Three-dimensional contrast-enhanced hepatic MR imaging: comparison between a centric technique and a linear approach with partial Fourier along both slice and phase directions.

摘要

PURPOSE: To compare the image quality of two variants of a three-dimensional (3D) gradient echo sequence (GRE) for hepatic MRI. MATERIALS AND METHODS: Thirty-nine patients underwent hepatic MRI on a 3.0 Tesla (T) magnet (Intera Achieva; Philips Medical Systems). The clinical protocol included two variants of a 3D GRE with fat suppression: (i) a "centric" approach, with elliptical centric k-space ordering and (ii) an "enhanced" approach using linear sampling and partial Fourier in both the slice and phase encoding direction. "Centric" and "Enhanced" 3D GRE images were obtained both precontrast (n = 32) and after gadoxetic acid injection (n = 39). Two reviewers jointly reviewed MR images for anatomic sharpness, overall contrast, homogeneity, and absence of artifacts. The liver-to-lesion signal difference ratio (SDR) was measured. Paired sample Wilcoxon test and paired t-tests were used. RESULTS: Enhanced 3D GRE images performed better than centric 3D GRE images with respect to anatomic sharpness (P = 0.0156), overall contrast (P = 0.0195), homogeneity (P < 0.0001), and absence of artifacts (P = 0.0003) on precontrast images. For postcontrast MRI, enhanced 3D GRE images showed better quality in terms of overall contrast (P = 0.0195), homogeneity (P < 0.0001), and absence of artifacts (P = 0.009). Liver-to-lesion SDR on enhanced 3D GRE images (0.48 +/- 0.13) was significantly higher than that of conventional 3D GRE images (0.40 +/- 0.19, P = 0.0004) on postcontrast images, but not on precontrast images. CONCLUSION: The enhanced 3D GRE sequence available on our scanner provided better hepatic image quality than the centric variant, without compromising lesion contrast.