516 AJR:186, February 2006 AJR 2006; 186:516–521 0361–803X/06/1862–516 © American Roentgen Ray Society M E D I C A L I M A G I N G A C E N T U R Y O F Merkle et al. 3.0 Versus 1.5 T for MR Cholangiogr aphy Hepatobiliary Imaging • Original Research 3.0- Versus 1.5-T MR Cholangiography: A Pilot Study E. M. Merkle 1 P. A. Haugan J. Thomas T. A. Jaffe C. Gullotto Merkle EM, Haugan PA, Thomas J, Jaffe TA, Gullotto C Keywords: biliary system, cholangiography, MRI, MR technique DOI:10.2214/AJR.04.1484 Received September 20, 2004; accepted after revision January 31, 2005. 1 All authors: Department of Radiology, Duke University Medical Center, Duke North, Rm. 1417, Erwin Rd., Durham, NC 27710. Address correspondence to E. M. Merkle (elmar.merkle@duke.edu). OBJECTIVE. The purpose of our study was to evaluate quantitative and qualitative image quality of MR cholangiography at a field strength of 3.0 T compared with the standard field strength of 1.5 T. MATERIALS AND METHODS. A standardized MR cholangiography sequence proto- col was used for 15 healthy male volunteers (mean age ± SD, 32.4 ± 4.3 years) who underwent both 1.5- and 3.0-T MRI within 2 hr in an alternating fashion. Dedicated circular polarized torso coils (1.5 and 3.0 T) were used. The sequence protocol included breath-hold single-slice rapid acquisition with relaxation enhancement (slice thickness, 50 mm; orientation, coronal and ± 20° oblique coronal); breath-hold multislice HASTE (slice thickness, 3 mm; coronal only); and a non-breath-hold, respiratory-triggered 3D turbo spin-echo (TSE) T2-weighted se- quence (slice thickness, 1 mm; 60 slices per slab; coronal only). Maximum intensity projections were generated from each multislice data set. Bile duct (common bile duct, right posterior seg- mental branch, and left hepatic duct) to periductal tissue contrast-to-noise ratios were com- pared at 1.5 and 3.0 T. Qualitative image analysis was performed by three independent review- ers. Qualitative analysis included delineation of the extra- and intrahepatic biliary anatomy, with specific attention given to the presence (or absence) of cystic or intrahepatic ductal vari- ants, using a 4-point confidence scale. Statistical analysis consisted of the paired Student’s t test and the signed rank test. RESULTS. Contrast-to-noise ratios between the bile duct and the periductal tissue were higher at 3.0 T in all three locations (common bile duct, right posterior segmental branch, and left hepatic duct). In each magnet class, the 3D TSE sequence offered the best contrast-to-noise ratio and qualitative analysis. Superiority of the 3D TSE sequence was statistically significant in all analyses. Five of the 15 volunteers had intrahepatic biliary variants that were detected with a higher level of confidence (p < 0.01) on the 3.0-T system than on the 1.5-T system. CONCLUSION. Compared with MR cholangiography at 1.5 T, MR cholangiography at 3.0 T offers improved contrast-to-noise ratio and a higher level of confidence for depicting in- trahepatic variants. ince its original description in 1991 by Wallner et al. [1], MR cholang- iography has gained general accep- tance, along with transabdominal sonography, as the noninvasive imaging method of choice for diseases of the biliary system. It has replaced endoscopic retrograde cholangiog- raphy, particularly in those cases in which an en- doscopic intervention seems unlikely at the out- set [2]. Although transabdominal sonography seems to be superior for imaging of the gallblad- der, MR cholangiography is favored for evalua- tion of extrahepatic biliary ductal disease [3]. Unfortunately, both imaging techniques are of limited use for evaluating the intrahepatic bil- iary anatomy, particularly if the biliary system is not dilated. The underlying reasons are mainly limitations in spatial resolution and the signal- to-noise ratio. However, a detailed anatomic de- piction of the nondistended intrahepatic biliary ductal system is occasionally needed, for exam- ple, for the preoperative evaluation of potential living liver donors. The introduction of whole-body 3.0-T MR systems in combination with dedicated circular polarized receive-only torso coils is an appeal- ing concept with the potential to overcome these limitations. We attempted to determine the potential of MR cholangiography, including visualization of the intrahepatic biliary ductal system, at a field strength of 3.0 T compared with the standard field strength of 1.5 T. S Downloaded from www.ajronline.org by 52.73.204.196 on 05/17/22 from IP address 52.73.204.196. Copyright ARRS. For personal use only; all rights reserved