T1-weighted Fat-suppressed Imaging of the Pelvis with a Dual-Echo Dixon Technique: Initial Clinical Experience

Abstract

To compare the image quality of water-only images generated from a dual-echo Dixon technique with that of standard fast spin-echo T1-weighted chemical shift fat-suppressed images obtained in patients evaluated for pelvic pain with a 1.5-T magnetic resonance (MR) system. The ethics board granted approval for this retrospective study; patient consent was not required. Twenty-five women underwent both standard axial T1-weighted fast spin-echo chemical shift fat-suppressed imaging and dual-echo Dixon imaging of the pelvis. Two readers independently scored the acquisitions for image quality, fat suppression quality, and artifact. On the basis of signal intensity measurements, the uniformity of fat suppression, the contrast between fat-suppressed and non-fat-suppressed tissue, and the contrast between pathologic lesions and suppressed fat were calculated. Values obtained with the T1-weighted fat-suppressed and dual-echo Dixon techniques were compared by using the Wilcoxon signed rank test. The images generated with the dual-echo Dixon technique were of higher quality, had better fat suppression, and had less artifact (qualitative scores: 4.4, 4.6, and 4.0, respectively) compared with the standard T1-weighted fat-suppressed images (qualitative scores: 3.4, 3.3, and 3.6, respectively; P < .01). Contrast between fat-suppressed and non-fat-suppressed tissue (contrast ratio: 0.86 for dual-echo Dixon technique vs 0.42 for T1-weighted fat-suppressed technique, P < .001) and between pathologic lesions and suppressed fat (contrast ratio: 0.88 for dual-echo Dixon technique vs 0.57 for T1-weighted fat-suppressed technique, P =.012) was significantly improved with the dual-echo Dixon technique. Twelve pathologic lesions were identified with dual-echo Dixon imaging versus eight that were identified with T1-weighted fat-suppressed imaging. Compared with standard T1-weighted fat-suppressed imaging, dual-echo Dixon imaging facilitates improved image quality of fat-suppressed images of the pelvis, enabling better delineation of pathologic lesions.