Visualization of pancreaticobiliary reflux in anomalous pancreaticobiliary junction by secretin-stimulated dynamic magnetic resonance cholangiopancreatography

Simultaneous laparoscopic removal of a Todani type II choledochal cyst and a microlithiasic cholecystitis

Diverticula of the choledochus, better known as Todani type II cysts, are very rare and represent a predominantly pediatric pathology. Their identification by radiological methods, even if occasional, requires clinical doctors to request a surgical consultation, even for asymptomatic subjects, to proceed with their removal, given the risk of associated neoplasms. The laparoscopic approach for surgical treatment of these cysts has been recently introduced with excellent results. Due to the poor clinical records, currently there are neither shared protocols about their management nor long-term follow-up of operated patients. We report a case of an adult female suffering for years from biliary colic due to the presence of a duodenal diverticulum associated with microlithiasis' cholecystitis, who was laparoscopically treated, with excellent results in terms of symptomatic regression, reduced hospitalization, and no surgery-related complications.

Secretin-Enhanced MRCP: How and Why-AJR Expert Panel Narrative Review

Secretin-enhanced MRCP (S-MRCP) has advantages over standard MRCP for imaging of the pancreaticobiliary tree. Through the use of secretin to induce fluid production from the pancreas and leveraging of fluid-sensitive MRCP sequences, S-MRCP facilitates visualization of ductal anatomy, and the findings provide insight into pancreatic function, allowing radiologists to provide additional insight into a range of pancreatic conditions. This narrative review provides detailed information on the practical implementation of S-MRCP, including patient preparation, logistics of secretin administration, and dynamic secretin-enhanced MRCP acquisition. Also discussed are radiologists' interpretation and reporting of S-MRCP examinations, including assessments of dynamic compliance of the main pancreatic duct and of duodenal fluid volume. Established indications for S-MRCP include pancreas divisum, anomalous pancreaticobiliary junction, Santorinicele, Wirsungocele, chronic pancreatitis, main pancreatic duct stenosis, and assessment of complex postoperative anatomy. Equivocal or controversial indications are also described along with an approach to such indications. These indications include acute and recurrent acute pancreatitis, pancreatic exocrine function, sphincter of Oddi dysfunction, and pancreatic neoplasms.

Anomalous Pancreaticobiliary Duct Junction in an Unusual Case of Synchronous Gallbladder and Bile Duct Malignancy

Synchronous malignancies involving the gallbladder and the bile duct are exceedingly rare. Moreover, their association with anomalous pancreaticobiliary duct junction (APBDJ) has been reported mostly from the Far Eastern countries. Over time, many studies have suggested the definite risk of malignancy attributable to the ‘carcinogenic anatomical configuration’ of the long common biliopancreatic channel, allowing reflux of pancreatic juices in the biliary tract. In this report, we present a case of an elderly man from South India who was initially diagnosed with synchronous gall bladder with bile duct malignancy; the patient turned out to have an APBDJ on further evaluation.

Imaging of Pancreaticobiliary Maljunction

Pancreaticobiliary maljunction (PBM) is a congenital malformation in which the pancreatic and bile ducts join outside the duodenal wall, usually forming a long common channel. A major issue in patients with PBM is the risk of biliary cancer. Because the sphincter of Oddi does not regulate the pancreaticobiliary junction in PBM, pancreatic juice frequently refluxes into the biliary tract and can cause various complications, including biliary cancer. Most cancers arise in the gallbladder or dilated common bile duct, suggesting that bile stasis is related to carcinogenesis. Early diagnosis and prophylactic surgery to reduce the risk of cancer are beneficial. The diagnosis of PBM is made mainly on the basis of imaging findings. The development of diagnostic imaging modalities such as multidetector CT and MR cholangiopancreatography has provided radiologists with an important role in diagnosis of PBM and its complications. Radiologists should be aware of PBM despite the fact that it is rare in non-Asian populations. In this review, the authors present an overview of PBM with emphasis on diagnosis and management of PBM and its complications. For early diagnosis, the presence of extrahepatic bile duct dilatation or gallbladder wall thickening may provide a clue to PBM with or without biliary dilatation, respectively. The pancreaticobiliary anatomy should be closely examined if imaging reveals these findings. Radiologists should also carefully evaluate follow-up images in PBM patients even years after prophylactic surgery because residual bile ducts remain at risk for cancer.^©RSNA, 2020.

Advanced MR Imaging Techniques for Pancreas Imaging

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

Automatic gallbladder segmentation using combined 2D and 3D shape features to perform volumetric analysis in native and secretin-enhanced MRCP sequences

OBJECTIVES

We aimed to develop the first fully automated 3D gallbladder segmentation approach to perform volumetric analysis in volume data of magnetic resonance (MR) cholangiopancreatography (MRCP) sequences. Volumetric gallbladder analysis is performed for non-contrast-enhanced and secretin-enhanced MRCP sequences.

MATERIALS AND METHODS

Native and secretin-enhanced MRCP volume data were produced with a 1.5-T MR system. Images of coronal maximum intensity projections (MIP) are used to automatically compute 2D characteristic shape features of the gallbladder in the MIP images. A gallbladder shape space is generated to derive 3D gallbladder shape features, which are then combined with 2D gallbladder shape features in a support vector machine approach to detect gallbladder regions in MRCP volume data. A region-based level set approach is used for fine segmentation. Volumetric analysis is performed for both sequences to calculate gallbladder volume differences between both sequences.

RESULTS

The approach presented achieves segmentation results with mean Dice coefficients of 0.917 in non-contrast-enhanced sequences and 0.904 in secretin-enhanced sequences.

CONCLUSION

This is the first approach developed to detect and segment gallbladders in MR-based volume data automatically in both sequences. It can be used to perform gallbladder volume determination in epidemiological studies and to detect abnormal gallbladder volumes or shapes. The positive volume differences between both sequences may indicate the quantity of the pancreatobiliary reflux.

Does secretin add value in pediatric magnetic resonance cholangiopancreatography?

BACKGROUND

Secretin--a hormone that stimulates pancreatic exocrine secretion--is described to improve visualization of the pancreatic duct by magnetic resonance cholangiopancreatography (MRCP). In our pediatric practice, however, we have not observed substantial benefit with the use of secretin.

OBJECTIVE

To determine whether secretin dilates and improves visualization of the pancreatic duct in pediatric MRCP.

MATERIALS AND METHODS

Retrospective evaluation of secretin-enhanced MRCPs performed over a 15-month period. One reviewer measured the pancreatic duct pre- and post-secretin and two reviewers, blinded to the administration of secretin, assessed image quality and subjective duct visibility. Similar assessments of the biliary tree served as internal controls.

RESULTS

We reviewed 20 MRCPs in 17 children. Following secretin administration, there was a small (0.3 mm) but statistically significant increase in pancreatic duct diameter (P = 0.002) and small (<0.2 mm) but significant increase in intrahepatic bile duct diameter (P = 0.0104). On subjective review, there was no significant difference in image quality or duct visibility based on the administration of secretin.

CONCLUSION

Secretin induces dilatation of the pancreatic duct but the value of that effect in pediatric MRCP is suspect given the small change in duct diameter and the lack of improvement in image quality and duct visibility.

Early diagnosis of gallbladder carcinoma: an algorithm approach

Gall bladder carcinoma is the most common biliary tract cancer. Delayed presentation and early spread of tumor make it one of the lethal tumors with poor prognosis. Considering that simple cholecystectomy for T1 disease could offer a potential cure, it is increasingly needed to identify it at early stages. Identification of high-risk cases and offering prophylactic cholecystectomy can decrease the incidence of gallbladder carcinoma. With advances in diagnostic tools like contrast-enhanced endoscopic ultrasound, elastography, multidetctor CT, MRI, and PET scan, we can potentially diagnose gallbladder carcinoma at early stages. This paper reviews the various diagnostic modalities available and an algorithmic approach to early diagnosis of gallbladder carcinoma.

Biliary cysts: Etiology, diagnosis and management

Biliary cysts (BC) are rare dilatations of different parts of a biliary tract. They account for approximately 1% of all benign biliary diseases. BC occur the most frequently in Asian and female populations. They are an important problem for pediatricians, gastroenterologists, radiologists and surgeons. Clinical presentation and management depend on the BC type. Cholangiocarcinoma is the most serious and dangerous BC complication. The other complications associated with BC involve cholelithiasis and hepatolithiasis, cholangitis, acute and chronic pancreatitis, portal hypertension, liver fibrosis and secondary liver cirrhosis and spontaneous cyst perforation. Different BC classifications have been described in the literature. Todani classification dividing BC into five types is the most useful in clinical practice. The early diagnosis and proper treatment are very important, because BC are associated with a risk of carcinogenesis. A malignancy risk increases with the age. Radiological investigations (ultrasonography, computed tomography, endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography) play an important role in BC diagnostics. Currently, prenatal diagnosis using ultrasonography is possible. It allows to differentiate biliary disorders in fetals and to perform the early surgical treatment that improves results. In most patients, total cyst excision with Roux-Y hepaticojejunostomy is the treatment of choice. Surgical treatment of BC is associated with high success rate and low morbidity and mortality. The early treatment is associated with a lower number of complications. Patients following BC surgery require permanent and careful postoperative observation using laboratory and imaging investigations because of possibility of biliary anastomosis stricture and biliary cancer in tissue remnant.

Many faces of pancreaticobiliary reflux

Pancreaticobiliary reflux may occur either as a result of an anatomically abnormal pancreaticobiliary junction or because of a functionally impaired sphincter despite a normal radiological appearance. It is associated with a wide spectrum of biliary diseases, including gall bladder and bile duct carcinoma. Pancreaticobiliary maljunction and related biliary reflux have been studied extensively in Southeast Asian populations and associations with choledochal cyst and biliary malignancy defined. However, reflux in the absence of ductal malunion has only been described relatively recently and its significance with respect to biliary malignancy requires clarification. We present four cases of pancreaticobiliary reflux to demonstrate the varied associations of this under-recognized disorder and review the related management issues.

Biliary reflux detection in anomalous union of the pancreatico-biliary duct patients

AIM: To demonstrate the imaging findings of biliopancreatic and pancreatico-biliary reflux in patients with anomalous union of the pancreatico-biliary duct (AUPBD) on gadoxetic acid-enhanced functional magnetic resonance cholangiography (fMRC).

METHODS: This study included six consecutive patients (two men and four women; mean age 47.5 years) with AUPBD. All subjects underwent endoscopic retrograde cholangiopancreatography (ERCP); one subject also underwent bile sampling of the common bile duct (CBD) to measure the amylase level because his gadoxetic acid-enhanced fMRC images showed evidence of pancreatico-biliary reflux of pancreatic secretions. Of the five patients with choledochal cysts, four underwent pylorus-preserving pancreaticoduodenectomy.

RESULTS: The five cases of choledochal cysts were classified as Todani classification I. In three of the six patients with AUPBD, injected contrast media reached the distal CBD and pancreatic duct on delay images, suggesting biliopancreatic reflux. In two of these six patients, a band-like filling defect was noted in the CBD on pre-fatty meal images, which decreased in size on delayed post-fatty meal images, suggesting pancreatico-biliary reflux of pancreatic secretions, and the bile sampled from the CBD in one patient had an amylase level of 113 000 IU/L. In one of the six patients with AUPBD, contrast media did not reach the distal CBD due to multiple CBD stones.

CONCLUSION: Gadoxetic acid-enhanced fMRC successfully demonstrated biliopancreatic reflux of bile and pancreatico-biliary reflux of pancreatic secretions in patients with AUPBD with and without choledochal cysts.

Endoscopic diagnosis of pancreaticobiliary maljunction

Pancreaticobiliary maljunction (PBM) is a congenital anomaly defined as a junction of the pancreatic and bile ducts located outside the duodenal wall, usually forming a markedly long common channel. As the action of the sphincter of Oddi does not functionally affect the junction in PBM patients, continuous pancreatobiliary reflux occurs, resulting in a high incidence of biliary cancer. PBM can be divided into PBM with biliary dilatation (congenital choledochal cyst) and PBM without biliary dilatation (maximal diameter of the bile duct ≤ 10 mm). The treatment of choice for PBM is prophylactic surgery before malignant changes can take place. Endoscopic retrograde cholangiopancreatography (ERCP) is the most effective examination method for close observation of the pattern of the junction site. When the communication between the pancreatic and bile ducts is maintained, despite contraction of the sphincter on ERCP, PBM is diagnosed. In these patients, levels of pancreatic enzymes in the bile are generally elevated, due to continuous pancreatobiliary reflux via a long common channel. Magnetic resonance cholangiopancreatography and 3D-computed tomography can diagnose PBM, based on findings of an anomalous union between the common bile duct and the pancreatic duct, in addition to a long common channel. Endoscopic ultrasonography and intraductal ultrasonography can demonstrate the junction outside the duodenal wall, and are useful for the diagnosis of associated biliary cancer. Gallbladder wall thickness on ultrasonography can be a screening test for PBM.

An unusual variant of anomalous pancreaticobiliary junction in a patient with pancreas divisum diagnosed with secretin-magnetic resonance cholangiopancreatography

Anomalous pancreaticobiliary junction is an unusual variant of pancreaticobiliary anatomy of clinical importance because it is associated with increased risk of pancreatitis and, also, for the development of cholangiocarcinoma. We report an unusual variant of anomalous pancreaticobiliary junction, occurring in a patient with pancreas divisum, with an anomalous communication between the dorsal pancreatic and the common bile duct. The patient presented with a distal biliary stricture. This variant anatomy was occult on magnetic resonance cholangiopancreatography but was diagnosed on magnetic resonance cholangiopancreatography that was performed with intravenous secretin administration and further delineated by endoscopic retrograde cholangiopancreatography. The features that allowed the diagnosis to be made and the implications of this diagnosis are described in this report.

Pancreaticobiliary maljunction

Pancreaticobiliary maljunction (PBM) is a congenital anomaly defined as a junction of the pancreatic and bile ducts located outside the duodenal wall, usually forming a markedly long common channel. In PBM patients, this anomaly allows regurgitation between the pancreatobiliary and biliopancreatic tract. Since hydrostatic pressure within the pancreatic duct is usually higher than that in the common bile duct, pancreatic juice frequently refluxes into the bile duct. As a result, pancreatic enzyme levels are generally very high in the bile and there is a related high incidence of biliary cancer. PBM can be divided into PBM with biliary dilatation (congenital choledochal cyst [CCC]) and PBM without biliary dilatation (maximal diameter of the bile duct <or= 10 mm). In 42 CCC patients, bile duct and gallbladder cancer was seen in 7 and in 8, respectively. In 49 PBM patients without biliary dilatation, only gallbladder cancer was detected in 33 patients. Because of the increased cell proliferation with random K-ras mutations, the gallbladder mucosa of PBM patients should be considered premalignant. CCC treatment is prophylactic flow-diversion surgery, but only prophylactic cholecystectomy is usually performed for PBM without biliary dilatation. Pancreatobiliary reflux and premalignant changes in the gallbladder can occur in patients with a relatively long common channel (high confluence of pancreaticobiliary ducts).

Biliopancreatic reflux-pathophysiology and clinical implications

The common bile duct and the main pancreatic duct open into the duodenum, where they frequently form a common channel. The sphincter of Oddi is located at the distal end of the pancreatic and bile ducts; it regulates the outflow of bile and pancreatic juice. In patients with a pancreaticobiliary maljunction, the action of the sphincter does not functionally affect the junction. Therefore, in these patients, two-way regurgitation (pancreatobiliary and biliopancreatic reflux) occurs. This results in various pathological conditions of the biliary tract and the pancreas. Biliopancreatic reflux could be confirmed by: operative or postoperative T-tube cholangiography; CT combined with drip infusion cholangiography; histological detection of gallbladder cancer cells in the main pancreatic duct; and reflux of bile on the cut surface of the pancreas. Biliopancreatic reflux occurs frequently in patients with a long common channel. Although the true prevalence, degree, and pathophysiology of biliopancreatic reflux remain unclear, biliopancreatic reflux is related to the occurrence of acute pancreatitis. Obstruction of a long common channel easily causes bile flow into the pancreas. Even if no obstruction is present, biliopancreatic reflux can still result in acute pancreatitis in some cases.

Diagnosis and clinical implications of pancreatobiliary reflux

The sphincter of Oddi is located at the distal end of the pancreatic and bile ducts and regulates the outflow of bile and pancreatic juice. A common channel can be so long that the junction of the pancreatic and bile ducts is located outside of the duodenal wall, as occurs in pancreaticobiliary maljunction (PBM); in such cases, sphincter action does not functionally affect the junction. As the hydropressure within the pancreatic duct is usually greater than in the bile duct, pancreatic juice frequently refluxes into the biliary duct (pancreatobiliary reflux) in PBM, resulting in carcinogenetic conditions in the biliary tract. Pancreatobiliary reflux can be diagnosed from elevated amylase level in the bile, secretin-stimulated dynamic magnetic resonance cholangiopancreatography, and pancreatography via the minor duodenal papilla. Recently, it has become obvious that pancreatobiliary reflux can occur in individuals without PBM. Pancreatobiliary reflux might be related to biliary carcinogenesis even in some individuals without PBM. Since few systemic studies exist with respect to clinical relevance and implications of the pancreatobiliary reflux in individuals with normal pancreaticobiliary junction, further prospective clinical studies including appropriate management should be performed.

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.

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.

Fentanyl-augmented MRCP

BACKGROUND

Drugs such as secretin and morphine have been used to augment the visualization of magnetic resonance cholangiopancreatography (MRCP). This study investigated the effectiveness of intravenous administration of a synthetic opioid, fentanyl, in improving the MRCP image quality.

METHODS

Thirty consecutive patients with a provisional diagnosis of benign biliary and/or pancreatic disease underwent MRCP. Coronal single-shot fast spin-echo heavily T2-weighted dynamic MRCP images were generated before and at every minute for 10 min after intravenous administration of fentanyl citrate at a dose of 1.0 mug/kg. Pre- and postinjection images were compared and analyzed qualitatively and quantitatively.

RESULTS

Qualitatively, visualization of intrahepatic bile ducts, common bile duct, and main pancreatic duct improved after fentanyl injection in five (16%), 11 (37%), and 19 (63%) patients, respectively. The pancreatobiliary junction and common channel were visualized better after fentanyl injection in eight of the 18 patients (44%). Quantitatively, signal intensity and diameters of the intrahepatic ducts, common bile duct, and main pancreatic duct measured at corresponding points on pre- and postinjection images showed an increase above preinjection values in 28 (93%), 27 (90%), and 21 (70%) and in 18 (60%), 26 (86%), and 22 (73%), respectively, and these changes were highly significant at all sites (p < 0.001).

CONCLUSIONS

Intravenous administration of fentanyl before MRCP improves qualitative and quantitative visualization of the ductal system anatomy that may be of value in clinical diagnosis and management.

Can MRCP replace the diagnostic role of ERCP for patients with choledochal cysts?

BACKGROUND

MRCP is rapidly replacing diagnostic ERCP in various pancreaticobiliary diseases. This study was designed to evaluate the accuracy of MRCP in detecting and determining the extent of choledochal cysts, as well as associated ductal anomalies or lesions.

METHODS

The study design was an 8-year retrospective survey conducted at a tertiary referral center, Asan Medical Center (University of Ulsan College of Medicine, Seoul, Korea). There were 72 patients with choledochal cysts. All patients underwent both MRCP and ERCP. MRCP findings were compared with those of ERCP as the criterion standard.

RESULTS

The overall detection rate of MRCP for choledochal cysts was 96% (69/72). The sensitivity, the specificity, the positive predictive value, and the negative predictive value of MRCP for classifying choledochal cysts according to Todani's classification were 81%, 90%, 86%, and 86% in type I, respectively; 73%, 100%, 100, and 95% in type III, respectively; 83%, 90%, 80%, and 91% in type IVa, respectively; 100%, 100%, 100%, and 100% in type IVb, respectively; and 100%, 100%, 100%, and 100% in type V, respectively. The sensitivity, the specificity, and the accuracy of MRCP for detecting ductal anomalies were 83%, 90%, and 86%, respectively. The detection rate of MRCP for concurrent cholangiocarcinoma and choledocholithiasis was 87% (13/15) and 100% (8/8), respectively.

CONCLUSIONS

MRCP showed overall good accuracy in the detection and the classification of choledochal cysts and revealed associated cholangiocarcinoma and choledocholithiasis with excellent accuracy. MRCP, therefore, may supersede the diagnostic role of ERCP for the patients with choledochal cysts. However, MRCP showed limited capacity to detect minor ductal anomalies or small choledochocele.