Pancreatic Steatosis and Fibrosis: Quantitative Assessment with Preoperative Multiparametric MR Imaging

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.

Extracellular volume fraction derived from dual-energy CT: a potential predictor for acute pancreatitis after pancreatoduodenectomy

OBJECTIVES

To investigate the value of extracellular volume (ECV) fraction and fat fraction (FF) derived from dual- energy CT (DECT) for predicting postpancreatectomy acute pancreatitis (PPAP) after pancreatoduodenectomy (PD).

METHODS

This retrospective study included patients who underwent DECT and PD between April 2022 and September 2022. PPAP was determined according to the International Study Group for Pancreatic Surgery (ISGPS) definition. Iodine concentration (IC) and FF of the pancreatic parenchyma were measured on preoperative DECT. The ECV fraction was calculated from iodine map images of the equilibrium phase. The independent predictors for PPAP were assessed by univariate and multivariable logistic regression analysis and receiver operating characteristic (ROC) curve analysis.

RESULTS

Sixty-nine patients were retrospectively enrolled (median age, 60 years; interquartile range, 55-70 years; 47 men). Of these, nine patients (13.0%) developed PPAP. These patients had lower portal venous phase IC, equilibrium phase IC, FF, and ECV fraction, and higher pancreatic parenchymal-to-portal venous phase IC ratio and pancreatic parenchymal-to-equilibrium phase IC ratio, compared with patients without PPAP. After multivariable analysis, ECV fraction was independently associated with PPAP (odd ratio [OR], 0.87; 95% confidence interval [CI]: 0.79, 0.96; p < 0.001), with an area under the curve (AUC) of 0.839 (sensitivity 100.0%, specificity 58.3%).

CONCLUSIONS

A lower ECV fraction is independently associated with the occurrence of PPAP after PD. ECV fraction may serve as a potential predictor for PPAP after PD.

CLINICAL RELEVANCE STATEMENT

DECT-derived ECV fraction of pancreatic parenchyma is a promising biomarker for surgeons to preoperatively identify patients with higher risk for postpancreatectomy acute pancreatitis after PD and offer selective perioperative management.

KEY POINTS

PPAP is a complication of pancreatic surgery, early identification of higher-risk patients allows for risk mitigation. Lower DECT-derived ECV fraction was independently associated with the occurrence of PPAP after PD. DECT aids in preoperative PAPP risk stratification, allowing for appropriate treatment to minimize complications.

Intravoxel incoherent motion diffusion-weighted imaging of pancreas: Probing evidence of β-cell dysfunction in asymptomatic adults with hyperglycemia in vivo

PURPOSE

Early evaluation of β-cell dysfunction of hyperglycemic patients in asymptomatic adults would be valuable for timely prevention of the diabetes. This study aimed to evaluate functional changes in the pancreas using intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and determine whether it could be used as a non-invasive method of assessing β-cell dysfunction.

METHODS

This prospective cohort study was conducted from August 2022 to November 2022 in Jinan University Affiliated Guangdong Second General Hospital. Three groups were enrolled and underwent IVIM-DWI: confirmed patients with type 2 diabetes (T2DM); hyperglycemic patients in asymptomatic adults; and the volunteers with normal glucose tolerance (NGT). Imaging parameters were obtained: apparent diffusion coefficient (ADC), the true diffusion coefficient (Dt), the pseudo-diffusion coefficient (Dp), and the perfusion fraction (f). The β-cell function indexes were calculated from blood examinations: composite insulin sensitivity index (ISI), 60-min insulinogenic index (IGI60), and the disposition index (DI). We compared imaging parameters among three groups, calculated the diagnostic performance of them for differentiating different groups, and the reproducibility of them was evaluated using intraclass correlation coefficient (ICC).

RESULTS

The imaging parameters except f gradually decreased among the groups with significant differences for ADC (p < 0.0001), Dt (p < 0.0001), and Dp (p = 0.013). Dt demonstrated the best diagnostic performance for differentiating asymptomatic patients from NGT (Area Under Curve [AUC] = 0.815, p < 0.0001). IVIM-DWI parameters correlated with composite ISI and DI, of which, Dt has the highest correlation with DI (Pearson correlation coefficient [r] = 0.546, p < 0.0001). The ICC of IVIM-DWI parameters was very good, Dt was highest (Interobserver ICC = 0.938, 95% Confidence Interval [CI], 0.899-0.963; Intraobserver ICC = 0.941, 95% CI, 0.904-0.965).

CONCLUSION

IVIM-DWI is a non-invasive quantitative method that can identify β-cell dysfunction in the pancreas.

Intrapancreatic fat deposition is unrelated to liver steatosis in metabolic dysfunction-associated steatotic liver disease

Background & Aims

Individuals with obesity may develop intrapancreatic fat deposition (IPFD) and fatty pancreas disease (FPD). Whether this causes inflammation and fibrosis and leads to pancreatic dysfunction is less established than for liver damage in metabolic dysfunction-associated steatotic liver disease (MASLD). Moreover, the interrelations of FPD and MASLD are poorly understood. Therefore, we aimed to assess IPFD and fibro-inflammation in relation to pancreatic function and liver disease severity in individuals with MASLD.

Methods

Seventy-six participants from the Amsterdam MASLD-MASH cohort (ANCHOR) study underwent liver biopsy and multiparametric MRI of the liver and pancreas, consisting of proton-density fat fraction sequences, T1 mapping and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI).

Results

The prevalence of FPD was 37.3%. There was a clear correlation between pancreatic T1 relaxation time, which indicates fibro-inflammation, and parameters of glycemic dysregulation, namely HbA1c (R = 0.59; p <0.001), fasting glucose (R = 0.51; p <0.001) and the presence of type 2 diabetes (mean 802.0 ms vs. 733.6 ms; p <0.05). In contrast, there was no relation between IPFD and hepatic fat content (R = 0.03; p = 0.80). Pancreatic IVIM diffusion (IVIM-D) was lower in advanced liver fibrosis (p <0.05) and pancreatic perfusion (IVIM-f), reflecting vessel density, inversely correlated to histological MASLD activity (p <0.05).

Conclusions

Consistent relations exist between pancreatic fibro-inflammation on MRI and endocrine function in individuals with MASLD. However, despite shared dysmetabolic drivers, our study suggests IPFD is a separate pathophysiological process from MASLD.

Impact and implications

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide and 68% of people with type 2 diabetes have MASLD. However, fat infiltration and inflammation in the pancreas are understudied in individuals with MASLD. In this cross-sectional MRI study, we found no relationship between fat accumulation in the pancreas and liver in a cohort of patients with MASLD. However, our results show that inflammatory and fibrotic processes in the pancreas may be interrelated to features of type 2 diabetes and to the severity of liver disease in patients with MASLD. Overall, the results suggest that pancreatic endocrine dysfunction in individuals with MASLD may be more related to glucotoxicity than to lipotoxicity.

Clinical trial number

NTR7191 (Dutch Trial Register).

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.

Evidence for a causal link between intra-pancreatic fat deposition and pancreatic cancer: A prospective cohort and Mendelian randomization study

Prior observational studies suggest an association between intra-pancreatic fat deposition (IPFD) and pancreatic ductal adenocarcinoma (PDAC); however, the causal relationship is unclear. To elucidate causality, we conduct a prospective observational study using magnetic resonance imaging (MRI)-measured IPFD data and also perform a Mendelian randomization study using genetic instruments for IPFD. In the observational study, we use UK Biobank data (N = 29,463, median follow-up: 4.5 years) and find that high IPFD (>10%) is associated with PDAC risk (adjusted hazard ratio [HR]: 3.35, 95% confidence interval [95% CI]: 1.60-7.00). In the Mendelian randomization study, we leverage eight out of nine IPFD-associated genetic variants (p < 5 × 10-8) from a genome-wide association study in the UK Biobank (N = 25,617) and find that genetically determined IPFD is associated with PDAC (odds ratio [OR] per 1-standard deviation [SD] increase in IPFD: 2.46, 95% CI: 1.38-4.40) in the Pancreatic Cancer Cohort Consortium I, II, III (PanScan I-III)/Pancreatic Cancer Case-Control Consortium (PanC4) dataset (8,275 PDAC cases and 6,723 non-cases). This study provides evidence for a potential causal role of IPFD in the pathogenesis of PDAC. Thus, reducing IPFD may lower PDAC risk.

Magnetic Resonance Imaging-Based Assessment of Pancreatic Fat Strongly Correlates With Histology-Based Assessment of Pancreas Composition

OBJECTIVE

The aim of the study is to assess the relationship between magnetic resonance imaging (MRI)-based estimation of pancreatic fat and histology-based measurement of pancreatic composition.

MATERIALS AND METHODS

In this retrospective study, MRI was used to noninvasively estimate pancreatic fat content in preoperative images from high-risk individuals and disease controls having normal pancreata. A deep learning algorithm was used to label 11 tissue components at micron resolution in subsequent pancreatectomy histology. A linear model was used to determine correlation between histologic tissue composition and MRI fat estimation.

RESULTS

Twenty-seven patients (mean age 64.0 ± 12.0 years [standard deviation], 15 women) were evaluated. The fat content measured by MRI ranged from 0% to 36.9%. Intrapancreatic histologic tissue fat content ranged from 0.8% to 38.3%. MRI pancreatic fat estimation positively correlated with microanatomical composition of fat (r = 0.90, 0.83 to 0.95], P < 0.001); as well as with pancreatic cancer precursor ( r = 0.65, P < 0.001); and collagen ( r = 0.46, P < 0.001) content, and negatively correlated with pancreatic acinar ( r = -0.85, P < 0.001) content.

CONCLUSIONS

Pancreatic fat content, measurable by MRI, correlates to acinar content, stromal content (fibrosis), and presence of neoplastic precursors of cancer.

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.

Intrapancreatic fat deposition and nutritional treatment: the role of various dietary approaches

Ectopic fat accumulation in various organs and tissues, such as the liver, muscle, kidney, heart, and pancreas, is related to impaired capacity of adipose tissue to accumulate triglycerides, as a consequence of overnutrition and an unhealthy lifestyle. Ectopic fat promotes organ dysfunction and is a key factor in the development and progression of cardiometabolic diseases. Interest in intrapancreatic fat deposition (IPFD) has developed in the last few years, particularly in relation to improvement in methodological techniques for detection of fat in the pancreas, and to growing evidence for the role that IPFD might have in glucose metabolism disorders and cardiometabolic disease. Body weight reduction represents the main option for reducing fat, and the evidence consistently shows that hypocaloric diets are effective in reducing IPFD. Changes in diet composition, independently of changes in energy intake, might offer a more feasible and safe alternative treatment to energy restriction. This current narrative review focused particularly on the possible beneficial role of the diet and its nutrient content, in hypocaloric and isocaloric conditions, in reducing IPFD in individuals with high cardiometabolic risk, highlighting the possible effects of differences in calorie quantity and calorie quality. This review also describes plausible mechanisms by which the various dietary approaches could modulate IPFD.

Quantification of ectopic fat storage in the liver and pancreas using six-point Dixon MRI and its association with insulin sensitivity and β-cell function in patients with central obesity

OBJECTIVES

To assess the association of ectopic fat deposition in the liver and pancreas quantified by Dixon magnetic resonance imaging (MRI) with insulin sensitivity and β-cell function in patients with central obesity.

MATERIALS AND METHODS

A cross-sectional study of 143 patients with central obesity with normal glucose tolerance (NGT), prediabetes (PreD), and untreated type 2 diabetes mellitus (T2DM) was conducted between December 2019 and March 2022. All participants underwent routine medical history taking, anthropometric measurements, and laboratory tests, including a standard glucose tolerance test to quantify insulin sensitivity and β-cell function. The fat content in the liver and pancreas was measured with MRI using the six-point Dixon technique.

RESULTS

Patients with T2DM and PreD had a higher liver fat fraction (LFF) than those with NGT, while those with T2DM had a higher pancreatic fat fraction (PFF) than those with PreD and NGT. LFF was positively correlated with homeostatic model assessment of insulin resistance (HOMA-IR), while PFF was negatively correlated with homeostatic model assessment of insulin secretion (HOMA-β). Furthermore, using a structured equation model, we found LFF and PFF to be positively associated with glycosylated hemoglobin via HOMA-IR and HOMA-β, respectively.

CONCLUSIONS

In patients with central obesity, the effects of LFF and PFF on glucose metabolism. were associated with HOMA-IR and HOMA-β, respectively. Ectopic fat storage in the liver and pancreas quantified by MR Dixon imaging potentially plays a notable role in the onset ofT2DM.

CLINICAL RELEVANCE STATEMENT

We highlight the potential role of ectopic fat deposition in the liver and pancreas in the development of type 2 diabetes in patients with central obesity, providing valuable insights into the pathogenesis of the disease and potential targets for intervention.

KEY POINTS

• Ectopic fat deposition in the liver and pancreas is associated with T2DM. • T2DM and prediabetes patients had higher liver and pancreatic fat fractions than normal individuals. • The results provide valuable insights into pathogenesis of T2DM and potential targets for intervention.

Progress in the application of dual-energy CT in pancreatic diseases

Pancreatic diseases are difficult to diagnose due to their insidious onset and complex pathophysiological developmental characteristics. In recent years, dual-energy computed tomography (DECT) imaging technology has rapidly advanced. DECT can quantitatively extract and analyze medical imaging features and establish a correlation between these features and clinical results. This feature enables the adoption of more modern and accurate clinical diagnosis and treatment strategies for patients with pancreatic diseases so as to achieve the goal of non-invasive, low-cost, and personalized treatment. The purpose of this review is to elaborate on the application of DECT for the diagnosis, biological characterization, and prediction of the survival of patients with pancreatic diseases (including pancreatitis, pancreatic cancer, pancreatic cystic tumor, pancreatic neuroendocrine tumor, and pancreatic injury) and to summarize its current limitations and future research prospects.

Application of ultrasound shear wave elastography in pre-operative and quantitative prediction of clinically relevant post-operative pancreatic fistula after pancreatectomy: a prospective study for the investigation of risk evaluation model

OBJECTIVES

The aim of this study was to modify recognized clinically relevant post-operative pancreatic fistula (CR-POPF) risk evaluation models with quantitative ultrasound shear wave elastography (SWE) values and identified clinical parameters to improve the objectivity and reliability of the prediction.

METHODS

Two prospective, successive cohorts were initially designed for the establishment of CR-POPF risk evaluation model and the internal validation. Patients who scheduled to receive pancreatectomy were enrolled. Virtual touch tissue imaging and quantification (VTIQ)-SWE was used to quantify pancreatic stiffness. CR-POPF was diagnosed according to 2016 International Study Group of Pancreatic Fistula standard. Recognized peri-operative risk factors of CR-POPF were analyzed, and the independent variables selected from multivariate logistic regression were used to build the prediction model.

RESULTS

Finally, the CR-POPF risk evaluation model was built in a group of 143 patients (cohort 1). CR-POPF occurred in 52/143 (36%) patients. Constructed from SWE values and other identified clinical parameters, the model achieved an area under the receiver operating characteristic curve of 0.866, with sensitivity, specificity, and likelihood ratio of 71.2%, 80.2%, and 3.597 in predicting CR-POPF. Decision curve of modified model revealed a better clinical benefit compared to the previous clinical prediction models. The models were then examined via internal validation in a separate collection of 72 patients (cohort 2).

CONCLUSIONS

Risk evaluation model based on SWE and clinical parameters is a potential non-invasive way to pre-operatively, objectively predict CR-POPF after pancreatectomy.

CLINICAL RELEVANCE STATEMENT

Our modified model based on ultrasound shear wave elastography may provide an easy access in pre-operative and quantitative evaluating the risk of CR-POPF following pancreatectomy and improve the objectivity and reliability of the prediction compared to previous clinical models.

KEY POINTS

• Modified prediction model based on ultrasound shear wave elastography (SWE) provides an easy access for clinicians to pre-operatively, objectively evaluate the risk of clinically relevant post-operative pancreatic fistula (CR-POPF) following pancreatectomy. • Prospective study with validation showed that the modified model provides better diagnostic efficacy and clinical benefits compared to previous clinical models in predicting CR-POPF. • Peri-operative management of CR-POPF high-risk patients becomes more possible.

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.

Effects of a peripherally acting µ-opioid receptor antagonist for the prevention of recurrent acute pancreatitis: study protocol for an investigator-initiated, randomized, placebo-controlled, double-blind clinical trial (PAMORA-RAP trial)

BACKGROUND

Acute and chronic pancreatitis constitute a continuum of inflammatory disease of the pancreas with an increasing incidence in most high-income countries. A subset of patients with a history of pancreatitis suffer from recurrence of acute pancreatitis attacks, which accelerate disease progression towards end-stage chronic pancreatitis with loss of exocrine and endocrine function. There is currently no available prophylactic treatment for recurrent acute pancreatitis apart from removing risk factors, which is not always possible. Pain is the primary symptom of acute pancreatitis, which induces the endogenous release of opioids. This may further be potentiated by opioid administration for pain management. Increased exposure to opioids leads to potentially harmful effects on the gastrointestinal tract, including, e.g. increased sphincter tones and decreased fluid secretion, which may impair pancreatic ductal clearance and elevate the risk for new pancreatitis attacks and accelerate disease progression. Peripherally acting µ-opioid receptor antagonists (PAMORAs) have been developed to counteract the adverse effects of opioids on the gastrointestinal tract. We hypothesize that the PAMORA naldemedine will reduce the risk of new pancreatitis attacks in patients with recurrent acute pancreatitis and hence decelerate disease progression.

METHODS

The study is a double-blind, randomized controlled trial with allocation of patients to either 0.2 mg naldemedine daily or matching placebo for 12 months. A total of 120 outpatients will be enrolled from five specialist centres in Denmark and Sweden. The main inclusion criteria is a history of recurrent acute pancreatitis (minimum of two confirmed pancreatitis attacks). The primary endpoint is time to acute pancreatitis recurrence after randomization. Secondary outcomes include changes in quality of life, gastrointestinal symptom scores, new-onset diabetes, exocrine pancreatic insufficiency, disease severity, health care utilization, adherence to treatment, and frequency of adverse events. Exploratory outcomes are included for mechanistic linkage and include the progression of chronic pancreatitis-related findings on magnetic resonance imaging (MRI) and changes in circulating blood markers of inflammation and fibrosis.

DISCUSSION

This study investigates if naldemedine can change the natural course of pancreatitis in patients with recurrent acute pancreatitis and improve patient outcomes.

TRIAL REGISTRATION

EudraCT no. 2021-000069-34.

CLINICALTRIALS

gov NCT04966559. Registered on July 8, 2021.

Genetic Evidence Causally Linking Pancreas Fat to Pancreatic Cancer: A Mendelian Randomization Study

Background & Aims

Pancreatic ductal adenocarcinoma (PDAC) is highly lethal, and any clues to understanding its elusive etiology could lead to breakthroughs in prevention, early detection, or treatment. Observational studies have shown a relationship between pancreas fat accumulation and PDAC, but the causality of this link is unclear. We therefore investigated whether pancreas fat is causally associated with PDAC using two-sample Mendelian randomization.

Methods

We leveraged eight genetic variants associated with pancreas fat (P<5×10 ^-8 ) from a genome-wide association study (GWAS) in the UK Biobank (25,617 individuals), and assessed their association with PDAC in the Pancreatic Cancer Cohort Consortium I-III and the Pancreatic Cancer Case-Control Consortium dataset (8,275 PDAC cases and 6,723 non-cases). Causality was assessed using the inverse-variance weighted method. Although none of these genetic variants were associated with body mass index (BMI) at genome-wide significance, we further conducted a sensitivity analysis excluding genetic variants with a nominal BMI association in GWAS summary statistics from the UK Biobank and the Genetic Investigation of Anthropometric Traits consortium dataset (806,834 individuals).

Results

Genetically determined higher levels of pancreas fat using the eight genetic variants was associated with increased risk of PDAC. For one standard deviation increase in pancreas fat levels (i.e., 7.9% increase in pancreas fat fraction), the odds ratio of PDAC was 2.46 (95%CI:1.38-4.40, P=0.002). Similar results were obtained after excluding genetic variants nominally linked to BMI (odds ratio:3.79, 95%CI:1.66-8.65, P=0.002).

Conclusions

This study provides genetic evidence for a causal role of pancreas fat in the pathogenesis of PDAC. Thus, reducing pancreas fat could lower the risk of PDAC.

MAGORINO: Magnitude-only fat fraction and R* 2 estimation with Rician noise modeling

PURPOSE

Magnitude-based fitting of chemical shift-encoded data enables proton density fat fraction (PDFF) and R 2 * $$ {R}_2^{\ast } $$ estimation where complex-based methods fail or when phase data are inaccessible or unreliable. However, traditional magnitude-based fitting algorithms do not account for Rician noise, creating a source of bias. To address these issues, we propose an algorithm for magnitude-only PDFF and R 2 * $$ {R}_2^{\ast } $$ estimation with Rician noise modeling (MAGORINO).

METHODS

Simulations of multi-echo gradient-echo signal intensities are used to investigate the performance and behavior of MAGORINO over the space of clinically plausible PDFF, R 2 * $$ {R}_2^{\ast } $$ , and SNR values. Fitting performance is assessed through detailed simulation, including likelihood function visualization, and in a multisite, multivendor, and multi-field-strength phantom data set and in vivo.

RESULTS

Simulations show that Rician noise-based magnitude fitting outperforms existing Gaussian noise-based fitting and reveals two key mechanisms underpinning the observed improvement. First, the likelihood functions exhibit two local optima; Rician noise modeling increases the chance that the global optimum corresponds to the ground truth. Second, when the global optimum corresponds to ground truth for both noise models, the optimum from Rician noise modeling is closer to ground truth. Multisite phantom experiments show good agreement of MAGORINO PDFF with reference values, and in vivo experiments replicate the performance benefits observed in simulation.

CONCLUSION

The MAGORINO algorithm reduces Rician noise-related bias in PDFF and R 2 * $$ {R}_2^{\ast } $$ estimation, thus addressing a key limitation of existing magnitude-only fitting methods. Our results offer insight into the importance of the noise model for selecting the correct optimum when multiple plausible optima exist.

A Simple Classification of Pancreatic Duct Size and Texture Predicts Postoperative Pancreatic Fistula: A classification of the International Study Group of Pancreatic Surgery

OBJECTIVE

The aim of this study was to develop a classification system for pancreas-associated risk factors in pancreatoduodenectomy (PD).

SUMMARY BACKGROUND DATA

Postoperative pancreatic fistula (POPF) is the most relevant PD-associated complication. A simple standardized surgical reporting system based on pancreas-associated risk factors is lacking.

METHODS

A systematic literature search was conducted to identify studies investigating clinically relevant (CR) POPF (CR-POPF) and pancreas-associated risk factors after PD. A meta-analysis of CR-POPF rate for texture of the pancreas (soft vs not-soft) and main pancreatic duct (MPD) diameter was performed using the Mantel-Haenszel method. Based on the results, the International Study Group of Pancreatic Surgery (ISGPS) proposes the following classification: A, not-soft (hard) texture and MPD >3 mm; B, not-soft (hard) texture and MPD ≤3 mm; C, soft texture and MPD >3 mm; D, soft texture and MPD ≤3 mm. The classification was evaluated in a multi-institutional, international cohort.

RESULTS

Of the 2917 articles identified, 108 studies were included in the analyses. Soft pancreatic texture was significantly associated with the development of CR-POPF [odds ratio (OR) 4.24, 95% confidence interval (CI) 3.67-4.89, P < 0.01) following PD. Similarly, MPD diameter ≤3 mm significantly increased CR-POPF risk compared with >3 mm diameter MPDs (OR 3.66, 95% CI 2.62-5.12, P < 0.01). The proposed 4-stage system was confirmed in an independent cohort of 5533 patients with CR-POPF rates of 3.5%, 6.2%, 16.6%, and 23.2% for type A-D, respectively ( P < 0.001).

CONCLUSION

For future pancreatic surgical outcomes studies, the ISGPS recommends reporting these risk factors according to the proposed classification system for better comparability of results.

Single- and multiparameter magnetic resonance imaging for diagnosing and severity grading of chronic pancreatitis

PURPOSE

The study aimed to determine the performance of advanced magnetic resonance imaging (MRI), including a multiparametric MRI-index, for diagnosing and severity grading of chronic pancreatitis (CP) at various functional stages with focus on detection of CP with preserved pancreatic function.

METHODS

Fifty-four CP patients and 35 healthy controls underwent MRI including assessment of pancreatic volume, main pancreatic duct (MPD) diameter, T1 relaxation time, magnetic resonance elastography (MRE) derived stiffness, and intravoxel incoherent motion (IVIM) diffusion-weighted imaging. Patients were categorized into three subgroups: Preserved pancreatic function (n = 14), partial pancreatic insufficiency (exocrine insufficiency or diabetes, n = 25), and complete pancreatic insufficiency (exocrine insufficiency and diabetes, n = 15). A multiparametric MRI-index was based on ordinal logistic regression analysis. Diagnostic performances of MRI parameters for diagnosing CP at different functional stages were determined using receiver operating characteristic (ROC) analysis.

RESULTS

All MRI parameters differed across CP subgroups and healthy controls (all P < 0.001), except for IVIM. T1 relaxation time (ROC area under the curve (ROC-AUC) 0.82), MRE (ROC-AUC 0.88), and MRI-index (ROC-AUC 0.86) showed the highest performance for detecting patients with preserved pancreatic function (early CP) vs. healthy controls. For detecting preserved pancreatic function vs. partial insufficiency, pancreatic volume, MRI-index, and T1 relaxation time performed best (all ROC-AUC > 0.75), with the MRI-index tending to outperform MRE (ROC-AUC 0.77 vs. 0.63; P = 0.10).

CONCLUSION

Quantitative assessments of T1 relaxation time and MRE-derived stiffness seem promising for diagnosing CP at different functional stages and may together with multiparametric MRI-index be used for early identification, staging and monitoring of CP.

Association between Intrapancreatic Fat Deposition and Lower High-Density Lipoprotein Cholesterol in Individuals with Newly Diagnosed T2DM

BACKGROUND

Intrapancreatic fat deposition (IPFD) usually occurs in individuals with type 2 diabetes mellitus (T2DM), but its physiopathological influence remains controversial. The present study aimed to investigate IPFD and its associations with various aspects of glucose and lipid metabolism in individuals with newly diagnosed T2DM.

METHODS

A total of 100 individuals were included, consisting of 80 patients with newly diagnosed T2DM and 20 age- and sex-matched healthy controls. Then, we assessed IPFD using magnetic resonance imaging (MRI) and various parameters of glucose and lipid metabolism.

RESULTS

Individuals with newly diagnosed T2DM had a significantly higher IPFD (median: 12.34%; IQR, 9.19-16.60%) compared with healthy controls (median: 6.35%; IQR, 5.12-8.96%) (p < 0.001). In individuals with newly diagnosed T2DM, IPFD was significantly associated with FINS and HOMA-IR in unadjusted model (β = 0.239, p=0.022; β = 0.578, p=0.007, respectively) and adjusted model for age and sex (β = 0.241, p=0.022; β = 0.535, p=0.014, respectively), but these associations vanished after adjustment for age, sex, and BMI. The OR of lower HDL-C for the prevalence of high IPFD was 4.22 (95% CI, 1.41 to 12.69; p=0.010) after adjustment for age, sex, BMI, and HbA1c.

CONCLUSIONS

Lower HDL-C was an independent predictor for a high degree of IPFD.

Fatty Pancreas: Linking Pancreas Pathophysiology to Nonalcoholic Fatty Liver Disease

Currently, scientific interest has focused on fat accumulation outside of subcutaneous adipose tissue. As various imaging modalities are available to quantify fat accumulation in particular organs, fatty pancreas has become an important area of research over the last decade. The pancreas has an essential role in regulating glucose metabolism and insulin secretion by responding to changes in nutrients under various metabolic circumstances. Mounting evidence has revealed that fatty pancreas is linked to impaired β-cell function and affects insulin secretion with metabolic consequences of impaired glucose metabolism, type 2 diabetes, and metabolic syndrome. It has been shown that there is a connection between fatty pancreas and the presence and severity of nonalcoholic fatty liver disease (NAFLD), which has become the predominant cause of chronic liver disease worldwide. Therefore, it is necessary to better understand the pathogenic mechanisms of fat accumulation in the pancreas and its relationship with NAFLD. This review summarizes the epidemiology, diagnosis, risk factors, and metabolic consequences of fatty pancreas and discusses its pathophysiology links to NAFLD.

Use of Magnetic Resonance Imaging to Quantify Fat and Steatosis in the Pancreas in Patients after Bariatric Surgery: a Retrospective Study

INTRODUCTION

Pancreatic steatosis (PS) has both metabolic consequences and local effects on the pancreas itself. Magnetic resonance imaging (MRI) is the most reliable non-invasive method for diagnosing PS. We investigated the impact of metabolic syndrome (MS) on the presence of PS, differences in individuals with and without PS, and the metabolic effects of bariatric procedures.

METHODS

Changes in anthropometric and basic biochemistry values and MS occurrence were evaluated in 34 patients with obesity who underwent a bariatric procedure. After the procedure, patients underwent MRI with manual 3D segmentation mask creation to determine the pancreatic fat content (PFC). We compared the differences in the PFC and the presence of PS in individuals with and without MS and compared patients with and without PS.

RESULTS

We found no significant difference in the PFC between the groups with and without MS or in the occurrence of PS. There were significant differences in patients with and without PS, especially in body mass index (BMI), fat mass, visceral adipose tissue (VAT), select adipocytokines, and lipid spectrum with no difference in glycemia levels. Significant metabolic effects of bariatric procedures were observed.

CONCLUSIONS

Bariatric procedures can be considered effective in the treatment of obesity, MS, and some of its components. Measuring PFC using MRI did not show any difference in relation to MS, but patients who lost weight to BMI < 30 did not suffer from PS and had lower overall fat mass and VAT. Glycemia levels did not have an impact on the presence of PS.

Histological pancreatic findings correlate with computed tomography attenuation and predict postoperative pancreatic fistula following pancreatoduodenectomy

BACKGROUND

Although a soft pancreas is a widely-accepted reliable risk factor for postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD), there is no established preoperative evaluation of pancreatic texture.

METHODS

Two hundred thirty-seven patients who underwent PD with histological pancreatic assessment were retrospectively enrolled. The degree of fibrosis and fatty infiltration was scored histologically as seven grades and five grades, respectively. Computed tomography (CT) attenuation of the pancreas was measured on preoperative unenhanced CT images. Correlations between the CT attenuation of the pancreas and the histological pancreatic findings, and the development of POPF were analyzed.

RESULTS

The fibrosis grade was significantly higher for hard pancreas than for soft pancreas (p < 0.001), whereas the fatty infiltration grade was similar between the two types (p = 0.161). CT attenuation of the pancreas was inversely correlated with both fibrosis grade (Spearman's rank correlation coefficient ([r] = -0.609, p < 0.001) and fatty infiltration grade (r = -0.382, p < 0.001). Multivariate analysis showed that body mass index ≥25 kg/m² (odds ratio [OR]: 5.64, p < 0.001) and fibrosis grade ≤2 (OR: 18.0, p < 0.001) were independent risk factors for clinically significant POPF.

CONCLUSION

Histological pancreatic texture can be evaluated with CT attenuation and might be helpful in preoperatively predicting the development of POPF after PD.

Simultaneous liver steatosis, fibrosis and iron deposition quantification with mDixon quant based on radiomics analysis in a rabbit model

PURPOSE

To evaluate the feasibility of simultaneous quantification of liver fibrosis, liver steatosis and abnormal iron deposition using mDixon Quant based on radiomics analysis, and to eliminate the interference among different histopathologic features.

METHODS

One hundred and twenty rabbits that were administered CCl4 for 4-16 weeks and a cholesterol rich diet for the initial 4 weeks in the experimental group and 20 rabbits in the control group were examined using mDixon. Radiomics features of the whole liver were extracted from PDFF and R2* and radiomics models for discriminating steatosis: S0-S1 vs. S2-S4, fibrosis: F0-F2 vs. F3-F4 and iron deposition: normal vs. abnormal were constructed respectively and evaluated using receiver operating characteristic (ROC) curves with the histopathological results as reference standard. Combined corrected models merging the radscore and the other two histopathologic features were evaluated using multiple logistic regression analyses and compared with radiomics models.

RESULTS

The area under the ROC curve (AUC) of the radiomics model with PDFF features was 0.886 and 0.843 in the training and the test set, respectively, for the diagnosis of liver steatosis grade S0-1 and S2-S4. The radiomics model based on R2* features were 0.815 and 0.801 for distinguishing F0-F2 and F3-F4 and 0.831 and 0.738 for discriminating abnormal iron deposition in the training and test set, respectively. The corrected model for liver steatosis and fibrosis (0.944 and 0.912 in the test set) outperformed the radiomics models by eliminating the interference of histopathologic features(P < 0.05), but had comparable diagnostic performance for abnormal iron deposition(P > 0.05).

CONCLUSIONS

It is feasible for mDixon to simultaneously quantify whole liver steatosis, fibrosis and iron deposition based on radiomics analysis. It is valuable to minimize the interference of different pathological features for the assessment of liver steatosis and fibrosis.

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.

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.

Intra-pancreatic fat deposition: bringing hidden fat to the fore

Development of advanced modalities for detection of fat within the pancreas has transformed understanding of the role of intra-pancreatic fat deposition (IPFD) in health and disease. There is now strong evidence for the presence of minimal (but not negligible) IPFD in healthy human pancreas. Diffuse excess IPFD, or fatty pancreas disease (FPD), is more frequent than type 2 diabetes mellitus (T2DM) (the most common disease of the endocrine pancreas) and acute pancreatitis (the most common disease of the exocrine pancreas) combined. FPD is not strictly a function of high BMI; it can result from the excess deposition of fat in the islets of Langerhans, acinar cells, inter-lobular stroma, acinar-to-adipocyte trans-differentiation or replacement of apoptotic acinar cells. This process leads to a wide array of diseases characterized by excess IPFD, including but not limited to acute pancreatitis, chronic pancreatitis, pancreatic cancer, T2DM, diabetes of the exocrine pancreas. There is ample evidence for FPD being potentially reversible. Weight loss-induced decrease of intra-pancreatic fat is tightly associated with remission of T2DM and its re-deposition with recurrence of the disease. Reversing FPD will open up opportunities for preventing or intercepting progression of major diseases of the exocrine pancreas in the future.

Pancreatic Steatosis Is Associated with Both Metabolic Syndrome and Pancreatic Stiffness Detected by Ultrasound Elastography

INTRODUCTION

There is increasing evidence that pancreatic steatosis (PS) is associated with metabolic syndrome (MS). However, it is not known whether it is associated with PS grade and pancreatic stiffness, or not. We aimed to evaluate the relationship between PS and its grade detected by transabdominal ultrasound, and pancreatic stiffness determined by two-dimensional shearwave elastography (2D-SWE), whether it has clinical significance and its relationship with MS.

METHODS

Patients with and without PS were evaluated prospectively.

RESULTS

Patients with PS had higher odds ratio for MS (OR 5.49). Also, ultrasonographic grade of PS was associated with MS parameters and hepatosteatosis. Pancreatic SWE value was significantly higher in PS group and positively correlated with PS grade, liver fat, MS, number of MS criteria.

DISCUSSION/CONCLUSION

PS and its grade were associated with MS. In this first comprehensive PS-SWE study, we found that pancreas stiffness increased in the presence of PS, in correlation with PS grade and MS.

Metabolic implications of pancreatic fat accumulation

Fat accumulation outside subcutaneous adipose tissue often has unfavourable effects on systemic metabolism. In addition to non-alcoholic fatty liver disease, which has received considerable attention, pancreatic fat has become an important area of research throughout the past 10 years. While a number of diagnostic approaches are available to quantify pancreatic fat, multi-echo Dixon MRI is currently the most developed method. Initial studies have shown associations between pancreatic fat and the metabolic syndrome, impaired glucose metabolism and type 2 diabetes mellitus. Pancreatic fat is linked to reduced insulin secretion, at least under specific circumstances such as prediabetes, low BMI and increased genetic risk of type 2 diabetes mellitus. This Review summarizes the possible causes and metabolic consequences of pancreatic fat accumulation. In addition, potential therapeutic approaches for addressing pancreatic fat accumulation are discussed.

Impact of Fatty Pancreas on Postoperative Pancreatic Fistulae: A Meta-Analysis

Background

Soft pancreas is widely recognized as an important risk factor for the development of postoperative pancreatic fistula (POPF). Although fatty pancreas (FP) has not been formally defined as a cause of pancreatic fistula, existing research has shown that it can increase the incidence of POPF by increasing pancreatic tenderness; therefore, it may be a potential risk factor. This study aimed to discern whether FP was associated with POPF.

Method

Two reviewers independently performed literature searches from five electronic databases. According to the established inclusion criteria, we extracted necessary data from the studies that met the criteria for further analysis. We pooled the odds ratios (ORs) from individual studies using a random-effects model to investigate the associations between POPF and the prognosis of FP.

Result

A total of 11 studies involving 2484 individuals were included. The pooled prevalence of POPF was 18% (95% CI: 12-24%). Body mass index (BMI) was associated with a significantly increased risk of POPF (OR=3.55; 95% CI: 1.83, 6.86; P=0.0002; I²=0). FP was obviously associated with the occurrence of POPF (OR=3.75; 95% CI: 1.64, 8.58; P=0.002; I²=78).

Conclusion

FP is closely associated with the development of POPF, and the early identification of these high-risk patients can help to reduce the incidence of POPF.

Systematic Review Registration

The Registration URL link is (https://www.crd.york.ac.uk/PROSPERO/). The ID is "CRD42021265141".

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.

T1 relaxation times and MR elastography-derived stiffness: new potential imaging biomarkers for the assessment of chronic pancreatitis

PURPOSE

Non-invasive imaging methods to detect morphological changes of the pancreas in patients with mild chronic pancreatitis (CP) are needed. This study aimed to compare magnetic resonance imaging-based parameters, pancreatic volume, T1 mapping, magnetic resonance elastography (MRE), and proton density fat fraction between CP patients and controls, and determine the diagnostic performance for diagnosing different stages of CP.

METHODS

Nineteen patients with mild CP (Cambridge grade 2 or less or recurring acute pancreatitis; n = 19), 30 with moderate/severe CP (Cambridge grade 3 and 4), and 35 healthy controls underwent pancreatic magnetic resonance imaging to assess the above mentioned magnetic resonance imaging-based parameters. The diagnostic performance of each parameter for detecting any mild and moderate/severe CP was determined using receiver operating characteristic analysis.

RESULTS

Pancreatic volume, T1 relaxation times, MRE-derived stiffness, and proton density fat fraction differed significantly between patients with mild CP, moderate/severe CP, and healthy controls (all p < 0.05). T1 mapping and MRE showed a very high diagnostic performance for distinguishing the mild CP group from the control group (T1 mapping: receiver operating characteristic area under the curve (ROC-AUC): 0.94; sensitivity: 84%; specificity: 91%, MRE: ROC-AUC: 0.93; sensitivity: 89%; specificity: 94%). T1 mapping and MRE also had the highest performance for diagnosing the presence of any CP from the control group (ROC-AUCs of 0.98 and 0.97, respectively).

CONCLUSION

Quantitative assessments of T1 relaxation time and MRE-derived stiffness had high performance in detecting mild CP and could probably reflect the early fibrotic changes in CP.

Estimation of pancreatic fibrosis and prediction of postoperative pancreatic fistula using extracellular volume fraction in multiphasic contrast-enhanced CT

OBJECTIVE

To investigate the diagnostic performance of the extracellular volume (ECV) fraction in multiphasic contrast-enhanced computed tomography (CE-CT) for estimating histologic pancreatic fibrosis and predicting postoperative pancreatic fistula (POPF).

METHODS

Eighty-five patients (49 men; mean age, 69 years) who underwent multiphasic CE-CT followed by pancreaticoduodenectomy with pancreaticojejunal anastomosis between January 2012 and December 2018 were retrospectively included. The ECV fraction was calculated from absolute enhancements of the pancreas and aorta between the precontrast and equilibrium-phase images, followed by comparisons among histologic pancreatic fibrosis grades (F0‒F3). The diagnostic performance of the ECV fraction in advanced fibrosis (F2‒F3) was evaluated using receiver operating characteristic curve analysis. Multivariate logistic regression analysis was used to evaluate the associations of the risk of POPF development with patient characteristics, histologic findings, and CT imaging parameters.

RESULTS

The mean ECV fraction of the pancreas was 34.4% ± 9.5, with an excellent intrareader agreement of 0.811 and a moderate positive correlation with pancreatic fibrosis (r = 0.476; p < 0.001). The mean ECV fraction in advanced fibrosis was significantly higher than that in no/mild fibrosis (44.4% ± 10.8 vs. 31.7% ± 6.7; p < 0.001), and the area under the receiver operating characteristic curve for the diagnosis of advanced fibrosis was 0.837. Twenty-two patients (25.9%) developed clinically relevant POPF. Multivariate logistic regression analysis demonstrated that the ECV fraction was a significant predictor of POPF.

CONCLUSIONS

The ECV fraction can offer quantitative information for assessing pancreatic fibrosis and POPF after pancreaticojejunal anastomosis.

KEY POINTS

• There was a moderate positive correlation of the extracellular volume (ECV) fraction of the pancreas in contrast-enhanced CT with the histologic grade of pancreatic fibrosis (r = 0.476; p < 0.001). • The ECV fraction was higher in advanced fibrosis (F2‒F3) than in no/mild fibrosis (F0‒F1) (p < 0.001), with an AUC of 0.837 for detecting advanced fibrosis. • The ECV fraction was an independent risk factor for predicting subclinical (odds ratio, 0.81) and clinical (odds ratio, 0.80) postoperative pancreatic fistula.

Clinical validation of the risk scoring systems of postoperative pancreatic fistula after laparoscopic pancreatoduodenectomy in Chinese cohorts: A single-center retrospective study

BACKGROUND

Although several prediction models for the occurrence of clinically relevant postoperative pancreatic fistula after laparoscopic pancreatoduodenectomy exist, most were established using Western cohorts. The utility of these models using a Chinese cohort has not been validated widely. The aim of the study was to validate the original Fistula Risk Score, the alternative Fistula Risk Score, and the updated alternative Fistula Risk Score for patients undergoing laparoscopic pancreatoduodenectomy in a large-scale Chinese cohort externally.

METHODS

Three clinically relevant postoperative pancreatic fistula risk models were selected for external validation with our database. Primary outcome was grade B/C postoperative pancreatic fistula (clinically relevant postoperative pancreatic fistula). Performance was measured based on sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratio, and area under the curve. The original Fistula Risk Score was also compared with the alternative Fistula Risk Score and the updated alternative Fistula Risk Score.

RESULTS

Of the 400 patients who underwent laparoscopic pancreatoduodenectomy, 60 (15.00%) developed clinically relevant postoperative pancreatic fistula. For the original Fistula Risk Score, the alternative Fistula Risk Score, and the updated alternative Fistula Risk Score, the sensitivity was 65.00%, 90.00%, and 90.00%; the specificity was 43.53%, 44.12%, and 37.65%; the positive predictive value was 16.88%, 22.13%, and 20.30%; the negative predictive value was 87.57%, 96.15%, and 95.52%; positive likelihood ratio was 1.151, 1.611, and 1.443; negative likelihood ratio was 0.804, 0.227, and 0.266, respectively. The area under the curve values were 0.608 (95% confidence interval 0.573-0.649), 0.733 (95% confidence interval 0.692-0.797), and 0.720 (95% confidence interval 0.688-0.763) on the original Fistula Risk Score, the alternative Fistula Risk Score, and the updated alternative Fistula Risk Score (P < .05).

CONCLUSION

The alternative Fistula Risk Score and the updated alternative Fistula Risk Score had similarly good predictive utility. The original Fistula Risk Score performed less well. We recommended to use the alternative Fistula Risk Score and the updated alternative Fistula Risk Score to predict occurrence of clinically relevant postoperative pancreatic fistula after laparoscopic pancreatoduodenectomy when applied to a Chinese cohort.

Quantitative MRI Assessment of Pancreatic Steatosis Using Proton Density Fat Fraction in Pediatric Obesity

Objective

To assess the feasibility of quantitatively assessing pancreatic steatosis using magnetic resonance imaging (MRI) and its correlation with obesity and metabolic risk factors in pediatric patients.

Materials and Methods

Pediatric patients (≤ 18 years) who underwent liver fat quantification MRI between January 2016 and June 2019 were retrospectively included and divided into the obesity and control groups. Pancreatic proton density fat fraction (P-PDFF) was measured as the average value for three circular regions of interest (ROIs) drawn in the pancreatic head, body, and tail. Age, weight, laboratory results, and mean liver MRI values including liver PDFF (L-PDFF), stiffness on MR elastography, and T2^* values were assessed for their correlation with P-PDFF using linear regression analysis. The associations between P-PDFF and metabolic risk factors, including obesity, hypertension, diabetes mellitus (DM), and dyslipidemia, were assessed using logistic regression analysis.

Results

A total of 172 patients (male:female = 125:47; mean ± standard deviation [SD], 13.2 ± 3.1 years) were included. The mean P-PDFF was significantly higher in the obesity group than in the control group (mean ± SD, 4.2 ± 2.5% vs. 3.4 ± 2.4%; p = 0.037). L-PDFF and liver stiffness values showed no significant correlation with P-PDFF (p = 0.235 and p = 0.567, respectively). P-PDFF was significantly associated with obesity (odds ratio 1.146, 95% confidence interval 1.006–1.307, p = 0.041), but there was no significant association with hypertension, DM, and dyslipidemia.

Conclusion

MRI can be used to quantitatively measure pancreatic steatosis in children. P-PDFF is significantly associated with obesity in pediatric patients.

Evaluating the Histopathology of Pancreatic Ductal Adenocarcinoma by Intravoxel Incoherent Motion-Diffusion Weighted Imaging Comparing With Diffusion-Weighted Imaging

Objectives

To explore the differences between intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and diffusion-weighted imaging (DWI) in evaluating the histopathological characters of pancreatic ductal adenocarcinoma (PDAC).

Methods

This retrospective study enrolled 50 patients with PDAC confirmed by pathology from December 2018 to May 2020. All patients underwent DWI and IVIM-DWI before surgeries. Patients were classified into low- and high-fibrosis groups. Apparent diffusion coefficient (ADC), diffusion coefficient (D), false diffusion coefficient (D*), and perfusion fraction (f) were measured by two radiologists, respectively in GE AW 4.7 post-processing station, wherein ADC values were derived by mono-exponential fits and f, D, D* values were derived by biexponential fits. The tumor tissue was stained with Sirius red, CD34, and CK19 to evaluate fibrosis, microvascular density (MVD), and tumor cell density. Furthermore, the correlation between ADC, D, D*, and f values and histopathological results was analyzed.

Results

The D values were lower in the high-fibrosis group than in the low-fibrosis group, while the f values were opposite. Further, no statistically significant differences were detected in ADC and D* values between the high- and low-fibrosis groups. The AUC of D and f values had higher evaluation efficacy in the high- and low-fibrosis groups than ADC values. A significant negative correlation was established between D values, and fibrosis and a significant positive correlation were observed between f values and fibrosis. No statistical difference was detected between DWI/IVIM parameters values and MVD or tumor cell density except for the positive correlation between D* values and tumor cell density.

Conclusions

D and f values derived from the IVIM model had higher sensitivity and diagnostic performance for grading fibrosis in PDAC compared to the conventional DWI model. IVIM-DWI may have the potential as an imaging biomarker for predicting the fibrosis grade of PDAC.

Noninvasive assessment of endometrial fibrosis in patients with intravoxel incoherent motion MR imaging

Recently, few noninvasive methods have been reported to evaluate endometrial fibrosis. Our study was to investigate the feasibility of intravoxel incoherent motion (IVIM) MR imaging in the detection of endometrial fibrosis in patients with intrauterine injury. 30 patients with hysteroscopy-confirmed endometrial fibrosis and 28 healthy women were enrolled to undergo MR examination including the IVIM sequence. Endometrial thickness (ET); apparent diffusion coefficient (ADC); and IVIM parameters, including pure diffusion coefficient (D), pseudodiffusion coefficient (D*) and vascular fraction (f) were evaluated. A multivariable model combing ADC, D, and f values using binary logistic regression analysis was built to diagnose endometrial fibrosis. Endometrial fibrosis patients demonstrated lower endometrial ADC, D, f values and ET (all p < 0.05). The multivariable model, ADC, D, f values and ET performed well in diagnosing endometrial fibrosis with AUC of 0.979, 0.965, 0.920, 0.901 and 0.833, respectively. The multivariable model revealed a better diagnostic accuracy than D, f and ET (all p < 0.05). Although ADC achieved a better diagnostic value than ET (z = 2.082, p < 0.05), no difference in AUC was shown among ADC, D, and f (all p > 0.05); between ET and D (p > 0.05); and between ET and f (p > 0.05). The reproducibility of ADC, D, f and D* values in patients with endometrial fibrosis and healthy women were good to excellent (ICC: 0.614-0.951). IVIM parameters exhibit promising potential to serve as imaging biomarkers in the noninvasive assessment of endometrial fibrosis.

Postoperative pancreatic fistula affects recurrence-free survival of pancreatic cancer patients

PURPOSE

Postoperative pancreatic fistula (POPF) with reported incidence rates up to 45% contributes substantially to overall morbidity. In this study, we conducted a retrospective evaluation of POPF along with its potential perioperative clinical risk factors and its effect on tumor recurrence.

METHODS

Clinical data on patients who had received pancreatoduodenectomy (PD), distal pancreatectomy (DP), or duodenum-preserving pancreatic head resection (DPPHR) were prospectively collected between 2007 and 2016. A Picrosirius red staining score was developed to enable morphological classification of the resection margin of the pancreatic stump. The primary end point was the development of major complications. The secondary end points were overall and recurrence-free survival.

RESULTS

340 patients underwent pancreatic resection including 222 (65.3%) PD, 87 (25.6%) DP, and 31 (9.1%) DPPHR. Postoperative major complications were observed in 74 patients (21.8%). In multivariable logistic regression analysis, POPF correlated with body mass index (BMI) (p = 0.025), prolonged stay in hospital (p<0.001), high Picrosirius red staining score (p = 0.049), and elevated postoperative levels of amylase or lipase in drain fluid (p≤0.001). Multivariable Cox regression analysis identified UICC stage (p<0.001), tumor differentiation (p<0.001), depth of invasion (p = 0.001), nodal invasion (p = 0.001), and the incidence of POPF grades B and C (p = 0.006) as independent prognostic markers of recurrence-free survival.

CONCLUSION

Besides the known clinicopathological risk factors BMI and amylase in the drain fluid, the incidence of POPF correlates with high Picrosirius red staining score in the resection margins of the pancreatic stumps of curatively resected pancreatic ductal adenocarcinoma (PDAC). Furthermore, clinically relevant POPF seems to be a prognostic factor for tumor recurrence in PDAC.

Ischemia-Reperfusion Injuries Assessment during Pancreas Preservation

Maintaining organ viability between donation and transplantation is of critical importance for optimal graft function and survival. To date in pancreas transplantation, static cold storage (SCS) is the most widely practiced method of organ preservation. The first experiments in ex vivo perfusion of the pancreas were performed at the beginning of the 20th century. These perfusions led to organ oedema, hemorrhage, and venous congestion after revascularization. Despite these early hurdles, a number of factors now favor the use of perfusion during preservation: the encouraging results of HMP in kidney transplantation, the development of new perfusion solutions, and the development of organ perfusion machines for the lung, heart, kidneys and liver. This has led to a resurgence of research in machine perfusion for whole organ pancreas preservation. This review highlights the ischemia-reperfusion injuries assessment during ex vivo pancreas perfusion, both for assessment in pre-clinical experimental models as well for future use in the clinic. We evaluated perfusion dynamics, oedema assessment, especially by impedance analysis and MRI, whole organ oxygen consumption, tissue oxygen tension, metabolite concentrations in tissue and perfusate, mitochondrial respiration, cell death, especially by histology, total cell free DNA, caspase activation, and exocrine and endocrine assessment.

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.

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.

The comparison of pancreatic and hepatic steatosis in healthy liver donor candidates

The aim of this study was to investigate the relationship between nonalcoholic fatty liver disease (NAFLD) and pancreatic steatosis (PS) in patients with biopsy-proven NAFLD. 228 patients with biopsy-proven NAFLD patients who admitted to the Faculty of Medicine of Demiroglu Bilim University between 2004 and 2019 were included in the study. Demographic, laboratory, histological and radiological findings of the patients were recorded retrospectively. Hepatosteatosis (HS) levels were measured by both CT and biopsy, while PS levels were measured by 3 different CT-based techniques. 89 (39%) of the patients were female and 139 (61%) were male. The mean body mass index (BMI) was 27.2 ± 4.0. Biochemical parameters were within normal limits. Liver biopsy showed a significant correlation with HS grade on CT scan (p < 0.001). When CT findings were compared, a significant correlation was found between PS and HS (p < 0.05), but there was no correlation between the HS level in biopsy and the pancreatic adiposity on CT (p > 0.05). Our study was the first to compare biopsy-proven NAFLD and PS, and no correlation was found between biopsy-proven NAFLD and PS.

Quantitative assessment of renal structural and functional changes in chronic kidney disease using multi-parametric magnetic resonance imaging

Background

Multi-parametric magnetic resonance imaging (MRI) provides the potential for a more comprehensive non-invasive assessment of organ structure and function than individual MRI measures, but has not previously been comprehensively evaluated in chronic kidney disease (CKD).

Methods

We performed multi-parametric renal MRI in persons with CKD (n = 22, 61 ± 24 years) who had a renal biopsy and measured glomerular filtration rate (mGFR), and matched healthy volunteers (HV) (n = 22, 61 ± 25 years). Longitudinal relaxation time (T₁), diffusion-weighted imaging, renal blood flow (phase contrast MRI), cortical perfusion (arterial spin labelling) and blood-oxygen-level-dependent relaxation rate (R₂*) were evaluated.

Results

MRI evidenced excellent reproducibility in CKD (coefficient of variation <10%). Significant differences between CKD and HVs included cortical and corticomedullary difference (CMD) in T₁, cortical and medullary apparent diffusion coefficient (ADC), renal artery blood flow and cortical perfusion. MRI measures correlated with kidney function in a combined CKD and HV analysis: estimated GFR correlated with cortical T₁ (r = −0.68), T₁ CMD (r = −0.62), cortical (r = 0.54) and medullary ADC (r = 0.49), renal artery flow (r = 0.78) and cortical perfusion (r = 0.81); log urine protein to creatinine ratio (UPCR) correlated with cortical T₁ (r = 0.61), T₁ CMD (r = 0.61), cortical (r = −0.45) and medullary ADC (r = −0.49), renal artery flow (r = −0.72) and cortical perfusion (r = −0.58). MRI measures (cortical T₁ and ADC, T₁ and ADC CMD, cortical perfusion) differed between low/high interstitial fibrosis groups at 30–40% fibrosis threshold.

Conclusion

Comprehensive multi-parametric MRI is reproducible and correlates well with available measures of renal function and pathology. Larger longitudinal studies are warranted to evaluate its potential to stratify prognosis and response to therapy in CKD.

Quantification of pancreas fat on dual-energy computed tomography: comparison with six-point Dixon magnetic resonance imaging

OBJECTIVES

Although it is important to quantify the degree of fatty degeneration of the pancreas, it is difficult to make such a quantification using conventional computed tomography (CT). The present study evaluated the feasibility of pancreatic fat quantification by dual-energy CT (DECT) compared with T2*-corrected six-point Dixon magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twenty-eight patients who underwent both DECT (100 and 150 kVp) and Dixon MRI without the use of contrast agents were analyzed. The region of interest (ROI) was placed at the head and body/tail of the pancreas on fat volume fraction (FVF) maps generated using the multi-material decomposition (MMD) algorithm on DECT. The FVF (%) of pancreatic parenchyma measured by DECT (CT-FVF) was compared with that measured on FVF maps calculated using Dixon MRI (MR-FVF) using the Spearman rank correlation coefficient.

RESULTS

The median CT-FVF (%) values of the head and body/tail of the pancreas on DECT were 14.2% (range 0.1-81.2%) and 9.4% (range 0-40.8%), respectively. The median MR-FVF (%) values of the head and body/tail of the pancreas on Dixon MRI were 12.2% (range 1.2-80.9%) and 8.1% (range 0.3-43.7%), respectively. CT-FVF (%) measured by DECT showed a significant correlation with the MR-FVF (%) measured by Dixon MRI in the head of the pancreas (ρ = 0.631, P < 0.001) as well as the body/tail of the pancreas (ρ = 0.526, P = 0.004).

CONCLUSION

DECT may be useful for quantifying the degree of fatty degeneration of the pancreas.

Use of Biomarkers and Imaging for Early Detection of Pancreatic Cancer

Pancreatic cancer remains one of the deadliest cancers worldwide, and it is typically diagnosed late, with a poor prognosis. Early detection is the most important underlying factor for improving the prognosis of pancreatic cancer patients. One of the most effective strategies for detecting cancers at an early stage is screening of the general population. However, because of the low incidence of pancreatic cancer in the general population, the stratification of subjects who need to undergo further examinations by invasive and expensive modalities is important. Therefore, minimally invasive modalities involving biomarkers and imaging techniques that would facilitate the early detection of pancreatic cancer are highly needed. Multiple types of new blood biomarkers have recently been developed, including unique post-translational modifications of circulating proteins, circulating exosomes, microRNAs, and circulating tumor DNA. We previously reported that circulating apolipoprotein A2 undergoes unique processing in the bloodstream of patients with pancreatic cancer and its precancerous lesions. Additionally, we recently demonstrated a new method for measuring pancreatic proton density in the fat fraction using a fat–water magnetic resonance imaging technique that reflects pancreatic steatosis. In this review, we describe recent developments in potential biomarkers and imaging modalities for the early detection and risk stratification of pancreatic cancer, and we discuss current strategies for implementing screening programs for pancreatic cancer.

Improving the slice interaction of 2.5D CNN for automatic pancreas segmentation

PURPOSE

Volumetric pancreas segmentation can be used in the diagnosis of pancreatic diseases, the research about diabetes and surgical planning. Since manual delineation is time-consuming and laborious, we develop a deep learning-based framework for automatic pancreas segmentation in three dimensional (3D) medical images.

METHODS

A two-stage framework is designed for automatic pancreas delineation. In the localization stage, a Square Root Dice loss is developed to handle the trade-off between sensitivity and specificity. In refinement stage, a novel 2.5D slice interaction network with slice correlation module is proposed to capture the non-local cross-slice information at multiple feature levels. Also a self-supervised learning-based pre-training method, slice shuffle, is designed to encourage the inter-slice communication. To further improve the accuracy and robustness, ensemble learning and a recurrent refinement process are adopted in the segmentation flow.

RESULTS

The segmentation technique is validated in a public dataset (NIH Pancreas-CT) with 82 abdominal contrast-enhanced 3D CT scans. Fourfold cross-validation is performed to assess the capability and robustness of our method. The dice similarity coefficient, sensitivity, and specificity of our results are 86.21 ± 4.37%, 87.49 ± 6.38% and 85.11 ± 6.49% respectively, which is the state-of-the-art performance in this dataset.

CONCLUSIONS

We proposed an automatic pancreas segmentation framework and validate in an open dataset. It is found that 2.5D network benefits from multi-level slice interaction and suitable self-supervised learning method for pre-training can boost the performance of neural network. This technique could provide new image findings for the routine diagnosis of pancreatic disease.

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.

Quantitative assessment of renal structural and functional changes in chronic kidney disease using multi-parametric magnetic resonance imaging

BACKGROUND

Multi-parametric magnetic resonance imaging (MRI) provides the potential for a more comprehensive non-invasive assessment of organ structure and function than individual MRI measures, but has not previously been comprehensively evaluated in chronic kidney disease (CKD).

METHODS

We performed multi-parametric renal MRI in persons with CKD (n = 22, 61 ± 24 years) who had a renal biopsy and measured glomerular filtration rate (mGFR), and matched healthy volunteers (HV) (n = 22, 61 ± 25 years). Longitudinal relaxation time (T1), diffusion-weighted imaging, renal blood flow (phase contrast MRI), cortical perfusion (arterial spin labelling) and blood-oxygen-level-dependent relaxation rate (R2*) were evaluated.

RESULTS

MRI evidenced excellent reproducibility in CKD (coefficient of variation <10%). Significant differences between CKD and HVs included cortical and corticomedullary difference (CMD) in T1, cortical and medullary apparent diffusion coefficient (ADC), renal artery blood flow and cortical perfusion. MRI measures correlated with kidney function in a combined CKD and HV analysis: estimated GFR correlated with cortical T1 (r = -0.68), T1 CMD (r = -0.62), cortical (r = 0.54) and medullary ADC (r = 0.49), renal artery flow (r = 0.78) and cortical perfusion (r = 0.81); log urine protein to creatinine ratio (UPCR) correlated with cortical T1 (r = 0.61), T1 CMD (r = 0.61), cortical (r = -0.45) and medullary ADC (r = -0.49), renal artery flow (r = -0.72) and cortical perfusion (r = -0.58). MRI measures (cortical T1 and ADC, T1 and ADC CMD, cortical perfusion) differed between low/high interstitial fibrosis groups at 30-40% fibrosis threshold.

CONCLUSION

Comprehensive multi-parametric MRI is reproducible and correlates well with available measures of renal function and pathology. Larger longitudinal studies are warranted to evaluate its potential to stratify prognosis and response to therapy in CKD.

Intravoxel incoherent motion magnetic resonance imaging for assessment of chronic pancreatitis with special focus on its early stage

Background

It is clinically necessary to validate a new non-invasive and reliable imaging method to detect early chronic pancreatitis. Intravoxel incoherent motion magnetic resonance imaging (MRI) is useful for quantitative assessment in abdominal solid organs.

Purpose

To investigate the usefulness of intravoxel incoherent motion MRI parameters in the diagnosis of chronic pancreatitis.

Material and Methods

Sixty patients with early chronic pancreatitis (n = 44) and chronic pancreatitis (n = 16) were assessed with intravoxel incoherent motion imaging. For comparison, a control group of 71 individuals without chronic pancreatitis was also enrolled. The perfusion fraction (f), pseudo-diffusion coefficient (D*), true diffusion coefficient (D), and apparent diffusion coefficient of pancreatic parenchyma were calculated. These measurements were compared between the three groups. The diagnostic accuracy of imaging parameters was assessed.

Results

The f values of the early chronic pancreatitis group and the chronic pancreatitis group were significantly lower than those of the control group ( P < 0.001 and P < 0.001, respectively). The D* value of the chronic pancreatitis group was significantly lower than that of the early chronic pancreatitis group ( P = 0.0025). The D values of the early chronic pancreatitis group and the chronic pancreatitis group were significantly higher than those of the control group ( P = 0.001 and P = 0.001, respectively). The perfusion fraction showed the highest diagnostic performance with an Az value of 0.76 for discriminating the control group from the early chronic pancreatitis and chronic pancreatitis groups.

Conclusion

Intravoxel incoherent motion MRI parameters may reflect the minimal histological changes in early chronic pancreatitis.

Traumatic pancreatitis

Post-traumatic pancreatitis can develop secondary to blunt or penetrating abdominal trauma, post-endoscopic retrograde cholangiopancreatography, or following pancreatic surgery. Clinical findings are often nonspecific, and imaging findings can be subtle on presentation. Early diagnosis of pancreatic duct injury is critical and informs management strategy; imaging plays important role in diagnosis of ductal injury and identification of delayed complications such as retroperitoneal fluid collections, pancreatic fistula, ductal strictures, and recurrent pancreatitis. Delayed diagnosis of pancreatic injury is associated with high mortality and morbidity, and therefore, heightened clinical suspicion is important in order for the radiologist to effectively impact patient care. There are accepted scoring systems for classification of post-traumatic pancreatic injuries and these should be included in radiology reports. Pancreatitis following ERCP appears similar on imaging to other causes of acute pancreatitis unless concomitant perforation occurs. Postoperative pancreatitis may be difficult to diagnose given associated or overlapping expected postoperative findings. Postoperative pancreatic fistulas typically arise from either a leaking pancreatic resection surface or the pancreatoenteric anastomosis and are more common in patients with a "soft" pancreas. Preoperative imaging biomarkers like duct diameter, pancreatic glandular steatosis and parenchymal fibrosis can help predict risk of development of postoperative pancreatic fistula. This review will illustrate the imaging features and the most important imaging findings in patients with post-traumatic pancreatitis.