MR cholangiography readies to supplant direct cholangiography

MR cholangiography now rivals direct cholangiography for imaging biliary stenosis. And with improvements in resolution, MRC should become the imaging method of choice for this patient population, according to researchers at the Hopital Edouard Herriot in Lyon, France.

Unlike most studies investigating MRC, Dr. Marion Courbiere and colleagues compared the technique with both methods of direct cholangiography: endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC).

"MRC may replace both ERCP and PTC in the initial diagnosis of biliary strictures," said coauthor Dr. Pierre-Jean Valette, chief of gastrointestinal radiology at Herriot. "It allows physicians to set a therapeutic strategy without the risk of complication from contrast injections."

Direct cholangiography is technically unsuccessful in 4% of patients and is associated with up to 7% morbidity and 1% mortality. Researchers suggest that ERCP and PTC be used only for therapeutic purposes, while MRC carry the initial diagnostic weight.

Investigators prospectively studied 49 patients who presented with bile duct stenosis. They performed PTC on 24 patients and ECRP on 25 patients. MRC was performed within seven days before direct cholangiography and stenosis location, extension, and type were recorded according to the Bismuth classification. All patients underwent RARE and HASTE MR sequences.

Compared with direct cholangiography, MRC correctly highlighted the level of biliary ductal obstruction in 96% of the patients. Common bile duct stenosis was identified in eight of nine patients on MRC versus direct cholangiography. MRC also identified 31 of 32 hepatic confluence stenoses and six of six intrahepatic stenoses.

Sensitivity and specificity values for MR cholangiography for common bile duct stenosis were 88% and 100%, respectively. For biliary confluence stenosis, the values were 96% and 93%.

Researchers identified intrahepatic bile duct dilation using direct cholangiography in 35 patients, while MR cholangiography identified 97% of the cases. The study was published in the May/June issue of the Journal of Computer Assisted Tomography.

According to Valette, MR cholangiography allows physicians to classify patients into two groups:

? Certainly not resectable: Conservative management with percutaneous or endoscopic stent placement may be undertaken without the need for extensive opacification or further explorations.
? Probably resectable: Preoperative management may be adapted to each case, including percutaneous drainage if needed to decrease a major cholestasis before extended hepatic resection.

Although MR cholangiography's image resolution is not as good as x-ray, it is still able to completely visualize all intrahepatic bile ducts, which may not always be obtained by direct cholangiography, Valette said.

The authors noted that the combination of conventional MR, MRC, and MR angiography provides an attractive option: a complete diagnostic evaluation of biliary diseases and staging tumors without the need for invasive imaging procedures.

For more information from the Diagnostic Imaging online archives:

Better resolution, faster scans emerge in biliary imaging
http://www.dimag.com/db_area/archives/2002/0204.multislice.di.shtml

MRCP challenges ERCP in pancreatobiliary ducts
http://www.dimag.com/db_area/archives/asia/2001/0106.mr.diap.shtml