Improvement of MR cholangiopancreatography at .5 T: Three‐dimensional half‐averaged single‐shot fast spin echo with multi‐breath‐hold technique

The purpose of this study was to determine the advantage of a three‐dimensional (3D) single‐shot fast‐spin‐echo (SSFSE) sequence to obtain MR cholangiopancreatography (MRCP) with a .5‐T MR unit by comparison with a two‐dimensional (2D) SSFSE sequence. MRCP with 2D‐SSFSE and with 3D‐SSFSE with 128 echo train lengths was performed on 15 volunteers and 38 patients with pancreatobiliary disease using a .5‐T MR unit. For maximum intensity projection (MIP) reconstruction, the section thickness of source images was 4 mm in the 2D‐SSFSE and 3 mm in the 3D‐SSFSE. 3D volume data in 3D‐SSFSE were obtained using repeated short breath‐hold of 2 seconds for every repetition time throughout the examination. The image quality, duct conspicuity, signal‐intensity ratio (SIR), and contrast‐to‐noise ratio (CNR) were evaluated. In 23 of the patients who underwent both MRCP and direct cholangiopancreatography (endoscopic retrograde cholangiopancreatography [ERCP]/percutaneous transhepatic cholangiography [PTC]), a comparison between these two modalities was also conducted. The image quality of the MIP image with 3D‐SSFSE (49 of 53, 92.5% graded excellent or good) was superior to that with 2D‐SSFSE (31 of 53, 58.4%). Duct conspicuity, SIR, and CNR were significantly higher with 3D‐SSFSE than with 2D‐SSFSE. 3D‐SSFSE also showed a stronger relationship with the ERCP/PTC findings compared to 2D‐SSFSE. 3D‐SSFSE provided satisfactory quality, SIR, and CNR of MRCP images, even when a .5‐T MR unit was used, because the breath‐hold technique used during 3D data sampling minimized all types of motion effects.