MR cholangiography in children and young adults with biliary disease

Pediatric MR cholangiopancreatography: principles, technique, and clinical applications

High-quality magnetic resonance (MR) cholangiopancreatographic images are difficult to obtain in children due to the small caliber of the pediatric bile ducts and to motion artifacts. However, there has been ongoing improvement in image quality, thanks to better coil technology, increased speed of acquisition, refinement in respiratory compensation techniques, and newer sequences. Heavily T2-weighted fast spin-echo (FSE) and single-shot FSE MR imaging sequences with long echo times are used to image the biliary and pancreatic ducts. Secretin has been shown to improve the visualization of the pancreatic duct and pancreaticobiliary junction. Factors that affect image quality in pediatric MR cholangiopancreatography include sedation, negative oral contrast material, radiofrequency coil selection, respiratory compensation techniques, echo time, echo train length, section-slab thickness, planes of scanning, field of view, and number of signals acquired. However, giving proper attention to these factors and tailoring the study to the body size of the patient (which varies considerably) can lead to high-quality diagnostic MR cholangiopancreatographic images. Use of MR cholangiopancreatography in children is limited by the need for sedation or anesthesia, high cost, limited availability, and long scanning times. Nonetheless, this modality can be a viable alternative to endoscopic retrograde cholangiopancreatography (ERCP) in the evaluation of various entities such as choledochal cyst, recurrent pancreatitis, primary sclerosing cholangitis, and a transplanted liver, and may obviate ERCP.

Predominant extrahepatic biliary disease in autosomal recessive polycystic kidney disease: a new association

Autosomal recessive polycystic kidney disease (ARPKD) is characterized by dilation of ectatic renal collecting ducts, intrahepatic biliary dysgenesis, and portal fibrosis. Portal hypertension and recurrent bacterial cholangitis can dominate the clinical picture in long-term survivors. Predominant extrahepatic bile duct disease was revealed in four patients who underwent magnetic resonance cholangiopancreatography. All four patients had portal hypertension, although liver biochemistries did not suggest biliary disease. In two of the patients, cholangitis was clinically ascribed to the bile duct disease. Western blot analysis of plasma membranes from normal rat extrahepatic bile duct and kidney revealed the presence of polyductin as a single approximately 440 kDa protein. Although the exact function of polyductin in the extrahepatic duct is unknown, it may have a role in the development and control of lumenal size. Clinical management of patients with ARPKD should include consideration of potential problems related to extrahepatic bile duct disease.

Liver disease in autosomal recessive polycystic kidney disease

Hepatic complications occur in a significant proportion of children with autosomal recessive polycystic kidney disease (ARPKD). PKHD1/fibrocystin, the defective gene in ARPKD, is expressed in the cilia of bile duct epithelium and leads to abnormalities in the rubric of the ductal plate malformation. Portal hypertension and biliary disease are the major liver problems seen in ARPKD. Complete blood counting, physical examination, ultrasonography and magnetic resonance (MR) cholangiography are indicated as screening procedures for hepatic disease in ARPKD. Medical and surgical interventions are potentially indicated for children with portal hypertension and/or biliary disease. A high index of suspicion for the diagnosis of cholangitis needs to be maintained in children with biliary disease. The implications of hepatic disease need to be considered in the decision-making regarding renal transplantation in ARPKD.

Imaging and intervention in the gastrointestinal tract in children

Vascular and interventional techniques have become an integral component of modern pediatric healthcare. Minimally invasive procedures of the gastrointestinal tract now comprise a large part of any active pediatric interventional practice. Magnetic resonance cholangiopancreatography offers a reliable, non-invasive means to evaluate patients with possible pancreatic or biliary pathology. This article reviews treatment of esophageal strictures and placement of gastronomy and gastrojejunostomy tubes and discusses new developments. Placement of percutaneous cecostomy tubes is a relatively new procedure that creatively uses the techniques developed for placement of percutaneous gastronomy tubes. This procedure offers significant benefits and lasting positive lifestyle changes for patients suffering from fecal incontinence. Liver biopsy in high-risk patients can be performed safely using measures designed to significantly decrease the risk of post-biopsy hemorrhage, such as track embolization or the transjugular approach.

Pediatric liver magnetic resonance imaging

Imaging is a standard part of the evaluation of pediatric liver disease. Advances in MR imaging have improved the detection, characterization, and staging of hepatic lesions. Clinical information, however, is still important in selecting the best imaging study and in correctly interpreting the examination. This article addresses the clinical and imaging features of the common hepatic and biliary lesions in children. In addition, the techniques for performing hepatic MR imaging are reviewed.

MR cholangiography in the evaluation of neonatal cholestasis: initial results

PURPOSE

To retrospectively analyze prospective magnetic resonance (MR) cholangiographic interpretations of findings and compare them with clinical outcome and to determine the accuracy of MR cholangiography in depicting extrahepatic biliary atresia and helping to distinguish it from other causes of neonatal jaundice.

MATERIALS AND METHODS

Twenty-six infants (15 male, 11 female; median age, 2 months) underwent MR cholangiography with a 1.5-T MR imaging unit. Original interpretations were compared with clinical outcome. Statistical analysis was performed to determine the accuracy of MR cholangiography in depicting extrahepatic biliary atresia. Equivocal cases and any cases lost to follow-up were excluded.

RESULTS

Findings in six of 26 infants were interpreted as normal, and none of five patients (one lost to follow-up) had biliary atresia or other surgical lesions; two were abnormal but not suggestive of biliary atresia (one false-negative finding); 12 were consistent with biliary atresia (three false-positive findings); four demonstrated a choledochal cyst; and two were equivocal. MR cholangiography accuracy was 82% (19 of 23); sensitivity, 90% (nine of 10); and specificity, 77% (10 of 13) for the detection of extrahepatic biliary atresia, with a positive predictive value of 75% (nine of 12) and a negative predictive value of 91% (10 of 11).

CONCLUSION

Results of this study found that MR cholangiography is 82% accurate, 90% sensitive, and 77% specific for depicting extrahepatic biliary atresia. Contrary to previous reports, false-positive and false-negative findings occur at MR cholangiography.

MR imaging of the pediatric liver

Applications of MR imaging of the pediatric abdomen are expanding rapidly. New techniques of MR imaging, such as MRA or MRCP, are becoming commonplace. MR imaging is particularly helpful in the diagnosis and characterization of liver and biliary tree disease in children. Consistent and reproducible quality imaging is achieved with faster imaging sequences tailored to reduce motion artifacts. The lack of radiation, the ability to directly acquire multiple imaging planes, and the superior contrast resolution, particularly with the administration of gadolinium, have contributed to the acceptance of MR imaging as an invaluable tool in the pediatric age group.