Utility of Direct Pancreatic Function Testing in Children

Semi-automated software improves interrater reliability and reduces processing time of magnetic resonance imaging-based exocrine pancreatic assessments in pediatric patients

OBJECTIVES

Magnetic resonance (MR) imaging with secretin stimulation (MR-PFTs) is a non-invasive test for pancreatic exocrine function based on assessing the volume of secreted bowel fluid in vivo. Adoption of this methodology in clinical care and research is largely limited to qualitative assessment of secretion as current methods for secretory response quantification require manual thresholding and segmentation of MR images, which can be time-consuming and prone to interrater variability. We describe novel software (PFTquant) that preprocesses and thresholds MR images, performs heuristic detection of non-bowel fluid objects, and provides the user with intuitive semi-automated tools to segment and quantify bowel fluid in a fast and robust manner. We evaluate the performance of this software on a retrospective set of clinical MRIs.

METHODS

Twenty MRIs performed in children (< 18 years) were processed independently by two observers using a manual technique and using PFTquant. Interrater agreement in measured secreted fluid volume was compared using intraclass correlation coefficients, Bland-Altman difference analysis, and Dice similarity coefficients.

RESULTS

Interrater reliability of measured bowel fluid secretion using PFTquant was 0.90 (0.76-0.96 95% C.I.) with - 4.5 mL mean difference (-39.4-30.4 mL 95% limits of agreement) compared to 0.69 (0.36-0.86 95% C.I.) with - 0.9 mL mean difference (-77.3-75.5 mL 95% limits of agreement) for manual processing. Dice similarity coefficients were better using PFTquant (0.88 +/- 0.06) compared to manual processing (0.85 +/- 0.10) but not significantly (p = 0.11). Time to process was significantly (p < 0.001) faster using PFTquant (412 +/- 177 s) compared to manual processing (645 +/- 305 s).

CONCLUSION

Novel software provides fast, reliable quantification of secreted fluid volume in children undergoing MR-PFTs. Use of the novel software could facilitate wider adoption of quantitative MR-PFTs in clinical care and research.

Exocrine Pancreatic Insufficiency in Children - Challenges in Management

Cystic fibrosis (CF) is the leading etiology for exocrine pancreatic insufficiency (EPI) in children, followed by chronic pancreatitis, Shwachman-Diamond syndrome, and other genetic disorders. Management of EPI in children poses several unique challenges such as difficulties in early recognition, lack of widespread availability of diagnostic tests and limited number of pediatric-specific pancreatic centers. Pancreatic enzyme replacement therapy is the cornerstone of EPI management and in young children difficulties in administering pancreatic enzymes are frequently encountered. Patients with EPI also should be screened for fat-soluble vitamin deficiencies and receive appropriate supplementation. Among disorders with EPI in children, CF is the relatively well-studied condition, and most management recommendations for EPI in children come from expert consensus and conventional practice guidelines. The impact of EPI can be greater in children given their high metabolic demands and rapid growth. Early diagnosis and aggressive management of EPI prevent consequences of complications such as malnutrition, fat-soluble vitamin deficiencies, and poor bone health and improve outcomes. Management by multi-disciplinary team is the key to success.

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.

Prevalence of Exocrine Pancreatic Dysfunction Based on Direct Function Testing in Pediatric Inflammatory Bowel Disease

OBJECTIVES

Patients with inflammatory bowel disease (IBD) frequently have extraintestinal manifestations. The goal of this pilot study was to assess exocrine pancreatic function in cases with suspicion for or an established diagnosis of IBD.

METHODS

Direct stimulated endoscopic pancreatic function test (ePFT) was performed in 74 children with IBD, in both newly diagnosed and established cases. Demographic, clinical, and laboratory parameters were entered into a database and analyzed.

RESULTS

Among the 74 children, 49 were newly diagnosed and 25 had an established diagnosis of IBD. A majority had the diagnosis of Crohn disease (CD) (n = 48; 32 new and 16 established cases) with male predominance (64.6%). Altogether, 42 (56.7%) children had either generalized or partial exocrine pancreatic insufficiency (EPI). Twenty-four of the 48 CD children (50%) had abnormal ePFT. In those with ulcerative colitis (UC), 18 of the 26 (62.9%) had abnormal ePFT. The highest abnormality rate was in lipase enzyme activity. Weight z scores were significantly lower in those with abnormal ePFT (Crohn cases: P = 0.008; UC cases: P = 0.046). Peak protein concentration in collected pancreatic fluid was significantly lower in children with CD who had abnormal ePFT ( P = 0.013).

CONCLUSIONS

This pilot study revealed a relatively high prevalence of EPI in children with IBD through use of ePFT. EPI can result in maldigestion, with decreased capacity to digest fat. Further prospective studies are needed to assess need and efficacy of pancreatic enzyme replacement therapy in children with IBD and abnormal ePFT.

Inherited causes of exocrine pancreatic insufficiency in pediatric patients: clinical presentation and laboratory testing

Pediatric patients with exocrine pancreatic insufficiency (EPI) have symptoms that include abdominal pain, weight loss or poor weight gain, malnutrition, and steatorrhea. This condition can be present at birth or develop during childhood for certain genetic disorders. Cystic fibrosis (CF) is the most prevalent disorder in which patients are screened for EPI; other disorders also are associated with pancreatic dysfunction, such as hereditary pancreatitis, Pearson syndrome, and Shwachman-Diamond syndrome. Understanding the clinical presentation and proposed pathophysiology of the pancreatic dysfunction of these disorders aids in diagnosis and treatment. Testing pancreatic function is challenging. Directly testing aspirates produced from the pancreas after stimulation is considered the gold standard, but the procedures are not standardized or widely available. Instead, indirect tests are often used in diagnosis and monitoring. Although indirect tests are more widely available and easier to perform, they have inherent limitations due to a lack of sensitivity and/or specificity for EPI.

Serial Measurement of Serum Pancreatic Lipase Immunoreactivity, Feline Trypsin-like Immunoreactivity, and Cobalamin Concentrations in Kittens

Serum concentrations of feline pancreatic lipase immunoreactivity (fPLI), feline trypsin-like immunoreactivity (fTLI), and cobalamin are commonly used for the diagnostic investigation of cats with gastrointestinal signs. No information on these parameters in healthy cats less than 1 year of age exists. We aimed to evaluate serum concentrations of fPLI, fTLI, and cobalamin in healthy cats at different time-points during their first 12 months of life. Fourteen healthy 2-month-old kittens were included. Blood was collected at 2, 3, 4, 6, and 12 months of age, and serum concentrations of fPLI, fTLI, and cobalamin were measured. While there was a statistically significant difference in serum fPLI concentrations over time, there was no statistically significant difference between individual time-points. There was no significant difference in serum fTLI concentrations over time. Serum cobalamin concentrations were below the reference interval in 3/13 cats at 2 months of age and were significantly lower by 3 months, when 13/14 had hypocobalaminemia. By 12 months, serum cobalamin had significantly increased, yet 4/12 cats still had hypocobalaminemia. Serum fPLI and fTLI concentrations did not show any statistically or clinically significant differences in young kittens. In contrast, serum cobalamin concentrations were commonly below the reference interval in kittens. Serum fPLI and fTLI concentrations are not practically affected by age in kittens as young as 2 months of age and could be used for the investigation of pancreatic diseases.

Assessment of exocrine pancreatic function in children and adolescents with direct and indirect testing

The exocrine pancreas plays an important role in digestion. Understanding of the physiology and regulation of exocrine function provides insight into disease processes and basis of functional testing. Specifically, exocrine pancreatic insufficiency (EPI) can cause maldigestion and thus a proper assessment of exocrine pancreatic function is important. There are indirect and direct methods for evaluating pancreatic function. Indirect methods are varied and include stool, serum, urine, and breath tests. Fecal elastase is a commonly used indirect test today. Direct methods involve stimulated release of pancreatic fluid that is collected from the duodenum and analyzed for enzyme activity. The most used direct test today is the endoscopic pancreatic function test. Indirect pancreatic function testing is limited in identifying cases of mild to moderate EPI, and as such in these cases, direct testing has higher sensitivity and specificity in diagnosing EPI. This review provides a comprehensive guide to indirect and direct pancreatic function tests as well as an in-depth look at exocrine pancreatic function including anatomy, physiology, and regulatory mechanisms.

Endoscopic Pancreatic Function Testing (ePFT) in Children: A Position Paper From the NASPGHAN Pancreas Committee

Endoscopic pancreatic function testing (ePFT) is one of the few ways to directly diagnose exocrine pancreatic insufficiency, and considerable confusion regarding indications, utility, and interpretation of the test remains. This position paper of the Pancreas Committee of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition reviews the history and indications for ePFT in children. We compare various methods in current practice and determine their strengths and limitations, and based on data from children and adults we provide guidance on a protocol on how to perform ePFT in children. Lastly, we pose areas in need of further research relating to ePFT in children.

Sterility Cultures Following Pancreatectomy with Islet Autotransplantation in the Pediatric Population: Do They Matter?

BACKGROUND

Pancreatectomy with islet autotransplantation (IAT) is a treatment option for children with debilitating chronic pancreatitis. Sterility cultures from preservation solutions are often positive, yet their impact has not been well studied in children.

METHODS

A retrospective review of all patients who underwent IAT from 2015 to 2018 at a single institution was performed. Sterility culture data were obtained from both the pancreas transport and islet transplant media. All patients received prophylactic perioperative meropenem and vancomycin for 72 h per our protocol. If cultures resulted positive, antibiotics were extended for a total of 7 days. Primary outcomes were postoperative fever and 30-day infectious complications.

RESULTS

Forty-one patients underwent IAT during the study period. Seventeen (41.5 %) patients had negative cultures of both the transport and transplant media, while 24 (58.5 %) patients had a positive culture from either sample. Of these patients, 13 (31.7 %) were positive in both, 10 (24.4 %) were positive in only the transport media, and 1 (2.4 %) was positive in only the transplant media. Patients with positive transplant media were similar with regard to age, gender, etiology, and disease duration compared to those with negative transplant media (all p > 0.05), but the positive group was more likely to have a pancreatic stent in place at the time of surgery (38.5 % vs. 4.2 %, p = 0.01). The overall postoperative infectious complication rate was 31.2 % (n = 13). No difference was detected between the transplant positive and negative culture groups in postoperative fever or 30-day infectious complications (p > 0.05 for each).

CONCLUSION

An existing pancreatic stent at the time of pancreatectomy with IAT is a risk factor for positive sterility cultures. However, positive islet transplant media culture was not associated with increased risk of post-IAT infection or morbidity in the setting of an empiric antibiotic protocol. Future work is necessary to study the optimal perioperative antibiotic regimen in pediatric IAT.

Report on the Short Endoscopic Exocrine Pancreatic Function Test in Children and Young Adults

OBJECTIVES

Endoscopic pancreatic function test (ePFT) has been in use for exocrine function testing since the 1990s. In patients, short ePFT assesses acinar function, unlike the longer version for ductal function in adults. The present study summarizes characteristics of 1913 short ePFTs (S-ePFT) performed at 2 centers since 2001.

METHODS

The main indications in patients presenting at ages infancy to 24.3 years, for the S-ePFT were failure to thrive, weight loss, diarrhea, and abdominal pain with bloating. Secretin was administered as bolus, and 4 aliquots of fluid were collected between 4 and 10 minutes after administration. Amylase, lipase, trypsin, and chymotrypsin activities were measured in the laboratory.

RESULTS

The pH of consecutive samples increased by 0.3 to 0.7. Overall, 36.7% had abnormal S-ePFT with selective amylase deficiency (9.5%) and generalized enzyme deficiency (8.9%) being the most frequent. Retest reproducibility, repeatability, and clinical validity were high. By adding S-ePFT to endoscopy for the suspicion of malabsorption, the abnormal findings increased by 36.9%.

CONCLUSIONS

Short ePFT assesses pancreatic acinar function in a reliable and clinically meaningful way in patients. Diagnostic yield of endoscopy increased substantially albeit with increased sedation time. By S-ePFT ductal function, cytokines and proteomics can also be assessed.

Assessment of Exocrine Pancreatic Function During Endoscopy in Children

This article will review briefly the physiology of pancreatic enzyme secretion and the role of stimulated endoscopic testing for assessing exocrine pancreatic function. Published studies in both the pediatric and adult literature are reviewed. The technique and utility of endoscopic pancreatic function testing as the method of choice in the differential diagnosis of pancreatic disorders in childhood is described. Finally, emerging, clinically useful markers that can be measured in the pancreatic fluid will be described.

3D MR elastography of the pancreas in children

PURPOSE

Early diagnosis of chronic pancreatitis (CP) remains elusive. Preliminary data suggest that MR elastography (MRE) may have diagnostic value in the identification of CP. We sought to measure pancreas stiffness by MRE in healthy children and to compare measured values to stiffness values in pediatric patients with acute recurrent pancreatitis (ARP) or CP.

METHODS

Under IRB approval, 49 healthy controls volunteered to be included, and 14 patients with ARP or CP that underwent 3D MRE on a 1.5T MR scanner were included in the study. A soft passive driver was utilized and vibrated at 40 Hz. Regions of interest for measurement of pancreatic stiffness were drawn by two blinded readers and statistical analysis were performed for comparisons between the two groups.

RESULTS

Mean age of the healthy controls was 11 ± 2.7 years and mean pancreas stiffness was 1.7 ± 0.3 (Reader 1) and 1.7 ± 0.3 (Reader 2) kPa. For patients with ARP or CP, mean age was 12.6 ± 4.4 years and mean pancreas stiffness was 0.9 ± 0.2 (Reader 1) and 1.1 ± 0.3 (Reader 2) kPa. Pancreas stiffness was significantly lower in patients with ARP and CP as compared to healthy controls (p < 0.001). Between readers, there was a strong and statistically significant agreement on measured pancreas stiffness (r = 0.81; p < 0.001). Bland-Altman difference analysis showed a mean bias of only 0.05 kPa (95% limits of agreement: - 0.49 to + 0.58) CONCLUSION: MRE of the pancreas can be performed in pediatric patients. Through this study, we have defined normal pancreas stiffness for children and have shown decreases in measured stiffness in patients with ARP or CP compared to healthy controls.

CLINICAL RELEVANCE

3D MRE of the pancreas offers a novel approach for detecting pancreatic disease based on changes in tissue mechanical properties.

Updates in Pediatric Pancreatology: Proceedings of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Frontiers in Pediatric Pancreatology Symposium

The Pancreas Committee of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition aims to promote awareness of pediatric pancreatic diseases, support clinical and basic science research in the field, educate pediatric gastroenterologists, and advocate on behalf of pediatric patients with pancreatic disorders. At the 2017 Annual North American Society for Pediatric Gastroenterology, Hepatology and Nutrition meeting, the Pancreas Committee held a full day symposium on pediatric pancreatic diseases, entitled, "Frontiers in Pediatric Pancreatology." The symposium served as a timely and novel academic meeting that brought together individuals with a vested interest in the care of children with pancreatic disorders. The objective of this day-long course was to update practicing gastroenterologists on the latest advances in research, management algorithms, endoscopic therapies, radiographic resources, surgical approaches, and novel drug therapies targeted to pediatric pancreatitis. Presentations were divided into 4 modules: diagnosis, risk factors, and natural history of pancreatitis; pancreatic imaging and exocrine function; management of pancreatitis; and new frontiers in pediatric pancreatitis research. The course fostered a unique ecosystem for interdisciplinary collaboration, in addition to promoting discussion and stimulating new research hypotheses regarding pediatric pancreatic disorders. Oral presentations by experts in various fields of pancreatology led to thought-provoking discussion; in addition, a meet-the-professor luncheon stimulated critical evaluation of current research in pediatric pancreatic diseases, highlighting knowledge gaps and future research endeavors. The current report summarizes the major learning points from this novel symposium focusing on the growing demographic of pediatric pancreatic diseases.

Incomplete functional and morphological recovery after acute and acute recurrent pancreatitis in children

BACKGROUND AND AIM

There is lack of data on functional and morphological recovery after an attack of acute pancreatitis (AP) or acute recurrent pancreatitis (ARP) in children. This study aims to evaluate the functional impairment and morphological changes in the pancreas after recovery.

METHODS

All consecutive patients presenting with AP (n = 61) or ARP (n = 35), as per standard diagnostic criteria, were enrolled. After 2 months of pancreatitis, fecal elastase-1 (FE-1) (μg/g) and 2-h oral glucose tolerance test to calculate oral disposition index (DI_o ) (mmol/L) (β-cell function) were performed. Morphological changes were assessed by endoscopic ultrasound and transabdominal ultrasound. Patients with chronic pancreatitis (CP) (n = 27) and healthy children (HC) (n = 26) were included as controls for functional parameters.

RESULTS

At a median follow up of 12 (4-44) and 11 (2-108) months, 66.7% and 75.9% (P = 0.57) of AP and ARP demonstrated exocrine insufficiency (FE-1 < 200), respectively. Mean (SD) FE-1 was 183.64 ± 150.94 (AP), 135.70 ± 103.80 (ARP), 46.56 ± 30.20 (CP), and 240.00 ± 181.83 (HC) (P < 0.001; anova) (AP vs CP, ARP vs CP, and CP vs HC; P < 0.001). Prediabetes due to insulin resistance was seen in 16.6% and 22.6% (P = 0.56) of AP and ARP. Median (interquartile range) DI_o (mmol/L) was comparable between AP (4.20 [2.36, 8.3]) and HC (5.20 [2.89, 8.68]), but was low in ARP (2.97 [1.80, 5.12]), which was comparable with CP (1.91 [1.20, 2.83]). Endoscopic ultrasound demonstrated morphological changes in 25% and 37% (P = 0.34) of AP and ARP, respectively.

CONCLUSION

There was high frequency of biochemical evidence of exocrine insufficiency. β-Cell function (DI_o ) was preserved among AP but was poor in ARP. Nearly one-third showed morphological changes in imaging.

Pancreatic Insufficiency: What Is the Gold Standard?

Endoscopic pancreatic function testing assesses exocrine insufficiency and chronic pancreatitis. Indirect pancreatic function tests have limited sensitivity and specificity in early disease stages. Magnetic resonance cholangiopancreatography shows promise in detecting early changes as a direct measure of pancreatic function. This article summarizes the evolution of pancreatic function testing and highlights areas for future research, such as development of diagnostic biomarkers to stratify disease severity and targeted therapies to retard disease progression.

Prospective Assessment of Normal Pancreatic Secretory Function Measured by MRI in a Cohort of Healthy Children

OBJECTIVES

Magnetic resonance imaging (MRI) with secretin stimulation promises to allow non-invasive testing for exocrine pancreatic insufficiency but normal data do not exist for children. The purpose of this study was to define, in healthy children, normal pancreatic secreted fluid volume and secretion rate, measured by MRI, in response to secretin.

METHODS

In this Institutional Review Board-approved, prospective, cross-sectional study, 50 healthy children ages 6 to <16 years underwent MRI with secretin stimulation. Images were obtained before and at 1, 5, 10 and 15 min after secretin administration to calculate total secreted fluid volume and secretion rate based on image segmentation. Regression was used to define the relationship between secretory function and participant size measures, and linear quantile regression was used to define normal secretory values based on size measures.

RESULTS

Median total secreted fluid volume post secretin was 79 mL (range: 32-162 mL; 5th and 95th percentiles: 43 and 123 mL) and median secretion rate was 5.1 mL/min (range: 2-9.4 mL/min; 5th and 95th percentiles: 2.3 and 7.7 mL/min). Secreted volume and secretion rate had the strongest correlation with body surface area (BSA) (r = 0.54 and 0.59, respectively) and multiple regression defined BSA as the only significant predictor of secretory function. Each 1 m² increase in BSA was associated with a 38 mL increase in secreted fluid volume.

CONCLUSIONS

In children, pancreatic secretory response to secretin, measured by MRI, depends on participant size, particularly BSA. Secreted volume <43 mL or a secretion rate <2.3 mL/min (5th percentile values) can be considered abnormal for children.

Pediatric chronic pancreatitis: Updates in the 21st century

Pediatric Pancreatitis has gained a lot of attention in the last decade. Updates in medical management include new testing technologies in genetics, function testing and imaging modalities. Updates in surgical management have taken place as well, with total pancreatectomy islet auto transplantation reserved for a specific patient population that meets the clinical criteria. Multidisciplinary team management is needed for patients with chronic pancreatitis to ensure optimal outcomes.

Secretin-Enhanced Magnetic Resonance Cholangiopancreatography for Assessing Pancreatic Secretory Function in Children

OBJECTIVE

To assess the accuracy and interrater reproducibility of measurements of pancreatic secretory function by magnetic resonance cholangiopancreatography in response to secretin administration and to describe our experience using the technique to noninvasively assess pancreatic secretory function in a pediatric population.

STUDY DESIGN

In the accuracy study, phantoms with varying fluid volume (47-206 mL) were imaged using the clinical quantification sequence. Fluid volume was measured by image segmentation (ImageJ). Measurement accuracy was expressed in terms of error (absolute and percent) relative to known fluid volume. In the reproducibility study and clinical experience, 31 patients with suspected pancreatic disease underwent 33 secretin-enhanced magnetic resonance cholangiopancreatography exams. Two-dimensional T2-weighted, fat-saturated single shot fast spin echo sequences were acquired before and after secretin injection (0.2 µg/kg, max 16 µg). Secreted fluid volume (postsecretin minus presecretin) was independently measured by 2 blinded reviewers. Between reviewer measurement reproducibility was assessed based on correlation (Spearman) and bias (Bland-Altman analysis).

RESULTS

For the accuracy study, fluid volumes were measured with mean volume errors of -0.3 to +12.5 mL (percent error -0.03% to +9.0%). For the reproducibility study, the mean secreted fluid volumes measured by reviewer 1 and reviewer 2 were 79.1 ± 54.3 mL (range 5.5-215.4) and 77.2 ± 47.1 mL (range 6.7-198.1 mL), respectively. Measured secreted fluid volumes were very strongly correlated (r = 0.922) between reviewers with a bias of only 1.9 mL (95% limits of agreement -40.5 to 44.2).

CONCLUSIONS

Measurement of fluid volume by magnetic resonance imaging is highly accurate with <10% (<13 mL) error in measured volume. Measurements of pancreatic secreted fluid volume in response to secretin by magnetic resonance cholangiopancreatography are highly reproducible with a bias of <2 mL between reviewers.