Magnetic resonance imaging of the bile ducts

Double-Duct Sign in the Clinical Context

OBJECTIVES

Double-duct sign (combined dilatation of the common bile duct and pancreatic duct) is an infrequently encountered finding in cross-sectional radiological imaging of the pancreatobiliary system. This sign is commonly deemed to signify on ominous pathology and suggests the presence of pancreatic or biliary malignancy.

METHODS

We aim to correlate double-duct sign discovered on magnetic resonance cholangiopancreatogram (MRCP) in the clinical context. We retrospectively analyzed MRCP database over a period of 4 years, January 2010 to December 2013. Follow-up information was available for a median of 27 months (range, 12-42 months)

RESULTS

The commonest cause of double-duct sign was choledocholithiasis followed closely by pancreatobiliary malignancy. Patients with jaundice in the context of double-duct sign had a higher incidence of malignancy (48%). None of the anicteric patients were found to have malignancy (P = 0.002).

CONCLUSIONS

In patients with MRCP evidence of double-duct sign, the absence of jaundice makes a malignant etiology unlikely. Conversely, in jaundiced patients, a malignant cause is much more likely. Figures from larger series are needed to support this conclusion.

Use of pineapple juice with gadopentetate dimeglumine as a negative oral contrast for magnetic resonance cholangiopancreatography: a multicentric study

We evaluated the efficacy of pineapple juice with gadopentetate dimeglumine as a negative oral contrast agent for magnetic resonance cholangiopancreatography (MRCP). Images were obtained before and after the intake of a negative oral contrast agent. Images obtained from six different areas of the biliary tree were analyzed by three different radiologists, who were blind to the exams; scores regarding image quality were given to each area. The statistical analysis showed a significant difference between images before and after the use of the contrast agent (P < 0.001) for the three radiologists (R1-R3). Mean scores given by radiologists before the intake of the contrast agent were 2.49 ± 0.42 (R1), 2.62 ± 0.32 (R2), and 2.22 ± 0.46 (R3). After the intake, mean scores were 3.38 ± 0.62 (R1), 3.48 ± 0.55 (R2), and 2.89 ± 0.69 (R3). The ducts that showed the highest scores were the common bile duct and duct of Wirsung, the distal portion of the common bile duct and the cystic duct. We suggest herein that the contrast agent pineapple juice with gadopentate dimeglumine constitutes an efficient negative oral contrast agent for MRCP, for it efficiently eliminates the signal of the digestive tube in MRCP images.

Diagnostic imaging of carcinomas of the gallbladder and the bile ducts

Early diagnosis and accurate staging of carcinomas of the gallbladder and the bile ducts are helpful in improving the prognosis. Ultrasonography (US), a useful initial modality when exploring the background of jaundice or non-specific gastrointestinal complaints, sensitively reveals bile duct obstruction in particular. In unclear cases, or if US suggests a resectable biliary malignancy, computed tomography (CT), magnetic resonance imaging (MRI) with magnetic resonance cholangiography (MRC) and / or traditional cholangiography often provide additional information, and imaging-guided fine-needle biopsy or an endoscopic brush sample may verify the malignant nature of the tumor. Complementary modalities are usually needed for accurate staging, and traditional cholangiography is often performed for therapeutic purposes as well. Comparative studies of MRI with MRC and multidetector CT in biliary cancers would be welcome.

Physical activity, health impairments, and disability in neuromuscular disease

Reduced physical activity is a consequence of progressive neuromuscular diseases, which negatively impacts quality of life and health outcomes. Reduced functional muscle mass is common to all neuromuscular diseases and results from both atrophy of disuse secondary to a sedentary lifestyle and muscle degeneration secondary to the disease itself. This review summarizes current concepts relating to the impact of reduced physical activity on health and fitness, potential determinants of physical activity levels in neuromuscular diseases, and new approaches to the quantitative measurement of physical activity in neuromuscular disease populations. The interrelationship of disease pathophysiology, impairment, functional limitation, disability, and societal limitation in the determination of physical activity in the community in neuromuscular diseases is discussed using Duchenne muscular dystrophy as an example. Future research pertaining to physical activity in neuromuscular disease will need to focus on the development of scientifically based recommendations concerning optimal exercise approaches with both disease-specific and general guidelines.

Pediatric magnetic resonance imaging techniques

Optimization of the MR image requires an understanding of technical parameters, pulse sequences, artifacts, and the use of contrast agents. More technical information and in-depth details about the practical concepts for performing MRI in children can be found in the references accompanying this article.

Magnetic resonance imaging and diseases of the liver and biliary tract. Part 2. Magnetic resonance cholangiography and angiography and conclusions

Magnetic resonance cholangiography (MRC) relies on the strong T2 signal from stationary liquids, in this case bile, to generate images. No contrast agents are required, and the failure rate and risk of serious complications is lower than with endoscopic retrograde cholangiopancreatography (ERCP). Data from MRC can be summated to produce an image much like the cholangiogram obtained by using ERCP. In addition, MRC and conventional MRI can provide information about the biliary and other anatomy above and below a biliary obstruction. This provides information for therapeutic intervention that is probably most useful for hilar and intrahepatic biliary obstruction. Magnetic resonance cholangiography appears to be similar to ERCP with respect to sensitivity and specificity in detecting lesions causing biliary obstruction, and in the diagnosis of choledocholithiasis. It is also suited to the assessment of biliary anatomy (including the assessment of surgical bile-duct injuries) and intrahepatic biliary pathology. However, ERCP can be therapeutic as well as diagnostic, and MRC should be limited to situations where intervention is unlikely, where intrahepatic or hilar pathology is suspected, to delineate the biliary anatomy prior to other interventions, or after failed or inadequate ERCP. Magnetic resonance angiography (MRA) relies on the properties of flowing liquids to generate images. It is particularly suited to assessment of the hepatic vasculature and appears as good as conventional angiography. It has been shown to be useful in delineating vascular anatomy prior to liver transplantation or insertion of a transjugular intrahepatic portasystemic shunt. Magnetic resonance angiography may also be useful in predicting subsequent variceal haemorrhage in patients with oesophageal varices.

The efficacy of magnetic resonance cholangiography for the evaluation of patients with suspected choledocholithiasis before laparoscopic cholecystectomy

BACKGROUND

Endoscopic retrograde cholangiography is the most commonly utilized tool for the identification of common bile duct stones (CBDS) before laparoscopic cholecystectomy, whereas the role of magnetic resonance cholangiography (MRC) for patient evaluation before laparoscopic cholecystectomy is currently undefined.

METHODS

We prospectively evaluated the efficacy of MRC for the identification of CBDS among patients with high risk for choledocholithiasis. Patient selection was based on clinical, sonographic, and laboratory criteria. Standard cholangiograms were obtained when possible for verification of MRC results.

RESULTS

Ninety-nine patients underwent evaluation with preoperative MRC. CBDS was visualized in 30% of patients. MRC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 85%, 90%, 77%, 94%, and 89%, respectively.

CONCLUSIONS

MRC is useful for the evaluation of patients with suspected choledocholithiasis. Advantages of MRC include its noninvasive nature, ease of application, and accuracy in identifying and estimating the size of CBDS. Application of MRC in this setting reduces the need for diagnostic endoscopic retrograde cholangiography. Future investigations should be directed at the development of cost-effective utilization strategies for MRC application.