Radiologic tumor border can further stratify prognosis in patients with pancreatic neuroendocrine tumor.

BACKGROUND AND OBJECTIVES: Pancreatic neuroendocrine tumor (PanNET), although rare in incidence, is increasing in recent years. Several clinicopathologic and molecular factors have been suggested for patient stratification due to the extensive heterogeneity of PanNETs. We aimed to discover the prognostic role of assessing the tumor border of PanNETs with pre-operative computed tomography (CT) images and correlate them with other clinicopathologic factors. METHODS: The radiologic, macroscopic, and microscopic tumor border of 183 surgically resected PanNET cases was evaluated using preoperative CT images (well defined vs. poorly defined), gross images (expansile vs. infiltrative), and hematoxylin and eosin-stained slides (pushing vs. infiltrative). The clinicopathologic and prognostic significance of the tumor border status was compared with other clinicopathologic factors. RESULTS: A poorly defined radiologic tumor border was observed in 65 PanNET cases (35.5 %), and were more frequent in male patients (P = 0.031), and tumor with larger size, infiltrative macroscopic growth pattern, infiltrative microscopic tumor border, higher tumor grade, higher pT category, lymph node metastasis, lymphovascular and perineural invasions (all, P < 0.001). Patients with PanNET with a poorly defined radiologic tumor border had significantly worse overall survival (OS) and recurrence-free survival (RFS; both, P < 0.001). Multivariable analysis revealed that PanNET with a poorly defined radiologic border is an independent poor prognostic factor for both OS (P = 0.049) and RFS (P = 0.027). CONCLUSION: Pre-operative CT-based tumor border evaluation can provide additional information regarding survival and recurrence in patients with PanNET.

Deep Learning-based Detection of Solid and Cystic Pancreatic Neoplasms at Contrast-enhanced CT.

Background Deep learning (DL) may facilitate the diagnosis of various pancreatic lesions at imaging. Purpose To develop and validate a DL-based approach for automatic identification of patients with various solid and cystic pancreatic neoplasms at abdominal CT and compare its diagnostic performance with that of radiologists. Materials and Methods In this retrospective study, a three-dimensional nnU-Net-based DL model was trained using the CT data of patients who underwent resection for pancreatic lesions between January 2014 and March 2015 and a subset of patients without pancreatic abnormality who underwent CT in 2014. Performance of the DL-based approach to identify patients with pancreatic lesions was evaluated in a temporally independent cohort (test set 1) and a temporally and spatially independent cohort (test set 2) and was compared with that of two board-certified radiologists. Performance was assessed using receiver operating characteristic analysis. Results The study included 852 patients in the training set (median age, 60 years [range, 19-85 years]; 462 men), 603 patients in test set 1 (median age, 58 years [range, 18-82 years]; 376 men), and 589 patients in test set 2 (median age, 63 years [range, 18-99 years]; 343 men). In test set 1, the DL-based approach had an area under the receiver operating characteristic curve (AUC) of 0.91 (95% CI: 0.89, 0.94) and showed slightly worse performance in test set 2 (AUC, 0.87 [95% CI: 0.84, 0.89]). The DL-based approach showed high sensitivity in identifying patients with solid lesions of any size (98%-100%) or cystic lesions measuring 1.0 cm or larger (92%-93%), which was comparable with the radiologists (95%-100% for solid lesions [P = .51 to P > .99]; 93%-98% for cystic lesions ≥1.0 cm [P = .38 to P > .99]). Conclusion The deep learning-based approach demonstrated high performance in identifying patients with various solid and cystic pancreatic lesions at CT. © RSNA, 2022 Online supplemental material is available for this article.

Prognostic value of tumor-to-parenchymal contrast enhancement ratio on portal venous-phase CT in pancreatic neuroendocrine neoplasms.

OBJECTIVES: We aimed to evaluate the prognostic value of tumor-to-parenchymal contrast enhancement ratio on portal venous-phase CT (CER on PVP) and compare its prognostic performance to prevailing grading and staging systems in pancreatic neuroendocrine neoplasms (PanNENs). METHODS: In this retrospective study, data on 465 patients (development cohort) who underwent upfront curative-intent resection for PanNEN were used to assess the performance of CER on PVP and tumor size measured by CT (CT-Size) in predicting recurrence-free survival (RFS) using Harrell's C-index and to determine their optimal cutoffs to stratify RFS using a multi-way partitioning algorithm. External data on 184 patients (test cohort) were used to validate the performance of CER on PVP in predicting RFS and overall survival (OS) and compare its predictive performance with those of CT-Size, 2019 World Health Organization classification system (WHO), and the 8th American Joint Committee on Cancer staging system (AJCC). RESULTS: In the test cohort, CER on PVP showed C-indexes of 0.83 (95% confidence interval [CI], 0.74-0.91) and 0.84 (95% CI, 0.73-0.95) for predicting RFS and OS, respectively, which were higher than those for the WHO (C-index: 0.73 for RFS [p = .002] and 0.72 for OS [p = .004]) and AJCC (C-index, 0.67 for RFS [p = .002] and 0.58 for OS [p = .002]). CT-Size obtained C-indexes of 0.71 for RFS and 0.61 for OS. CONCLUSIONS: CER on PVP showed superior predictive performance on postoperative survival in PanNEN than current grading and staging systems, indicating its potential as a noninvasive preoperative prognostic tool. KEY POINTS: • In pancreatic neuroendocrine neoplasms, the tumor-to-parenchymal enhancement ratio on portal venous-phase CT (CER on PVP) showed acceptable predictive performance of postoperative outcomes. • CER on PVP showed superior predictive performance of postoperative survival over the current WHO classification and AJCC staging system.

Combined Hepatocellular-Cholangiocarcinoma: Magnetic Resonance Imaging Features and Prognosis According to Risk Factors for Hepatocellular Carcinoma.

BACKGROUND: Combined hepatocellular-cholangiocarcinoma (cHCC-CCA) can develop in patients with and without risk factors for hepatocellular carcinoma (HCC). PURPOSE: To compare the clinical and magnetic resonance imaging (MRI) characteristics of cHCC-CCA in patients with and without risk factors for HCC, and to assess the influence of risk factors on patient prognosis. STUDY TYPE: Retrospective. POPULATION: A total of 152 patients with surgically confirmed cHCC-CCA. FIELD STRENGTH/SEQUENCE: 1.5-T and 3-T/T1-weighted dual gradient-echo in- and opposed-phase, T2-weighted turbo-spin-echo, diffusion-weighted single-shot spin-echo echo-planar, and T1-weighted three-dimensional gradient-echo contrast-enhanced sequences. ASSESSMENT: MRI features according to the Liver Imaging Reporting and Data System (LI-RADS) and pathologic findings based on revised classification were compared between patients with and without risk factors for HCC. Overall survival (OS) and recurrence-free survival (RFS) were also compared between the two groups, and factors associated with survival were evaluated. STATISTICAL TESTS: The clinico-pathologic and MRI features of the two groups were compared using Student's t-tests, Mann-Whitney U-tests, and chi-square tests. OS and RFS were evaluated by the Kaplan-Meier method, and factors associated with survival were evaluated by Cox proportional hazard model. RESULTS: cHCC-CCA in patients with risk factors were more frequently classified as LI-RADS category 4 or 5 (LR-4/5; probably or definitely HCC) (48.7%), whereas those without risk factors were more frequently classified as category M (LR-M; probably malignant, not specific for HCC) (63.6%). RFS and OS did not differ significantly according to risk factors (P = 0.63 and 0.83). Multivariable analysis showed that pathologic tumor type (hazard ratio 2.02; P < 0.05) and LI-RADS category (hazard ratio 2.19; P < 0.05) were significantly associated with RFS and OS, respectively. DATA CONCLUSION: Although MRI features of cHCC-CCA differed significantly between patients with and without risk factors for HCC, postsurgical prognosis did not. LI-RADS category and pathologic tumor type were independently correlated with postsurgical prognosis in patients with cHCC-CCA. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

Meta-analysis of CT and MRI for differentiation of autoimmune pancreatitis from pancreatic adenocarcinoma.

OBJECTIVES: To systematically determine the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC), with a comparison between the two imaging modalities. METHODS: Literature search was conducted using PubMed and EMBASE databases to identify original articles published between 2009 and 2019 reporting the diagnostic performance of CT and MRI for differentiating AIP from PDAC. The meta-analytic sensitivity and specificity of CT and MRI were calculated, and compared using a bivariate random effects model. Subgroup analysis for differentiating focal AIP from PDAC was performed. RESULTS: Of the 856 articles screened, 11 eligible articles are remained, i.e., five studies for CT, four for MRI, and two for both. The meta-analytic summary sensitivity and specificity of CT were 59% (95% confidence interval [CI], 41-75%) and 99% (95% CI, 88-100%), respectively, while those of MRI were 84% (95% CI, 68-93%) and 97% (95% CI, 87-99%). MRI had a significantly higher meta-analytic summary sensitivity than CT (84% vs. 59%, p = 0.02) but a similar specificity (97% vs. 99%, p = 0.18). In the subgroup analysis for focal AIP, the sensitivity for distinguishing between focal AIP and PDAC was lower than that for the overall analysis. MRI had a higher sensitivity than CT (76% vs. 50%, p = 0.28) but a similar specificity (97% vs. 98%, p = 0.07). CONCLUSION: MRI might be clinically more useful to evaluate patients with AIP, particularly for differentiating AIP from PDAC. KEY POINTS: • MRI had an overall good diagnostic performance to differentiate AIP from PDAC with a meta-analytic summary estimate of 83% for sensitivity and of 97% for specificity. • CT had a very high specificity (99%), but a suboptimal sensitivity (59%) for differentiating AIP from PDAC. • Compared with CT, MRI had a higher sensitivity, but a similar specificity.

CT in the prediction of margin-negative resection in pancreatic cancer following neoadjuvant treatment: a systematic review and meta-analysis.

OBJECTIVES: We aimed to systematically evaluate the diagnostic accuracy of CT-determined resectability following neoadjuvant treatment for predicting margin-negative resection (R0 resection) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: Original studies with sufficient details to obtain the sensitivity and specificity of CT-determined resectability following neoadjuvant treatment, with a reference on the pathological margin status, were identified in PubMed, EMBASE, and Cochrane databases until February 24, 2020. The identified studies were divided into two groups based on the criteria of R0 resectable tumor (ordinary criterion: resectable PDAC alone; extended criterion: resectable and borderline resectable PDAC). The meta-analytic summary of the sensitivity and specificity for each criterion was estimated separately using a bivariate random-effect model. Summary results of the two criteria were compared using a joint-model bivariate meta-regression. RESULTS: Of 739 studies initially searched, 6 studies (6 with ordinary criterion and 5 with extended criterion) were included for analysis. The meta-analytic summary of sensitivity and specificity was 45% (95% confidence interval [CI], 19-73%; I2 = 88.3%) and 85% (95% CI, 65-94%; I2 = 60.5%) for the ordinary criterion, and 81% (95% CI, 71-87%; I2 = 0.0%) and 42% (95% CI, 28-57%; I2 = 6.2%) for the extended criterion, respectively. The diagnostic accuracy significantly differed between the two criteria (p = 0.02). CONCLUSIONS: For determining resectability on CT, the ordinary criterion might be highly specific but insensitive for predicting R0 resection, whereas the extended criterion increased sensitivity but would decrease specificity. Further investigations using quantitative parameters may improve the identification of R0 resection. KEY POINTS: • CT-determined resectability of PDAC after neoadjuvant treatment using the ordinary criterion shows low sensitivity and high specificity in predicting R0 resection. • With the extended criterion, CT-determined resectability shows higher sensitivity but lower specificity than with the ordinary criterion. • CT-determined resectability with both criteria achieved suboptimal diagnostic performances, suggesting that care should be taken while selecting surgical candidates and when determining the surgical extent after neoadjuvant treatment in patients with PDAC.

Multiparametric MRI for prediction of treatment response to neoadjuvant FOLFIRINOX therapy in borderline resectable or locally advanced pancreatic cancer.

OBJECTIVES: To identify multiparametric MRI biomarkers to predict the tumor response to neoadjuvant FOLFIRINOX therapy in patients with borderline resectable (BR) or locally advanced (LA) pancreatic ductal adenocarcinoma (PDAC). METHODS: From May 2016 to March 2018, adult patients with BR or LA PDAC were prospectively enrolled in this study. They received eight cycles of FOLFIRINOX therapy and underwent multiparametric MRI twice (at baseline and after the second cycle). MRI evaluations included dynamic contrast-enhanced MRI, intravoxel incoherent motion diffusion-weighted imaging, and assessment of T2* relaxivity (R2*) and the change in T1 relaxivity (ΔR1, equilibrium phase R1 minus non-enhanced R1) of the tumors. Factors to predict the responders determined by the best overall response during FOLFIRINOX therapy and those to predict progression-free survival (PFS) and overall survival (OS) were evaluated using multivariable logistic regression and the Cox proportional hazard model. RESULTS: Forty-one patients (mean age, 60.3 years ± 9.3; 24 men) were included. Among the clinical and MRI factors, the baseline ΔR1 (adjusted odds ratio, 31.07; p = 0.008) was the only independent predictor for tumor response. The baseline ΔR1 was also an independent predictor for PFS (adjusted hazard ratio, 0.40; p = 0.033) along with R0 resection. The use of a cutoff ΔR1 value of ≥ 1.31 s-1 enabled prognostic stratification (median PFS, 16.0 months vs.10.0 months; p = 0.029; median OS, 34.9 months vs. 16.6 months; p = 0 .023, respectively). CONCLUSIONS: The baseline tumor ΔR1 value may be useful to predict tumor response and survival in patients with BR or LA PDAC receiving FOLFIRINOX neoadjuvant therapy. KEY POINTS: • Baseline ΔR1 was an independent predictor for tumor response (adjusted odds ratio, 31.07; p = 0.008) and progression-free survival (adjusted hazard ratio, 0.40; p = 0.033) in patients with borderline resectable or locally advanced pancreatic ductal adenocarcinoma receiving neoadjuvant FOLFIRINOX therapy. • The criterion of baseline ΔR1 value ≥ 1.31 s-1 allowed for the prediction of favorable tumor response and survival outcome after neoadjuvant FOLFIRINOX therapy.

CT-determined resectability of borderline resectable and unresectable pancreatic adenocarcinoma following FOLFIRINOX therapy.

OBJECTIVES: We aimed to assess the ability of CT-determined resectability, as defined by a recent version of NCCN criteria, and associated CT findings to predict margin-negative (R0) resection in patients with PDAC after neoadjuvant FOLFIRINOX chemotherapy. METHODS: Sixty-four patients (36 men and 28 women; mean age, 58.8 years) with borderline resectable or unresectable PDAC who received neoadjuvant FOLFIRINOX were evaluated retrospectively. CT findings were independently assessed by two abdominal radiologists according to NCCN criteria (version 3. 2019). Tumor resectability was classified as resectable, borderline resectable, or unresectable, and change in resectability was classified as regression, stability, or progression. The associations of R0 resection rate with CT-determined resectability and change in resectability categories were evaluated, as were the sensitivity and specificity of NCCN criteria for R0 resection. Factors associated with R0 resection were identified by logistic regression analysis. RESULTS: R0 resection rate did not differ significantly among the resectable, borderline resectable, or unresectable PDAC (67-73%, p = 0.95) or among PDAC with regression, stability, or progression (56-77%, p = 0.39). The sensitivity and specificity for R0 resection were 67% and 37%, respectively, for resectability (resectable/borderline vs. unresectable) and 80% and 21%, respectively, for changes in resectability (regression/stable vs. progression). Low-contrast enhancement of soft tissue contacting artery (≤ 46.4 HU) was independently associated with R0 resection (p = 0.01). CONCLUSION: CT-determined resectability after neoadjuvant FOLFIRINOX chemotherapy was relatively insensitive and non-specific for predicting R0 resection. Low-contrast enhancement of soft tissue contacting artery may increase the ability of CT to predict R0 resection. KEY POINTS: • Margin-negative resection rate of pancreatic cancer following FOLFIRINOX therapy did not differ among each resectability (67-73%, p = 0.95) based on NCCN criteria or changes in resectability categories (56-77%, p = 0.39). • The sensitivity and specificity for margin-negative resection were 67% and 37% for resectability (resectable/borderline vs. unresectable) and 80% and 21% for changes in resectability (regression/stable vs. progression). • Low-contrast enhancement of soft tissue contacting artery (≤ 46.4 HU) was independently associated with margin-negative resection (p = 0.01).

Estimating Recurrence after Upfront Surgery in Patients with Resectable Pancreatic Ductal Adenocarcinoma by Using Pancreatic CT: Development and Validation of a Risk Score.

Background No preoperative model is available for predicting postsurgical prognosis of patients with resectable pancreatic ductal adenocarcinoma (PDAC). Purpose To develop and validate a preoperative risk scoring system using clinical and CT variables to predict recurrence-free survival (RFS) after upfront surgery in patients with resectable PDAC. Materials and Methods In this retrospective study, consecutive patients with resectable PDAC underwent upfront surgery from January 2014 to December 2015 (development set) and from January 2016 to January 2017 (test set). In the development set, multivariable Cox proportional hazard modeling with bootstrapping was used to select clinical and CT variables associated with RFS and to construct a risk scoring system. The discrimination capability of the risk score was assessed by using the Harrell C-index and compared with that of pathologic American Joint Committee on Cancer tumor stage. The risk score was validated in the test set. Results A total of 395 patients were evaluated, including 262 patients (mean age ± standard deviation, 64 years ± 10; 155 men) in the development set and 133 (mean age, 64 years ± 9; 79 men) in the test set. Five independent variables predicted risk of recurrence or death: tumor size (hazard ratio [HR], 1.23; 95% confidence interval [CI]: 1.05, 1.44; P = .009), hypodense tumor in the portal venous phase (HR, 1.66; 95% CI: 1.01, 2.73; P = .04), tumor necrosis (HR, 2.04; 95% CI: 1.38, 3.03; P < .001), peripancreatic tumor infiltration (HR, 1.50; 95% CI: 1.07, 2.11; P = .02), and suspicious metastatic lymph nodes (HR, 1.94; 95% CI: 1.38, 2.72; P < .001). In the test set, the risk score showed good discrimination capability (C-index of 0.68; 95% CI: 0.63, 0.74) and outperformed the pathologic tumor stage (C-index of 0.60; 95% CI: 0.55, 0.66; P = .03). Patients were categorized into favorable, intermediate, and poor prognosis groups with 1-year RFS of 0.87, 0.58, and 0.26, respectively. Conclusion The presented preoperative risk score can predict recurrence-free survival after upfront surgery in patients with resectable pancreatic ductal adenocarcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Pandharipande and Anderson in this issue.

Comparison between neuroendocrine carcinomas and well-differentiated neuroendocrine tumors of the pancreas using dynamic enhanced CT.

OBJECTIVES: To identify CT features distinguishing neuroendocrine carcinomas (NECs) of pancreas from well-differentiated neuroendocrine tumors (NETs) according to the World Health Organization 2017 and 2019 classification systems. METHODS: This retrospective study included 69 patients with pathologically confirmed pancreatic neuroendocrine neoplasms who underwent dynamic CT (17, 17, 18, and 17 patients for well-differentiated grade 1, 2, 3 NET and NEC, respectively). CT was used to perform qualitative analysis (component, homogeneity, calcification, peripancreatic infiltration, main pancreatic ductal dilatation, bile duct dilatation, intraductal extension, and vascular invasion) and quantitative analysis (interface between tumor and parenchyma [delta], arterial enhancement ratio [AER], portal enhancement ratio [PER], and dynamic enhancement pattern). Uni- and multivariate logistic regression analyses were performed to identify features indicating NEC. Optimal cutoff values for enhancement ratios were determined. RESULTS: NECs demonstrated significantly higher frequencies of main pancreatic ductal dilatation, bile duct dilatation, vascular invasion, and significantly lower delta (i.e., lower conspicuity), AER, and PER than well-differentiated NET (p < 0.05). On multivariate analysis, PER was the only independent factor selected by the model for differentiation of NEC from well-differentiated NET (odds ratio, < 0.001; 95% confidence interval [CI], < 0.001-0.012). PER < 0.8 showed the sensitivity of 94.1% (95% CI, 71.3-99.9) and the specificity of 88.5% (95% CI, 76.6-95.6). When three significant CT features were combined, the sensitivity and specificity for diagnosing NEC were 88.2% and 88.5%, respectively. CONCLUSIONS: Tumor-parenchyma enhancement ratio in portal phase is a useful CT feature to distinguish NECs from well-differentiated NETs. Combining qualitative and quantitative CT features may aid in achieving good diagnostic accuracy in the differentiation between NEC and well-differentiated NET. KEY POINTS: • Neuroendocrine carcinoma of the pancreas should be distinguished from well-differentiated neuroendocrine tumor in line with the revised grading and staging system. • Neuroendocrine carcinoma of the pancreas can be differentiated from well-differentiated neuroendocrine tumor on dynamic CT based on assessment of the portal enhancement ratio, arterial enhancement ratio, tumor conspicuity, dilatation of the main pancreatic duct or bile duct, and vascular invasion. • Tumor-parenchyma enhancement ratio in portal phase of dynamic CT is a useful feature, which may help to distinguish neuroendocrine carcinoma from well-differentiated neuroendocrine tumor of the pancreas.

Differentiating focal autoimmune pancreatitis and pancreatic ductal adenocarcinoma: contrast-enhanced MRI with special emphasis on the arterial phase.

OBJECTIVES: To compare focal-type autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDA) using contrast-enhanced MR imaging (CE-MRI), and to assess diagnostic performance of the lesion contrast at arterial phase (AP) (ContrastAP) for differentiating between the two diseases. METHODS: Thirty-six patients with focal-type AIP and 72 patients with PDA were included. All included patients underwent CE-MRI with triple phases. The signal intensity (SI) of the mass and normal pancreas was measured at each phase, and the lesion contrast (SIpancreas/SImass) was compared between AIP and PDA groups. The sensitivity and specificity of ContrastAP using an optimal cutoff point were compared with those of key imaging features specific to AIP and PDA. RESULTS: The lesion contrast differed significantly between AIP and PDA groups at all phases of CE-MRI; the maximum difference was observed at AP. For AIP, the sensitivity (94.4%) and specificity (87.5%) of ContrastAP (cutoff ≤ 1.41) were comparable or significantly higher than those of all key imaging features (sensitivity, 38.9-88.9%; specificity, 48.6-95.8%), except for the halo sign. For PDA, the sensitivity (87.5%) and specificity (94.4%) of ContrastAP (cutoff > 1.41) were comparable or significantly higher than those of all key imaging features (sensitivity, 40.3-68.1%; specificity, 72.2-94.4%), except for the discrete mass. CONCLUSIONS: Quantitative analysis of the lesion contrast using CE-MRI, particularly at AP, was helpful to differentiate focal-type AIP from PDA. The diagnostic performance of ContrastAP was mostly comparable or higher than those of the key imaging features. KEY POINTS: • Diagnosis of focal-type AIP vs. PDA using imaging techniques is extremely challenging. • Lesion contrast in the arterial-phase MRI differs significantly between focal-type AIP and PDA. • Quantitative analysis of lesion contrast using CE-MRI, particularly at the arterial phase, is helpful to differentiate focal-type AIP from PDA.

Growth rate of serous pancreatic neoplasms in vivo: a retrospective, observational study.

BACKGROUND: Determining the growth rate of pancreatic cystic lesions on follow-up imaging is important in managing patients with these lesions. However, the growth rates of serous pancreatic neoplasms (SPNs) have been reported to vary among studies. PURPOSE: To determine the in vivo growth rate of SPNs. MATERIAL AND METHODS: This retrospective, single-institutional study included patients diagnosed with SPNs during 2006-2015. The diagnosis of SPNs was based on the results of surgery, endoscopic ultrasonography (EUS)-guided fine needle aspiration (FNA) or core needle biopsy (CNB), or typical radiologic features of SPN. A linear mixed-effects model was utilized to determine whether the diagnostic intervention was associated with tumor growth rate in all patients. The in vivo growth rate of SPNs was estimated from patients without or before diagnostic intervention. SPN growth rates were compared before and after diagnostic intervention. RESULTS: SPN growth rates in the overall patient cohort (n = 304) differed significantly between patients who did and did not undergo diagnostic interventions. The in vivo SPN growth rate in 204 patients without or before diagnostic intervention was 1.9 mm/year (95% confidence interval [CI] = 1.6-2.2). In the 130 patients who underwent diagnostic intervention, the SPN growth rate was significantly greater before than after diagnostic intervention (1.8 vs. 0.2 mm/year). CONCLUSIONS: In the absence of diagnostic intervention, the in vivo growth rate of SPNs was 1.9 mm/year (95% CI = 1.6-2.2). EUS-guided FNA or CNB may affect the growth rate of SPNs.

Pancreatic Cancer CT: Prediction of Resectability according to NCCN Criteria.

Purpose To evaluate the diagnostic performance of CT in the determination of pancreatic cancer resectability according to the National Comprehensive Cancer Network (NCCN) criteria to predict R0 resection. Materials and Methods Structured reports of pancreatic CT clinically prepared by board-certified abdominal radiologists from January 2014 to March 2017 were retrospectively reviewed to assess resectability (resectable, borderline resectable, or unresectable) according to NCCN criteria (version 1.2017) in 616 patients (369 men, 247 women; mean age, 63 years ± 10 [standard deviation]) with pancreatic cancer. Negative resection margin (R0) rates were assessed based on CT resectability status in patients who underwent upfront surgery. R0 resection-associated factors were identified by using logistic regression analysis. Results In 371 patients who underwent surgery, R0 resection rates were 73% (171 of 235), 55% (57 of 104), and 16% (five of 32) for resectable, borderline resectable, and unresectable disease, respectively (P < .001). At multivariable analysis, tumor diameter larger than 4 cm (P < .001) and abutment to the portomesenteric vein (P < .001) were significantly associated with margin-positive resection in patients with resectable disease at CT. R0 resection rates were 80% (123 of 154) for resectable disease without portomesenteric vein abutment, 59% (48 of 81) for resectable disease with portomesenteric vein abutment, 83% (57 of 69) for resectable disease 2 cm or smaller, and 29% (five of 17) for tumors larger than 4 cm. Conclusion CT resectability is used to stratify patients with pancreatic cancer according to the possibility of R0 resection. Larger tumor size and tumor abutment to the portomesenteric vein are associated with margin-positive resection in patients with resectable pancreatic cancer. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Fowler in this issue.

Xanthogranulomatous cholecystitis shows overlapping histological features with IgG4-related cholecystitis.

AIMS: Xanthogranulomatous cholecystitis (XGC), an unusual histological variant of chronic cholecystitis, is characterised by mixed foamy histiocytic and lymphoplasmocytic infiltration and fibrosis. Radiologically, the poorly defined nodular growth pattern often leads to the misinterpretation of XGC as gallbladder cancer. In this study, we aimed to identify the relationship of XGC with IgG4-related cholecystitis. METHODS AND RESULTS: We re-evaluated 57 surgically resected XGCs and 104 conventional chronic cholecystitis cases, according to the histological features observed in IgG4-related disease, including lymphoplasmocytic infiltration, storiform fibrosis, obliterative phlebitis, and IgG4-positive plasma cells. XGCs contained a significantly increased mean number of IgG4-positive plasma cells [34.8/high-power field (HPF)] as compared with conventional chronic cholecystitis (4.8/HPF; P < 0.001), and 16 XGCs (28%) harboured >50 IgG4-positive cells per HPF. Nine XGCs (16%), including one case with IgG4-related autoimmune pancreatitis, showed 'the histological features suggestive of IgG4-related disease', as described in the consensus statement regarding this condition. Extracholecystic inflammatory extension (seven cases, P = 0.009) and mass-forming lesions (eight cases, P < 0.001) were more frequently seen in XGC cases with histological features suggestive of IgG4-related disease than in cases without those microscopic changes. CONCLUSIONS: XGCs with IgG4-positive cell infiltration are considered to be mimickers, as xanthogranulomatous inflammation generally contradicts a diagnosis of IgG4-related disease and is weakly associated with other typical organ manifestations of IgG4-related disease. However, XGC may be a concurrent condition, particularly in patients with IgG4-related disease in other organs.

Noninvasive assessment of hepatic sinusoidal obstructive syndrome using acoustic radiation force impulse elastography imaging: A proof-of-concept study in rat models.

OBJECTIVES: To determine the feasibility of acoustic radiation force impulse (ARFI) elastography in the evaluation of hepatic sinusoidal obstruction syndrome (SOS) in rat models. METHODS: Rat SOS models of various severities were created by monocrotaline gavage (n = 40) or by intraperitoneal injection of 5-fluorouracil, leucovorin and oxaliplatin (FOLFOX) (n = 16). Liver shear-wave velocity (SWV) was measured using ARFI elastography. Liver samples were analysed for the SOS score, steatosis, lobular inflammation and fibrosis. RESULTS: The liver SWV was significantly elevated in the SOS models (1.29-2.24 m/s) compared with that of the matched control rats (1.01-1.09; p≤.09; veFor seven FOLFOX-treated rats which were longitudinally followed-up, the liver SWV significantly increased at 7 weeks (1.32±0.13 m/s) compared with the baseline (1.08±0.1 m/s, p=.015) and then significantly declined after a 2-week, treatment-free period (1.15±0.13 m/s; p=.048). Multivariate analysis revealed that the SOS score (p<.001) and lobular inflammation (p=.044) were independently correlated with the liver SWV. CONCLUSION: Liver SWV is elevated in SOS in proportion to the degree of sinusoidal injury and lobular inflammation in rat SOS models. ARFI elastography has potential as an examination for diagnosis, severity assessment and follow-up of SOS. KEY POINTS: • Liver SWV using ARFI elastography was significantly elevated in SOS rat. • Sinusoidal injury and lobular inflammation grades had correlation with liver SWV. • ARFI elastography has potential for diagnosis, severity assessment, and follow-up of SOS.

Comparison of diagnostic performance between CT and MRI in differentiating non-diffuse-type autoimmune pancreatitis from pancreatic ductal adenocarcinoma.

OBJECTIVES: To intraindividually compare the diagnostic performance of CT and MRI in differentiating non-diffuse-type autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDA). METHODS: Sixty-one patients with non-diffuse-type AIP and 122 patients with PDA, who underwent dynamic contrast-enhanced CT and MRI with MR pancreatography, were included. Two blinded radiologists independently rated their confidence in differentiating the two diseases on a 5-point scale, and the diagnostic performances of CT and MRI were compared. The presence of key imaging features to differentiate AIP and PDA were compared between CT and MRI. RESULTS: The area under the receiver operating characteristic curve was significantly greater on MRI (0.993-0.995) than on CT (0.953-0.976) for both raters (p≤0.035). The sensitivities of MRI were higher than those of CT for the diagnosis of AIP (88.5-90.2% vs. 77-80.3%, p≤0.07) and PDA (97.5-99.2% vs. 91.8-94.3%, p≤0.031) for both raters, although the difference for AIP was statistically marginal (p=0.07) for rater 1. In AIP, multiple pancreatic masses, delayed homogeneous enhancement of the pancreatic mass, and multiple main pancreatic duct (MPD) strictures were observed significantly more frequently using MRI than CT (p≤0.008). In PDA, discrete pancreatic mass and MPD stricture were observed significantly more frequently using MRI than CT (p≤0.012). CONCLUSIONS: The diagnostic performance of MRI is better for differentiating non-diffuse-type AIP from PDA, which is due to the superiority of MRI over CT in demonstrating the key distinguishing features of both diseases. KEY POINTS: • Imaging differential diagnosis of non-diffuse-type AIP and PDA is challenging. • MRI has better diagnostic performance than CT in differentiating non-diffuse-type AIP from PDA. • MRI is superior to CT in demonstrating key distinguishing features of non-diffuse-type AIP and PDA.

Intraductal Papillary Neoplasm of the Bile Duct: Clinical, Imaging, and Pathologic Features.

OBJECTIVE: We outline the concept of intraductal papillary neoplasm of the bile duct (IPNB), discuss the morphologic features of IPNB and the differential diagnoses, and describe the radiologic approaches used in multidisciplinary management. CONCLUSION: The concept of IPNB has been evolving. Because the imaging features of IPNB can be variable, different mimickers according to IPNB subtype can be considered. A multimodality approach is essential to obtain an optimal diagnosis and establish treatment plans.

Intravoxel incoherent motion diffusion-weighted imaging of the pancreas: Characterization of benign and malignant pancreatic pathologies.

PURPOSE: To evaluate the diagnostic value of apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters in differentiating patients with either a normal pancreas (NP), pancreatic ductal adenocarcinoma (PDAC), neuroendocrine tumor (NET), solid pseudopapillary tumor (SPT), acute pancreatitis (AcP), vs. autoimmune pancreatitis (AIP). MATERIALS AND METHODS: In all, 84 pathologically confirmed pancreatic tumors (60 PDACs, 15 NETs, 9 SPTs), 20 pancreatitis (13 AcPs, 7 AIPs), and 30 NP subjects underwent IVIM diffusion-weighted imaging using 10 b-values (0-900 sec/mm2 ) at 1.5T. The ADC, pure molecular diffusion coefficient (Dslow ), perfusion fraction (f), and perfusion-related diffusion coefficient (Dfast ) were calculated and compared using a Kruskal-Wallis test and post-hoc Dunn procedure. Receiver operating characteristic (ROC) analysis was performed to assess diagnostic performance. RESULTS: The f and Dfast of the PDAC were significantly lower than that of the NP (f = 0.10 vs. 0.24; Dfast = 42.21 vs. 71.74 × 10-3 mm2 /sec; P < 0.05). In ROC analysis, f showed the best diagnostic performance (area-under-the-curve, 0.919) among all parameters in differentiating PDAC from NP (P ≤ 0.001). The f values of AcP (0.11) and AIP (0.13) and the Dfast values of SPT (20.48 × 10-3 mm2 /sec) and AcP (24.49 × 10-3 mm2 /sec) were significantly lower compared with NP (f = 0.24; Dfast = 71.74 × 10-3 mm2 /sec; P < 0.05). For NET, the f (0.21) was significantly higher than that of PDAC (0.10, P < 0.01). CONCLUSION: Perfusion-related parameters f and Dfast are more helpful in characterizing pancreatic diseases than ADC or Dslow . The PDCA, SPT, AcP, and AIP were characterized by reduced f and Dfast values compared with normal pancreas. The f value might help in differentiating between PDAC and NET. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:260-269.

Transcatheter Arterial Embolization for Gastrointestinal Bleeding Associated with Gastric Carcinoma: Prognostic Factors Predicting Successful Hemostasis and Survival.

PURPOSE: To evaluate outcomes of transcatheter arterial embolization (TAE) for gastric cancer-related gastrointestinal (GI) bleeding and factors associated with successful TAE and improved survival after TAE. MATERIALS AND METHODS: This retrospective study included 43 patients (34 men; age 60.6 y ± 13.6) with gastric cancer-related GI bleeding undergoing angiography between January 2000 and December 2015. Clinical course, laboratory findings, and TAE characteristics were reviewed. Technical success of TAE was defined as target area devascularization, and clinical success was defined as bleeding cessation with hemodynamic stability during 72 hours after TAE. Student t test was used for comparison of continuous variables, and Fisher exact test was used for categorical variables. Univariate and multivariate analysis were performed to identify predictors of successful TAE and 30-day survival after TAE. RESULTS: TAE was performed in 40 patients. Technical and clinical success rates of TAE were 85.0% and 65.0%, respectively. Splenic infarction occurred in 2 patients as a minor complication. Rebleeding after TAE occurred in 7 patients. Death related to bleeding occurred in 5 patients. Active bleeding (P = .044) and higher transfusion requirement (3.3 U ± 2.6 vs 1.8 U ± 1.7; P = .039) were associated with TAE failure. Successful TAE predicted improved 30-day survival after TAE on univariate and multivariate analysis (P = .018 and P = .022; odds ratio, 0.132). CONCLUSION: TAE for gastric cancer-associated GI bleeding may be a lifesaving procedure. Severe bleeding with a higher transfusion requirement and active bleeding on angiography predicted TAE failure.

Validation of the 2012 International Consensus Guidelines Using Computed Tomography and Magnetic Resonance Imaging: Branch Duct and Main Duct Intraductal Papillary Mucinous Neoplasms of the Pancreas.

OBJECTIVE: To validate the 2012 guidelines for intraductal papillary mucinous neoplasm (IPMN) of the pancreas and to compare diagnostic performances of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating malignant from benign IPMN. BACKGROUND: As IPMN has variable risks of malignancy and management of this entity is closely related to its malignant potential, it is important to predict risks of IPMN malignancy. METHODS: This retrospective study included 158 patients with surgically confirmed IPMN of the pancreas who underwent both preoperative CT and MRI. Two radiologists evaluated the "high-risk stigmata" and "worrisome features" of the 2012 guidelines for branch duct (BD)-IPMN and main duct (MD)-IPMN. Univariate and multivariable analyses were used to identify significant predictors of malignancy in IPMN. The diagnostic performance was compared between CT and MRI. RESULTS: Malignant IPMN was seen in 8 of 60 patients (13.3%) with BD-IPMN and 44 of 98 patients (44.9%) with MD-IPMN. Presence of mural nodule was the most important predictor in BD-IPMN and MD-IPMN (odds ratios, 9.2 and 7.6, respectively, P = 0.01 on CT; and odds ratios, 5.7 and 13.3, respectively, P ≤ 0.04 on MRI), whereas mural nodule size and lymphadenopathy were significant only in MD-IPMN (P < 0.05). The diagnostic performance of CT and MRI for significant findings was not statistically different in both types of IPMN (P > 0.34). CONCLUSIONS: The presence of mural nodule was the most important predictor of malignancy in both types of IPMN. Mural nodule size and lymphadenopathy were also significant predictors in MD-IPMN. Computed tomography and MRI showed similar diagnostic performances for differentiating malignant from benign IPMN.