How reliable is MRCP with an SS-FSE sequence at 3.0 T: comparison between SS-FSE BH and 3D-FSE BH ASSET sequences

Abstract

Purpose: The purpose of the present study was to evaluate the visibility and the image quality of the biliary and pancreatic duct system on magnetic resonance cholangiopancreatography (MRCP) images based on two breath-hold (BH) methods using array spatial sensitivity technique: a single-shot fast spin-echo (SS-FSE) sequence and a three-dimensional single slab fast spin-echo (3D-FSE) sequence.

Materials and methods: In the present prospective comparative study, 47 patients (22 male and 25 female, mean age=50 years, age range=22-82 years) that were referred for MRCP during a 12-month period are included. All of them were referred with suspected pancreaticobiliary disease. All patients underwent MRCP with both a SS-FSE BH sequence and a 3D-FSE BH sequence. Qualitative evaluation regarding the depiction of three segments of the pancreaticobiliary tree and the frequency of artifacts was performed. Two radiologists graded each sequence of the obtained studies in a blinded fashion. Quantitative evaluation including calculation of relative signal intensity (rSI) and relative contrast (RC) ratios at seven segments of the pancreaticobiliary tree between fluid-filled ductal structures and organ parenchyma at the same ductal segments was performed. In order to evaluate the parameters' differences of the two sequences, either in qualitative or in quantitative analysis, the Wilcoxon paired signed-rank test was performed.

Results: On quantitative evaluation, both rSI and RC ratios of all segments of the pancreaticobiliary tree at SS-FSE BH sequence were higher than those at 3D-FSE BH sequences. This finding was statistically significant (P<.01). On qualitative evaluation, the two radiologists found intrahepatic ducts and pancreatic ducts to be better visualized with SS-FSE BH than with 3D-FSE BH sequence. This finding was statistically significant (P<.02). One of them found extrahepatic ducts to be significantly better visualized with SS-FSE BH sequence. Moreover, the frequency of artifacts was lower in the SS-FSE sequence, a finding that was of statistical significance. Interobserver agreement analysis found at least substantial agreement (κ>0.60) between the two radiologists.

Conclusion: The SS-FSE sequence is performed faster and significantly improves image quality; thus, it should be included into the routine MRCP sequence protocol at 3.0 T. Furthermore, we recommended SS-FSE BH MRCP examination to be applied to uncooperative patients or patients in emergency because of its short acquisition time (1 s).