Fibrosis and postoperative fistula of the pancreas: correlation with MR imaging findings--preliminary results

Evaluation of postoperative pancreatic fistula prediction scales following pancreatoduodenectomies based on magnetic resonance imaging: A diagnostic test study

BACKGROUND

Postoperative pancreatic fistula (POPF) is one of the most feared and common complications following pancreatoduodenectomies. This study aims to evaluate the performance of different scales in predicting POPF using magnetic resonance imaging (MRI), including estimation of the pancreatic duct diameter, pancreatic texture, main duct index, relation to the portal vein, and intra-abdominal fat thickness.

MATERIALS AND METHODS

A retrospective diagnostic test study was designed. Between January 2017 and December 2021, 133 pancreatoduodenectomies were performed at our institution. The performance for predicting overall POPF and clinically relevant POPF (CR-POPF) was evaluated using a receiver operating characteristic (ROC) curve.

RESULTS

A total of 96 patients were included in the study, of whom 26 patients experienced overall POPF, and 8 patients had CR-POPF. When analyzing the predictive value of each of the different scores applied, the Birmingham score showed the highest performance for predicting overall POPF and CR-POPF with an AUC (area under the curve) of 0.815 (95 % CI 0.725-0.906) and 0.813 (0.679-0.947), respectively.

CONCLUSION

The Birmingham scale demonstrated the highest predictive performance for POPF. It is a simple scale with only two variables that can be obtained preoperatively using MRI. Based on these results, we recommend its use in patients undergoing pancreatoduodenectomy.

Association between paravertebral muscle radiological parameter alterations and non-alcoholic fatty liver disease

PURPOSE

To assess changes in laboratory indices, paravertebral muscle (PVM) fat infiltration and multi b-value DWI parameters and their potential correlation with NAFLD.

METHODS

This retrospective analysis included 178 patients with histopathologically confirmed NAFLD, incluiding 76 with non-alcoholic steatohepatitis (NASH). Differences in PVM fat infiltration ratio (FIR), DWI parameters, and laboratory indices were compared between two groups. The correlation between FIR and NAFLD activity score (NAS) was also analysed. Binary logistic regression was used to identify the independent risk factors for NASH. The clinical utility of PVM fat infiltration, DWI parameters, and laboratory indices for diagnosing NASH in patients with NAFLD was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

The FIRs at the L2 and L3 levels were significantly higher in the with NASH group than those in the without NASH group. The heterogeneity index (α) and perfusion fraction (f) values at the L3 level of PVM were lower in the with NASH group. Moreover, the FIR at the L3 level was positively correlated with NAS. FIR at the L3 level was an independent risk factor for NASH along with alanine aminotransferase level. The area under the ROC curve (AUC) using L3 level PVM radiological parameters and laboratory indices for diagnosing NASH in patients with NAFLD was significantly higher than that using the degree of PVM fat infiltration, DWI parameters, or laboratory indices alone.

CONCLUSIONS

Radiological parameters of the PVM were correlated with NAFLD. An integrated curve combining PVM radiological parameters may help distinguish NASH from NAFLD, thereby offering novel insights into the diagnosis of NASH.

Cross-sectional imaging of the pancreas in diabetes

Diabetes mellitus presents a global health challenge characterized by dysregulated glucose metabolism and insulin resistance. Pancreas dysfunction contributes to the development and progression of diabetes. Cross-sectional imaging modalities have provided new insight into the structural and functional alterations of the pancreas in individuals with diabetes. This review summarizes MRI and CT studies that characterize pancreas alterations in both type 1 and type 2 diabetes and discusses future applications of these techniques.

The Signal Intensity Ratio of Pancreas to Spleen in Magnetic Resonance Imaging Can Predict Nonalcoholic Fatty Liver Disease After Pancreaticoduodenectomy

OBJECTIVES

Signal intensity ratio of pancreas to spleen (SI ratio p/s ) on fat-suppressed T1-weighted images of magnetic resonance imaging has been associated with pancreatic exocrine function. We here investigated the predictive value of the SI ratio p/s for the development of nonalcoholic fatty liver disease (NAFLD) after pancreaticoduodenectomy (PD).

MATERIALS AND METHODS

This study comprised 208 patients who underwent PD. NAFLD was defined as a liver-to-spleen attenuation ratio of <0.9 calculated by a computed tomography 1 year after surgery. SI ratio p/s was calculated by dividing the average pancreas SI by the spleen SI. We retrospectively investigated the association of clinical variables including the SI ratio p/s and NAFLD by univariate and multivariate analyses.

RESULTS

NAFLD after 1 year was developed in 27 patients (13%). In multivariate analysis, the SI ratio p/s < 1 ( P < 0.001) was an independent predictor of incidence of NAFLD. The SI ratio p/s < 1 was associated with low amylase level of the pancreatic juice ( P < 0.001) and progressed pancreatic fibrosis ( P = 0.017). According to the receiver operating characteristics curve, the SI ratio p/s had better prognostic ability of NAFLD than the remnant pancreas volume.

CONCLUSIONS

The SI ratio p/s is useful to predict NAFLD development after PD. Moreover, the SI ratio p/s can be a surrogate marker, which represents exocrine function of the pancreas.

Comparing the distal pancreatectomy fistula risk score (D-FRS) and DISPAIR-FRS for predicting pancreatic fistula after distal pancreatectomy

BACKGROUNDS

Distal pancreatectomy fistula risk score (D-FRS) and DISPAIR-FRS has not been widely validated for predicting postoperative pancreatic fistula (POPF) after distal pancreatectomy (DP).

METHODS

We retrospectively analysed 104 patients undergoing DP. The predictive value of the D-FRS and DISPAIR-FRS were compared. Risk factors associated with POPF were investigated by multivariate analysis.

RESULTS

Of the 104 patients, 23 (22.1%) were categorized into the POPF group (all grade B). The areas under the ROC (AUCs) of the D-FRS (preoperative), D-FRS (intraoperative), and DISPAIR-FRS were 0.737, 0.809, and 0.688, respectively. Stratified by the D-FRS (preoperative), the POPF rates in low-risk, intermediate-risk, and high-risk groups were 5%, 22.6%, and 36.4%, respectively. By the D-FRS (intraoperative), the POPF rates in low-risk, intermediate-risk, and high-risk groups were 8.8%, 47.1%, and 47.4%, respectively. By the DISPAIR-FRS, the POPF rates in low-risk, intermediate-risk, and extreme-high-risk groups were 14.8%, 23.8% and 62.5%, respectively. Body mass index and main pancreatic duct diameter were independent risk factors of POPF both in preoperative (P = 0.014 and P = 0.033, respectively) and intraoperative (P = 0.015 and P = 0.039) multivariate analyses.

CONCLUSION

Both the D-FRS (preoperative), D-FRS (intraoperative), and DISPAIR-FRS has good performance in POPF prediction after DP. The risk stratification was not satisfactory in current Asian cohort.

Tomoelastography and Pancreatic Extracellular Volume Fraction Derived From MRI for Predicting Clinically Relevant Postoperative Pancreatic Fistula

BACKGROUND

Pancreatic stiffness and extracellular volume fraction (ECV) are potential imaging biomarkers for pancreatic fibrosis. Clinically relevant postoperative fistula (CR-POPF) is one of the most severe complications after pancreaticoduodenectomy. Which imaging biomarker performs better for predicting the risk of CR-POPF remains unknown.

PURPOSE

To evaluate the diagnostic performance of ECV and tomoelastography-derived pancreatic stiffness for predicting the risk of CR-POPF in patients undergoing pancreaticoduodenectomy.

STUDY TYPE

Prospective.

POPULATION

Eighty patients who underwent multiparametric pancreatic MRI before pancreaticoduodenectomy, among whom 16 developed CR-POPF and 64 did not.

FIELD STRENGTH/SEQUENCE

3 T/tomoelastography and precontrast and postcontrast T1 mapping of the pancreas.

ASSESSMENT

Pancreatic stiffness was measured on the tomographic c-map, and pancreatic ECV was calculated from precontrast and postcontrast T1 maps. Pancreatic stiffness and ECV were compared with histological fibrosis grading (F0-F3). The optimal cutoff values for predicting CR-POPF were determined, and the correlation between CR-POPF and imaging parameters was evaluated.

STATISTICAL TESTS

The Spearman's rank correlation and multivariate linear regression analysis was conducted. The receiver operating characteristic curve analysis and logistic regression analysis was performed. A double-sided P < 0.05 indicated a statistically significant difference.

RESULTS

Pancreatic stiffness and ECV both showed a significantly positive correlation with histological pancreatic fibrosis (r = 0.73 and 0.56, respectively). Patients with advanced pancreatic fibrosis had significantly higher pancreatic stiffness and ECV compared to those with no/mild fibrosis. Pancreatic stiffness and ECV were also correlated with each other (r = 0.58). Lower pancreatic stiffness (<1.38 m/sec), lower ECV (<0.28), nondilated main pancreatic duct (<3 mm) and pathological diagnosis other than pancreatic ductal adenocarcinoma were associated with higher risk of CR-POPF at univariate analysis, and pancreatic stiffness was independently associated with CR-POPF at multivariate analysis (odds ratio: 18.59, 95% confidence interval: 4.45, 77.69).

DATA CONCLUSION

Pancreatic stiffness and ECV were associated with histological fibrosis grading, and pancreatic stiffness was an independent predictor for CR-POPF.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 5.

Quantitative Magnetic Resonance Imaging for the Pancreas: Current Status

ABSTRACT

Magnetic resonance imaging (MRI) is important for evaluating pancreatic disorders, and anatomical landmarks play a major role in the interpretation of results. Quantitative MRI is an effective diagnostic modality for various pathologic conditions, as it allows the investigation of various physical parameters. Recent advancements in quantitative MRI techniques have significantly improved the accuracy of pancreatic MRI. Consequently, this method has become an essential tool for the diagnosis, treatment, and monitoring of pancreatic diseases. This comprehensive review article presents the currently available evidence on the clinical utility of quantitative MRI of the pancreas.

The Role of Diffusion-Weighted Imaging in the Evaluation of Treatment of Newly Diagnosed Type 2 Diabetic Patients

INTRODUCTION

To compare the pre and post-treatment pancreatic apparent diffusion coefficient (ADC) values of type II diabetes patients with control subjects, and also to evaluate its effectiveness in evaluating the response to treatment.

METHODS

The study included 35 newly diagnosed type 2 diabetic patients and 35 non-diabetic participants, matched for sex and age. Insulin and metformin treatment was given to the patients. Abdominal diffusion-weighted MR imaging was performed before and after the treatment. ADCs of the control group and patients pre and post-treatment were compared. In addition, the clinical parameters of the patients related to diabetes were recorded.

RESULTS

There was a significant difference between the median pancreatic ADC values of the patients pre and post-treatment. While there was a significant difference between the median pancreatic ADC values of the patient and the control groups before the treatment, no significant difference after the treatment was observed. There was a positive correlation between mean pancreatic ADC values and age, as well as a negative correlation with Hb1Ac level and eGFR.

CONCLUSION

Pancreatic ADC values of newly diagnosed type II diabetes patients can be used as a marker of pancreatic function in the evaluation of response to treatment and clinical decisions.

Diagnosis of chronic pancreatitis using semi-quantitative MRI features of the pancreatic parenchyma: results from the multi-institutional MINIMAP study

PURPOSE

To determine the diagnostic performance of parenchymal MRI features differentiating CP from controls.

METHODS

This prospective study performed abdominal MRI scans at seven institutions, using 1.5 T Siemens and GE scanners, in 50 control and 51 definite CP participants, from February 2019 to May 2021. MRI parameters included the T1-weighted signal intensity ratio of the pancreas (T1 score), arterial-to-venous enhancement ratio (AVR) during venous and delayed phases, pancreas volume, and diameter. We evaluated the diagnostic performance of these parameters individually and two semi-quantitative MRI scores derived using logistic regression: SQ-MRI Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume).

RESULTS

When compared to controls, CP participants showed a significantly lower mean T1 score (1.11 vs. 1.29), AVR venous (0.86 vs. 1.45), AVR delayed (1.07 vs. 1.57), volume (54.97 vs. 80.00 ml), and diameter of the head (2.05 vs. 2.39 cm), body (2.25 vs. 2.58 cm), and tail (1.98 vs. 2.51 cm) (p < 0.05 for all). AUCs for these individual MR parameters ranged from 0.66 to 0.79, while AUCs for the SQ-MRI scores were 0.82 and 0.81 for Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume), respectively. After propensity-matching adjustments for covariates, AUCs for Models A and B of the SQ-MRI scores increased to 0.92 and 0.93, respectively.

CONCLUSION

Semi-quantitative parameters of the pancreatic parenchyma, including T1 score, enhancement ratio, pancreas volume, diameter and multi-parametric models combining these parameters are helpful in diagnosis of CP. Longitudinal analyses including more extensive population are warranted to develop new diagnostic criteria for CP.

Radiological parameters to predict pancreatic texture: Current evidence and future perspectives

Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management, thereby minimizing postoperative morbidity. Pancreatic duct diameter can be readily measured by any routine imaging used to diagnose pancreatic disease. However, radiological evaluation of pancreatic texture, an important determinant of pancreatic fistula, has not been widely used to predict the risk of postoperative pancreatic fistula. Qualitative and quantitative assessment of pancreatic fibrosis and fat fraction provides the basis for predicting pancreatic texture. Traditionally computed tomography has been utilized in identifying and characterizing pancreatic lesions and background parenchymal pathologies. With the increasing utilisation of endoscopic ultrasound and magnetic resonance imaging for evaluating pancreatic pathologies, elastography is emerging as a promising tool for predicting pancreatic texture. Also, recent studies have shown that early surgery for chronic pancreatitis is associated with better pain relief and preservation of pancreatic function. Pancreatic texture assessment can allow early diagnosis of chronic pancreatitis, facilitating early intervention. The present review outlines the current evidence in utilizing various imaging modalities for determining the pancreatic texture based on different parameters and image sequences. However, multidisciplinary investigations using strong radiologic-pathologic correlation are needed to standardize and establish the role of these non-invasive diagnostic tools in predicting pancreatic texture.

Automated whole-volume measurement of CT fat fraction of the pancreas: correlation with Dixon MR imaging

OBJECTIVES

This study aimed to assess the feasibility of pancreatic steatosis quantification by automated whole-volume measurement of the fat fraction of the pancreas on CT in comparison to MRI using proton-density fat fraction (PDFF) techniques.

METHODS

Fifty-nine patients who underwent both CT and MRI were analyzed. Automated whole-volume measurement of pancreatic fat on unenhanced CT was performed by a histogram analysis with local thresholding. Three sets of CT fat volume fraction (FVF) (%) values with thresholds of -30 Hounsfield unit (HU), -20 HU and -10 HU were compared to MR-FVF (%) values measured on a PDFF map.

RESULTS

The median -30 HU CT-FVF, -20 HU CT-FVF, -10 HU CT-FVF and MR-FVF values of the pancreas were 8.6% (interquartile range (IQR), 11.3), 10.5% (IQR, 13.2), 13.4% (IQR, 16.1) and 10.9% (IQR, 9.7), respectively. The -30 HU CT-FVF (%), -20 HU CT-FVF (%) and -10 HU CT-FVF (%) of the pancreas showed a significant positive correlation with the MR-FVF (%) of the pancreas (ρ = 0.898, p < 0.001, ρ = 0.905, p < 0.001, ρ = 0.909, p < 0.001, respectively). The -20 HU CT-FVF (%) displayed reasonable agreement with the MR-FVF (%) with a low absolute fixed bias (mean difference, 0.32%; limit of agreement from -10.1 to 10.7%).

CONCLUSION

The automated whole-volume measurement of the CT fat fraction of the pancreas using the threshold CT attenuation value of -20 HU may be a feasible, non-invasive, and convenient technique for quantifying pancreatic steatosis.

ADVANCES IN KNOWLEDGE

CT-FVF value of the pancreas had a positive correlation with the MR-FVF value. The -20 HU CT-FVF may be a convenient technique for quantifying pancreatic steatosis.

T2-weighted MRI and reduced-FOV diffusion-weighted imaging of the human pancreas at 5 T: A comparison study with 3 T

PURPOSE

The purpose of this study was to explore the feasibility of pancreatic imaging at 5 T and evaluate the practical improvement of T2-weighted MRI and diffusion-weighted imaging (DWI) at 5 T as compared with 3 T.

METHODS

Eighteen healthy subjects were recruited for this pilot study. MRI examinations were performed using 3 and 5 T scanners. MRI sequences included T2-weighted fast spin-echo and DWI with reduced field-of-view. Subjective image analysis using a four-point Likert scale was performed by two experienced radiologists. The SNR, contrast ratio, and apparent diffusion coefficient (ADC) were measured in the pancreatic head, body, and tail. The coefficient of variation (CV) of the ADC was calculated. A series of paired Wilcoxon tests were used to compare the subjective image quality, mean ADC value, and CV of ADC between the 3 and 5 T measurements. p <0.05 was considered statistically significant.

RESULTS

For T2-weighted images, there were no significant differences in image quality ratings between 3 and 5 T. On DWI images (b = 0 and 800 s/mm² ), the image quality ratings were significantly higher at 5 T than at 3 T. The SNRs of both T2-weighted and DWI images were significantly higher at 5 T. There was no significant difference in the mean ADC values and CV of ADC between 3 and 5 T.

CONCLUSION

This initial study proved that 5 T MRI can be used to acquire pancreatic images with higher SNR and sufficient image quality compared to 3 T MRI.

Quantitative MRI of chronic pancreatitis: results from a multi-institutional prospective study, magnetic resonance imaging as a non-invasive method for assessment of pancreatic fibrosis (MINIMAP)

PURPOSE

To determine if quantitative MRI techniques can be helpful to evaluate chronic pancreatitis (CP) in a setting of multi-institutional study.

METHODS

This study included a subgroup of participants (n = 101) enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study (NCT03099850) from February 2019 to May 2021. MRI was performed on 1.5 T using Siemens and GE scanners at seven clinical centers across the USA. Quantitative MRI parameters of the pancreas included T1 relaxation time, extracellular volume (ECV) fraction, apparent diffusion coefficient (ADC), and fat signal fraction. We report the diagnostic performance and mean values within the control (n = 50) and CP (n = 51) groups. The T1, ECV and fat signal fraction were combined to generate the quantitative MRI score (Q-MRI).

RESULTS

There was significantly higher T1 relaxation time; mean 669 ms (± 171) vs. 593 ms (± 82) (p = 0.006), ECV fraction; 40.2% (± 14.7) vs. 30.3% (± 11.9) (p < 0.001), and pancreatic fat signal fraction; 12.2% (± 5.5) vs. 8.2% (± 4.4) (p < 0.001) in the CP group compared to controls. The ADC was similar between groups (p = 0.45). The AUCs for the T1, ECV, and pancreatic fat signal fraction were 0.62, 0.72, and 0.73, respectively. The composite Q-MRI score improved the diagnostic performance (cross-validated AUC: 0.76).

CONCLUSION

Quantitative MR parameters evaluating the pancreatic parenchyma (T1, ECV fraction, and fat signal fraction) are helpful in the diagnosis of CP. A Q-MRI score that combines these three MR parameters improves diagnostic performance. Further studies are warranted with larger study populations including patients with acute and recurrent acute pancreatitis and longitudinal follow-ups.

T1 signal intensity ratio of the pancreas as an imaging biomarker for the staging of chronic pancreatitis

PURPOSE

Our purpose was to validate the T1 SIR (T1 score) as an imaging biomarker for the staging of CP in a large, multi-institutional, prospective study.

METHODS

The prospective study population included 820 participants enrolled in the PROCEED study from nine clinical centers between June 2017 and December 2021. A radiologist at each institution used a standardized method to measure the T1 signal intensity of the pancreas and the reference organs (spleen, paraspinal muscle, liver), which was used to derive respective T1 scores. Participants were stratified according to the seven mechanistic stages of chronic pancreatitis (MSCP 0-6) based on their clinical history, MRCP, and CT findings.

RESULTS

The mean pancreas-to-spleen T1 score was 1.30 in participants with chronic abdominal pain, 1.22 in those with acute or recurrent acute pancreatitis, and 1.03 in definite CP. After adjusting for covariates, we observed a linear, progressive decline in the pancreas-to-spleen T1 score with increasing MSCP from 0 to 6. The mean pancreas-to-spleen T1 scores were 1.34 (MSCP 0), 1.27 (MSCP 1), 1.21 (MSCP 2), 1.16 (MSCP 3), 1.18 (MSCP 4), 1.12 (MSCP 5), and 1.05 (MSCP 6) (p < 0.0001). The pancreas-to-liver and pancreas-to-muscle T1 scores showed less linear trends and wider confidence intervals.

CONCLUSION

The T1 score calculated by SIR of the pancreas-to-spleen shows a negative linear correlation with the progression of chronic pancreatitis. It holds promise as a practical imaging biomarker in evaluating disease severity in clinical research and practice.

The pancreas-to-muscle signal intensity ratio on T1-weighted MRI as a predictive biomarker for postoperative pancreatic fistula after distal pancreatectomy: a single-center retrospective study

BACKGROUND

Postoperative pancreatic fistula (POPF) is one of the serious complications of pancreatic surgery. When POPF occurs and becomes severe, it causes secondary complications and a longer treatment period. We previously reported a correlation between pancreatic fibrosis and magnetic resonance imaging (MRI) findings, and MRI may have the potential to predict POPF. This study aimed to assess the predictive ability of the pancreas-to-muscle signal intensity ratio on T₁-weighted MRI (SIR on T₁-w MRI) for POPF after distal pancreatectomy (DP).

METHODS

This single-institution retrospective study comprised 117 patients who underwent DP. It was conducted between 2010 and 2021 at the Gifu University Hospital. We statistically analyzed pre-, intra-, and postoperative factors to assess the correlation with POPF.

RESULTS

According to the definition and grading of the International Study Group of Pancreatic Fistula (ISGPF), 29 (24.8%) of the 117 patients had POPF grades B and C. In the univariate analysis, POPF was significantly associated with the pancreas-to-muscle SIR on T₁-w MRI, the drainage fluid amylase concentration (D-Amy) levels on postoperative day (POD) 1 and 3, white blood cell count on POD 1 and 3, C-reactive protein level on POD 3, and heart rate on POD 3. In multivariate analysis, only the pancreas-to-muscle SIR on T₁-w MRI (>1.37; odds ratio [OR] 23.25; 95% confidence interval [CI] 3.93-454.03; p < 0.01) and D-Amy level on POD 3 (>737 U/l; OR 3.91; 95% CI 1.02-16.36; p = 0.046) were identified as independent predictive factors.

CONCLUSIONS

The pancreas-to-muscle SIR on T₁-w MRI and postoperative D-Amy levels were able to predict the development of POPF after DP. The pancreas-to-muscle SIR on T₁-w MRI may be a potential objective biomarker reflecting pancreatic status.

Early Predictive Factors for Postoperative Pancreatic Fistula After Distal Pancreatectomy for Pancreatic Cancer

BACKGROUND/AIM

Postoperative pancreatic fistula (POPF) is the most serious complication of distal pancreatectomy (DP). When POPF occurs and becomes severe, it causes secondary complications and leads to a longer treatment period. This study aimed to identify early predictive factors of POPF after DP for pancreatic cancer (PC).

PATIENTS AND METHODS

This retrospective, single-institution study comprised of 55 patients with PC who underwent DP between 2010 and 2021 at the Gifu University Hospital. We statistically analyzed pre-, intra-, and post-operative factors to identify early predictive factors for POPF.

RESULTS

According to the definition and grading of the International Study Group of Pancreatic Fistula (ISGPF), 12 (21.8%) of 55 patients had POPF grades B and C. In the univariate analysis, POPF was significantly associated with the pancreas-to-muscle signal intensity ratio on T ₁ -weighted magnetic resonance imaging (SIR on T ₁ -w MRI), the drainage fluid amylase (D-Amy) levels on postoperative day 3 (POD3), C-reactive protein (CRP) on POD3, and heart rate on POD3. In multivariate analysis, pancreas-to-muscle SIR on T ₁ -w MRI [>1.37; odds ratio (OR)=17.08; 95% confidence interval (CI)=1.64-598.16; p=0.02], D-Amy levels on POD3 (>1,200 U/l; OR=20.00; 95% CI=1.73-563.83; p=0.02) and heart rate on POD3 (>100 bpm; OR=15.33; 95% CI=1.53-258.45; p=0.02) were identified as independent early predictive factors.

CONCLUSION

Preoperative pancreas-to-muscle SIR on T ₁ -w MRI and postoperative D-Amy levels and heart rate significantly correlated with POPF after DP for PC. Postoperative management based on these predictive factors may improve the postoperative course.

Histopathologic correlation of pancreatic fibrosis with pancreatic magnetic resonance imaging quantitative metrics and Cambridge classification

PURPOSE

To determine the correlation of the T1-weighted signal intensity ratio (T1 SIR, or T1 Score) and arterial-to-delayed venous enhancement ratio (ADV ratio) of the pancreas with pancreatic fibrosis on histopathology.

METHODS

Sixty consecutive adult CP patients who had an MRI/MRCP study prior to pancreatic surgery were analyzed. Three blinded observers measured T1 SIR of pancreas to spleen (T1 SIR p/s), pancreas-to-paraspinal muscle (T1 SIR p/m), ADV ratio, and Cambridge grade. Histopathologic grades were given by a gastrointestinal pathologist using Ammann's fibrosis score. Statistical analysis included Spearman's correlation coefficient of the T1 SIR, ADV ratio, Cambridge grade with the fibrosis score, and weighted kappa for interobserver agreement.

RESULTS

The study population included 31 female and 29 male patients, with an average age of 52.1 (26-78 years). Correlations between fibrosis score and T1 SIR p/s, T1 SIR p/m, and ADV ratio were ρ = - 0.54 (p = 0.0001), ρ = - 0.19 (p = 0.19), and ρ = - 0.39 (p = 0.003), respectively. The correlation of Cambridge grade with fibrosis score was ρ = 0.26 (p = 0.07). There was substantial interobserver agreement (weighted kappa) for T1 SIR p/s (0.78), T1 SIR p/m (0.71), and ADV ratio (0.64). T1 SIR p/s of ≤ 1.20 provided a sensitivity of 74% and specificity of 50% (AUC: 0.74), while ADV ratio of ≤ 1.10 provided a sensitivity of 75% and specificity of 55% (AUC: 0.68) to detect a fibrosis score of ≥ 6.

CONCLUSION

There is a moderate negative correlation between the T1 Score (SIR p/s) and ADV ratio with pancreatic fibrosis and a substantial interobserver agreement. These parenchymal metrics show a higher correlation than the Cambridge grade.

Dual-Energy CT Iodine Concentration to Evaluate Postoperative Pancreatic Fistula after Pancreatoduodenectomy

Background Pancreatic fibrosis and fatty infiltration are associated with postoperative pancreatic fistula (POPF), but accurate preoperative assessment remains a challenge. Iodine concentration (IC) and fat fraction derived from dual-energy CT (DECT) may reflect the amount of fibrosis and steatosis, potentially enabling the preoperative prediction of POPF. Purpose To identify multiphasic DECT-derived IC and fat fraction that improve the prediction of POPF risks compared with contrast-enhanced CT attenuation values and to evaluate the underlying histopathologic changes. Materials and Methods This retrospective study included patients who underwent pancreatoduodenectomy and DECT (including pancreatic parenchymal, portal venous, and delayed phase scanning) between January 2020 and December 2020. The relationships of the quantitative DECT-derived IC and fat fraction, along with CT attenuation values from enhanced images with POPF risk, were analyzed with logistic regression analysis. The predictive performance of the IC was compared with that of the CT values. The histopathologic underpinnings of IC were evaluated with multivariable linear regression analysis. Results A total of 107 patients (median age, 65 years; interquartile range, 57-70 years; 56 men) were included. Of these, 23 (21%) had POPF. The pancreatic parenchymal-to-portal venous phase IC ratio (adjusted odds ratio [OR], 13; 95% CI: 2, 162; P < .001) was an independent predictor of POPF occurrence. The accuracy of the pancreatic parenchymal-to-portal venous phase IC ratio in predicting POPF was higher than that of the CT value ratio in the same phases (78% vs 65%, P < .001). The pancreatic parenchymal-to-portal venous phase IC ratio was independently associated with pancreatic fibrosis (β = -1.04; 95% CI: -0.44, -1.64; P = .001). Conclusion A higher pancreatic parenchymal-to-portal venous phase IC ratio was associated with less histologic fibrosis and greater risk of POPF. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Lee and Yoon in this issue.

Non-Invasive Monitoring of Increased Fibrotic Tissue and Hyaluronan Deposition in the Tumor Microenvironment in the Advanced Stages of Pancreatic Ductal Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with a poor prognosis. A better understanding of the tumor microenvironment may help better treat the disease. Magnetic resonance imaging may be a great tool for monitoring the tumor microenvironment at different stages of tumor evolution. Here, we used multi-parametric magnetic resonance imaging techniques to monitor underlying pathophysiologic processes during the advanced stages of tumor development and correlated with histologic measurements.

Abstract

Pancreatic ductal adenocarcinomas are characterized by a complex and robust tumor microenvironment (TME) consisting of fibrotic tissue, excessive levels of hyaluronan (HA), and immune cells. We utilized quantitative multi-parametric magnetic resonance imaging (mp-MRI) methods at 14 Tesla in a genetically engineered KPC (Kras^LSL-G12D/+, Trp53^LSL-R172H/+, Cre) mouse model to assess the complex TME in advanced stages of tumor development. The whole tumor, excluding cystic areas, was selected as the region of interest for data analysis and subsequent statistical analysis. Pearson correlation was used for statistical inference. There was a significant correlation between tumor volume and T2 (r = −0.66), magnetization transfer ratio (MTR) (r = 0.60), apparent diffusion coefficient (ADC) (r = 0.48), and Glycosaminoglycan-chemical exchange saturation transfer (GagCEST) (r = 0.51). A subset of mice was randomly selected for histological analysis. There were positive correlations between tumor volume and fibrosis (0.92), and HA (r = 0.76); GagCEST and HA (r = 0.81); and MTR and CD31 (r = 0.48). We found a negative correlation between ADC low-b (perfusion) and Ki67 (r = −0.82). Strong correlations between mp-MRI and histology results suggest that mp-MRI can be used as a non-invasive tool to monitor the tumor microenvironment.

Association between pancreatic fibrosis and development of pancreoprivic diabetes after pancreaticoduodenectomy

This study investigated the correlation between pancreatic fibrosis (PF) and development of pancreoprivic diabetes after pancreaticoduodenectomy (PD). Ninety-five patients who underwent PD at Gangnam Severance Hospital between 2014 and 2017 were enrolled. PF grade was evaluated with alpha-smooth muscle actin (SMA) and Masson’s trichrome (TRC) staining. New-onset pancreoprivic diabetes and recurrence of disease were evaluated using fasting blood glucose measurement and radiography taken at 3-month intervals. Sixty-one patients did not have preoperative diabetes, however, 40 (65.6%) patients developed pancreoprivic diabetes after PD. High-grade PF was more common in the diabetes group than in the normal group (SMA, 42.5% vs. 28.6%, P = 0.747; TRC, 47.5% vs. 28.6%, P = 0.361). The 1-year cumulative incidence of hyperglycemia/pancreoprivic diabetes was higher with high-grade PF than low-grade PF (SMA, 94.4% vs. 73.0%, P = 0.027; TRC, 89.3% vs. 75.0%, P = 0.074). The SMA-TRC combined high-grade group had a higher proportion of primary pancreatic disease than the combined low-grade group (90.0% vs. 37.5%, P = 0.001). The 5-year disease-free survival of patients with pancreatic cancer was worse with high-grade PF than low-grade PF (SMA, 24.5% vs. 66.3%, P = 0.026; TRC, 23.6% vs. 58.4%, P = 0.047). In conclusion, patients with severe PF are more likely to develop pancreoprivic diabetes after PD and have worse disease-free survival.

Prediction of pancreatic fistula after pancreatectomy by virtual touch tissue imaging and quantification (VTIQ) technology

OBJECTIVES

The aim of this study was to quantitatively evaluate the stiffness of pancreatic parenchyma and solid focal pancreatic lesions (FPLs) by virtual touch tissue imaging and quantification (VTIQ) technique and to investigate the potential usefulness of VTIQ method in the prediction of post-operative pancreatic fistula (POPF) after pancreatectomy.

METHODS

In this prospective study, patients who scheduled to undergo pancreatectomy were initially enrolled and received VTIQ assessment within one week before surgery. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used to measure the shear wave velocity (SWV) value of FPLs and the body part pancreatic parenchyma. The palpation stiffness of pancreas was qualitatively evaluated during operation by surgeons. POPF was finally diagnosed and graded through a three-weeks post-operative follow-up according to international study group of pancreatic fistula (ISGPF). SWV values were compared between POPF positive and negative group. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy of SWV value in predicting POPF.

RESULTS

From December 2020 to June 2021, 44 patients were finally enrolled in this study, among which, 26 patients were identified to develop POPF after pancreatectomy. The SWV value of pancreatic parenchyma in POPF positive group was significantly lower than that in POPF negative group (P = 0.001). However, there was no significant difference in palpation stiffness between the two groups (P = 0.124). Besides, neither the SWV value of FPL nor the SWV ratio between FPL to surrounding pancreatic parenchyma differ significantly between POPF positive and negative group (P > 0.05). Taking SWV value of pancreatic parenchyma >1.10 m/s as a cut-off value for predicting POPF, area under the receiver operating characteristic curve (AUROC) was 0.864 with 72.2% sensitivity, 92.3% specificity, 86.7% positive predictive value (PPV) and 82.8% negative predictive value (NPV), respectively.

CONCLUSIONS

VTIQ technique might be a potential non-invasive imaging method to predict POPF before pancreatectomy in future clinical practice.

A modified alternative fistula risk score (a-FRS) obtained from the computed tomography enhancement pattern of the pancreatic parenchyma predicts pancreatic fistula after pancreatoduodenectomy

BACKGROUND

Alternative fistula risk score (a-FRS) is useful to predict clinically relevant postoperative pancreatic fistula (CR-POPF) after pancreatoduodenectomy (PD).

METHODS

Clinical data from 239 patients undergoing PD were collected. The CT value of the pancreatic parenchyma was measured in the nonenhanced (N), arterial (A), portal venous (P), and late (L) phases. The A/N, A/P, P/L and A/L ratios were calculated and their correlation with CR-POPF were analyzed. By replacing pancreatic texture with the best CT attenuation ratio, a modified a-FRS was developed.

RESULTS

Forty-seven patients developed CR-POPF. The A/P ratio (P < 0.001), P/L ratio (P = 0.002) and A/L ratio (P < 0.001) were significantly higher in the CR-POPF group. The A/L ratio performed best in predicting CR-POPF (AUC: 0.803) and the cut-off value is 1.36. A/L ratio >1.36 (P < 0.001), body mass index (P = 0.005) and duct diameter (P = 0.037) were independently associated with CR-POPF. By replacing soft texture with an A/L ratio >1.36, a modified a-FRS was developed and performed better than the a-FRS (AUC: 0.823 vs 0.748, P = 0.006) in predicting CR-POPF.

CONCLUSIONS

The modified a-FRS is an objective and preoperative model for predicting the occurrence of CR-POPF after PD.

Role of standardized reporting and novel imaging markers in chronic pancreatitis

PURPOSE OF REVIEW

This article reviews recent efforts about standardized imaging features and reporting of chronic pancreatitis and recently published or ongoing imaging studies, which aim to establish novel imaging biomarkers for detection of parenchymal changes seen in chronic pancreatitis.

RECENT FINDINGS

New novel MRI techniques are being developed to increase the diagnostic yield of chronic pancreatitis specifically in the early stage. T1 relaxation time, T1 signal intensity ratio and extracellular volume fraction offer potential advantages over conventional cross-sectional imaging, including simplicity of analysis and more objective interpretation of observations allowing population-based comparisons. In addition, standardized definitions and reporting guidelines for chronic pancreatitis based on available evidence and expert consensus have been proposed. These new imaging biomarkers and reporting guidelines are being validated for prognostic/therapeutic assessment of adult patients participating in longitudinal studies of The Consortium for the Study of Chronic Pancreatitis, Diabetes and Pancreatic Cancer.

SUMMARY

New imaging biomarkers derived from novel MRI sequences promise a new chapter for diagnosis and severity assessment of chronic pancreatitis; a cross-sectional imaging-based diagnostic criteria for chronic pancreatitis combining ductal and parenchymal findings. Standardized imaging findings and reporting guidelines of chronic pancreatitis would enhance longitudinal assessment of disease severity in clinical trials and improve communication between radiologists and pancreatologists in clinical practice.

Can magnetic resonance imaging radiomics of the pancreas predict postoperative pancreatic fistula?

OBJECTIVES

To evaluate whether a magnetic resonance imaging (MRI) radiomics-based machine learning classifier can predict postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD) and to compare its performance to T1 signal intensity ratio (T1 SIratio).

METHODS

Sixty-two patients who underwent 3 T MRI before PD between 2008 and 2018 were retrospectively analyzed. POPF was graded and split into clinically relevant POPF (CR-POPF) vs. biochemical leak or no POPF. On T1- and T2-weighted images, 2 regions of interest were placed in the pancreatic corpus and cauda. 173 radiomics features were extracted using pyRadiomics. Additionally, the pancreas-to-muscle T1 SIratio was measured. The dataset was augmented and split into training (70 %) and test sets (30 %). A Boruta algorithm was used for feature reduction. For prediction of CR-POPF models were built using a gradient-boosted tree (GBT) and logistic regression from the radiomics features, T1 SIratio and a combination of the two. Diagnostic accuracy of the models was compared using areas under the receiver operating characteristics curve (AUCs).

RESULTS

Five most important radiomics features were identified for prediction of CR-POPF. A GBT using these features achieved an AUC of 0.82 (95 % Confidence Interval [CI]: 0.74 - 0.89) when applied on the original (non-augmented) dataset. Using T1 SIratio, a GBT model resulted in an AUC of 0.75 (CI: 0.63 - 0.84) and a logistic regression model delivered an AUC of 0.75 (CI: 0.63 - 0.84). A GBT model combining radiomics features and T1 SIratio resulted in an AUC of 0.90 (CI 0.84 - 0.95).

CONCLUSION

MRI-radiomics with routine sequences provides promising prediction of CR-POPF.

Evaluation of Pancreatic Fibrosis Grading by Multi Parametric Quantitative Magnetic Resonance Imaging

BACKGROUND

Early detection and grading of pancreatic fibrosis (PF) are important and challenging clinical goals.

PURPOSE

To determine main pancreatic duct (MPD) diameter, pancreatic thickness, and grades of PF via magnetic resonance elastography (MRE), T1 mapping, and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), assessing respective diagnostic performances.

STUDY TYPE

Prospective.

SUBJECTS

Histopathologic and imaging records (MRE, T1 mapping, and IVIM-DWI) generated by 144 patients between December 2018 and May 2020 were collected for analysis. Grades of PF were distributed as follows: F0, 82; F1, 22; F2, 22; and F3, 18.

FIELD STRENGTH/SEQUENCE

3 T pancreatic MRI, encompassing MRE, T1 mapping, and IVIM-DWI.

ASSESSMENT

In all patients, T1 relaxation times, pancreatic stiffness values, IVIM-DWI parameters, MPD diameter, and pancreatic thickness were measured.

STATISTICAL TESTS

Receiver operating characteristic (ROC) analysis served to assess imaging parameters useful in diagnosing PF. To identify relations between specific parameters and grades of PF, logistic regression analysis was invoked.

RESULTS

Both pancreatic stiffness (r = 0.754; P < 0.001) and T1 relaxation time (r = 0.433; P < 0.001) correlated significantly with PF (%). To determine PF grades ≥F1, a combined model (area under the curve [AUC] = 0.906) performed significantly better than pancreatic stiffness (AUC = 0.855; P < 0.001) or T1 relaxation time (AUC = 0.754; P < 0.001) alone. For PF grades ≥F2 or grade F3, both the combined model (≥F2: AUC = 0.910; F3: AUC = 0.939) and pancreatic stiffness (≥F2: AUC = 0.906; F3: AUC = 0.929) outperformed T1 relaxation time (≥F2: AUC = 0.768 [P = 0.005 and P = 0.004, respectively]; F3: AUC = 0.816 [both P < 0.005]). All IVIM-DWI parameters generated AUC values <0.700.

DATA CONCLUSION

A combination of MRE and T1 mapping seems promising in diagnosing various grades of PF, particularly at an early stage.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.

Use of gadoxetic acid-enhanced MRI to predict the development of postoperative pancreatic fistulas by estimating the degree of pancreatic fibrosis

BACKGROUND

Postoperative pancreatic fistula (POPF) can be life-threatening, and gadoxetic acid-enhanced MRI is routinely performed in patients undergoing pancreatic surgery. However, previous reports have not investigated if gadoxetic acid-enhanced MRI can be used to predict POPF risk.

OBJECTIVE

This study aims to explore if gadoxetic acid-enhanced MRI can predict pancreatic fibrosis and the need for POPF treatment before surgery.

METHOD

We retrospectively analyzed gadoxetic acid-enhanced MR images from 142 patients who underwent pancreatic surgery between January 1, 2011, and April 30, 2018. Pre-dynamic signal intensity (SI) and values for portal, transitional, and hepatobiliary phase standardized based on pre-dynamic study values were analyzed. The diameter of the main pancreatic duct (DMPD) was measured, and the degree of pancreatic fibrosis was classified as F0-F3. We defined POPF higher than grade B as significant.

RESULTS

Odds ratios for combinations that led to any degree of fibrosis higher than grade B were defined as significant risk factors. The highest odds ratio was obtained for F0 vs. F1-F3 (p = 0.038). DMPD (p < 0.001), pre-SI (p = 0.008), portal-SI/pre-SI (p < 0.001), transitional-SI/pre-SI (p < 0.001), and hepatobiliary-SI/pre-SI (p = 0.012) were significantly correlated with the presence of fibrosis. The presence of fibrosis was best detected by DMPD (AUC = 0.777). Individual specificity values of transitional-SI/pre-SI and DMPD were 95.5% and 86.6%, respectively, and their combined specificity was 97.7%.

CONCLUSION

The absence of pancreatic fibrosis is a risk factor for developing POPF higher than grade B. DMPD was the most useful diagnostic indicator of the presence of fibrosis among our analysis, and its specificity increased when combined with transitional-SI/pre-SI.

Differentiation between non-hypervascular pancreatic neuroendocrine tumors and mass-forming pancreatitis using contrast-enhanced computed tomography

BACKGROUND

Non-hypervascular pancreatic neuroendocrine tumors (PNETs) showed slight or iso-enhancement in contrast-enhanced computed tomography (CE-CT), which shared similar imaging findings with mass-forming pancreatitis (MFPs).

PURPOSE

To explore the value of CT imaging features in differentiating the two diseases.

MATERIAL AND METHODS

Fifty-one patients with histologically proved MFPs (n = 27) or non-hypervascular PNETs (n = 24) were included. Two radiologists reviewed CT imaging findings and clinical features. Logistic regression analysis was performed to identify relevant features in differentiating non-hypervascular PNETs and MFPs. Receiver operating characteristic (ROC) curve analysis was used to show the performance of the optimal parameters in differentiating non-hypervascular PNETs and MFPs.

RESULTS

A well-defined margin was more common in non-hypervascular PNETs (P < 0.05) than that in MFPs. MFPs often occurred in older people (P < 0.01) and the head-neck of the pancreas compared with non-hypervascular PNETs (P < 0.05). Metastases only presented in non-hypervascular PNETs (P < 0.05). CT values at venous phase and delay phase of MFPs were higher (P = 0.010 and P = 0.029) than those in non-hypervascular PNETs. Logistic analysis showed gender, tumor margin, CT values at venous phase, and tumor components were independent predictors in differentiating the two lesions. The area under the curve (AUC) was 0.938 with a sensitivity of 87.5% and specificity of 92.6% for combined predicators.

CONCLUSION

Gender, tumor margin, CT values at venous phase, and tumor components were useful predicators in differentiating non-hypervascular PNETs and MFPs.

[Predictors of external pancreatic fistulae after pancreatic resection]

Despite a significant decrease in postoperative mortality after pancreatic resections in recent years (5.2-15% after pancreatoduodenectomy and about 5% after distal pancreatectomy), incidence of postoperative complications remains high (30-50% and 22-50%, respectively). Postoperative pancreatic fistula is one of the most common and formidable complications. Currently, most authors use the classification proposed by the International Study Group for Pancreatic Fistula (biochemical failure, fistula type B and C). Prediction of the risk of postoperative fistula is still a complex and unresolved problem of modern surgical pancreatology. According to the literature, the main risk factors of postoperative pancreatic fistulae are obesity and high body mass index, concomitant cardiovascular diseases, no neoadjuvant chemo- and radiotherapy, soft pancreatic texture, narrow pancreatic duct, no fibrotic changes in parenchyma, adipose infiltration of the pancreas, advanced intraoperative blood loss, as well as center experience. Most often, magnetic resonance imaging, computed tomography, ultrasound elastography and various multivariate risk assessment systems are used to estimate the risk of pancreatic fistulae. However, a generally accepted technique does not exist. This manuscript is devoted to analysis of risk factors of postoperative pancreatic fistulae and diagnostic methods for assessment of this risk.

Computed tomography-adjusted fistula risk score for predicting clinically relevant postoperative pancreatic fistula after pancreatoduodenectomy: Training and external validation of model upgrade

BACKGROUND

To develop a modified Fistula Risk Score (FRS) for predicting clinically relevant postoperative pancreatic fistula (CR-POPF) after pancreatoduodenectomy (PD) based on both FRS and contrast-enhanced computed tomography (CE-CT).

METHODS

In this multicenter retrospective analysis, we focused on 990 consecutive patients with pancreatoduodenectomy performed at four institutions between 2009 and 2019. The enhanced CT-FRS model initially targeted 26 pre- and intraoperative factors, including CT descriptors, FRS elements and clinical factors, using LASSO-penalized multivariable logistic regression for predicting CR-POPF events in discovery (n = 718) and externally validated (n = 272) datasets. Probabilities generated were further correlated with histologic features of pancreatic stumps in 356 patients. C-indices were analyzed to compare the predictive potential between the original FRS and the CT-FRS.

FINDINGS

CR-POPF developed in 112 (15.6%) and 36 (13.2%) patients in discovery and validation datasets, respectively. The final CT-FRS construct, incorporating remnant pancreatic volume (RPV), stump area, fat and atrophy scores by CT, and main pancreatic duct size, offered significantly greater overall predictability than the original FRS in discovery (C-index: 0.825 vs 0.794; p = 0.04) and validation (0.807 vs 0.741; p = 0.05) cohorts. Importantly, it outperformed the FRS in patients at moderate risk levels (FRS: 3-6), showing remarkably improved C-indices (discovery: 0.729 vs 0.626 [p<0.001], validation: 0.722 vs 0.573 [p = 0.006]). CT-FRS probabilities increased in conjunction with less extensive pancreatic fibrosis (p<0.001), ample glandular acini (p<0.001), and advanced lipomatosis (p<0.001).

INTERPRETATION

The enhanced CT-FRS performed significantly better than the original FRS in predicting CR-POPF occurrences after PD, especially at moderate FRS levels.

Evaluation of Chronic Pancreatitis With T1 ρ MRI: A Preliminary Study

BACKGROUND

Chronic pancreatitis (CP) can result in persistent damage to the endocrine and exocrine tissues of the pancreas. There is an unmet need for quantitative methods to evaluate CP noninvasively.

PURPOSE

To investigate the utility of T₁ ρ magnetic resonance imaging (MRI) for the assessment of CP.

STUDY TYPE

Prospective.

POPULATION

Twenty patients with CP and 24 healthy volunteers.

FIELD STRENGTH/SEQUENCE

3T MRI including T₁ ρ sequence (spin lock time = 0, 1, 10, 20, 40, 60 msec).

ASSESSMENT

Pancreatic T₁ ρ values and anterior-posterior (AP) diameters in the head, body, and tail were measured in all participants. Regions of interest with circle (ROI_circle ) and free-hand (ROI_FH ) were drawn for T₁ ρ value measurements.

STATISTICAL TESTS

Mann-Whitney U-test; Wilcoxon Signed Ranks test; receiver operating characteristic (ROC) curve; and Bland-Altman analysis.

RESULTS

The T₁ ρ values of pancreatic tail and the mean T₁ ρ values for ROI_circle and the T₁ ρ values of pancreatic tail for ROI_FH in patients with CP were significantly higher than those in healthy volunteers (all P < 0.05). Pancreatic head AP diameter significantly increased, while pancreatic tail AP diameter significantly decreased in patients with CP compared with healthy volunteers (both P < 0.05). The areas under the ROC curves (AUCs) of pancreatic tail T₁ ρ values with ROI_circle and tail AP diameter in diagnosing CP were 0.744 and 0.798, respectively. A combination of pancreatic tail T₁ ρ values with ROI_circle and tail AP diameter achieved good performance for diagnosing CP (AUC = 0.838).

DATA CONCLUSION

T₁ ρ MRI might be a potential technique for the noninvasive evaluation of CP. Level of Evidence 2 Technical Efficacy Stage 2 J. MAGN. RESON. IMAGING 2021;53:577-584.

Prediction of clinically relevant Pancreatico-enteric Anastomotic Fistulas after Pancreatoduodenectomy using deep learning of Preoperative Computed Tomography

Rationale: Clinically relevant postoperative pancreatic fistula (CR-POPF) is among the most formidable complications after pancreatoduodenectomy (PD), heightening morbidity/mortality rates. Fistula Risk Score (FRS) is a well-developed predictor, but it is an intraoperative predictor and quantifies >50% patients as intermediate risk. Therefore, an accurate and easy-to-use preoperative index is desired. Herein, we test the hypothesis that quantitative analysis of contrast-enhanced computed tomography (CE-CT) with deep learning could predict CR-POPFs.

Methods: A group of 513 patients underwent pancreatico-enteric anastomosis after PD at three institutions between 2006 and 2019 was retrospectively collected, and formed a training (70%) and a validation dataset (30%) randomly. A convolutional neural network was trained and generated a deep-learning score (DLS) to identify the patients with higher risk of CR-POPF preoperatively using CE-CT images, which was further externally tested in a prospective cohort collected from August 2018 to June 2019 at the fourth institution. The biological underpinnings of DLS were assessed using histomorphological data by multivariate linear regression analysis.

Results: CR-POPFs developed in 95 patients (16.3%) in total. Compared to FRS, the DLS offered significantly greater predictability in training (AUC:0.85 [95% CI, 0.80-0.90] vs. 0.78 [95% CI, 0.72-0.84]; P = 0.03), validation (0.81 [95% CI, 0.72-0.89] vs. 0.76 [95% CI, 0.66-0.84], P = 0.05) and test (0.89 [95% CI, 0.79-0.96] vs. 0.73 [95% CI, 0.61-0.83], P < 0.001) cohorts. Especially in the challenging patients of intermediate risk (FRS: 3-6), the DLS showed significantly higher accuracy (training: 79.9% vs. 61.5% [P = 0.005]; validation: 70.3% vs. 56.3% [P = 0.04]; test: 92.1% vs. 65.8% [P = 0.013]). Additionally, DLS was independently associated with pancreatic fibrosis (coefficients: -0.167), main pancreatic duct (coefficients: -0.445) and remnant volume (coefficients: 0.138) in multivariate linear regression analysis (r² = 0.512, P < 0.001). The user satisfaction score in the test cohort was 4 out of 5.

Conclusions: Preoperative CT based deep-learning model provides a promising novel method for predicting CR-POPF occurrences after PD, especially at intermediate FRS risk level. This has a potential to be integrated into radiologic reporting system or incorporated into surgical planning software to accommodate the preferences of surgeons to optimize preoperative strategies, intraoperative decision-making, and even postoperative care.

Predictive Value of the Texture Analysis of Enhanced Computed Tomographic Images for Preoperative Pancreatic Carcinoma Differentiation

Purpose

To assess the utility of texture analysis for predicting the pathological degree of differentiation of pancreatic carcinoma (PC).

Methods

Eighty-three patients with PC who went through postoperative pathology diagnose and CT examination were selected at Anhui Provincial Hospital. Among them, 34 cases were moderately differentiated, 13 cases were poorly differentiated, and 36 cases were moderately poorly differentiated. The images in the arterial and venous phase (VP) with the lesions at their largest cross section were selected to manually outline the region of interest (ROI) to delineate lesions using open-source software. A total of 396 features were extracted from the ROI using AK software. Spearman correlation analysis and random forest selection by filter (rfSBF) in the caret package of R studio were used to select the discriminating features. The receiver operating characteristic ROC analysis was used to evaluate their discriminative performance.

Results

Twelve and six features were selected in the arterial and VPs, respectively. The areas under the ROC curve (AUC) in the arterial phase (AP) for diagnosing poorly differentiated, moderately differentiated and moderate-poorly differentiated cases were 0.80, 1, and 0.80 in the training group and 0.77, 1, and 0.77 in the test group; in the VP, the values were 0.81, 1, and 0.82 in the training group and 0.74, 1, and 0.74 in the test group.

Conclusion

Texture analysis based on contrast-enhanced CT images can be used as an adjunct for the preoperative assessment of the pathological degrees of differentiation of PC.

Diffusion Kurtosis Imaging-A Superior Approach to Assess Tumor-Stroma Ratio in Pancreatic Ductal Adenocarcinoma

Extensive desmoplastic stroma is a hallmark of pancreatic ductal adenocarcinoma (PDAC) and contributes to tumor progression and to the relative resistance of tumor cells towards (radio) chemotherapy. Thus, therapies that target the stroma are under intense investigation. To allow the stratification of patients who would profit from such therapies, non-invasive methods assessing the stroma content in relation to tumor mass are required. In the current prospective study, we investigated the usefulness of diffusion-weighted magnetic resonance imaging (DW-MRI), a radiologic method that measures the random motion of water molecules in tissue, in the assessment of PDAC lesions, and more specifically in the desmoplastic tumor stroma. We made use of a sophisticated DW-MRI approach, the so-called diffusion kurtosis imaging (DKI), which possesses potential advantages over conventional and widely used monoexponential diffusion-weighted imaging analysis (cDWI). We found that the diffusion constant D from DKI is highly negatively correlated with the percentage of tumor stroma, the latter determined by histology. D performed significantly better than the widely used apparent diffusion coefficient (ADC) from cDWI in distinguishing stroma-rich (>50% stroma percentage) from stroma-poor tumors (≤50% stroma percentage). Moreover, we could prove the potential of the diffusion constant D as a clinically useful imaging parameter for the differentiation of PDAC-lesions from non-neoplastic pancreatic parenchyma. Therefore, the diffusion constant D from DKI could represent a valuable non-invasive imaging biomarker for assessment of stroma content in PDAC, which is applicable for the clinical diagnostic of PDAC.

Advanced MR Imaging of the Pancreas

MR imaging can be optimized to evaluate a spectrum of pancreatic disorders with advanced sequences aimed to provide quantitative results and increase MR diagnostic capabilities. The pancreas remains a challenging organ to image because of its small size and location deep within the body. Besides its anatomic limitations, pancreatic pathology can be difficult to identify in the early stages. For example, subtle changes in ductal anatomy and parenchymal composition seen in early chronic pancreatitis are imperceptible with other modalities, such as computed tomography. This article reviews the application of MR imaging techniques and emerging MR sequences used in pancreas imaging.

Advanced imaging techniques for chronic pancreatitis

MRI and MRCP play an important role in the diagnosis of chronic pancreatitis (CP) by imaging pancreatic parenchyma and ducts. MRI/MRCP is more widely used than computed tomography (CT) for mild to moderate CP due to its increased sensitivity for pancreatic ductal and gland changes; however, it does not detect the calcifications seen in advanced CP. Quantitative MR imaging offers potential advantages over conventional qualitative imaging, including simplicity of analysis, quantitative and population-based comparisons, and more direct interpretation of detected changes. These techniques may provide quantitative metrics for determining the presence and severity of acinar cell loss and aid in the diagnosis of chronic pancreatitis. Given the fact that the parenchymal changes of CP precede the ductal involvement, there would be a significant benefit from developing MRI/MRCP-based, more robust diagnostic criteria combining ductal and parenchymal findings. Among cross-sectional imaging modalities, multi-detector CT (MDCT) has been a cornerstone for evaluating chronic pancreatitis (CP) since it is ubiquitous, assesses primary disease process, identifies complications like pseudocyst or vascular thrombosis with high sensitivity and specificity, guides therapeutic management decisions, and provides images with isotropic resolution within seconds. Conventional MDCT has certain limitations and is reserved to provide predominantly morphological (e.g., calcifications, organ size) rather than functional information. The emerging applications of radiomics and artificial intelligence are poised to extend the current capabilities of MDCT. In this review article, we will review advanced imaging techniques by MRI, MRCP, CT, and ultrasound.

Prediction of pancreatic atrophy after steroid therapy using equilibrium-phase contrast computed tomography imaging in autoimmune pancreatitis

Background and Aims

Imaging tools for predicting pancreatic atrophy after steroid therapy in autoimmune pancreatitis (AIP) have not been established. As delayed equilibrium‐phase contrast enhancement in computed tomography (CE‐CT) may reflect interstitial fibrosis, we evaluated the ability of equilibrium‐phase CT imaging for predicting pancreatic atrophy.

Methods

Forty‐six steroid‐treated AIP patients who underwent contrast‐enhanced CT at our university hospital were included in this retrospective study. CT attenuation (Hounsfield units [HU]) values in noncontrast images (NC) and equilibrium‐phase images (EP) and the differences in HU values between NC and EP images (SUB) were measured. Pancreatic volume was measured in CE‐CT before (Vol_pre) and after (Vol_post) steroid therapy. The volume reduction rate was calculated. The relationships of CT values with pancreatic atrophy, Vol_post, volume reduction rate, and diabetes exacerbation were investigated.

Results

CT values in the EP and SUB images before steroid therapy were associated with pancreatic atrophy after steroid therapy (atrophy vs nonatrophy 114.5 ± 12.8 vs 99.5 ± 11.1, P = 0.0002; 70.9 ± 14.72 vs 57.2 ± 13.1, P = 0.003, respectively), but CT values in NC images were not (P = 0.42). CT values in EP and SUB images before steroid therapy were correlated with Vol_post (EP images r = −0.70, P = 0.002; SUB images r = −0.68, P = 0.03) and volume reduction rate after steroid therapy (EP images: r = −0.55, P < 0.0001; SUB images r = −0.45, P = 0.002). Diabetes exacerbation was associated with higher EP and SUB values (P = 0.009 and P = 0.04, respectively).

Conclusion

Equilibrium‐phase contrast CT imaging may facilitate prediction of pancreatic atrophy after steroid therapy in AIP.

Quantitative Magnetic Resonance Imaging of the Pancreas of Individuals With Diabetes

Magnetic resonance imaging (MRI) has the potential to improve our understanding of diabetes and improve both diagnosis and monitoring of the disease. Although the spatial resolution of MRI is insufficient to directly image the endocrine pancreas in people, the increasing awareness that the exocrine pancreas is also involved in diabetes pathogenesis has spurred new MRI applications. These techniques build upon studies of exocrine pancreatic diseases, for which MRI has already developed into a routine clinical tool for diagnosis and monitoring of pancreatic cancer and pancreatitis. By adjusting the imaging contrast and carefully controlling image acquisition and processing, MRI can quantify a variety of tissue pathologies. This review introduces a number of quantitative MRI techniques that have been applied to study the diabetic pancreas, summarizes progress in validating and standardizing each technique, and discusses the need for image analyses that account for spatial heterogeneity in the pancreas.

The potential of machine learning to predict postoperative pancreatic fistula based on preoperative, non-contrast-enhanced CT: A proof-of-principle study

BACKGROUND

Postoperative pancreatic fistula remains an unsolved challenge after pancreatoduodenectomy. Important in this regard is the presence of a soft pancreatic texture which is a major risk factor. Advances in machine learning and texture analysis of medical images allow identification of features of parenchyma that are invisible to the human eye. The aim of this study was to investigate the potential of machine learning to predict postoperative pancreatic fistula based on preoperative, non-contrast-enhanced computed tomography.

METHODS

We screened a prospectively assessed database including all patients undergoing pancreatoduodenectomy at a tertiary center from 2008 until 2018 for patients based on the occurrence of postoperative pancreatic fistula. In total, 110 patients were included, consisting of 55 patients who developed a postoperative pancreatic fistula and 55 without postoperative pancreatic fistula. For machine learning-based texture analysis preoperative, non-contrast-enhanced computed tomography axial images were used. Machine learning results were tested using 10-fold cross validation. Previously validated clinical fistula risk scores (original and alternative fistula risk scores) served as reference tests.

RESULTS

Both the original and the alternative fistula risk scores showed good discrimination between patients without and with postoperative pancreatic fistula (area under the curve 0.76 and 0.72, respectively). Machine learning-based texture analysis showed potential to detect histologic fibrosis (area under the curve 0.84, sensitivity 75%; specificity 92%), histologic lipomatosis (area under the curve 0.82, sensitivity 78%; specificity 89%), and intraoperative pancreatic hardness (area under the curve 0.70, sensitivity 78%; specificity 74%). The features of the machine learning-based texture analysis were most accurate in predicting the occurrence of postoperative pancreatic fistula (area under the curve 0.95, sensitivity of 96%; specificity 98%) after pancreatoduodenectomy.

CONCLUSION

This proof-of-principle study suggests the ability of machine learning in recognizing important features of pancreatic texture associated with an increased risk of postoperative pancreatic fistula based on preoperative computed tomography.

Normal T1 relaxometry and extracellular volume of the pancreas in subjects with no pancreas disease: correlation with age and gender

OBJECTIVE

Determine normal T₁ and extracellular volume (ECV) of the pancreas in subjects with no pancreas disease and correlate with age and gender.

SUBJECTS AND METHODS

We imaged 120 healthy subjects (age range 20-78 years) who are on annual screening with MRI/MRCP for the possibility of pancreatic cancer. Subjects had a predisposition to develop pancreatic cancer, but no history of pancreas disease or acute symptoms. Equal number (n = 60) of subjects were scanned on either 1.5 T or 3 T scanner using dual flip angle spoiled gradient echo technique incorporating fat suppression and correction for B₁ field inhomogeneity. Optimization of imaging parameters was performed using a T₁ phantom. ECV was calculated using pre- and post-contrast T₁ of the pancreas and plasma. Regression analysis and Mann-Whitney tests were used for statistical analysis.

RESULTS

Median T₁ on 1.5 T was 654 ms (IQR 608-700); median T₁ on 3 T was 717 ms (IQR 582-850); median ECV on 1.5 T was 0.28 (IQR 0.21-0.33), and median ECV on 3 T was 0.25 (IQR 0.19-0.28). Age had a mild positive correlation with T₁ (r = 0.24, p = 0.009), but not with ECV (r = 0.06, p = 0.54). T₁ and ECV were similar in both genders (p > 0.05).

CONCLUSION

This study measured the median T₁ and ECV of the pancreas in subjects with no pancreas disease. Pancreas shows longer T₁ relaxation times in older population, whereas extracellular fraction remains unchanged. Median T₁ values were different between two magnet strengths; however, no difference was seen between genders and ECV fractions.

Magnetic resonance imaging as a non-invasive method for the assessment of pancreatic fibrosis (MINIMAP): a comprehensive study design from the consortium for the study of chronic pancreatitis, diabetes, and pancreatic cancer

Characteristic features of chronic pancreatitis (CP) may be absent on standard imaging studies. Quantitative Magnetic Resonance Imaging (MRI) techniques such as T₁ mapping, extracellular volume (ECV) fraction, diffusion-weighted imaging (DWI) with apparent diffusion coefficient map (ADC), MR elastography (MRE), and T₁-weighted signal intensity ratio (SIR) have shown promise for the diagnosis and grading severity of CP. However, radiologists still use the Cambridge classification which is based on traditional ductal imaging alone. There is an urgent need to develop new diagnostic criteria that incorporate both parenchymal and ductal features of CP seen by MRI/MRCP. Designed to fulfill this clinical need, we present the MINIMAP study, which was funded in September 2018 by the National Institutes of Health. This is a comprehensive quantitative MR imaging study which will be performed at multiple institutions in well-phenotyped CP patient cohorts. We hypothesize that quantitative MRI/MRCP features can serve as valuable non-invasive imaging biomarkers to detect and grade CP. We will evaluate the role of T₁ relaxometry, ECV, T₁-weighted gradient echo SIR, MRE, arteriovenous enhancement ratio, ADC, pancreas volume/atrophy, pancreatic fat fraction, ductal features, and pancreatic exocrine output following secretin stimulation in the assessment of CP. We will attempt to generate a multi-parametric pancreatic tissue fibrosis (PTF) scoring system. We anticipate that a quantitative scoring system may serve as a biomarker of pancreatic fibrosis; hence this imaging technique can be used in clinical practice as well as clinical trials to evaluate the efficacy of agents which may slow the progression or reverse measures of CP.

Preoperative Evaluation of Pancreatic Fibrosis and Lipomatosis: Correlation of Magnetic Resonance Findings With Histology Using Magnetization Transfer Imaging and Multigradient Echo Magnetic Resonance Imaging

OBJECTIVES

The purpose of this study was to evaluate the diagnostic performance of magnetization transfer (MT) imaging and multigradient echo magnetic resonance imaging (MRI) to quantify pancreatic fibrosis and lipomatosis in patients before pancreatoduodenectomy for postoperative risk stratification with histopathology as the reference standard.

MATERIALS AND METHODS

Twenty-four patients (age, 68 ± 8 years, 16 males) prospectively underwent quantitative MT imaging using a 2-dimensional gradient echo sequence with and without MT prepulse and multigradient echo imaging on a 3 T MRI 1 day before pancreatoduodenectomy due to adenocarcinoma of the pancreatic head region (n = 20), neuroendocrine tumor (n = 3), or intraductal papillary mucinous neoplasm (n = 1). Magnetization transfer ratio (MTR) and proton density fat fraction (PDFF) were measured in pancreatic tail (PT) and at the resection margin (RM). Histopathologically, pancreatic fibrosis was graded as mild, moderate, or severe (F1-F3), lipomatosis was graded as 0% to 10%, 11% to 30%, and greater than 30% fat deposition (L1-L3). In addition, MTR and histopathologic fibrosis was assessed in pancreatic adenocarcinoma. Mann-Whitney U test and Spearman correlation were used.

RESULTS

Patients with advanced pancreatic fibrosis (F3) showed a significantly higher MTR compared with the F1 group at the RM and PT (38 ± 4 vs 32.3 ± 1.6, P = 0.018 and 39.7 ± 5.5 vs 31.2 ± 1.7, P = 0.001). Spearman correlation coefficient of MTR and fibrosis grade was r = 0.532 (P = 0.011) and 0.554 (P = 0.008), respectively. Pancreatic parenchyma with advanced fat deposition (L2-L3) showed significantly higher PDFF compared with lipomatosis grade L1 (RM: P = 0.002 and PT: P = 0.001). Proton density fat fraction of pancreatic parenchyma exhibited a moderate and significant correlation with histopathologic lipomatosis grade (RM: r = 0.668 and PT: r = 0.707, P < 0.001). Magnetization transfer ratio was significantly higher in pancreatic adenocarcinoma compared with pancreatic parenchyma (44 ± 5.5 vs 36.0 ± 4.4 and 37.4 ± 5.4, P = 0.004).

CONCLUSIONS

Multiparametric MRI of the pancreas including MTR and PDFF maps may provide quantitative and noninvasive information on pancreatic fibrosis and lipomatosis before surgery.

Pancreatic MRI associated with pancreatic fibrosis and postoperative fistula: comparison between pancreatic cancer and non-pancreatic cancer tissue

AIM

To evaluate the potential value of magnetic resonance imaging (MRI) for predicting postoperative pancreatic fistula (POPF) in patients with pancreatic cancer (PC) and non-pancreatic cancer (non-PC).

MATERIAL AND METHODS

This retrospective study was approved by the institutional review board and written informed consent was waived. Forty patients underwent pancreatoduodenectomy due to PC (n=31) and non-PC (n=9). The pancreas-to-muscle signal intensity ratio (SIR) on three-dimensional (3D)- fast field echo (FFE) T1-, in- and opposed-phase T1-, and T2-weighted images, as well as the apparent diffusion coefficient (ADC) value of the pancreas were measured. The frequency of POPF and MRI measurements were compared between patients with PC and non-PC. The MRI measurements were also compared with the grade of pancreatic fibrosis on pathological findings, fat deposition, and interstitial oedema.

RESULTS

The frequency of POPF was significantly higher in patients with non-PC than in those with PC (p=0.0067), with an odds ratio of 10.4. The SIR on 3D-FFE T1-weighted images was significantly higher in patients with non-PC (p=0.0001) and those with POPF (p=0.017) than in those with PC and those without POPF, respectively. Multiple regression analysis demonstrated that the SIR on 3D-FFE T1-weighted image was independently associated with the grade of pancreatic fibrosis (p<0.0001).

CONCLUSION

The frequency of POPF was significantly higher in patients with non-PC than in those with PC was inversely related to the grade of pancreatic fibrosis. The SIR on 3D-FFE T1-weighted image might be a potential imaging biomarker for predicting POPF.

Assessment of acute obstructive pancreatitis by magnetic resonance imaging: Predicting the occurrence of pancreatic fistula following pancreatoduodenectomy

The aim of the present study was to assess the effect of preoperative acute obstructive pancreatitis on the risk of the occurrence of pancreatic fistula (PF) following pancreaticoduodenectomy. A total of 22 patients who developed postoperative PF were carefully matched with 22 control patients without PF according to demographic data, pancreatic pathology, presenting symptoms and other surgery-associated parameters. These parameters were compared between these two groups. The mean pancreatic apparent diffusion coefficient (ADC) values in the fistula group were 1.14±0.31×10^-3 mm²/s, which was significantly decreased compared with the non-fistula group (1.48±0.44×10^-3 mm²/s) (P=0.005). The pancreas-muscle signal intensity (SI) ratio on fat-suppressed T1 weighted image (rT1) in the fistula group was 1.71±0.25, which was significantly increased compared with the non-fistula group (1.25±0.29) (P<0.001). The pancreas-muscle SI ratios on fat-suppressed T2 weighted image (T2WI) in the fistula group and the non-fistula group were 0.72±0.08 and 0.62±0.07, respectively (P=0.79). There was no significant difference in pancreas-muscle SI ratio on fat-suppressed T2-weighted image (rT2) value between these two groups. Based on the receiver operating characteristic curve, the optimal cut-off value of ADC as a criterion for prediction of pancreatic fistula was 1.29×10^-3 mm²/s, which yielded a sensitivity of 77.3% and a specificity of 63.6%. In conclusion, the severity of acute obstructive pancreatitis was negatively associated with ADC values and pancreas-muscle SI ratio on rT1 images, which may be useful for predicting the occurrence of PF preoperatively.

Advanced MR Imaging Techniques for Pancreas Imaging

Advances in MR imaging with optimization of hardware, software, and techniques have allowed for an increased role of MR in the identification and characterization of pancreatic disorders. Diffusion-weighted imaging improves the detection and staging of pancreatic neoplasms and aides in the evaluation of acute, chronic and autoimmune pancreatitis. The use of secretin-enhanced MR cholangiography improves the detection of morphologic ductal anomalies, and assists in the characterization of pancreatic cystic lesions and evaluation of acute and chronic pancreatitis. Emerging MR techniques such as MR perfusion, T1 mapping/relaxometry, and MR elastography show promise in further evaluating pancreatic diseases.

Diffusion-weighted magnetic resonance imaging in the pancreas of fulminant type 1 diabetes

Abrupt disease onset and severe metabolic disorders are main characteristics of fulminant type 1 diabetes. Diffusion-weighted magnetic resonance imaging (DWI) is an imaging technique that reflects restricted diffusion in organs and can detect mononuclear cell infiltration into the pancreas at the onset of the disease. Fourteen patients with fulminant type 1 diabetes who underwent abdominal magnetic resonance imaging were recruited for the measurement of apparent diffusion coefficient (ADC) values of the pancreas that were compared with those of 21 non-diabetic controls. The ADC values of all parts of the pancreas were significantly lower in fulminant type 1 diabetes than in controls (head, 1.424 ± 0.382 × 10^-3 vs. 1.675 ± 0.227 × 10^-3 mm²/s; body, 1.399 ± 0.317 × 10^-3 vs. 1.667 ± 0.170 × 10^-3 mm²/s; tail, 1.336 ± 0.247 × 10^-3 vs. 1.561 ± 0.191 × 10^-3 mm²/s; mean, 1.386 ± 0.309 × 10^-3 vs. 1.634 ± 0.175 × 10^-3 mm²/s) (p < 0.01). The best cut-off value indicated that the sensitivity was 86% and the specificity was 71% when using DWI, which was also efficient in two atypical patients with fulminant type 1 diabetes without elevated levels of exocrine pancreatic enzymes or with high HbA1c levels due to the preexistence of type 2 diabetes. The ADC values were significantly correlated to plasma glucose levels and arterial pH, and tended to increase with the lapse of time. DWI may be an additional tool for making an efficient diagnosis of fulminant type 1 diabetes.

Reporting Standards for Chronic Pancreatitis by Using CT, MRI, and MR Cholangiopancreatography: The Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer

Chronic pancreatitis is an inflammatory condition of the pancreas with clinical manifestations ranging from abdominal pain, acute pancreatitis, exocrine and/or endocrine dysfunction, and pancreatic cancer. There is a need for longitudinal studies in well-phenotyped patients to ascertain the utility of cross-sectional imaging findings of chronic pancreatitis for diagnosis and assessment of disease severity. CT and MR cholangiopancreatography are the most common cross-sectional imaging studies performed for the evaluation of chronic pancreatitis. Currently, there are no universal reporting standards for chronic pancreatitis. Several features of chronic pancreatitis are applied clinically, such as calcifications, parenchymal T1 signal changes, focal or diffuse gland atrophy, or irregular contour of the gland. Such findings have not been incorporated into standardized diagnostic criteria. There is also lack of consensus on quantification of disease severity in chronic pancreatitis, other than by using ductal features alone as described in the Cambridge classification. The Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC) was established by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Cancer Institute in 2015 to undertake collaborative studies on chronic pancreatitis, diabetes mellitus, and pancreatic adenocarcinoma. CPDPC investigators from the Adult Chronic Pancreatitis Working Group were tasked with development of a new consensus approach to reporting features of chronic pancreatitis aimed to standardize diagnosis and assessment of disease severity for clinical trials. This consensus statement presents and defines features of chronic pancreatitis along with recommended reporting metrics. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Megibow in this issue.

Correlation of quantitative pancreatic T1 value and HbA1c value in subjects with normal and impaired glucose tolerance

BACKGROUND

Signal intensity on T₁ -weighted images (T₁ WI) is associated with pancreatic fibrosis and HbA1c levels.

PURPOSE

To evaluate the feasibility of the pancreatic T₁ value for assessment of subjects with normal and impaired glucose tolerance (IGT).

STUDY TYPE

A prospective single-institution study.

POPULATION

In all, 95 consecutive patients with a known or suspected pancreatic disease.

FIELD STRENGTH/SEQUENCES

3T/fast pancreatic T₁ mapping using a modified Look-Locker sequence.

ASSESSMENT

Following the American Diabetes Association criteria, patients were classified into three groups, as follows: no-diabetes subject, HbA1c < 5.7%; prediabetes, 5.7% ≤ HbA1c < 6.5%; and type 2 diabetes mellitus (T2DM), HbA1c ≥ 6.5%. Pancreatic T₁ value and signal intensity ratio (SIR = SI_pancreas /SI_muscle ) using T₁ WI were compared with the HbA1c values.

STATISTICAL TESTS

Quantitative data were assessed with one-way analysis of variance, Fisher's and Mann-Whitney U tests, and receiver-operating characteristic analysis.

RESULTS

The pancreatic T₁ value was significantly longer in T2DM than in no-diabetes and prediabetes subjects (P < 0.05) and was significantly longer in prediabetes than in no-diabetes subjects (P < 0.05). The mean pancreatic T₁ value was significantly lower in the low-value group (HbA1c < 5.7%) (906.3 msec) compared with the high-value group (HbA1c ≥ 6.5%) (993.8 msec) (P < 0.0001). SIR on T₁ WI was significantly higher in the low-value group compared with the high-value group (P = 0.029). The sensitivities, specificities, and area under the receiver-operating characteristic curve (AUCs) for differentiating the low- and high-value groups were 74.1%, 83.8%, and 0.82 in the pancreatic T₁ values and 77.8%, 54.4%, and 0.63 in SIR on T₁ WI, respectively. The specificity (P < 0.0001) and AUC (P = 0.0020) were significantly higher in the pancreatic T₁ values than in SIR on T₁ WI.

DATA CONCLUSION

Pancreatic T₁ value has the potential of being an imaging biomarker for the assessment of IGT.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:711-718.