Objectives: To identify MRI features that are helpful for the differentiation of gallbladder neuroendocrine tumors (GB-NETs) from gallbladder adenocarcinomas (GB-ADCs) and to evaluate their prognostic values., Methods: Between January 2008 and December 2018, we retrospectively enrolled patients who underwent MRI for GB malignancy. Two radiologists independently assessed the MRI findings and reached a consensus. Significant MRI features, which distinguish GB-NETs from GB-ADCs, were identified. Cox regression analyses were performed to find MRI features that were prognostic for overall survival., Results: There were 63 patients with GB-NETs (n = 21) and GB-ADCs (n = 42). Compared with GB-ADCs, GB-NETs more frequently demonstrated the following MRI features: well-defined margins, intact overlying mucosa, and thick rim contrast enhancement and/or diffusion restriction (ps < 0.001). Liver metastases were more common and demonstrated thick rim contrast enhancement and diffusion restriction in GB-NETs (ps < 0.001). Lymph node (LN) metastasis showed thick rim diffusion restriction more often in GB-NETs than in GB-ADCs (p = 0.009). On quantitative analysis, the sizes of the GB mass and metastatic LNs in GB-NETs were larger than those in GB-ADCs (p = 0.002 and p = 0.010, respectively). The ratio of apparent diffusion coefficient values between the lesion and the spleen was lower in the GB mass, liver metastases, and LN metastases of GB-NETs than those of GB-ADCs (p < 0.001, p = 0.017, and p < 0.001, respectively). Survival analysis revealed that a large metastatic LN (hazard ratio 1.737; 95% confidence interval, 1.112-2.712) was the only poor prognostic factor (p = 0.015)., Conclusion: Several MRI features aided in differentiating between GB-NETs and GB-ADCs. A large metastatic LN was associated with poor survival., Key Points: • Compared with gallbladder adenocarcinomas (GB-ADCs), neuroendocrine tumors (GB-NETs) and their metastases to the liver and lymph nodes more frequently demonstrated a thick rim appearance on contrast-enhanced MRI and diffusion-weighted images. • The ratio of apparent diffusion coefficient values between the lesion and the spleen was significantly lower for the primary mass, liver metastases, and lymph node metastases of GB-NETs than for those of GB-ADCs. • A large metastatic lymph node was the only poor prognostic factor for overall survival in patients with GB-NETs and GB-ADCs.

Objectives: The aim of this study was to evaluate the clinical feasibility of gadoxetic acid-enhanced isotropic high-resolution (IHR) 3-dimensional (3D) T1-weighted (T1W) magnetic resonance cholangiography (MRC) using an iterative denoising (ID) algorithm for evaluation of the biliary anatomy of living liver donors in comparison with conventional 3D multislice T2-weighted (T2W) MRC., Materials and Methods: In this institutional review board-approved retrospective study, a total of 75 living liver donors who underwent conventional 3D multislice T2W-MRC and IHR-3D-T1W-MRC on a 3 T scanner and subsequent right hepatectomy for liver donation were included. Isotropic high-resolution T1W-MRCs were obtained in both axial and coronal planes using the 3D VIBE Dixon sequence and an ID algorithm implemented with wavelet thresholding of 3D complex-valued data of the noise level, g-factor, and k-space filtering. Thereafter, 3 board-certified radiologists independently reviewed the examinations for visibility and sharpness of the bile ducts (BDs), as well as overall image quality on a 5-point scale. For diagnostic performance, anatomic variations of the BD, length of right hepatic duct, and the expected number of BD openings at right hepatectomy were also recorded. As the reference standard, BD variation was determined by surgeons in consensus using intraoperative real-time fluorescent cholangiography., Results: Mean acquisition times of 3D-T2W-MRC and IHR-T1W-MRC were 367 seconds and 17 seconds (P < 0.001), respectively. Compared with 3D-T2W-MRCs, IHR-T1W-MRCs yielded significantly improved visibility and sharpness of all evaluated intrahepatic bile ducts (all Ps < 0.05), and higher overall image quality (P < 0.01). The IHR-T1W-MRCs also demonstrated significantly higher agreement in BD variation (87.6% vs 81.3%, P = 0.03) and expected BD openings (76.9% vs 70.2%, P = 0.006) than 3D-T2W-MRC compared with the reference standard. Interobserver agreement in estimating the length of right hepatic duct, IHR-T1W-MRC showed excellent interobserver agreement (intraclass correlation coefficient, 0.94), whereas 3D-T2W-MRC showed good interobserver agreement (intraclass correlation coefficient, 0.78)., Conclusions: Isotropic high-resolution T1W-MRCs with ID provided significantly improved BD image quality and more accurate depiction of the BD anatomy and BD openings at right donor hemihepatetomy than 3D-T2W-MRC.

Purpose: To validate usefulness of magnetic resonance (MR) lymphangiography for evaluation of peripheral lymphedema in upper extremities by comparison with lymphoscintigraphy., Materials and Methods: This prospective study had institutional review board approval and written informed consent was obtained from all patients. Initially, protocol of MR lymphangiography for upper extremity was established in seven healthy volunteers with 3.0T fat-saturated three-dimensional gradient-echo MR after gadobutrol injection. Then six patients with unilateral lymphedema of the upper extremities were examined with MR lymphangiography and lymphoscintigraphy, and the results were correlated with each other. Four categories were defined to scale the quality of drainage. Results of both techniques were separately evaluated by two radiologists and a nuclear physician. We evaluated sensitivity, specificity and correlation of both techniques., Results: MR lymphangiography showed sensitivities of 100% for all four categories, while lymphoscintigraphy yielded a sensitivity of 83.3% for delineation of lymph vessels and 100% for the other three categories. Specificity of MR lymphangiography was 85.7% for delay of drainage and 100% for other three categories, while lymphoscintigraphy showed specificity of 66.7% for pattern of lymphatic drainage and 100% for other three categories. Delay and pattern of drainage was same in 83.3% and non-visualization of axillary LNs was indistinguishably noted in all patients on both techniques. Anatomic level of enhanced lymph vessel was identical in 66.7% of the patients., Conclusion: MR lymphangiography showed better performance for depiction of lymph vessels. MR lymphangiography and lymphoscintigraphy yielded same results in all or most patients for evaluation of axillary lymph nodes enhancement and lymphatic drainage in upper extremity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background & Aims: To assess diagnostic accuracy of gadoxetic acid-enhanced MR for small hypervascular hepatocellular carcinoma (HCC) detected by C-arm CT and concordance rate of Liver Imaging Reporting and Data System (LI-RADS)., Methods: In this retrospective study, we recruited 4,544 patients suspected of having HCC underwent C-arm CT from November 2008 to May 2013. Among these patients, gadoxetic acid-enhanced MR was performed in 167 patients with HCC (n = 379; 257 > 1 cm, 122 ≤ 1 cm). HCC was confirmed by MR, CT, or follow-up images. Two radiologists graded likelihood of HCC and assessed MR features. Jackknife alternative free-response receiver operating characteristic (JAFROC) analysis was performed. All HCCs were evaluated concordance rate of LI-RADS., Results: Mean JAFROC figure of merit for large (>1-cm) HCC was 0.948, while that for small HCC was 0.787 with fair agreement (κ = 0.409). Mean sensitivity and positive predictive value (PPV) were 91% and 90% for large HCC versus 63.0% and 79% for small HCC, respectively. Seventeen of 122 small HCCs (13.9%) were not visible on MR. Among 379 HCCs, 99 met LR-5, and 259 met LR-4. Common features for small HCC included arterial enhancement (81.9%), hepatobiliary phase hypointensity (80.3%), and delayed washout (72.9%)., Conclusion: Diagnostic accuracy of gadoxetic acid-enhanced MR imaging for small, hypervascular HCCs (Mean figure of merit = 0.787) was still low compared with large HCC (Mean figure of merit = 0.948). LR-5 and LR-4 covered 94% (358/379) of the HCCs.

Background: Pancreatobiliary MRI is often recommended for patients at risk of developing pancreas cancer. But the surveillance MRI protocol has not yet been widely accepted. Purpose: To establish an accelerated MRI protocol targeting the table time of 15 minutes for pancreatic cancer surveillance and test its performance in lesion characterization. Study type: Prospective. Population: A total of 30 participants were enrolled, who were undergoing follow‐up care for intraductal papillary mucinous neoplasms or newly diagnosed pancreatic cysts (≥10 mm) and were scheduled for or had recently undergone contrast‐enhanced CT (CECT). Field strength/sequence: A 3 T; heavily T2WI, 3D MRCP, DWI, dynamic T1WI, two‐point Dixon. Assessment: In‐room time and table time were measured. Seven radiologists independently reviewed image quality of MRI and then the presence of high‐risk stigmata and worrisome features in addition to diagnostic confidence for accelerated MRI, CECT, and the noncontrast part of accelerated MRI (NC‐MRI). Statistical analysis: Fisher's exact test was used for categorical variables and either the Student's t‐test or Mann–Whitney test was performed for continuous variables. The generalized estimated equation was used to compare the diagnostic performance of examinations on a per‐patient basis. Interobserver agreement was evaluated via Fleiss kappa. A P value of <0.05 was considered to be statistically significant. Results: The in‐room time was 18.5 ± 2.6 minutes (range: 13.7–24.9) and the table time was 13.9 ± 1.9 minutes (range: 10.7–17.5). There was no significant difference between the diagnostic performances of the three examinations (pooled sensitivity: 75% for accelerated MRI and CECT, 68% for NC‐MRI, P = 0.95), with the highest significant diagnostic confidence for accelerated MRI (4.2 ± 0.1). With accelerated MRI, the interobserver agreement was fair to excellent for high‐risk stigmata (κ = 0.34–0.98). Data Conclusion: Accelerated MRI protocol affords a table time of 15 minutes, making it potentially suitable for cancer surveillance in patients at risk of developing pancreatic cancer. Evidence level: 2 Technical efficacy stage: 2 [ABSTRACT FROM AUTHOR]

• AC on ATI significantly correlated with HFF on 1H-MRS (ρ = 0.674, P < 0.001). • ATI well detected significant fatty liver among potential liver donors (AUC = 0.923). • ATI showed a high NPV of 97.2% (95% confidence interval = 90.3–99.2%), for detecting significant fatty liver. In living donor liver transplantation (LDLT), fatty liver adversely affects the outcome in donors or in recipients. The attenuation imaging (ATI) may be valuable for detecting fatty liver in potential liver donors. We aimed to investigate the role of ATI in screening liver donors. In this prospective study, potential liver donors undergoing MR examination, including proton MR spectroscopy (1H-MRS), were enrolled between January 2020 and December 2021 (study identifier: KCT0004486). All participants underwent ATI examinations to assess fatty liver disease. The reference standard for fatty liver was the hepatic fat fraction (HFF) on 1H-MRS, with 8% defined as the threshold for significant fatty liver. The correlation between attenuation coefficient (AC) and HFF was evaluated using Spearman's correlation coefficient. The diagnostic performance of AC for the detection of fatty liver disease was evaluated using receiver operating characteristic curve analysis. A total of 102 participants (median age, 37 [range, 20–61] years; 65 men) were enrolled. Nineteen participants (18.6%) had significant fatty liver on 1H-MRS. AC significantly correlated with HFF on 1H-MRS (ρ = 0.674, P < 0.001), and was significantly higher in patients with HFF on 1H-MRS ≥ 8% than in patients with HFF on 1H-MRS < 8% (0.76 vs. 0.59, P < 0.001). By using the cutoff value of 0.66, the area under the curve of AC for the detection of significant fatty liver on 1H-MRS was 0.923 (95% confidence interval [CI]: 0.853–0.967), with sensitivity, specificity, and negative predictive values of 89.5% (95% CI: 66.9–98.7%), 83.1% (95% CI: 73.3–90.5%), and 97.2% (95% CI: 90.3–99.2%), respectively. ATI showed good diagnostic performance with a high negative predictive value for the detection of significant fatty liver among potential liver donors. [ABSTRACT FROM AUTHOR]

Purpose: To determine the normal liver stiffness values using magnetic resonance elastography (MRE) at 3.0 T and to compare spin-echo echo-planar imaging (SE-EPI) and gradient-recalled-echo (GRE) MRE.Materials and Methods: This retrospective study included 54 living liver donors who had normal clinical and pathological results without underlying liver disease and underwent MRE using both SE-EPI and GRE at 3.0 T. Two radiologists placed four or six freehand regions of interest (ROI) on the elastograms and measured liver stiffness as well as the area of ROIs. The mean liver stiffness values and area of ROIs were compared between genders, among age groups, and between groups of different body mass indexes using the t-test and one-way analysis of variance, respectively. Interobserver agreement was analyzed using intraclass correlation coefficient. The mean liver stiffness values and area of ROIs were compared between SE-EPI and GRE using the paired t-test and Bland-Altman analysis.Results: The liver stiffness values in living liver donors ranged from 1.52 to 3.12 kPa on SE-EPI and 1.51 to 2.67 kPa on GRE. The mean liver stiffness values did not differ significantly according to the gender, age, and body mass index. Measurement of liver stiffness using MRE showed excellent interobserver agreement on both pulse sequences. The mean value of liver stiffness was higher on SE-EPI (2.14 ± 0.33 kPa) than on GRE (2.06 ± 0.25 kPa), and the difference was statistically significant (P < 0.05). The mean area of ROI was significantly larger with GRE (3387 mm2) than with SE-EPI (2691 mm2) (P < 0.05).Conclusions: The mean liver stiffness values in living donors measured by SE-EPI and GRE were not affected by gender, age, or body mass index and showed excellent interobserver agreement. The area of ROI was larger with GRE than with SE-EPI. [ABSTRACT FROM AUTHOR]