Pancreaticobiliary Juice Reflux in Patients With a Morphologically Normal Ductal System: Assessment Using Unenhanced MRI With Spin Labeling

Pancreaticobiliary Reflux with Normal and Relatively Long Common Channels Causing Cholelithiasis and Acute Pancreatitis in Children

Background and Aims: Pancreaticobiliary maljunction (PBMJ) has a long common channel (CC) that causes pancreaticobiliary reflux (PBR), which has been implicated in gallstones, cholangiocarcinoma, and pancreatitis. By contrast, PBR has occurred in cases with normal and longer CCs than normal but shorter than PBMJ. This pathophysiology has been primarily reported in adults and rarely in children. We sometimes observe this pathophysiology in children with pancreatitis and cholelithiasis. Herein, we report the clinical figures on the diagnosis of children with PBR in normal and relatively long CCs. Patients and Methods: This study included seven children who complained of refractory pancreatitis and cholelithiasis diagnosed with PBR in normal and relatively long CCs at our institution from August 2018 to September 2024. We measured the lengths of their CCs and sphincter of Oddi muscles via endoscopic retrograde cholangiopancreatography (ERCP) and cholangiography. In addition, amylase and lipase levels in bile juice were measured. Results: All seven children demonstrated elevated amylase and lipase levels in bile juice obtained from gallbladder drainage and/or the common bile duct. ERCP and cholangiography indicated 2.2-5.5-mm lengths of CCs in their cases, which are normal lengths in two cases and relatively longer (0.3-1.1 mm: mean 0.6 mm) than the normal upper limit of CC in children in five cases, with their CCs shorter than the sphincters of Oddi. All children underwent extrahepatic bile duct resection and bilio-jejunal anastomosis, demonstrating no clinical symptom recurrence postoperatively. Conclusions: Some children with cholelithiasis and pancreatitis exhibit normal and relatively long CCs, causing PBR and inducing gastrointestinal diseases. Careful investigation by ERCP and cholangiography focused on the CC length, and pancreatic enzyme level assessments in bile juice are useful for diagnosing PBR in children with cholelithiasis and refractory pancreatitis.

Comparison of Slab and Pencil Beam Labeling in Spin-labeled MR Imaging for Pancreatic Juice Flow Visualization

The usefulness of a highly targeted pencil beam (PB) label was compared with the commonly used slab label for direct visualization of pancreaticobiliary reflux using the time-spatial labeling inversion pulse (time-SLIP) technique. Signal profiles of flow phantom images obtained with a 1.5T MRI were analyzed. Both labels had similar labeling capabilities, but the edge characteristics of the PB label were blunt. Next, sixty-eight patients were classified into two groups according to the angle of the pancreaticobiliary ducts, and the displacement of the pancreatic ducts in respiratory fluctuation was measured. The results were approximately 7 mm in both groups. The blunt edge characteristics of the PB label suggest that it is robust to respiratory fluctuations. The overall labeling ability of the PB is comparable to that of the slab. In the larger angle of pancreaticobiliary ducts, the PB label may be able to label the pancreatic duct more selectively.

Pancreatobiliary reflux increases macrophage-secreted IL-8 and activates the PI3K/NFκB pathway to promote cholangiocarcinoma progression

BACKGROUND

Persistent pancreaticobiliary reflux (PBR) is associated with a high risk of biliary malignancy. This study aimed to evaluate the proportion of PBR in biliary tract diseases and mechanisms by which PBR promoted cholangiocarcinoma progression.

METHODS

Overall 227 consecutive patients with primary biliary tract disease participated in this study. The amylase levels in the collected bile were analyzed. The mechanisms underlying the effect of high-amylase bile on bile duct epithelial and cholangiocarcinoma cells progression were analyzed. The source of interleukin-8 (IL-8) and its effects on the biological functions of cholangiocarcinoma cells were investigated.

RESULTS

The bile amylase levels in 148 of 227 patients were higher than the upper serum amylase limit of 135 IU/L. PBR was significantly correlated with sex, pyrexia, and serum gamma-glutamyl transferase (GGT) levels in the patient cohort. High-amylase bile-induced DNA damage and genetic differences in the transcript levels of the gallbladder mucosa and facilitated the proliferation and migration of bile duct cancer cells (HUCCT1 and QBC939 cells). The concentration of many cytokines increased in high-amylase bile. IL-8 is secreted primarily by macrophages via the mitogen-activated protein kinase pathway and partially by bile duct epithelial cells. IL-8 promotes the progression of HUCCT1 and QBC939 cells by regulating the expression of epithelial-mesenchymal transition-associated proteins and activating the phosphatidylinositol 3-kinase/nuclear factor kappa-B pathway.

CONCLUSIONS

PBR is one of the primary causes of biliary disease. IL-8 secreted by macrophages or bile duct epithelial cells stimulated by high-amylase bile promotes cholangiocarcinoma progression.

Age and incidence of occult pancreaticobiliary reflux in patients with benign gallbladder diseases

BACKGROUND

Occult pancreaticobiliary reflux (OPBR) has a significant correlation with diseases of the gallbladder and biliary system. This study examined the incidence of OPBR by age in patients with benign gallbladder diseases.

METHODS

We assessed 475 patients with benign gallbladder diseases who underwent surgery at Shanghai East Hospital from December 2020 to December 2021. Bile samples collected during surgery were tested for amylase. Patients with bile amylase >110 U/L (n = 64) were classified as the OPBR group; the rest (n = 411) as controls.

RESULTS

Of the participants, 375 had gallbladder stone (GS), 170 had gallbladder polyp (GP), and 49 had gallbladder adenomyomatosis (GA). The OPBR group was generally older, with OPBR incidence increasing with age, peaking post-45. Rates by age were: 4.9% (<35), 5.2% (35-44), 20.7% (45-54), 22.5% (55-64) and 17.6% (≥65), mainly in GS patients. ROC analysis for predicting OPBR by age yielded an area under the curve of 0.656, optimal cut-off at 45 years. Logistic regression indicated age > 45, GP, male gender, and BMI ≥ 24 kg*m-2 as independent OPBR predictors in GS patients. Based on these variables, a predictive nomogram was constructed, and its effectiveness was validated using the ROC curve, calibration curve and decision curve analysis (DCA). Further stratification revealed that among GS patients ≤ 45, concurrent GA was an OPBR risk; for > 45, it was GP and male gender.

CONCLUSIONS

The incidence of OPBR in GS patients is notably influenced by age, with those over 45, especially males without GP, being at heightened risk.

Using Spin-labeled MR Imaging to Depict Slow Pancreatic Juice Flow

This study evaluated the dependence of the signal characteristics of time-spatial labeling inversion pulse (time-SLIP) on flow velocity and tag thickness to depict the pancreatic juice flow by analyzing signal profile using a tube phantom study. The tag edge property was evaluated by edge rise distance (ERD). For various slow flow velocities and tag thicknesses, the signal profile characteristics were evaluated using two indices: the tag center value (RTCV) reduction rate and the total signal value along the tube (TSVT). ERD, which was about 10% of the tag thickness, was higher for thicker tags, making slow flow detection difficult. TSVT was proportional to the thickness of the tag and was preserved irrespective of the flow velocity. RTCV became lower with higher flow velocity and decreased significantly with thinner tags. These results suggest that the visualization of pancreatic juice flow might improve stability by considering the appropriate tag thickness.

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.