Healthy pancreatic parenchymal volume and its relationship to exocrine function

Pancreas volumes in pediatric patients following index acute pancreatitis and acute recurrent pancreatitis

BACKGROUND/OBJECTIVES

Pancreas volume derived from imaging may objectively reveal volume loss relevant to identifying sequelae of acute pancreatitis (AP) and ultimately diagnosing chronic pancreatitis (CP). The purposes of this study were to: (1) quantify pancreas volume by imaging in children with either (a) a single episode of AP or (b) acute recurrent pancreatitis (ARP), and (2) compare these volumes to normative volumes.

METHODS

This retrospective study was institutional review board approved. A single observer segmented the pancreas (3D Slicer; slicer.org) on n = 30 CT and MRI exams for 23 children selected from a prospective registry of patients with either an index attack of AP or with ARP after a known index attack date. Patients with CP were excluded. Segmented pancreas volumes were compared to published normal values.

RESULTS

Mean pancreas volumes normalized to body surface area (BSA) in the index AP and ARP groups were 38.2 mL/m2 (range: 11.8-73.5 mL/m2) and 27.9 mL/m2 (range: 8.0-69.2 mL/m2) respectively. 43 % (6/14) of patients post-AP had volumes below the 25th percentile, 1 (17 %) of which was below the 5th percentile (p = 0.3027 vs. a normal distribution). Post-ARP, 44 % (7/16) of patients had volumes below the 5th percentile (p < 0.001).

CONCLUSIONS

A significant fraction (40 %) of children with ARP have pancreas volumes <5th percentile for BSA even in the absence of CP. A similar, but not statistically significant, fraction have pancreas volumes <25th percentile after an index attack of AP. Pancreatic parenchymal volume deserves additional investigation as an objective marker of parenchymal damage from acute pancreatitis and of progressive pancreatitis in children.

Goat Milk Improves Glucose Metabolism in Type 2 Diabetic Mice and Protects Pancreatic β-Cell Functions

SCOPE

Consuming goat milk is known to benefit high-fat diet-fed and streptozocin (STZ)-induced diabetic rats, but the underlying mechanisms are unknown. This study is conducted to investigate the metabolic effects of a goat milk diet (a form of goat milk powder) on glucose homeostasis and pancreatic conditions in a mouse model of Type 2 diabetes mellitus (T2DM) induced by STZ.

METHODS AND RESULTS

T2DM mice are fed with a goat-milk-based diet containing 10.3% w/w goat milk powder for 10 weeks for investigating the in vivo effects; a β-cell line MIN6 cells are used to test the in vitro effects of digested goat milk (DGM). Goat milk diet improves the deleterious effects of STZ on fasting glucose levels and glucose tolerance, accelerates pancreatic structure recovery, and alters blood metabolites in mice. Based on the significant differences observed in metabolites, the key pathways, metabolite regulatory enzymes, metabolite molecular modules, and biochemical reactions are identified as critical integrated pathways. DGM promotes the cell activity, glucose transportation, and AKT activation in cultured STZ-treated MIN6 cells in vitro.

CONCLUSIONS

Goat milk diet improves glucose homeostasis and pancreatic conditions of T2DM mice, in association with improved blood metabolite profiles and activation of pancreatic AKT pathway.

Image or scope: Magnetic resonance imaging and endoscopic testing for exocrine and endocrine pancreatic insufficiency in children

OBJECTIVES

We sought to evaluate associations between Magnetic Resonance Imaging (MRI) findings, exocrine pancreatic insufficiency (EPI) and endocrine insufficiency (prediabetes or diabetes) in children.

METHODS

This was a retrospective study that included patients<21 years of age who underwent MRI and endoscopic pancreatic function testing (ePFT; reference standard for pancreatic exocrine function) within 3 months. MRI variables included pancreas parenchymal volume, secreted fluid volume in response to secretin, and T1 relaxation time. Data were analyzed for the full sample as well as the subset without acute pancreatitis (AP) at the time of imaging.

RESULTS

Of 72 patients, 56% (40/72) were female with median age 11.4 years. A 5 mL decrease in pancreas parenchymal volume was associated with increased odds of exocrine pancreatic dysfunction by both ePFT (OR = 1.16, p = 0.02 full sample; OR = 1.29, p = 0.01 no-AP subset), and fecal elastase (OR = 1.16, p = 0.04 full sample; OR = 1.23, p = 0.02 no-AP subset). Pancreas parenchymal volume had an AUC 0.71 (95% CI: 0.59, 0.83) for predicting exocrine pancreatic dysfunction by ePFT and when combined with sex and presence of AP had an AUC of 0.82 (95% CI: 0.72, 0.92). Regarding endocrine function, decreased pancreas parenchymal volume was associated with increased odds of diabetes (OR = 1.16, p = 0.03), and T1 relaxation time predicted glycemic outcomes with an AUC 0.78 (95% CI: 0.55-1), 91% specificity and 73% sensitivity.

CONCLUSIONS

Pancreas parenchymal volume is an MRI marker of exocrine and endocrine pancreatic dysfunction in children. A model including sex, AP, and pancreas volume best predicted exocrine status. T1 relaxation time is also an MRI marker of endocrine insufficiency.

Pancreas volumes and predictive factors in healthy children

BACKGROUND

Pancreas volume might be a quantitative metric of pancreas health and function in children.

OBJECTIVE

To establish normative pancreas volumes and determine factors associated with pancreas volume.

MATERIALS AND METHODS

We conducted a retrospective study of 140 healthy children (balanced from 0 to 18 years, stratified by age and gender) who underwent contrast-enhanced CT of the abdomen. Pancreas volume was manually segmented by a single reviewer using 3D Slicer and corrected by a pediatric radiologist. We used Bland-Altman difference analysis to quantify differences in initial and refined segmented pancreas volume, and the Mann-Whitney U test to compare continuous variables. We used Pearson correlation for univariate associations. To determine predictors, we used multivariable regression. Finally, we generated quantile regression equations to determine pancreas volume based on age or body surface area (BSA).

RESULTS

Pancreas volume for the study sample ranged from 2 mL to 99 mL. Age (r=0.90, P<0.0001), body mass index (BMI) (r=0.66, P<0.0001), BSA (r=0.94, P<0.0001), height (r=0.91, P<0.0001) and weight (r=0.90, P<0.0001) were all positively correlated with pancreas volume on univariate analysis. On multivariable analysis, BSA (+36 mL/m², P<0.0001) and female gender (-2.8 mL, P=0.062) were significant independent predictors of pancreas volume. The mean difference between initial and refined segmentation was 0.80 mL (95% limits of agreement: -7.9 mL to 9.5 mL).

CONCLUSION

We report pancreas volumes for healthy children. We found that age, BMI, BSA, height and weight were each significantly, positively correlated with pancreas volume in univariate analyses, while BSA and female gender were significant independent predictive factors on multivariable analysis.

Volumetric Pancreas Segmentation on Computed Tomography: Accuracy and Efficiency of a Convolutional Neural Network Versus Manual Segmentation in 3D Slicer in the Context of Interreader Variability of Expert Radiologists

PURPOSE

This study aimed to compare accuracy and efficiency of a convolutional neural network (CNN)-enhanced workflow for pancreas segmentation versus radiologists in the context of interreader reliability.

METHODS

Volumetric pancreas segmentations on a data set of 294 portal venous computed tomographies were performed by 3 radiologists (R1, R2, and R3) and by a CNN. Convolutional neural network segmentations were reviewed and, if needed, corrected ("corrected CNN [c-CNN]" segmentations) by radiologists. Ground truth was obtained from radiologists' manual segmentations using simultaneous truth and performance level estimation algorithm. Interreader reliability and model's accuracy were evaluated with Dice-Sorenson coefficient (DSC) and Jaccard coefficient (JC). Equivalence was determined using a two 1-sided test. Convolutional neural network segmentations below the 25th percentile DSC were reviewed to evaluate segmentation errors. Time for manual segmentation and c-CNN was compared.

RESULTS

Pancreas volumes from 3 sets of segmentations (manual, CNN, and c-CNN) were noninferior to simultaneous truth and performance level estimation-derived volumes [76.6 cm 3 (20.2 cm 3 ), P < 0.05]. Interreader reliability was high (mean [SD] DSC between R2-R1, 0.87 [0.04]; R3-R1, 0.90 [0.05]; R2-R3, 0.87 [0.04]). Convolutional neural network segmentations were highly accurate (DSC, 0.88 [0.05]; JC, 0.79 [0.07]) and required minimal-to-no corrections (c-CNN: DSC, 0.89 [0.04]; JC, 0.81 [0.06]; equivalence, P < 0.05). Undersegmentation (n = 47 [64%]) was common in the 73 CNN segmentations below 25th percentile DSC, but there were no major errors. Total inference time (minutes) for CNN was 1.2 (0.3). Average time (minutes) taken by radiologists for c-CNN (0.6 [0.97]) was substantially lower compared with manual segmentation (3.37 [1.47]; savings of 77.9%-87% [ P < 0.0001]).

CONCLUSIONS

Convolutional neural network-enhanced workflow provides high accuracy and efficiency for volumetric pancreas segmentation on computed tomography.

Current and emerging artificial intelligence applications for pediatric abdominal imaging

Artificial intelligence (AI) uses computers to mimic cognitive functions of the human brain, allowing inferences to be made from generally large datasets. Traditional machine learning (e.g., decision tree analysis, support vector machines) and deep learning (e.g., convolutional neural networks) are two commonly employed AI approaches both outside and within the field of medicine. Such techniques can be used to evaluate medical images for the purposes of automated detection and segmentation, classification tasks (including diagnosis, lesion or tissue characterization, and prediction), and image reconstruction. In this review article we highlight recent literature describing current and emerging AI methods applied to abdominal imaging (e.g., CT, MRI and US) and suggest potential future applications of AI in the pediatric population.

Magnetic resonance imaging glossary of findings of pediatric pancreatitis and the revised Atlanta classification

While still uncommon, the incidence of acute pancreatitis in children has been increasing over the last two decades. The Atlanta classification for acute pancreatitis, developed for adults, stratifies cases of acute pancreatitis based on imaging and clinical criteria. This classification scheme allows for standardized use of terminology to facilitate treatment and prognostication. Although US and CT should be used in critical or unstable patients, MRI is an ideal imaging modality in pediatric patients with acute pancreatitis because of its ability to characterize tissue without ionizing radiation. We review MRI examples specific to Atlanta classification terminology in pediatric patients. Chronic pancreatitis has also been increasingly diagnosed in children, and imaging plays a key role in the diagnosis and management of this insidious disease. MRI with magnetic resonance cholangiopancreatography is the optimal modality for assessing the pancreas in a child with known or suspected chronic pancreatitis because it provides tissue characterization and high-contrast imaging of the pancreatic duct without the use of invasive instrumentation or ionizing radiation. We also review and demonstrate accepted MRI findings of chronic pancreatitis.

Current State of Imaging of Pediatric Pancreatitis: AJR Expert Panel Narrative Review

Pancreatitis is as common in children as it is in adults, though causes and accepted imaging strategies differ in children. In this narrative review we discuss the epidemiology of childhood pancreatitis and key imaging features for pediatric acute, acute recurrent, and chronic pancreatitis. We rely heavily on our collective experience in discussing advantages and disadvantages of different imaging modalities; practical tips for optimization of ultrasound, CT, and MRI with MRCP in children; and image interpretation pearls. Challenges and considerations unique to imaging pediatric pancreatitis are discussed, including timing of imaging, role of secretin-enhanced MRCP, utility of urgent MRI, severity prediction, autoimmune pancreatitis, and best methods for serial imaging. We suggest a methodical approach to pancreatic MRI interpretation in children and have included a sample structured report, and we provide consensus statements according to our experience imaging children with pancreatitis.

Imaging prediction of islet yield and post-operative insulin requirement in children undergoing total pancreatectomy with islet autotransplantation

BACKGROUND

Predicting post-operative glycemic control in children undergoing total pancreatectomy with islet autotransplantation (TPIAT) remains difficult. The purpose of our study was to explore preoperative imaging as a marker for islet yield and insulin need in pediatric patients undergoing TPIAT.

METHODS

This was a retrospective study of children (≤18 years) who had undergone TPIAT between April 2015 and December 2018 and had 6 or more months of post-TPIAT follow-up. Patient specific factors (height, weight, body mass index [BMI], body surface area [BSA]) and pancreas volume segmented from the most recent pre-operative cross-sectional imaging were explored as predictors of islet yield (total islet counts [TIC], total islet equivalents [TIE], islet equivalents per kilogram body weight [IEQ/kg]) and glycemic control (total daily dose of insulin per kilogram body weight [TDD/kg], insulin independence) using Pearson correlation and univariate and multiple regression.

RESULTS

Thirty-three patients, median age 13 years (IQR: 10-15 years), 64% female (21/33) met inclusion criteria. Nine patients (27%) achieved insulin independence at six months. Median TIE isolated was 310,000 (IQR: 200,000-460,000). Segmented pancreas volume was moderately associated with TIE (coefficient estimate = 0.34, p = 0.034). On multiple regression analysis, there was no significant predictor of insulin independence but number of attacks of pancreatitis (estimate = 0.024; p = 0.018) and segmented pancreas volume by body weight (estimate = -0.71; p < 0.001) were significant predictors of insulin TDD/kg.

CONCLUSION

Pancreas volume segmented from pre-TPIAT imaging has predictive performance for post-TPIAT insulin need in children.

Validation of threshold values for pancreas thickness and T1-weighted signal intensity ratio in the pediatric pancreas

BACKGROUND

Pancreas atrophy and the loss of T1-weighted signal intensity by magnetic resonance imaging (MRI) are findings of chronic pancreatitis.

OBJECTIVE

The purpose of this study was to test published normal values and cutoffs for pancreas thickness and the pancreas:spleen T1-weighted signal intensity ratio in children without pancreatic disease.

MATERIALS AND METHODS

This was a secondary analysis of prospectively collected MRI data for 50 children (range: 6.3-15.9 years; 27 female) with no history of pancreatic disease. Two observers (R1, R2) measured linear pancreas thickness on axial T1-weighted, fat-saturated gradient recalled echo images and placed regions of interest in the pancreas and spleen to calculate the T1-weighted signal intensity ratio. Measurements were compared to published pediatric normal values (computed tomography [CT], ultrasound [US]) and adult cutoffs (CT, MRI).

RESULTS

Compared to published pediatric values for CT, 68% (R1: 34/50) or 40% (R2: 22/50) of participants had ≥1 pancreas segment with thickness below the normal range. No participant had a thickness value below the normal range published for US. Compared to cutoff values in adults, 84% (R1: 42/50) or 80% (R2: 40/50) of participants met the criteria for pancreas atrophy. Mean T1-weighted signal intensity ratio was 1.33±0.15 (R1) and 1.32±0.16 (R2). Twelve (R1: 24.5% of 49) or 11/49 (R2: 22.4%) participants had a T1-weighted signal intensity ratio below the threshold associated with exocrine insufficiency in adults.

CONCLUSION

Previously defined thresholds for pancreas thickness and pancreas:spleen T1-weighted signal intensity ratio appear too restrictive for a pediatric population. Further study is needed to define optimal quantitative metrics for findings of chronic pancreatitis in children.