Improvement of MR cholangio-pancreatography 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-dimensi onal (3D) single-shot fast-spin-echo (SSFSE) sequence to obtain MR cholangi o-pancreatography (MRCP) with a,.5-T MR unit by comparison with a two-dimen sional (2D) SSFSE sequence. MRCP with 2D-SSFSE and with 3D-SSFSE with 128 e cho train lengths was performed on 15 volunteers and 38 patients with pancr eatobiliary disease using a,.5-T MR mit, 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 obtaine d using repeated short breath-hold of 2 seconds for every repetition time t hroughout the examination. The image quality, duct conspicuity, signal-inte nsity ratio (SIR), and contrast-to-noise ratio (CNR) were evaluated, Ir 23 of the patients who underwent both MRCP and direct cholangiopancreatography (endoscopic retrograde cholangiopancreatography [ERCP]/percutaneous transh epatic cholangiography [PTC]), a comparison between these two modalities wa s also conducted. The image quality of the MMP image with 3D-SSFSE (49 of 5 3, 92.5% graded excellent or good) was superior to that with 2D-SSFSE (31 o f 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 satisfac tory quality, SIR. and CNR of MRCP images, even when a,.5-T MR unit was use d, because the breath-hold technique used during 3D data sampling minimized all types of motion effects.