Imaging diagnosis of pancreato-biliary diseases: A control study

Diagnostic value of dynamic contrast-enhanced magnetic resonance imaging in the evaluation of the biliary obstruction

Purpose. In this study, our purpose was to investigate the diagnostic efficacy of the dynamic contrast-enhanced magnetic resonance imaging (MRI) method in the patients with bile duct obstruction. Materials and Methods. 108 consecutive patients (53 men, 55 women, mean age; 55.77 ± 14.62, range 18–86 years) were included in this study. All the patients underwent conventional upper abdomen MRI using intravenous contrast material (Gd-DTPA) and MRCP in 1.5 Tesla MRI scanner. MRCP images were evaluated together with the T1 and T2w images, and both biliary ducts and surrounding tissues were examined for possible pathologies that may cause obstruction. Results. MRI/MRCP findings compared with final diagnoses, MRI/MRCP in the demonstration of bile duct obstruction sensitivity 96%, the specificity 100%, and accuracy 96.3%, in the detection of presence and level of obstruction, the sensitivity 96.7%, specificity 100%, and accuracy 97.2%, in the diagnosis of choledocholithiasis, the sensitivity 82.3%, specificity 96%, and accuracy 91.7%, and in the determination of the character of the stenosis, sensitivity 95.6%, specificity 91.3%, and accuracy 94.5% were found. Conclusion. The combination of dynamic contrast-enhanced MRI and MRCP techniques in patients with suspected biliary obstruction gives the detailed information about the presence of obstruction, location, and causes and is a highly specific and sensitive method.

Role of diffusion-weighted magnetic resonance imaging in the diagnosis of extrahepatic cholangiocarcinoma

AIM: To determine the clinical value of diffusion-weighted imaging (DWI) for the diagnosis of extrahepatic cholangiocarcinoma (EHCC) by comparing the diagnostic sensitivity of DWI and magnetic resonance cholangiopancreatography (MRCP).

METHODS: Magnetic resonance imaging examination was performed in 56 patients with suspected EHCC. T1-weighted imaging, T2-weighted imaging, MRCP and DWI sequence, DWI using single-shot spin-echo echo-planar imaging sequence with different b values (100, 300, 500, 800 and 1000 s/mm²), were performed. All cases were further confirmed by surgery or histopathological diagnosis. Two radiologists jointly performed the analysis of the DWI and MRCP images. Apparent diffusion coefficient (ADC) value and signal-noise ratio were calculated for EHCC. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value were tested using DWI with a b value of 500 s/mm² and MRCP images, respectively.

RESULTS: Histopathological diagnosis confirmed that among the 56 cases, 35 were EHCC (20 hilar and 15 distal extrahepatic), 16 were cholangitis, and 5 were calculus of bile duct. Thirty-three out of the 35 EHCC cases were detected by DWI. EHCC exhibited differential levels of high signal intensity in DWI and low signal intensity in the ADC map. The mean value for ADC was (1.31 ± 0.29) × 10^-3 mm²/s. The detection rate of EHCC was significantly higher by DWI (94.3%) than by MRCP (74.3%) (P < 0.05). There was a significant difference in sensitivity (94.3% vs 74.3%), specificity (100% vs 71.4%), accuracy (96.4% vs 73.2%), positive predictive value (100% vs 81.3%), and negative predictive value (91.3% vs 62.5%) between DWI and MRCP in diagnosing EHCC.

CONCLUSION: DWI has a high sensitivity for the detection of EHCC as it shows the EHCC lesion more unambiguously than MRCP does. DWI can also provide additional clinically important information in EHCC patients when added to routine bile duct MR imaging protocols.

Evaluation of the biliary and pancreatic system with 2D SSFSE, breathhold 3D FRFSE and respiratory-triggered 3D FRFSE sequences

PURPOSE

The authors compared biliary and pancreatic imaging obtained through 2D single-shot fast spin-echo (SSFSE), breath-hold 3D fast recovery fast spin-echo (FRFSE) and respiratory-triggered 3D FRFSE sequences.

MATERIALS AND METHODS

A total of 106 magnetic resonance cholangiopancreatography (MRCP) examinations performed between December 2007 and September 2008 were evaluated with a comparison of 2D SSFSE (thin section and thick slab), breath-hold 3D FRFSE and respiratory-triggered 3D FRFSE sequences. The biliary tract was divided into seven segments: right hepatic duct, left hepatic duct, common hepatic duct, cystic duct, common bile duct, cystic duct junction and biliary-pancreatic confluence. The main pancreatic duct was divided into three segments (head, body and tail). Visualisation of biliary variants was also compared. Two blinded radiologists evaluated segment visibility using a quantitative scale. The Student's t test for paired samples was used for statistical analysis.

RESULTS

Compared with 2D SSFSE, respiratory-triggered 3D FRFSE sequences showed better visibility of the right hepatic duct (p=0.0277), the cystic duct (p=0.0081), the cystic duct junction (p=0.0010), the biliary-pancreatic confluence (p=0.0334) and biliary variants (p=0.0198). In the comparison between breath-hold 3D FRFSE and 2D SSFSE, a significant statistical difference was found in visualisation of the cystic duct (p=0.027), the cystic duct junction (p=0.020), the biliary-pancreatic confluence (p=0.0338) and biliary variants (p=0.0311).

CONCLUSIONS

Three-dimensional FRFSE offers a significant benefit over conventional 2D imaging.

Choledochal cyst cholangiocarcinoma arising from adenoma: case report and a review of the literature

A case of cholangiocarcinoma arising in an unresected choledochal cyst in adulthood is presented. Although typically diagnosed in pediatric population, as many as 20% to 30% of choledochal cysts can be discovered in adulthood. Unresected choledochal cyst is clearly associated with increased risk of cholangiocarcinoma. Proper surgical treatment includes cyst resection and bilioenteric anastomosis. Asymptomatic patients with choledochal cyst previously treated by biliary diversion without cyst resection present a challenging issue and should be considered for cyst resection. Association of choledochal cyst with pancreaticobiliary anomalies is reviewed.

A comparison of MR cholangiopancreatography at 1.5 and 3.0 Tesla

Clinical MR systems operating at 3.0 Tesla have the potential to significantly improve spatial resolution due to the boost in intrinsic signal to noise ratio. However, body imaging at these field strengths presents a number of technical challenges. We performed a prospective pilot study in which 10 patients underwent an MR cholangiopancreatography (MRCP) examination consecutively on 1.5 and 3.0 Tesla systems (both Philips Intera). An axial half Fourier segmented turbo spin echo (HASTE) sequence and a coronal thick-slab 2D turbo-spin echo (TSE) sequence were compared on both systems. A reader measured the signal intensity (SI) ratios of common bile duct (CBD): liver, and CBD: fat on HASTE images and CBD: liver on the TSE images. A second reader performed a qualitative analysis of the intrahepatic and extrahepatic biliary anatomy. Quantitative data was compared using the paired t-test and qualitative data with the paired Wilcoxon signed rank test with p < 0.05. The quantitative analysis of the HASTE sequences showed a slightly higher signal intensity ratio (CBD:liver) at 3.0 Tesla compared with 1.5 Tesla (8.1 vs 5.6, p = 0.002). No significant difference was found between the SI ratios of (CBD:fat) on HASTE images or (CBD:liver) on TSE images. The qualitative analysis showed superior image quality of 3.0 Tesla over 1.5 Tesla images on both HASTE (31 vs 25, p = 0.032), and TSE sequences (34 vs 28, p = 0.043). This pilot study shows that MRCP is feasible at 3.0 Tesla with some improvement in image quality and signal characteristics. Further development may be achieved with sequence optimization and improved coil design.

Magnetic resonance cholangiopancreatography

The current imaging technique and clinical application of MR cholangiopancreatography (MRCP) is reviewed. MRCP has evolved into a feasible method of non-invasively evaluating the pancreaticobiliary system and has considerable clinical utility. If endoscopic retrograde cholangiopancreatography (ERCP) is incomplete or has failed, or in patients with biliary and gastrointestinal surgical procedures, MRCP is a useful alternative modality. In the near future, MRCP may supplant diagnostic ERCP such that ERCP is reserved primarily for therapeutic interventions. Furthermore, when MRCP is performed in conjunction with abdominal MR and MR angiography, the 'all-in-one' examination can evaluate the solid organs and vessels of the abdomen as well as the ductal systems.

Evaluation of magnetic resonance cholangiography in patients with suspected common bile duct stones before laparoscopic cholecystectomy

AIM: To evaluate the clinical predictive value of magnetic resonance cholangiography (MRC) in selected patients before laparoscopic cholecystectomy (LC).

METHODS: A total of 267 patients scheduled for elective LC from March 1999 to May 2001, with risk factors for common bile duct (CBD) stones, underwent MRC followed by endoscopic retrograde cholangiography (ERC) or intraoperative cholangiography (IOC) to detect the stones in common bile duct and value accuracy of MRC. Suspected patient selection was based on clinical, ultrasonographic, and laboratory criteria. All those with a history of previous jaundice, previous mild gallstone pancreatitis (acute abdominal pain and at least a fourfold increase in serum amylase activity), abnormal liver function test results (especially abnormal bilirubin result) or a dilated common bile duct (more than 8 mm) on ultrasonography were considered to have high suspicion for choledocholithiasis.

RESULTS: During a 26-month period, 267 patients were studied. MRC identified all patients (78 patients) found to have CBD stones by ERC or laparoscopic cholangiography in the study group. 7 patients were incorrectly diagnosed as having CBD stones by MRC. In our study, MRC had a sensitivity of 100.0%, specificity of 96.3%, positive predictive value of 91.8% and negative predictive value of 100.0% for the detection of common bile duct stones. There were 19 patients (7.1%) occurring the ERC procedure-related complications; 11 patients were cholangitis, 7 pancreatitis, and 1 papillary bleeding. The information obtained from MRC could be utilized to select patients who would benefit from preoperative ERC. Using the information, 68.2% (182/267) patients in our group could be away from ERC and its distress. And the complications of preoperative examination would be minimized significantly.

CONCLUSION: ERC is an invasive technique with a well-documented complication rate. MRC is an accurate and simple non-invasive imaging technique for preoperative screening for CBD stones in at-risk patients, which could minimize the need for non-therapeutic ERC.