MAGNETIC RESONANCE CHOLANGIOGRAPHY

Abstract

MR cholangiography offers a noninvasive method of obtaining images of the biliary system without the use of a contrast agent. There is no radiation exposure. Pulse sequences can be chosen to obtain bright bile or black bile cholangiograms. Image processing algorithms can be selected to obtain a three-dimensional representation of biliary anatomy and pathology, and those images can be rotated in any plane so that ductal anatomy and pathology can be seen to best advantage. In patients with a nonobstructed biliary system, the RHD, LHD, CHD, CBD, and distal PD are usually visible. In patients with choledocholithiasis, the CE-FAST technique has demonstrated higher diagnostic accuracy than the FSE approach, although TRAP image reconstruction probably would improve the accuracy of the FSE technique in detecting stones. In patients with malignant biliary obstruction, FSE is considerably more accurate in determining the cause of obstruction than is CE-FAST. Furthermore, MR cholangiography compares favorably with ERCP, prompting one author to suggest that, in selected patients, MR cholangiography might be used instead of direct cholangiography or to direct invasive techniques. With continued technologic advancements, MR cholangiography will no doubt improve as well. In particular, the possibility of a breath-hold, multicoil, FSE cholangiogram, obtained with the stronger gradients on an echo planar system, potentially combines the key advantages of CE-FAST and conventional FSE techniques. It may be that in the not-too-distant future, all patients with obstructive jaundice will be imaged first with MR imaging. In addition to the typical axial images of the abdomen required for staging, an MR cholangiogram will be obtained in a matter of a few seconds. An MR angiogram will also be performed to determine vascular anatomy and pathology. MR spectroscopy might also be used to obtain additional diagnostic information. All of this would be done in less than an hour, noninvasively, and with no radiation. Some patients would then require percutaneous transhepatic cholangiography or ERCP. Others would undergo MR-guided biopsy. Eventually, still other patients might go directly to surgery.