2D Thick-Slab MR Cholangiopancreatography: Does Parallel Imaging with Sensitivity Encoding Improve Image Quality and Duct Visualization?

Abstract

Our objective was to determine whether the theoretic advantages of parallel imaging are realized when applied to 2D thick-slab single-shot fast spin-echo (SSFSE) MR cholangiopancreatography (MRCP) with respect to image quality and duct conspicuity. Thirty-nine patients (18 men and 21 women; mean age, 51.8 years) were referred for MRCP. Multiangled thick-slab breath-hold SSFSE imaging was performed without and with integrated parallel imaging with sensitivity encoding (SENSE). Images were retrospectively reviewed. A 4-point rating scale was used to grade overall image quality and visibility of 10 ductal segments. A Wilcoxon's signed rank test compared the two techniques. Analysis of signal intensities and relative contrast of fluid-filled structures to background tissue on the basis of region of interest was calculated. Differences between the techniques were compared using a Student's t test. Two-dimensional thick-slab SSFSE with integrated parallel imaging showed a mild but statistically significant increase in the relative contrast (p = 0.01) of ductal segments. Image quality deteriorated slightly with parallel imaging, but the results were not statistically significant (p = 0.06). Parallel imaging improved duct conspicuity of the medial and lateral segments of the left lobe and the posterior segment of the right lobe. However, statistical improvement was achieved only for the medial segment of the left lobe (p = 0.03). The mean scores of the remaining ducts were either unchanged or worse with parallel imaging, but the differences were not significant. Although there was improvement in the relative contrast of bile to background tissue, improvement in overall image quality was not observed with parallel imaging. However, application of parallel imaging to thick-slab SSFSE may improve depiction of the smallest-caliber ducts.