Microbial stimulation of oxytocin release from the intestinal epithelium via secretin signaling

Intestinal microbes impact the health of the intestine and organs distal to the gut. Limosilactobacillus reuteri is a human intestinal microbe that promotes normal gut transit, the anti-inflammatory immune system, wound healing, normal social behavior in mice, and prevents bone reabsorption. Oxytocin impacts these functions and oxytocin signaling is required for L. reuteri-mediated wound healing and social behavior; however, the events in the gut leading to oxytocin stimulation and beneficial effects are unknown. Here we report evolutionarily conserved oxytocin production in the intestinal epithelium through analysis of single-cell RNA-Seq datasets and imaging of human and mouse intestinal tissues. Moreover, human intestinal organoids produce oxytocin, demonstrating that the intestinal epithelium is sufficient to produce oxytocin. We find that L. reuteri facilitates oxytocin secretion from human intestinal tissue and human intestinal organoids. Finally, we demonstrate that stimulation of oxytocin secretion by L. reuteri is dependent on the gut hormone secretin, which is produced in enteroendocrine cells, while oxytocin itself is produced in enterocytes. Altogether, this work demonstrates that oxytocin is produced and secreted from enterocytes in the intestinal epithelium in response to secretin stimulated by L. reuteri. This work thereby identifies oxytocin as an intestinal hormone and provides mechanistic insight into avenues by which gut microbes promote host health.

Assembly mechanism of a Tad secretion system secretin-pilotin complex

The bacterial Tight adherence Secretion System (TadSS) assembles surface pili that drive cell adherence, biofilm formation and bacterial predation. The structure and mechanism of the TadSS is mostly unknown. This includes characterisation of the outer membrane secretin through which the pilus is channelled and recruitment of its pilotin. Here we investigate RcpA and TadD lipoprotein from Pseudomonas aeruginosa. Light microscopy reveals RcpA colocalising with TadD in P. aeruginosa and when heterologously expressed in Escherichia coli. We use cryogenic electron microscopy to determine how RcpA and TadD assemble a secretin channel with C13 and C14 symmetries. Despite low sequence homology, we show that TadD shares a similar fold to the type 4 pilus system pilotin PilF. We establish that the C-terminal four residues of RcpA bind TadD - an interaction essential for secretin formation. The binding mechanism between RcpA and TadD appears distinct from known secretin-pilotin pairings in other secretion systems.

Loss of the Secretin Receptor Impairs Renal Bicarbonate Excretion and Aggravates Metabolic Alkalosis in Mice during Acute Base-Loading

SIGNIFICANCE STATEMENT

During acute base excess, the renal collecting duct β -intercalated cells ( β -ICs) become activated to increase urine base excretion. This process is dependent on pendrin and cystic fibrosis transmembrane regulator (CFTR) expressed in the apical membrane of β -ICs. The signal that leads to activation of this process was unknown. Plasma secretin levels increase during acute alkalosis, and the secretin receptor (SCTR) is functionally expressed in β -ICs. We find that mice with global knockout for the SCTR lose their ability to acutely increase renal base excretion. This forces the mice to lower their ventilation to cope with this challenge. Our findings suggest that secretin is a systemic bicarbonate-regulating hormone, likely being released from the small intestine during alkalosis.

BACKGROUND

The secretin receptor (SCTR) is functionally expressed in the basolateral membrane of the β -intercalated cells of the kidney cortical collecting duct and stimulates urine alkalization by activating the β -intercalated cells. Interestingly, the plasma secretin level increases during acute metabolic alkalosis, but its role in systemic acid-base homeostasis was unclear. We hypothesized that the SCTR system is essential for renal base excretion during acute metabolic alkalosis.

METHODS

We conducted bladder catheterization experiments, metabolic cage studies, blood gas analysis, barometric respirometry, perfusion of isolated cortical collecting ducts, immunoblotting, and immunohistochemistry in SCTR wild-type and knockout (KO) mice. We also perfused isolated rat small intestines to study secretin release.

RESULTS

In wild-type mice, secretin acutely increased urine pH and pendrin function in isolated perfused cortical collecting ducts. These effects were absent in KO mice, which also did not sufficiently increase renal base excretion during acute base loading. In line with these findings, KO mice developed prolonged metabolic alkalosis when exposed to acute oral or intraperitoneal base loading. Furthermore, KO mice exhibited transient but marked hypoventilation after acute base loading. In rats, increased blood alkalinity of the perfused upper small intestine increased venous secretin release.

CONCLUSIONS

Our results suggest that loss of SCTR impairs the appropriate increase of renal base excretion during acute base loading and that SCTR is necessary for acute correction of metabolic alkalosis. In addition, our findings suggest that blood alkalinity increases secretin release from the small intestine and that secretin action is critical for bicarbonate homeostasis.

A gut-brain axis mediates sodium appetite via gastrointestinal peptide regulation on a medulla-hypothalamic circuit

Salt homeostasis is orchestrated by both neural circuits and peripheral endocrine factors. The colon is one of the primary sites for electrolyte absorption, while its potential role in modulating sodium intake remains unclear. Here, we revealed that a gastrointestinal hormone, secretin, is released from colon endocrine cells under body sodium deficiency and is indispensable for inducing salt appetite. As the neural substrate, circulating secretin activates specific receptors in the nucleus of the solitary tracts, which further activates the downstream paraventricular nucleus of the hypothalamus, resulting in enhanced sodium intake. These results demonstrated a previously unrecognized gut-brain pathway for the timely regulation of sodium homeostasis.

Protein biomarkers in pancreatic juice and serum for identification of pancreatic cancer

BACKGROUND AND AIMS

To date, surveillance of high-risk individuals for pancreatic ductal adenocarcinoma (PDAC) has not lived up to expectations, as identification of curable stages through imaging remains challenging. Biomarkers are therefore needed. Pancreatic juice (PJ) may be a promising source, because it is in direct contact with the ductal epithelial lining from which PDAC arises. We aimed to develop a panel of biomarkers from serum and PJ to detect PDAC for future surveillance purposes.

METHODS

All patients who underwent PJ collection on secretin stimulation at the Erasmus MC were included. Both PJ and serum were evaluated. Protein levels were determined by the Lowry assay. Potential biomarkers (interleukin-8, interferon-γ, neutrophil gelatinase-associated lipocalin [NGAL], mucin 5, subtype AC [MUC5AC], mucin 2, phospholipase A2 group IB) were selected based on previously reported outcomes and assessed with enzyme-linked immunosorbent assay. Serum carbohydrate antigen 19-9 (CA19-9) values were determined by electrochemiluminescence immunoassay.

RESULTS

This study included 59 cases and 126 surveilled control subjects (who underwent PJ collection), of whom 71 had a hereditary predisposition (35 genetic, 36 familial) and 55 had (suspected neoplastic) pancreatic cysts. CA19-9 values were available for 53 cases and 48 control subjects. Serum CA19-9, as well as PJ interleukin-8, NGAL and MUC5AC, were associated with PDAC independent of age, gender, and presence of diabetes mellitus. Serum CA19-9 had a significantly higher area under the curve (AUC; .86; 95% confidence interval [CI], .79-.94) than individual PJ markers (AUC, .62-.70). A combination of PJ markers and serum CA19-9 (panel 2: sensitivity 42% [95% CI, 29-57] and specificity 96% [95% CI, 86-100]) did not improve diagnostic performance compared with CA19-9 alone (sensitivity 70% [95% CI, 56-82] and specificity 85% [95% CI, 72-94]).

CONCLUSIONS

High levels of serum CA19-9 and PJ-derived proteins are associated with PDAC. Prospective surveillance studies including individuals at risk of developing PDAC are required to validate these findings.

Secretin Stimulation Test and Early Diagnosis of Gastrinoma in MEN1 Syndrome: Survey on the MEN1 Florentine Database

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited endocrine cancer syndrome. Multiple gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) affect 30% to 80% of MEN1 patients, with the most common functioning GEP-NET being gastrinoma. Biochemical identification of hypergastrinemia may help to recognize the presence of gastrinomas before they are detectable by instrumental screening, enabling early diagnosis and start of therapy, preferably before tumor progression and metastases occurrence.

OBJECTIVE

Evaluate the effectiveness of secretin stimulation test to precociously diagnose the presence of gastrin-secreting tumors.

DESIGN

Results of secretin stimulation tests, performed between 1991 and February 2020, were retrospectively analyzed, as aggregate, in a cohort of MEN1 patients with GEP-NETs.

SETTING

Data were extracted from the MEN1 Florentine database.

PATIENTS

The study included 72 MEN1 patients with GEP-NETs who underwent a secretin stimulation test for the evaluation of gastrin secretion.

OUTCOMES

A positive secretin stimulation test was assumed with a difference between basal fasting serum gastrin (FSG) and the maximum stimulated value of gastrin over 120 pg/mL.

RESULTS

The secretin stimulation test showed a secretin-induced hypergastrinemia in 27.8% (20/72) of patients with GEP-NETs, and a positive test in 18 cases. The test allowed the identification of a positively stimulated hypergastrinemia in 75.0% (3/4) of patients who presented a basal FSG within the normal range.

CONCLUSIONS

Diagnosis of gastrinoma is complex, difficult, and controversial. Results of this study confirm that a positive secretin stimulation test allows early diagnosis of gastrinomas, even in the presence of borderline or normal levels of nonstimulated FSG.

[Effect of secretin on the expression of cPLA2 and mPGEs-1 in mouse endometrial stromal cell during early pregnancy]

Secretin, a gastrointestinal peptide, has been found to be expressed in mouse endometrial stromal cells (mESCs) during early pregnancy. In order to further investigate the function of secretin during embryo implantation, the expression levels of secretin, secretin receptor, cytosolic phospholipase A₂ (cPLA₂) and membrane prostaglandin E synthase 1 (mPGEs-1) were detected in the mice uterus from day 4 to 8 of pregnancy by real-time PCR, ELISA and in situ hybridization. mESCs isolated and cultured from day 4 of pregnancy were transfected with secretin expression vectors or treated with H89, a PKA inhibitor. Then the expression levels of cPLA₂, mPGEs-1 and cAMP responsive element-binding protein (CREB) were detected by real-time PCR and Western blot. The concentration of prostaglandin E2 (PGE₂) in the supernatant was determined by ELISA. The result showed that secretin, cPLA₂ and mPGEs-1 mRNA expression increased gradually in implantation sites from day 5 to day 7 of pregnancy with the same tendency. The secretin levels in serum were significantly higher on days 6, 7 and 8 of pregnancy than that on day 5 of pregnancy. The concentration of secretin was significantly higher in implantation sites on days 6, 7 than that in non-implantation site on day 5. Transfection of secretin expression vector promoted cPLA₂, p-cPLA₂ and mPGEs-1 expressions in mESCs, but not PGE₂ level in the supernatant. H89 could effectively inhibit the expression of CREB, p-CREB, p-cPLA₂ and cPLA₂ induced by secretin. The results showed that the increased secretin expression in mESCs during embryo implantation may promote p-cPLA₂, cPLA₂ and mPGEs-1 expression, and the promotion may be through PKA signaling pathway.

Incremental value of secretin-enhanced magnetic resonance cholangiopancreatography in detecting ductal communication in a population with high prevalence of small pancreatic cysts

PURPOSE

We investigated the incremental diagnostic yield of S-MRCP in a population with high prevalence of small pancreatic cysts.

METHODS

Standard MRCP protocol was performed with and without secretin using 1.5 T units in subjects undergoing pancreatic screening because of a strong family history of pancreatic cancer as part of the multicenter Cancer of the Pancreas Screening-3 trial (CAPS 3). All studies were reviewed prospectively by two independent readers who recorded the presence and number of pancreatic cysts, the presence of visualized ductal communication before and after secretin, and the degree of confidence in the diagnoses.

RESULT

Of 202 individuals enrolled (mean age 56 years, 46% males), 93 (46%) had pancreatic cysts detected by MRCP, and 64 of the 93 had pre-and post-secretin MRCP images available for comparison. Data from the 128 readings show that 6 (6/128=4.7%) had ductal communication visualized only on the secretin studies compared to pre-secretin studies (odds ratio 1.28, p=0.04). In addition, there was a statistically significant increase in confidence in reporting ductal communication after secretin compared to before secretin (p<0.0005).

CONCLUSION

At 1.5 T MRI, the use of secretin can improve the visualization of ductal communication of cystic pancreatic lesions.

Anatomic variants of the pancreatic duct and their clinical relevance: an MR-guided study in the general population

OBJECTIVES

To investigate the frequency of pancreatic duct (PD) variants and their effect on pancreatic exocrine function in a population-based study using non-invasive secretin-stimulated magnetic resonance cholangiopancreatography (sMRCP).

METHODS

Nine hundred and ninety-five volunteers, 457 women and 538 men, aged 51.9 ± 13.4 years, underwent navigator-triggered, T2-weighted, 3D turbo spin echo MRCP on a 1.5 T system after 1 unit/kg secretin administration. Two readers evaluated images for PD variants. Pancreatic exocrine function and morphological signs of chronic pancreatitis such as abnormalities of the main PD, side branch dilatation, and pancreatic cysts were evaluated and related to PD variants using a Kruskal-Wallis test and post hoc analysis.

RESULTS

Of all sMRCP, 93.2% were of diagnostic quality. Interobserver reliability for detection of PD variants was found to be kappa 0.752 (95 %CI, 0.733 - 0.771). Normal PD variants were observed in 90.4% (n = 838/927). Variants of pancreas divisum was identified in 9.6% (n = 89/927). Abnormalities of the main PD, side branch dilatation, and pancreatic cysts were observed in 2.4%, 16.6%, and 27.7%, respectively, and were not significantly different between pancreas divisum and non-divisum group (P = 0.122; P = 0.152; P = 0.741). There was no association between PD variants and pancreatic exocrine function (P = 0.367).

CONCLUSION

PD variants including pancreas divisum are not associated with morphological signs of chronic pancreatitis or restriction of pancreatic exocrine function.

KEY POINTS

MRCP allows the evaluation of pancreatic duct variants and morphological change. Pancreatic duct variants are not associated with morphological signs of chronic pancreatitis. Pancreas divisum is not accompanied by restriction of pancreatic exocrine function. Pancreatic duct variants including pancreas divisum are limited in their clinical relevance.

Pancreatic morphological changes in long-term follow-up after initial episode of acute alcoholic pancreatitis

OBJECTIVE

The long-term morphological changes induced by a single episode of alcoholic pancreatitis are not known. Our aim was to study these morphological changes in secretin-stimulated magnetic resonance cholangiopancreatography (S-MRCP) after the first episode of alcohol-associated acute pancreatitis and to evaluate the risk factors and possible protective factors potentially associated with later chronic findings. We have previously reported 2-year follow-up results in pancreatic morphology. This study extends the follow-up to 9 years.

PATIENTS AND METHODS

In this prospective follow-up study, S-MRCP imaging was performed for 44 (41 M, 3 F; mean age, 46 (25-68) years) patients after their first episode of alcohol-associated pancreatitis. Pancreatic morphology was evaluated at 3 months and at 2, 7, and 9 years after hospitalization. Recurrent attacks of pancreatitis were studied and pancreatic function was monitored by laboratory tests. Patients' alcohol consumption was evaluated with questionnaires, laboratory markers, and self-estimated alcohol consumption via interview. Smoking and body mass index were annually recorded.

RESULTS

At 3 months, 32 % of the patients had normal findings in S-MRCP, 52 % had acute, and 16 % had chronic changes. At 7 years, S-MRCP was performed on 36 patients with normal findings in 53 %, the rest (47 %) having chronic findings. Pancreatic cyst was present in 36 %, parenchymal changes in 28 %, and atrophy in 28 % of the cases. There were no new changes in the pancreas in the attending patients between 7 and 9 years (18 patients). Of the patients with only acute findings at 3 months, 60 % resolved to normal in 7 years, but the rest (40 %) showed chronic changes later on. The initial attack was mild in 65 %, moderate in 25 %, and severe in 10 % of the patients. Patients with mild first attack had fewer chronic changes at 7 years compared to patients with moderate or moderate and severe together (p = 0.03, p = 0.01). Of the patients in the seventh year of S-MRCP, 22 % had suffered a recurrent episode of acute pancreatitis (mean, 22 (2-60) months) and 11 % had a clinical diagnosis of chronic pancreatitis. At 7 years, 88 % of the patients with recurrences had chronic findings in S-MRCP versus 36 % with nonrecurrent pancreatitis (p = 0.02). Six (17 %) patients abstained from alcohol throughout follow-up (mean, 8.7 (7-9.1) years), but even one of these developed pancreatic atrophy. Out of the non-abstinent patients who did not suffer recurrences, 4/22 (18 %) had developed new findings during at follow-up S-MRCP (NS). In univariate analysis, heavy smoking showed no correlation with increased chronic changes compared to nonsmoking.

CONCLUSIONS

Morphological pancreatic changes increase with recurrent episodes of acute pancreatitis. Patients with mild first attack have fewer chronic changes in the pancreas in the long term. However, even a single episode of acute alcoholic pancreatitis may induce chronic morphological changes in long-term follow-up.

Morphological and functional evaluation of chronic pancreatitis with magnetic resonance imaging

Magnetic resonance imaging (MRI) techniques for assessment of morphology and function of the pancreas have been improved dramatically the recent years and MRI is very often used in diagnosing and follow-up of chronic pancreatitis (CP) patients. Standard MRI including fat-suppressed T1-weighted and T2-weighted imaging techniques reveal decreased signal and glandular atrophy of the pancreas in CP. In contrast-enhanced MRI of the pancreas in CP the pancreatic signal is usually reduced and delayed due to decreased perfusion as a result of chronic inflammation and fibrosis. Thus, morphological changes of the ductal system can be assessed by magnetic resonance cholangiopancreatography (MRCP). Furthermore, secretin-stimulated MRCP is a valuable technique to evaluate side branch pathology and the exocrine function of the pancreas and diffusion weighted imaging can be used to quantify both parenchymal fibrotic changes and the exocrine function of the pancreas. These standard and advanced MRI techniques are supplementary techniques to reveal morphological and functional changes of the pancreas in CP. Recently, spectroscopy has been used for assessment of metabolite concentrations in-vivo in different tissues and may have the potential to offer better tissue characterization of the pancreas. Hence, the purpose of the present review is to provide an update on standard and advanced MRI techniques of the pancreas in CP.

Quantification of pancreatic exocrine function of chronic pancreatitis with secretin-enhanced MRCP

AIM: To obtain reference values for pancreatic flow output rate (PFR) and peak time (PT) in healthy volunteers and chronic pancreatitis (CP); to correlate quantification of secretin enhanced magnetic resonance cholangiopancreatography (SMRCP) of pancreatic fluid output following secretin with fecal elastase-1 (FE-1) tests.

METHODS: The present study includes 53 subjects comprised of 17 healthy individuals and 36 patients with CP from April 2011 to January 2013. The 36 patients with CP were divided into three groups of mild CP (n = 14), moderate CP (n = 19) and advanced CP (n = 3) by M-ANNHEIM classification for CP.. Fifty-three cases underwent FE-1 test and magnetic resonance imaging using 3.0 T-device (Signa EXCITE, GE Healthcare). Coronal T₂-weighted single-shot turbo spin-echo, spiratory triggered, covering the papillae, duodenum and small bowel. MRCP was performed with a heavily T₂-weighted fat-suppressed long TE HASTE sequence (thick slab 2D MRCP sequence), repeated every 2 min up to 11 min after 0.1 mL/kg secretin injection (Secrelux, Sanochemia^®, Germany). FE-1 test used sandwich enzyme-linked immunosorbent assay (ELISA) test (ScheBo. Tech^®, Germany).

RESULTS: A good linear correlation showed between the calculated volume and the actual volume by Phantom experiments. Fifty-three paired Quantification of secretin enhanced magnetic resonance cholangiopancreatography (MRCPQ) and FE-1 data sets were analyzed. The mean FE-1 of 53 cases was 525.41 ± 94.44 μg/g for 17 healthy volunteers, 464.95 ± 136.13 μg/g for mild CP, 301.55 ± 181.55 μg/g for moderate CP, 229.30 ± 146.60 μg/g for advanced CP. Also, there was statistically significant difference in FE-1 (P = 0.0001) between health and CP. The mean values of PFR and PT were 8.18 ± 1.11 mL/min, 5.76 ± 1.71 min for normal; 7.27 ± 2.04 mL/min, 7.71 ± 2.55 min for mild CP; 4.98 ± 2.57 mL/min, 9.10 ± 3.00 min for moderate CP; 4.13 ± 1.83 mL/min, 12.33 ± 1.55 min for advanced CP. Further, statistically significant difference in PFR (P = 0.0001) and PT (P = 0.0001) was observed between health and CP. Besides, there was correlation (r = 0.79) and consistency (K = 0.6) between MRCPQ and ELISA Test. It was related between M-ANNHEIM classification and PFR (r = 0.55), FE-1 (r = 0.57).

CONCLUSION: SMRCP can provide a safe, non-invasive and efficient method to evaluate the exocrine function of the pancreas.

Exocrine pancreatic function in hepatocyte nuclear factor 1β-maturity-onset diabetes of the young (HNF1B-MODY) is only moderately reduced: compensatory hypersecretion from a hypoplastic pancreas

OBJECTIVES

To examine the exocrine pancreatic function in carriers of the hepatocyte nuclear factor 1β gene (HNF1B) mutation by direct testing.

METHODS

Patients with HNF1B mutations and control subjects were assessed using rapid endoscopic secretin tests and secretin-stimulated magnetic resonance imaging. Seven patients and 25 controls underwent endoscopy, while eight patients and 20 controls had magnetic resonance imaging. Ductal function was assessed according to peak bicarbonate concentrations and acinar function was assessed according to peak digestive enzyme activities in secretin-stimulated duodenal juice. The association of pancreatic exocrine function and diabetes status with pancreatic gland volume was examined.

RESULTS

The mean increase in secretin-stimulated duodenal fluid was smaller in patients than controls (4.0 vs 6.4 ml/min; P = 0.003). We found lower ductal function in patients than controls (median peak bicarbonate concentration: 73 vs 116 mEq/L; P < 0.001) and lower acinar function (median peak lipase activity: 6.4 vs 33.5 kU/ml; P = 0.01; median peak elastase activity: 0.056 vs 0.130 U/ml; P = 0.01). Pancreatic fluid volume outputs correlated significantly with pancreatic gland volumes (r² = 0.71, P = 0.008) in patients. The total fluid output to pancreatic gland volume ratios were higher in patients than controls (4.5 vs 1.3 ml/cm³; P = 0.03), suggesting compensatory hypersecretion in the remaining gland.

CONCLUSION

Carriers of the HNF1B mutation have lower exocrine pancreatic function involving both ductal and acinar cells. Compensatory hypersecretion suggests that the small pancreas of HNF1B mutation carriers is attributable to hypoplasia, not atrophy.

Mutant GNAS detected in duodenal collections of secretin-stimulated pancreatic juice indicates the presence or emergence of pancreatic cysts

OBJECTIVE

Pancreatic cysts are commonly detected in patients undergoing pancreatic imaging. Better approaches are needed to characterise these lesions. In this study we evaluated the utility of detecting mutant DNA in secretin-stimulated pancreatic juice.

DESIGN

Secretin-stimulated pancreatic juice was collected from the duodenum of 291 subjects enrolled in Cancer of the Pancreas Screening trials at five US academic medical centres. The study population included subjects with a familial predisposition to pancreatic cancer who underwent pancreatic screening, and disease controls with normal pancreata, chronic pancreatitis, sporadic intraductal papillary mucinous neoplasm (IPMN) or other neoplasms. Somatic GNAS mutations (reported prevalence ≈ 66% of IPMNs) were measured using digital high-resolution melt-curve analysis and pyrosequencing.

RESULTS

GNAS mutations were detected in secretin-stimulated pancreatic juice samples of 50 of 78 familial and sporadic cases of IPMN(s) (64.1%), 15 of 33 (45.5%) with only diminutive cysts (<5 mm), but none of 57 disease controls. GNAS mutations were also detected in five of 123 screened subjects without a pancreatic cyst. Among 97 subjects who had serial pancreatic evaluations, GNAS mutations detected in baseline juice samples predicted subsequent emergence or increasing size of pancreatic cysts.

CONCLUSION

Duodenal collections of secretin-stimulated pancreatic juice from patients with IPMNs have a similar prevalence of mutant GNAS to primary IPMNs, indicating that these samples are an excellent source of mutant DNA from the pancreas. The detection of GNAS mutations before an IPMN is visible suggests that analysis of pancreatic juice has the potential to help in the risk stratification and surveillance of patients undergoing pancreatic screening.

Quantitative MRCP assessment of pancreatic exocrine reserve and its correlation with faecal elastase-1 in patients with chronic pancreatitis

PURPOSE

This retrospective study was done to correlate a quantitative assessment of the pancreatic exocrine reserve by dynamic secretin magnetic resonance cholangiopancreatography (MRCPQ) with the faecal elastase-1 (FE-1) test in patients with chronic pancreatitis.

MATERIALS AND METHODS

Thirty-five patients with a clinical diagnosis of chronic (CP) or acute recurrent (ARP) pancreatitis were enrolled. FE-1 was indicative of the pancreatic exocrine reserve. Subsequently, the patient population was subdivided into two groups according to a clinical threshold value of 200 μg/g. All patients underwent MRCP examination during secretin administration. Duodenal filling volume was calculated on T2-weigthed rapid acquisition with relaxation enhancement (RARE) MRCP images obtained 10 min after secretin injection. Duodenal filling volumes were compared with FE-1 values. Scatter plots, Pearson correlation coefficient and the Mann-Whitney U test were performed.

RESULTS

Thirty-five paired MRCPQ-FE1 data sets were analysed. MRCPQ was significantly different (p=0.007) between patients with impaired and preserved pancreatic function; median and interquartile range (IQR) were 150.7 ml (137.3-205.5 ml; n=9) and 332.4 ml (190.6-506.9 ml; n=26). Both Pearson correlation coefficient (p<0.001) and the Mann-Whitney U test (p=0.007) were significant.

CONCLUSIONS

MRCPQ significantly correlates with FE-1 values. It is possible to discriminate impaired and preserved pancreatic exocrine function using MRCPQ.

Imaging of the pancreas with secretin enhancement

Magnetic resonance cholangiopancreatography is a noninvasive imaging technique for evaluation of the pancreatic duct and the biliary tree. Secretin is a polypeptide hormone that has numerous physiological effects, including stimulation of the pancreatic secretion of bicarbonate-rich fluid and transient increase in the tone in the sphincter of Oddi. As a result, secretin administration usually results in distention of the pancreatic duct; therefore, visualization of the pancreatic ductal anatomy is often substantially improved. Awareness of its value by referring clinicians and radiologists will increase its use in the future.

Magnetic resonance imaging in pancreas transplantation

Magnetic resonance imaging (MRI) plays an important role in the evaluation of pancreas transplantation. Standard MRI, magnetic resonance angiography, and MR cholangiopancreatography can demonstrate the changes of the anatomy after transplantation. Vascular complications are assessed by MR angiography. Magnetic resonance cholangiopancreatography reveals ductal changes resulting from acute and/or chronic rejection and determines leaks with the use of a secretin-stimulated MR cholangiopancreatography. Serial contrast-enhanced MRI may detect the diminished perfusion that is related to the graft rejection or vascular complications. In this paper, we reviewed types of pancreas transplantation procedures, complications that arise in a short and/or a long term after the transplantation, and their assessment by MRI.

Collateral branches IPMTs: secretin-enhanced MRCP

Recently, the fantastic evolution of imaging modalities (especially MR, MDCT, EUS) has raised many issues regarding the correct classification of smaller and smaller lesions, their preoperative evaluations, and indications of most appropriate treatment. However, it is still debated which technique should be employed for the diagnosis and the follow-up of intraductal papillary mucinous tumours (IPMTs). Despite the superb spatial resolution of MDCT, nowadays most of the authors agree on considering MR with magnetic resonance cholangiopancreatography (MRCP) the imaging modality of choice in studying IPMTs. In particular, MRCP is rapid, non-invasive, and accurate in detecting, localizing, and correctly classifying IPMT. The diagnostic performance of MRCP is even improved after the introduction of secretin stimulation. In fact, dynamic MRCP studies after secretin administration, besides facilitating the depiction of the structural characteristics of the lesions, make easier the detection of the communicating duct of branch duct IPMTs with the main pancreatic duct, especially if the newest high resolution 3D heavily T2-weighted sequences are utilized. Secretin stimulation is also useful in the demonstration of early changes of associated chronic pancreatitis. Consequently, we believe that secretin-enhanced MRCP is the most suitable imaging modality in the diagnosis and follow-up of IPMTs of the collateral branches.

[Secretin-enhanced magnetic resonance cholangiopancreaticography: value for the diagnosis of chronic pancreatitis]

Endoscopic retrograde cholangiopancreaticography (ERCP) is the morphologic gold standard for the diagnosis of chronic pancreatitis. Magnetic Resonance Imaging (MRI) enables the visualization of not only the pancreatic duct but also the surrounding parenchyma using T2- and T1-weighted sequences before and after the application of a contrast agent. Moreover, it allows the depiction of ductal segments distal to a stenosis or occlusion. However, conventional Magnetic Resonance Cholangiopancreaticography (MRCP) was not able to achieve accuracy similar to that of ERCP. Despite many technological innovations, such as fast breath-hold acquisitions or respiratory-gated 3D sequences, this drawback could not be overcome. In recent years, secretin-enhanced MRCP has been used for the diagnosis of chronic pancreatitis. A recent study showed that secretin not only improves the visibility of the pancreatic duct and its side branches but it also enhances the diagnostic accuracy of MRCP. The sensitivity, specificity, and positive and negative predictive values were improved by the application of secretin. Moreover, the agreement between independent observers increased after the use of secretin. In addition, quantitative post-processing tools have been developed that enable the measurement of the exocrine pancreatic output non-invasively using secretin-enhanced MRCP. These tools facilitate applications, such as functional follow-up after pancreaticogastrostomy and pancreaticogastric anastomoses, evaluation of the functional status of the graft after pancreas transplantation and follow-up of pancreatic drainage procedures and duct disruption.

Prospective comparison of secretin-stimulated MRCP with manometry in the diagnosis of sphincter of Oddi dysfunction types II and III

Is the role of secretin in causing a choleresis clinically significant enough to be a “stress test” for biliary SOD?

Prospective comparison of secretin-stimulated magnetic resonance cholangiopancreatography with manometry in the diagnosis of sphincter of Oddi dysfunction types II and III

BACKGROUND

In sphincter of Oddi dysfunction (SOD), sphincter of Oddi manometry (SOM) predicts the response to sphincterotomy, but is invasive and associated with complications.

AIM

To evaluate the role of secretin-stimulated magnetic resonance cholangiopancreatography (ss-MRCP) in predicting the results of SOM in patients with suspected type II or III SOD.

METHODS

MRCP was performed at baseline and at 1, 3, 5 and 7 min after intravenous secretin. SOD was diagnosed when the mean basal sphincter pressure at SOM was >40 mm Hg. Long-term outcome after SOM, with or without endoscopic sphincterotomy, was assessed using an 11-point (0-10) Likert scale.

RESULTS

Of 47 patients (male/female 9/38; mean age 46 years; range 27-69 years) referred for SOM, 27 (57%) had SOD and underwent biliary and/or pancreatic sphincterotomy. ss-MRCP was abnormal in 10/16 (63%) type II and 0/11 type III SOD cases. The diagnostic accuracy of ss-MRCP for SOD types II and III was 73% and 46%, respectively. During a mean follow-up of 31.6 (range 17-44) months, patients with normal SOM and SOD type II experienced a significant reduction in symptoms (mean Likert score 8 vs 4; p = 0.03, and 9 vs 1.6; p = 0.0002, respectively), whereas in patients with SOD type III, there was no improvement in pain scores. All patients with SOD and an abnormal ss-MRCP (n = 12) reported long-term symptom improvement (mean Likert score 9.2 v 1.2, p<0.001).

CONCLUSIONS

ss-MRCP is insensitive in predicting abnormal manometry in patients with suspected type III SOD, but is useful in selecting patients with suspected SOD II who are most likely to benefit from endotherapy.

Secretin-stimulated MRCP

Secretin-stimulated magnetic resonance cholangiopancreatography not only facilitate the depiction of anatomic variations or morphologic changes of the pancreatic duct in the normal and diseased pancreas but also help assessing functional abnormalities of the exocrine pancreas. In this article, we illustrate findings of normal pancreas and various pancreatic diseases on magnetic resonance cholangiopancreatography after secretin stimulation.

Comparison of endoscopic ultrasound chronic pancreatitis criteria to the endoscopic secretin-stimulated pancreatic function test

Endosonography (EUS) has emerged as a major diagnostic tool in pancreatic imaging. Direct tests of pancreatic function are considered the most sensitive and accurate method to establish a diagnosis of chronic pancreatitis (CP), particularly when imaging studies are inconclusive. The aim of this study was to compare current EUS CP criteria with our newly described, purely endoscopic, secretin-stimulated pancreatic function test (ePFT). Fifty-six patients (25 male, mean age = 44 years) who were referred for evaluation/treatment of chronic abdominal pain with or without CP underwent both EUS and ePFT. The EUS protocol included the following: (1) EUS images were obtained in a standardized fashion from both gastric and duodenal stations, and (2) EUS images were scored independently by one of three therapeutic endoscopists for 0--9 parenchymal/ductal criteria as follows: 0-3 = normal, 4-5 = equivocal, >/=6 = definite CP. Endoscopic pancreatic function test (ePFT) protocol included the following: (1) upper endoscopy, (2) intravenous synthetic porcine secretin (0.2 mcg/kg, ChiRhoClin, Inc.) after test dose, (3) duodenal fluid aspirated every 15 min for 1 h, and (4) autoanalyzed for [HCO3] cutpoint of 80 mEq/L. According to EUS, 33 were normal, 13 equivocal, and 10 definite for CP. The mean peak [HCO3 -] range (in mEq/L) for each group was normal CP (83.7, range = 58-118), equivocal CP (68, range = 30-88), and definite CP (56, range=19-84). Using a peak [HCO3 -] of </=80 mEq/L as diagnostic for CP, the referent values (sensitivity%/specificity%) for EUS in the diagnosis of CP were normal (60/72), equivocal (36/94), and definite (26/100), respectively. An EUS score or greater than 5 had the best specificity (100%) and negative predictive value (100%). We conclude that endoscopic pancreatic function testing with secretin confirms that as EUS score increases, the peak pancreatic fluid bicarbonate decreases. We also conclude that EUS has excellent statistical inferences for diagnosing CP when at least 6 or more criteria are present. EUS as a screening test in patients with chronic abdominal pain and equivocal imaging studies may be of limited value.

Secretin-stimulating MRCP in patients with pancreatobiliary maljunction and occult pancreatobiliary reflux: direct demonstration of pancreatobiliary reflux

We propose the hypothesis that the enlargement of the common bile duct (CBD) or gallbladder (GB) that is occasionally demonstrated on magnetic resonance cholangiopancreatography (MRCP) after secretin stimulation is caused by pancreatobiliary reflux. Recently, occult pancreatobiliary reflux (OPR) has been demonstrated in patients without morphological pancreatobiliary maljunction (MPBM). The aim of this study was to evaluate the efficacy of secretin-stimulating MRCP (SMRCP) in the diagnosis of pancreatobiliary reflux. The study included 14 patients with MPBM and 32 patients with a normal pancreatobiliary junction. OPR was evaluated by bile collection and diagnosed in seven of the 32 patients. All the patients underwent SMRCP; the related findings were considered positive when enlargement of the CBD or GB was observed. Positive findings on SMRCP were observed in all MPBM patients. In the patients with normal pancreatobiliary junction, there was significant difference between the mean amylase levels in the patients with positive and negative SMRCP findings (mean, 4,755.7 and 29.7 IU/l). The sensitivity and specificity of SMRCP for diagnosing OPR was 85.7% and 68.0%, respectively. SMRCP provides a non invasive method for excluding PBR and can identify patients who could benefit from bile duct sampling to diagnose OPR.

Comparison of the secretin stimulated endoscopic pancreatic function test to retrograde pancreatogram

Duodenal intubation techniques with hormonal stimulation are the most accurate at diagnosing early chronic pancreatitis. Pancreatography (ERCP), the radiologic gold standard, can accurately diagnose chronic pancreatitis, but is expensive, may expose the patient to radiation, and/or induce acute pancreatitis. We have developed an endoscopic pancreatic function test (ePFT) that can assess pancreatic secretory function during upper endoscopy. We sought to determine the accuracy of the endoscopic secretin pancreatic function test using retrograde pancreatogram as the gold standard. Patients referred to The Pancreas Clinic for the evaluation and management of chronic abdominal pain and suspected chronic pancreatitis who had both endoscopic function testing and pancreatic duct imaging (ERCP) were studied. Pancreatograms were scored for duct morphologic characteristics (Cambridge classification) and compared to peak bicarbonate concentration in secretin stimulated duodenal juice. The ePFT consisted of a test dose of intravenous synthetic porcine secretin (0.2 microg), full-dose intravenous secretin (0.2 microg/kg) over 1 min, (3) upper endoscopy with moderate sedation, (4) gastric fluid aspirated and discarded, (5) duodenal fluid aspirations at 0, 15, 45, and 60 min after secretin injection, and (6) fluid analysis with lab autoanalyzer for bicarbonate concentration (historical normal cutpoint >80 mEq/L). Thirty-six patients had both the endoscopic function test and ERCP. Seventeen had chronic abdominal pain with normal pancreatograms, and nineteen had chronic abdominal pain with abnormal pancreatograms, consistent with chronic pancreatitis. The sensitivity and specificity of the endoscopic function test were 94% and 79%, respectively. The positive and negative predictive values were 80% and 94%, respectively. Overall agreement with ERCP was 86%. The ePFT with synthetic porcine secretin has excellent correlation with abnormal pancreatogram (chronic pancreatitis). Furthermore, a normal bicarbonate (negative function test, HCO(3) >80 mEq/L) essentially rules out chronic pancreatitis as a diagnostic cause of abdominal pain. Endoscopic pancreatic function testing may decrease the need for ERCP in patients with chronic abdominal pain.

Pancreatic transplants: secretin-stimulated MR pancreatography

BACKGROUND

Our study was aimed to evaluate the functional status of pancreatic transplants using dynamic MR pancreatography after secretin stimulation.

METHODS

Thirteen asymptomatic patients previously submitted to isolated pancreas (n = 6) or combined kidney-pancreas (n = 7) transplantation, with enteric-portal pancreatic drainage, underwent MR examination at 1.5 T using a phased-array coil. After the acquisition of axial and coronal T1- and T2-weighted sequences, dynamic MR pancreatography was performed using a coronal breath-hold, thick-slab (40-60 mm), single-shot T2-weighted fast spin-echo sequence. After the intravenous administration of secretin (Secrelux, Sanochemia; 1 cU/kg body/weight), a single-slice image acquisition was repeated every 30 s up to 15 min. We estimated the calibre changes of the pancreatic ductal system and the filling of the donor's duodenum on the basis of pancreatic secretion after secretin stimulation, also evaluated by using a mean signal intensity/time histogram in a chosen region of interest including the transplanted pancreas and the connected small bowel.

RESULTS

All patients well tolerated the examination, and no side effects were reported after secretin administration. In 12/13 cases, a significant increase (more than 1 mm) in the diameter of the mean pancreatic duct was observed after secretin stimulation; in all patients, a noticeable filling of the duodenal graft was demonstrated during dynamic MR pancreatography on both qualitative and quantitative analyses.

CONCLUSIONS

Dynamic MR imaging after secretin administration allows non-invasive evaluation of exocrine function of the pancreatic transplants and could be used to differentiate patients with graft rejection from those with normal graft function.

Technology insight: applications of MRI for the evaluation of benign disease of the pancreas

This article reviews the role of MRI in the evaluation of benign pancreatic disease. Although MRI and magnetic resonance cholangiopancreatography (MRCP) are most often used to evaluate the liver and bile duct, technical advances such as the use of secretin stimulation also allow for high-quality imaging of the pancreas and pancreatic ductal system. Secretin-stimulated MRCP (S-MRCP) can aid the diagnosis of acute and chronic pancreatitis, and delineate ductal pathology such as benign strictures and duct leaks. There seems to be a role for S-MRCP in the assessment of pancreatic function and (possibly) sphincter of Oddi dysfunction. When endoscopic or surgical therapy is planned, S-MRCP can help to establish a diagnosis as well as offer a 'road map' to guide therapy. S-MRCP is noninvasive and almost entirely without risk to the patient, which gives it a distinct advantage over traditional endoscopic methods of diagnosis for conditions such as pancreas divisum and other ductal pathology. The information provided by S-MRCP, obtained before endoscopic or surgical therapy is attempted, can assist the patient and physician in making a fully informed decision with regard to the risks and probable benefits of any planned intervention.

Diagnosis of early-stage chronic pancreatitis by secretin-enhanced magnetic resonance cholangiopancreatography

A diagnostic means of detecting chronic pancreatitis at an early stage, when the disease is still reversible, needs to be developed. Magnetic resonance cholangiopancreatography (MRCP) has recently been evolving as an important tool for the evaluation of chronic pancreatitis. In patients with moderate chronic pancreatitis, the pancreatic parenchyma displays an abnormal enhancement pattern on T1-weighted sequences after gadolinium administration. The presence of a signal intensity ratio of <1.7 in the arterial phase and/or delayed peak enhancement after contrast administration has a sensitivity of 92% and a specificity of 75% for the demonstration of early chronic pancreatitis. The secretin-induced pancreatic T2 signal intensity changes are significantly reduced in patients with a mild exocrine pancreatic insufficiency as compared with healthy volunteers. MRCP visualizes fluid in the pancreatic and biliary ducts as high signal intensity on heavily T2-weighted sequences. However, visualization of normal or minimally dilated pancreatic ducts by MRCP is more challenging because of their small size. Secretin administration stimulates fluid and bicarbonate secretion by the exocrine pancreas; consequently, it improves the pancreatic duct and side-branch delineation and allows an evaluation of the exocrine pancreatic function. Side-branch ectasia, mild ductal dilatation with loss of the normal gentle taper, and mural irregularities are the pathognomonic MRCP features of early-stage chronic pancreatitis. Through measurement of the duodenal filling, secretin-MRCP allows quantitative assessment of the exocrine pancreatic function, even in patients with a mild exocrine insufficiency. The morphology of the pancreatic ducts, particularly in the early stages, does not always correlate with the functional status. MRCP permits visualization of the ductal changes and furnishes functional information on the pancreas; this combination may enhance its diagnostic accuracy so that MRCP can become a valuable diagnostic means in early-stage chronic pancreatitis.

Secretin receptors in the human liver: expression in biliary tract and cholangiocarcinoma, but not in hepatocytes or hepatocellular carcinoma

BACKGROUND/AIMS

Gut hormone receptors are over-expressed in human cancer and allow receptor-targeted tumor imaging and therapy. A novel promising receptor for these purposes is the secretin receptor. The secretin receptor expression was investigated in the human liver because the liver is a physiological secretin target and because novel diagnostic and treatment modalities are needed for liver cancer.

METHODS

Nineteen normal livers, 10 cirrhotic livers, 35 cholangiocarcinomas, and 45 hepatocellular carcinomas were investigated for secretin receptor expression by in vitro receptor autoradiography using (125)I-[Tyr(10)] rat secretin and, in selected cases, for secretin receptor mRNA by RT-PCR.

RESULTS

Secretin receptors were present in normal bile ducts and ductules, but not in hepatocytes. A significant receptor up-regulation was observed in ductular reaction in liver cirrhosis. Twenty-two (63%) cholangiocarcinomas were positive for secretin receptors, while hepatocellular carcinomas were negative. RT-PCR revealed wild-type receptor mRNA in the non-neoplastic liver, wild-type and spliced variant receptor mRNAs in cholangiocarcinomas found receptor positive in autoradiography experiments, and no receptor transcripts in autoradiographically negative cholangiocarcinomas.

CONCLUSIONS

The expression of secretin receptors in the biliary tract is the molecular basis of the secretin-induced bicarbonate-rich choleresis in man. The high receptor expression in cholangiocarcinomas may be used for in vivo secretin receptor-targeting of these tumors and for the differential diagnosis with hepatocellular carcinoma.

Endoscopy-based pancreatic function tests

Direct pancreatic function tests have been the mainstay for the diagnosis of pancreatic exocrine insufficiency. Due to their cumbersome nature and limited availability there is a continuous search for a rapid and inexpensive test of pancreatic function. Endoscopic approaches to evaluate pancreatic function have been assessed. This article critically reviews the current evidence related to this novel approach, outlining some elements for further refinement.

Dynamic study of pancreaticobiliary reflux using secretin-stimulated magnetic resonance cholangiopancreatography in patients with choledochal cysts

BACKGROUND/PURPOSE

Refluxes through pancreaticobiliary maljunctions play an important role in the pathophysiology of choledochal cysts. Dynamic studies of the pancreaticobiliary tract were performed using secretin-stimulated magnetic resonance cholangiopancreatography.

METHODS

Six patients with choledochal dilation were recruited for this study. Four patients exhibited cystic and 2 exhibited fusiform dilatation of the common bile duct (CBD). Magnetic resonance cholangiopancreatography images were obtained every minute during the 15-minute period after secretin stimulation. The sequential morphological changes in the biliary trees, pancreas, and duodenum were assessed, and the total pixel values of these organs were measured for each image, then plotted as a ratio against the baseline image.

RESULTS

In 2 cases involving cystic dilatation, the intensity of bile duct images continued to rise after secretin stimulation. In a case involving fusiform dilatation, a transitory elevation in CBD intensity was observed. In 3 cases involving fusiform or cystic dilatation, the intensity of CBD did not change notably. In all cases, the duodenum was filled well after secretin stimulation.

CONCLUSIONS

The sustained elevation in bile duct intensity after secretin stimulation indicates reflux and bile stasis. Transitory elevation may indicate reflux without stasis. This method allows assessment of the dynamics of pancreatic and bile fluid under more physiologic condition.

Does secretin-stimulated MRCP predict exocrine pancreatic insufficiency?: A comparison with noninvasive exocrine pancreatic function tests

BACKGROUND

Data on magnetic resonance cholangiopancreatography with secretin stimulation (S-MRCP) for the assessment of exocrine pancreatic insufficiency (EPI) are limited. We compared pancreatic function tests with the findings of S-MRCP in patients with chronic pancreatitis (CP) and disease controls.

METHODS

S-MRCP was performed in 23 patients (18 CP, 5 disease controls). MRCP images were analyzed for secretin-induced duodenal liquid filling (0=no filling; 1=duodenal bulb; 2=up to lower flexure; 3=beyond lower flexure). EPI was evaluated by fecal elastase, fecal fat concentration, and a 13C mixed chain triglyceride breath test. Clinically relevant EPI was stated if 2 of 3 tests were pathologic.

RESULTS

EPI was diagnosed in 10 of 18 patients with CP. Patients without EPI showed either grade 2 (n=4) or grade 3 (n=9) duodenal filling, whereas only 1/10 patients with EPI showed grade 3 duodenal filling. Sensitivity and specificity of S-MRCP for the diagnosis of EPI were 69% and 90%, respectively.

CONCLUSIONS

Assessment of duodenal filling should be performed in patients who undergo S-MRCP for the evaluation of pancreatic morphology. However, minor degrees of duodenal filling are equivocal and require further diagnostic evaluation.

Dynamic secretin-enhanced MR cholangiopancreatography

Secretin causes temporary dilatation of pancreatic ducts, principally by increasing pancreatic exocrine secretions, and thus allows better visualization of the ducts at magnetic resonance (MR) cholangiopancreatography. Secretin-enhanced MR cholangiopancreatography is useful for detection and diagnosis of a variety of congenital, inflammatory, and neoplastic conditions of the pancreas. Although MR cholangiopancreatography without secretin is a reliable method for evaluating the pancreatobiliary ductal system, the authors believe that secretin-enhanced MR cholangiopancreatography gives additional valuable functional and anatomic information about the pancreatic duct and pancreatic excretory capacity.

Diagnosis of duct disruption and assessment of pancreatic leak with dynamic secretin-stimulated MR cholangiopancreatography

OBJECTIVE

The management of pancreatic duct disruption is complex and depends on several factors including the cause, morphology, and degree of disruption. ERCP can show duct disruption in as many as 75% of patients but is invasive and cannot detect disruption beyond an obstruction. We studied the role of secretin MR cholangiopancreatography in patients with suspected pancreatic duct disruption.

CONCLUSION

Secretin MR cholangiopancreatography is a safe, noninvasive test that can provide additional useful information about duct integrity and facilitate management.

Changing treatment strategy for gastrinoma in patients with Zollinger-Ellison syndrome

We overviewed the recent development of curative surgery for gastrinoma that has been rapidly improved since the development of new localization techniques, especially the selective arterial secretagogue injection test (SASI test) and somatostatin receptor scintigraphy (SRS). A number of new pathological findings of gastrinomas in patients with Zollinger-Ellison syndrome have been accumulated in accordance with the increase of curative resection of gastrinomas, and these new findings also have contributed to the progress of the treatment strategy for grastrinomas.

A randomized crossover study of secretin-stimulated endoscopic and dreiling tube pancreatic function test methods in healthy subjects

OBJECTIVES

We have developed an endoscopic method of secretin endoscopic pancreatic function testing (ePFT) to simplify duodenal fluid collection. Validation of the ePFT requires a direct comparison to the traditional PFT using a Dreiling tube (DT). Our aim was to compare bicarbonate concentrations [HCO3-] obtained by the ePFT and DT methods in healthy subjects (HS).

METHODS

HS were randomized to either DT or ePFT, then crossed over to the other test after a minimum 1-wk washout. An age/weight-based sedation bolus was used for each test. DT protocol: Endoscopic placement of a DT was confirmed by fluoroscopy. After a baseline 15-min collection and administration of IV synthetic secretin, fluid was continuously collected in 15-min aliquots for an hour. ePFT protocol: Endoscopy was performed using a 6-mm endoscope. After gastric aspiration and discard and IV secretin, duodenal aspirates were obtained every 15-min for an hour. Fluid specimens were auto-analyzed for [HCO3-].

RESULTS

Twelve HS were enrolled (6F, mean age 37 yr). The difference in [HCO3-] between the two methods was not significant at the 0-, 30-, 45-, or 60-min collections. An excellent correlation in peak [HCO3-] was observed (R2 = 0.84, p < 0.001). Using a peak [HCO3-] cutpoint 80 mEq/L, there was 100% agreement between the methods; using cutpoint 90 mEq/L, there was 83% agreement.

CONCLUSIONS

The accuracy of the ePFT is similar to DT: There were minimal differences in [HCO3-] at each of the timed collections and at peak. There is an excellent correlation in peak [HCO3-] and high level of diagnostic agreement between the tests.

Diffusion-weighted MR imaging in the evaluation of pancreatic exocrine function before and after secretin stimulation

OBJECTIVES

To evaluate diffusion weighted MR imaging before and after secretin stimulation in the assessment of pancreatic exocrine function in the setting of chronic pancreatitis.

METHODS

Nine patients with severe chronic pancreatitis and sixteen patients without chronic pancreatitis but with a history of chronic alcohol consumption were enrolled in the chronic pancreatitis and risk groups, respectively. Thirty-eight patients without any pancreatic disease or history of alcohol consumption were included in the control group. Diffusion weighted images were obtained before and after secretin administration in all patients. The peak ADC values and times were determined and intergroup differences were compared. A receiver operating characteristic curve (ROC) was used to identify the cutoff values of the peak ADC times for discrimination of control group from risk and chronic pancreatitis groups.

RESULTS

In the control group, a peak increase in ADC value of 57-120% (median: 75%) was observed between 90 s and 4 min (median: 2 min) after administration of secretin (Pattern 1). In the risk group, in 13 patients, a peak increase of 52-150% was observed between 4 and 8 min (median: 7 min; Pattern 2). Peak times were significantly longer in risk group (p < 0.01). In three patients in the risk group, and in all patients in the chronic pancreatitis group, no ADC peak was observed within 10 min following secretin administration (Pattern 3). Using a peak time of 4 min as the cut-off value, a sensitivity of 100% and specificity of 94.7% were achieved in discriminating the control group from the combined risk and chronic pancreatitis groups.

CONCLUSION

Diffusion-weighted MR imaging before and after secretin administration could yield clinically useful information for detecting pathophysiologic alterations in the setting of chronic pancreatitis.

Exocrine pancreatic function: evaluation with MR imaging before and after secretin stimulation

Secretin-stimulated magnetic resonance cholangiopancreatography (SS-MRCP) enhances standard pancreatic imaging in chronic pancreatitis. Diffusion-weighted MRI added to SS-MRCP allows a qualitative and potentially quantitative estimate of pancreatic exocrine secretion, providing an alternative to standard "tube" tests.