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Background: Pancreatic ductal adenocarcinoma (PDAC) stromal viscoelasticity can be measured using MR elastography (MRE). Bowel preparation regimens could affect MRE quality and knowledge on repeatability is crucial for clinical implementation. Purpose: To assess effects of four bowel preparation regimens on MRE quality and to evaluate repeatability and differentiate patients from healthy controls. Study Type: Prospective. Population: 15 controls (41 ± 16 years; 47% female), 16 PDAC patients (one excluded, 66 ± 12 years; 40% female) with 15 age‐/sex‐matched controls (65 ± 11 years; 40% female). Final sample size was 25 controls and 15 PDAC. Field Strength/Sequence: 3‐T, spin‐echo echo‐planar‐imaging, turbo spin‐echo, and fast field echo gradient‐echo. Assessment: Four different regimens were used: fasting; scopolaminebutyl; drinking 0.5 L water; combination of 0.5 L water and scopolaminebutyl. MRE signal‐to‐noise ratio (SNR) was compared between all regimens. MRE repeatability (test–retest) and differences in shear wave speed (SWS) and phase angle (ϕ) were assessed in PDAC and controls. Regions‐of‐interest were defined for tumor, nontumorous (n = 8) tissue in PDAC, and whole pancreas in controls. Two radiologists delineated tumors twice for evaluation of intraobserver and interobserver variability. Statistical Tests: Repeated measures analysis of variance, coefficients of variation (CoVs), Bland–Altman analysis, (un)paired t‐test, Mann–Whitney U‐test, and Wilcoxon signed‐rank test. P‐value<0.05 was considered statistically significant. Results: Preparation regimens did not significantly influence MRE‐SNR. Therefore, the least burdensome preparation (fasting only) was continued. CoVs for tumor SWS were: intrasession (12.8%) and intersession (21.7%), and intraobserver (7.9%) and interobserver (10.3%) comparisons. For controls, CoVs were intrasession (4.6%) and intersession (6.4%). Average SWS for tumor, nontumor, and healthy tissue were: 1.74 ± 0.58, 1.38 ± 0.27, and 1.18 ± 0.16 m/sec (ϕ: 1.02 ± 0.17, 0.91 ± 0.07, and 0.85 ± 0.08 rad), respectively. Significant differences were found between all groups, except for ϕ between healthy–nontumor (P = 0.094). Data Conclusion: The proposed bowel preparation regimens may not influence MRE quality. MRE may be able to differentiate between healthy tissue–tumor and tumor–nontumor. Level of Evidence: 2 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]

Background: Pancreatic ductal adenocarcinoma (PDAC) stromal disposition is thought to influence chemotherapy efficacy and increase tissue stiffness, which could be quantified noninvasively via MR elastography (MRE). Current methods cause position‐based errors in pancreas location over time, hampering accuracy. It would be beneficial to have a single breath‐hold acquisition. Purpose: To develop and test a single breath‐hold three‐dimensional MRE technique utilizing prospective undersampling and a compressed sensing reconstruction (CS‐MRE). Study Type: Prospective. Population: A total of 30 healthy volunteers (HV) (31 ± 9 years; 33% male) and five patients with PDAC (69 ± 5 years; 80% male). Field Strength/Sequence: 3‐T, GRE Ristretto MRE. Assessment: First, optimization of multi breath‐hold MRE was done in 10 HV using four combinations of vibration frequency, number of measured wave‐phase offsets, and TE and looking at MRE quality measures in the pancreas head. Second, viscoelastic parameters delineated in the pancreas head or tumor of CS‐MRE were compared against (I) 2D and (II) 3D four breath‐hold acquisitions in HV (N = 20) and PDAC patients. Intrasession repeatability was assessed for CS‐MRE in a subgroup of healthy volunteers (N = 15). Statistical Tests: Tests include repeated measures analysis of variance (ANOVA), Bland–Altman analysis, and coefficients of variation (CoVs). A P‐value <.05 was considered statistically significant. Results: Optimization of the four breath‐hold acquisitions resulted in 40 Hz vibration frequency, five wave‐phases, and echo time (TE) = 6.9 msec as the preferred method (4BH‐MRE). CS‐MRE quantitative results did not differ from 4BH‐MRE. Shear wave speed (SWS) and phase angle differed significantly between HV and PDAC patients using 4BH‐MRE or CS‐MRE. The limits of agreement for SWS were [−0.09, 0.10] m/second and the within‐subject CoV was 4.8% for CS‐MRE. Data Conclusion: CS‐MRE might allow a single breath‐hold MRE acquisition with comparable SWS and phase angle as 4BH‐MRE, and it may still enable to differentiate between HV and PDAC. Level of Evidence: 2 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]

Background Magnetic resonance imaging is increasingly used to assess treatment response in Crohn's disease clinical trials. We aimed to describe the definition of MRI response and remission as assessed by magnetic resonance enterography [MRE] to evaluate treatment efficacy in these patients. Methods Electronic databases were searched up to May 1, 2023. All published studies enrolling patients with inflammatory bowel disease and assessment of treatment efficacy with MRE were eligible for inclusion. Results Eighteen studies were included. All studies were performed in patients with Crohn's disease. The study period ranged from 2008 to 2023. The majority of studies used endoscopy as the reference standard [61.1%]. MRE response was defined in 11 studies [61.1%]. Five scores and nine different definitions were proposed for MRE response. MRE remission was defined in 12 studies [66.7%]. Three scores and nine different definitions for MRE remission were described. The MaRIA score was the most frequent index used to evaluate MRE response [63.6%] and remission [41.7%]. MRE response was defined as MaRIA score <11 in 63.6% of studies using this index. In 60% of studies using the MaRIA score, MRE remission was defined as MaRIA score <7. In addition, 11 different time points of assessment were reported, ranging from 6 weeks to years. Conclusion In this systematic review, significant heterogeneity in the definition of MRE response and remission evaluated in patients with Crohn's disease was observed. Harmonization of eligibility and outcome criteria for MRE in Crohn's Disease clinical trials is needed. [ABSTRACT FROM AUTHOR]

Simple Summary: For patients with colorectal cancer with liver metastases, it is important to determine the genetic mutations (e.g., KRAS mutations) of the liver metastases. Around 35–45% of patients with colorectal cancer liver metastases (CRLM) have a KRAS mutation, and genetic mutations are used in treatment planning and prognostication. The aim of this study was to assess if KRAS mutations could be identified on CT scans using radiomics. In the discovery cohort of 255 patients, KRAS mutations could be identified with a good accuracy. In the external validation cohort consisting of 129 patients, the radiomics model performed poorly. These results indicate that radiomics might be used to determine genetic mutations such as KRAS, but foremost emphasize the importance of the external validation of radiomics models. External validation is crucial for the assessment of clinical applicability and should be mandatory in all future studies in the field of radiomics. For patients with colorectal cancer liver metastases (CRLM), the genetic mutation status is important in treatment selection and prognostication for survival outcomes. This study aims to investigate the relationship between radiomics imaging features and the genetic mutation status (KRAS mutation versus no mutation) in a large multicenter dataset of patients with CRLM and validate these findings in an external dataset. Patients with initially unresectable CRLM treated with systemic therapy of the randomized controlled CAIRO5 trial (NCT02162563) were included. All CRLM were semi-automatically segmented in pre-treatment CT scans and radiomics features were calculated from these segmentations. Additionally, data from the Netherlands Cancer Institute (NKI) were used for external validation. A total of 255 patients from the CAIRO5 trial were included. Random Forest, Gradient Boosting, Gradient Boosting + LightGBM, and Ensemble machine-learning classifiers showed AUC scores of 0.77 (95%CI 0.62–0.92), 0.77 (95%CI 0.64–0.90), 0.72 (95%CI 0.57–0.87), and 0.86 (95%CI 0.76–0.95) in the internal test set. Validation of the models on the external dataset with 129 patients resulted in AUC scores of 0.47–0.56. Machine-learning models incorporating CT imaging features could identify the genetic mutation status in patients with CRLM with a good accuracy in the internal test set. However, in the external validation set, the models performed poorly. External validation of machine-learning models is crucial for the assessment of clinical applicability and should be mandatory in all future studies in the field of radiomics. [ABSTRACT FROM AUTHOR]

Background: Accurately predicting the risk of clinically relevant postoperative pancreatic fistula after pancreatoduodenectomy before surgery may assist surgeons in making more informed treatment decisions and improved patient counselling. The aim was to evaluate the predictive accuracy of a radiomics-based preoperative-Fistula Risk Score (RAD-FRS) for clinically relevant postoperative pancreatic fistula. Methods: Radiomic features were derived from preoperative CT scans from adult patients after pancreatoduodenectomy at a single centre in the Netherlands (Amsterdam, 2013–2018) to develop the radiomics-based preoperative-Fistula Risk Score. Extracted radiomic features were analysed with four machine learning classifiers. The model was externally validated in a single centre in Italy (Verona, 2020–2021). The radiomics-based preoperative-Fistula Risk Score was compared with the Fistula Risk Score and the updated alternative Fistula Risk Score. Results: Overall, 359 patients underwent a pancreatoduodenectomy, of whom 89 (25 per cent) developed a clinically relevant postoperative pancreatic fistula. The radiomics-based preoperative-Fistula Risk Score model was developed using CT scans of 118 patients, of which three radiomic features were included in the random forest model, and externally validated in 57 patients. The model performed well with an area under the curve of 0.90 (95 per cent c.i. 0.71 to 0.99) and 0.81 (95 per cent c.i. 0.69 to 0.92) in the Amsterdam test set and Verona data set respectively. The radiomics-based preoperative-Fistula Risk Score performed similarly to the Fistula Risk Score (area under the curve 0.79) and updated alternative Fistula Risk Score (area under the curve 0.79). Conclusion: The radiomics-based preoperative-Fistula Risk Score, which uses only preoperative CT features, is a new and promising radiomics-based score that has the potential to be integrated with hospital CT report systems and improve patient counselling before surgery. The model with underlying code is readily available via www.pancreascalculator.com and www.github.com/PHAIR-Consortium/POPF-predictor. Accurately predicting clinically relevant postoperative pancreatic fistula before surgery may assist surgeons in better counselling patients. The radiomics preoperative-Fistula Risk Score was generated using computed tomography features and shown to accurately predict postoperative pancreatic fistula. After further validation it has the potential to be integrated in hospital CT report systems. [ABSTRACT FROM AUTHOR]