Normal Vaterian sphincter complex: evaluation of morphology and contractility with dynamic single-shot MR cholangiopancreatography

Management of Patients With Common Bile Duct Dilatation Without a Sonographic Evident Cause: Evaluating the Yield of Subsequent Magnetic Resonance Imaging and Findings Correlated With Causative Pancreaticobiliary Pathology

OBJECTIVES

The aims of the study were to evaluate the yield of magnetic resonance imaging (MRI) in patients with common bile duct (CBD) dilatation without a sonographic evident cause and to investigate sonographic and laboratory findings at presentation that might predict identification of underlying pancreaticobiliary pathology.

METHODS

Included were consecutive patients in whom MRI was performed for further evaluation of CBD dilatation detected on ultrasound (US), without a sonographic evident cause, from January 1, 2014, to December 31, 2014. Magnetic resonance imaging and clinical data were retrospectively reviewed. Patients were divided into two groups: patients with and without identified underlying causative pancreaticobiliary pathology. Ultrasound findings and laboratory results at presentation were compared between groups to identify findings suggestive of underlying pancreaticobiliary pathology.

RESULTS

Fifty-seven patients, with a mean age of 54 ± 16 years including 37 females (65%), underwent MRI. Specific pancreaticobiliary causes for CBD dilatation were identified in 38 patients (66%, 31 benign and 7 malignant). In the remaining patients, no cause was identified in 17 (30%) and MRIs were nondiagnostic in 2 patients. Magnetic resonance imaging accuracy for correctly identifying the underlying cause of CBD dilatation was 91%. Patients with associated intrahepatic bile duct dilatation on US and elevated alanine aminotransferase and alkaline phosphatase were more likely to have underlying pancreaticobiliary pathology (P < 0 .05). No patient with initial negative MRI had pancreaticobiliary malignancy.

CONCLUSIONS

Magnetic resonance imaging seems to be an accurate noninvasive method for identifying the underlying cause in most patients with CBD dilatation on US and in excluding pancreaticobiliary malignancy. Patients with associated intrahepatic bile duct dilatation and/or elevated liver enzymes are at higher risk of harboring underlying pancreaticobiliary pathology.

High-grade precursor lesions can be used as surrogate markers to identify the epicenter of periampullary carcinomas

Identifying the accurate origin of periampullary cancers is important because different origins may trigger different clinicopathological behaviors. The presence of intraepithelial precursor lesions, including high-grade pancreatic intraepithelial neoplasias (PanINs) and/or high-grade biliary intraepithelial neoplasias (BilINs), may be suggestive of the origin of the periampullary carcinoma in challenging cases. To prove the usefulness of high-grade intraepithelial precursor lesions in identifying the origin of ambiguous periampullary cancers, the status and grades of PanINs and BilINs were evaluated in 256 periampullary carcinomas with a well-defined cancer origin as a test set, including 114 pancreatic cancers, 82 distal bile duct cancers, 54 ampullary cancers, and 6 duodenal cancers. One hundred twelve periampullary carcinomas with clinically equivocal epicenter either by radiologic imaging or by endoscopic finding used as a validation set. High-grade PanINs were found more commonly in pancreatic cancers than in distal bile duct, ampullary, and duodenal cancers both in test (P = .002) and validation sets (P < .001). Similarly, high-grade BilINs were identified more frequently in distal bile duct cancers than in ampullary, pancreatic, and duodenal cancers both in test (P < .001) and validation sets (P = .039). High-grade PanINs were found most commonly in pancreatic cancers, whereas high-grade BilINs were seen most frequently in distal bile duct cancers. In addition, both high-grade PanINs and high-grade BilINs are uncommonly noted in ampullary or duodenal cancers. The recognition of high-grade intraepithelial lesions can help identify the primary origin of periampullary cancers, especially when the epicenter of the periampullary cancer is ambiguous.

Magnetic resonance cholangiography: Current and future perspectives

Magnetic resonance cholangiography (MRC) has become the standard of reference for imaging of the biliary ducts. The use of three-dimensional (3D) sequences has resulted in improved spatial resolution with virtually isotropic voxel and improved signal/noise ratio. In addition to MRC images, 3D fat suppressed T1-weighted MR images should be systematically obtained to search for intrahepatic calculi. MRC plays a major role in the diagnosis of cholangiocarcinoma and assessment of its resectability. With modern MR systems the performance of MR is basically the same that of CT for evaluation of arterial and portal vein extent. MRC is a key imaging modality for the diagnosis of primary sclerosing cholangitis. Different imaging patterns may be observed including multifocal intra- and extrahepatic strictures alternating with slightly dilated ducts. Focal signal abnormality of the liver parenchyma and focal parenchymal atrophy represent the consequences of biliary duct obstruction on liver parenchyma. Diagnosis of biliary lithiasis is performed by combination of MRC and T1-weighted MR imaging. MRC can be performed for the diagnosis of secondary cholangitis including ascending cholangitis, ischemic cholangitis and IgG4-related sclerosing cholangitis. Hepatobiliary contrast agents could be used for demonstrating the site of biliary duct leakage after surgery and for functional imaging. MR imaging can also be used to determine the prognosis of PSC. The inherent limitations of MRC of bile ducts are still the suboptimal spatial resolution for evaluation of distal intrahepatic biliary ducts.

MRI Findings of Intrinsic and Extrinsic Duodenal Abnormalities and Variations

This pictorial review aims to illustrate the magnetic resonance imaging (MRI) findings and presentation patterns of anatomical variations and various benign and malignant pathologies of the duodenum, including sphincter contraction, major papilla variation, prominent papilla, diverticulum, annular pancreas, duplication cysts, choledochocele, duodenal wall thickening secondary to acute pancreatitis, postbulbar stenosis, celiac disease, fistula, choledochoduodenostomy, external compression, polyps, Peutz-Jeghers syndrome, ampullary carcinoma and adenocarcinoma. MRI is a useful imaging tool for demonstrating duodenal pathology and its anatomic relationships with adjacent organs, which is critical for establishing correct diagnosis and planning appropriate treatment, especially for surgery.

Post-cholecystectomy syndrome: spectrum of biliary findings at magnetic resonance cholangiopancreatography

Post-cholecystectomy syndrome (PCS) is defined as a complex of heterogeneous symptoms, consisting of upper abdominal pain and dyspepsia, which recur and/or persist after cholecystectomy. Nevertheless, this term is inaccurate, as it encompasses biliary and non-biliary disorders, possibly unrelated to cholecystectomy. Biliary manifestations of PCS may occur early in the post-operative period, usually because of incomplete surgery (retained calculi in the cystic duct remnant or in the common bile duct) or operative complications, such as bile duct injury and/or bile leakage. A later onset is commonly caused by inflammatory scarring strictures involving the sphincter of Oddi or the common bile duct, recurrent calculi or biliary dyskinesia. The traditional imaging approach for PCS has involved ultrasound and/or CT followed by direct cholangiography, whereas manometry of the sphincter of Oddi and biliary scintigraphy have been reserved for cases of biliary dyskinesia. Because of its capability to provide non-invasive high-quality visualisation of the biliary tract, magnetic resonance cholangiopancreatography (MRCP) has been advocated as a reliable imaging tool for assessing patients with suspected PCS and for guiding management decisions. This paper illustrates the rationale for using MRCP, together with the main MRCP biliary findings and diagnostic pitfalls.

Ampulla of Vater: comprehensive anatomy, MR imaging of pathologic conditions, and correlation with endoscopy

Endoscopic retrograde cholangiopancreaticography with or without an endoscopic biopsy is the method for making a definitive diagnosis of disease in or around the ampulla of Vater. However, the endoscopic findings of neoplastic and non-neoplastic conditions involving the perimapullary area may be similar and an endoscopic assessment is not entirely reliable for diagnosis. Recent MR and MRCP can allow the detection of lesions in a small complex structure such as the ampulla of Vater, and distinguish between an ampullary from periampullary lesion. This article reviews the normal anatomy of the ampulla of Vater, describes the role of MR in the detection and characterization of the lesion in or around the ampulla of Vater, and attempts to correlate them with ERCP.

Choledocholithiasis: repetitive thick-slab single-shot projection magnetic resonance cholangiopancreaticography versus endoscopic ultrasonography

This prospective study compares repetitive thick-slab single-shot projection magnetic resonance cholangiopancreatography (MRCP) with endoscopic ultrasonography (EUS) for the detection of choledocholithiasis. Fifty-seven consecutive patients (36 women, mean age 61) referred for suspected choledocholithiasis underwent MRCP, followed by EUS. Each procedure was performed by different operators blinded to the results of the other investigation. MR technique included a turbo spin-echo T2-weighted axial sequence with selective fat saturation (SPIR/TSE, TE=70 ms, TR=1,600 ms), followed by coronal dynamic MRCP. The same thick-slab slice was sequentially acquired 12 times as breath-hold single-shot projection imaging (SSh, TE=900 ms, TE=8,000 ms) centred on the common bile duct (CBD). Two experienced radiologists independently and blindly evaluated MR images for the detection of CBD stones. Their inter-observer agreement kappa was determined. Secondly, the two observers read MR images in consensus again. CBD stones were demonstrated in 18 out of 57 patients (31.6 %) and confirmed by endoscopic retrograde cholangiography (ERCP, n=17) or intraoperative cholangiography (n=1). Clinical follow-up served as the "gold standard" in patients with negative results without following invasive procedure (n=28). Sensitivity, specificity, accuracy, positive and negative predictive value for MRCP resulting from consensus reading were 94.9%, 94.4%, 94.7%, 97.4% and 89.5%, respectively. Corresponding values of EUS were 97.4%, 94.4%, 96.5%, 97.4% and 94.4%. Inter-observer agreement kappa was 0.81. Repetitive thick-slab single-shot projection MRCP is an accurate non-invasive imaging modality for suspected choledocholithiasis and should be increasingly used to select those patients who require a subsequent therapeutic procedure, namely ERCP.

Role of Magnetic Resonance Cholangiography in the Diagnosis of Bile Duct Lithiasis

AIM

The aim of our study was to assess diagnostic value of magnetic resonance cholangiography (MRC) in patients with suspected common bile duct (CBD) stones focusing on the capability of this noninvasive method to replace invasive diagnostic procedures in these patients and to limit the use of endoscopic retrograde cholangiography (ERC) to the patients who need simultaneous therapeutic intervention.

MATERIALS AND METHODS

Single-shot fast-spin-echo rapid-acquisition thick-section MRC images were obtained in 310 patients recruited into this prospective study. There were 136 male and 174 female patients aged 21-95 years [mean +/- standard deviation (SD) 64.9 +/- 13.6 years]. Patients were subsequently classified into different risk groups (high, moderate, low) according to biochemical abnormalities or morphological features on abdominal ultrasonography and computed tomography. Direct cholangiography was the reference method of CBD evaluation.

RESULTS

CBD stones were diagnosed in 115 (37%) patients; 86 of 175 patients in the high-risk group, 24 of 83 patients in the moderate-risk group, and 5 of 50 patients in the low-risk group. In dependent risk groups, the mean CBD caliber was 9.7 +/- 4.5, 7.1 +/- 2.0, and 4.8 +/- 1.2 mm, respectively. The difference was significant between all three groups (P < 0.05). The median size of CBD stones was 7 mm (range 3-21 mm). MRC achieved accuracy and positive and negative predictive values of 97%, 94%, and 98%, respectively.

CONCLUSIONS

MRC has a potential to substitute diagnostic ERC in all patients with suspected choledocholithiasis due to its high accuracy, reducing invasive direct cholangiography to patients who require therapeutic intervention.

Does intravenous glucagon improve common bile duct visualisation during magnetic resonance cholangiopancreatography? Results in 42 patients

INTRODUCTION

Magnetic resonance cholangiopancreatography (MRCP) has been demonstrated as a reliable, non-invasive means of biliary tract imaging among patients with suspected choledocholithiasis. The aim of this study was to establish the impact of intravenous glucagon administration (IVGA) upon visualisation of the common bile duct (CBD) and ampulla of Vater during MRCP.

MATERIALS AND METHODS

Forty-two consecutive, non-diabetic subjects with a working diagnosis of symptomatic choledocholithiasis were scanned, pre- and post-IVGA using the half-Fourier, single shot, turbo-spin-echo (HASTE) sequence. Maximum intensity projections (optimised for the extra-hepatic biliary tree and ampulla of Vater) were reviewed blindly by three consultant radiologists. The CBD images were graded (0-3) according to the length of duct seen. The ampullary images were graded according to whether to it was visualised clearly (1), or not (0).

RESULTS

Following IVGA the CBD was visualised at grade 3 (75-100% of length seen) in 14 additional patients compared with images prior to IVGA. Furthermore, ampullary visualisation was considered diagnostic in 18 additional patients post-IVGA. No glucagon-associated adverse effects were observed.

CONCLUSION

These results demonstrate that IVGA improved visualisation of the CBD and ampulla of Vater during magnetic resonance cholangiopanctreatography. This may reduce the requirement for repeat investigation or recourse to invasive diagnostic procedures (e.g. endoscopic retrograde cholangiopancreatography (ERCP)).

Periampullary Tumors: High-Spatial-Resolution MR Imaging and Histopathologic Findings in Ampullary Region Specimens

PURPOSE

To prospectively determine the magnetic resonance (MR) signal intensity characteristics of structures of the ampullary region and to assess the potential use of MR imaging in evaluation of the extent of periampullary tumors in resected specimens.

MATERIALS AND METHODS

Twenty-five specimens from the ampullary region obtained in four autopsy cases without periampullary tumors and in 21 patients with periampullary tumors were examined with a 1.5-T MR system and a circular surface coil with 5-inch (12.7-cm) diameter. High-spatial-resolution MR images were obtained with field of view of 100 x 100 mm, matrix of 256 x 256 or 512 x 256, and section thickness of 2 mm. MR imaging findings were compared with histopathologic findings. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissues were evaluated by two radiologists.

RESULTS

T1- and T2-weighted MR images clearly depicted normal structures in the ampullary region that included Oddi muscle, duodenal wall, common bile duct, and pancreas; these findings corresponded well with histologic findings. In 20 (95%) of 21 tumors, high-spatial-resolution MR imaging depicted location and extension of periampullary tumors precisely. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of high-spatial-resolution MR imaging for assessment of tumor invasion into surrounding tissue were 88%, 100%, 96%, 100%, and 94%, respectively.

CONCLUSION

In this study, MR imaging correctly depicted location, extension, and origin of tumor. High-spatial-resolution MR imaging has potential for presurgical staging of tumors in this region.

Radio-anatomic study of the pancreatic duct by MR cholangiopancreatography

To compare the performance of MR-cholangiopancreatography (MRCP) and that of classical anatomy in the depiction of the main pancreatic duct, 50 MRCP examinations were done in patients free of pancreatic disease. Axial and coronal sections 20 mm thick were obtained in a Single Shot Fast Spin Echo (SSFSE) sequence. The following were analyzed: (1) visibility of pancreatic duct structures, (2) form of the main pancreatic duct, (3) various angulations of the duct and (4) diameter of the duct. Anatomic variants were noted. These findings were compared with anatomic and radio-anatomic (ERCP) data in the literature. The main pancreatic duct was visualized in 100% of cases and the accessory pancreatic duct in 61%. The form, diameter and angulations of the various segments of the pancreatic duct were similar to those reported in the literature. These findings are reported in the axial and coronal planes. Comparison with major anatomic classifications was not possible. MRCP enables in vivo anatomic exploration of the main pancreatic duct. Horizontal sections provided new radio-anatomic information. The technique nevertheless remains limited by poor spatial resolution.

Differential diagnosis of periampullary carcinomas at MR imaging

Periampullary carcinomas arise within 2 cm of the major duodenal papilla and comprise carcinomas of the ampulla, distal common bile duct, pancreas, and duodenum. Their clinical features and anatomic locations are similar, as are the therapeutic approaches; however, their long-term outcomes vary. Magnetic resonance (MR) images of 89 pathologically proved periampullary carcinomas (29 ampullary carcinomas, 27 distal common bile duct carcinomas, 21 pancreatic carcinomas, six duodenal carcinomas, and six unclassified carcinomas) were reviewed. Ampullary carcinoma manifests as a small mass, periductal thickening, or bulging of the duodenal papilla. Pancreatic carcinoma is characterized by a discrete parenchymal mass, which enhances poorly on dynamic gadolinium-enhanced images. Sometimes, two proximal and two distal pancreatic and biliary ducts appear as four separate ducts (the four-segment sign). Dilatation of side branches of the pancreatic ducts is frequently seen in pancreatic carcinoma but not in other periampullary carcinomas. Distal bile duct carcinoma manifests as luminal obliteration and wall thickening or as an intraductal polypoid mass. A dilated proximal bile duct, a nondilated distal bile duct, and a dilated or nondilated pancreatic duct may form the three-segment sign. MR cholangiopancreatography and sectional MR imaging are useful in determining the origins of periampullary carcinomas.

Using kinematic MR cholangiopancreatography to evaluate biliary dilatation

OBJECTIVE

The purpose of this study was to evaluate the usefulness of kinematic MR cholangiopancreatographic (MRCP) images as an aid in predicting the need for intervention in patients with biliary dilatation.

SUBJECTS AND METHODS

Fifty patients with suspected pancreaticobiliary disorders were separated into three groups. Group I patients had biliary dilatation with periampullary lesions (n = 16), group II patients had supraampullary obstructive lesions (n = 17), and group III patients had biliary dilatation without obstruction (n = 17). Twenty consecutive single thick-slice MRCP images were obtained in the 15 degrees or 30 degrees left anterior oblique coronal plane. Two radiologists jointly reviewed the images without knowledge of the final diagnosis. The numbers of images showing relaxation of the sphincteric segment and the configuration of the distal margin of the common bile duct for the three groups were compared.

RESULTS

Relaxation of the sphincteric segment was observed on the images of only two patients (12%) in group I but on the images of all patients in groups II and III, although not on all images. Lack of visualization of sphincteric relaxation on the kinematic MRCP images had a sensitivity of 88% and a specificity of 100% for the diagnosis of periampullary lesions. Most patients whose images did not show sphincteric relaxation required biliary intervention at the sphincter level.

CONCLUSION

Nonvisualization of sphincteric relaxation on kinematic MRCP indicates ampullary or periampullary lesions. Kinematic MRCP can be used to determine the necessity of biliary intervention in patients with biliary dilatation.

Diagnostic accuracy of magnetic resonance cholangiopancreatography and ultrasound compared with direct cholangiography in the detection of choledocholithiasis

AIM

To determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) and trans-abdominal ultrasound in the detection of choledocholithiasis, and to compare bile duct stone characteristics using endoscopic retrograde cholangiopancreatography (ERCP), MRCP and ultrasound.

MATERIALS AND METHODS

Of 191 consecutive patients referred for diagnostic ERCP, choledocholithiasis was diagnosed in 34 patients using direct cholangiography. The latter took the form of ERCP (n = 29), intraoperative cholangiography (n = 3) or percutaneous transhepatic cholangiography (n = 2). All patients underwent MRCP and ultrasound examinations and their findings for choledocholitiasis were compared with those at direct cholangiography. Finally, in the 29 patients with choledocholithiasis diagnosed under ERCP, stone characteristics were compared across the three investigations of ERCP, MRCP and ultrasound.

RESULTS

Compared with direct cholangiography, MRCP showed a sensitivity, specificity and diagnostic accuracy of 91%, 98% and 97%, respectively, in the diagnosis of choledocholithiasis. MRCP resulted in three false-negative and three false-positive findings, four of which occurred due to confusion with lesions at the ampulla. Ultrasound showed a sensitivity, specificity and diagnostic accuracy of 38%, 100% and 89%, respectively, in the diagnosis of choledocholithiasis. ERCP revealed a greater number of stones and these were more proximally distributed within the bile ducts when compared to MRCP.

CONCLUSIONS

MRCP is highly accurate in the diagnosis of choloedocholithiasis and has the potential to replace diagnostic ERCP. MRCP underestimates the number of bile duct stones present.

Biliary tract imaging

In addition to the detection of gallstones, common bile duct stones, and narrowed and dilated bile ducts, recent advancements in imaging techniques now make it possible to diagnose microlithiasis, pathology of normal-size ducts, and dysfunction of the gallbladder and the sphincter of Oddi (SO). More and more frequently, noninvasive imaging techniques obviate the risk of invasive investigation. These techniques can also take the place of unsuccessful or contraindicated direct cholangiography, and they play an essential role in treatment planning and diagnosis of postoperative complications. Transabdominal ultrasonography (TUS) remains fundamental for initial assessment of the biliary tract. Technical developments make magnetic resonance cholangiopancreatography the most promising diagnostic technique of the biliary tract. Endoscopic ultrasonography (EUS) is most helpful for detection of microlithiasis and evaluation of the ampullary region, the periductal structures, and the regional lymph nodes in neoplastic diseases. Cholescintigraphy is most valuable to assess bile dynamics in the diagnosis of gallbladder and SO dysfunction and in postoperative bile leakage.