Fat-subtracted three-dimensional time-of-flight MR angiography of the neck by use of fat-only images with the two-point Dixon technique.

Abstract

For improvement of three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) image quality in the neck, fat-subtracted MRA by use of the two-point Dixon technique was compared with conventional fat-suppressed MRA techniques. Three different types of neck 3D-TOF-MRA were obtained [minimum echo time (TE) (1.9ms), opposed-phase TE (3.4ms), and chemical shift selective fat suppression (CHESS) (TE=1.9ms)] on five volunteers at 3.0 T. MRA was obtained with subtraction of fat-only images (produced by a two-point Dixon sequence) from minimum-TE MRA images, and compared with other fat-suppressed MRA images. Fat-subtracted MRA demonstrated uniform fat suppression compared with other techniques. The mean vessel-to-fat contrast in fat-subtracted MRA was significantly higher (p<0.01) than in other MRA images (minimum-TE: 0.137±0.086, opposed-phase TE: 0.268±0.102, CHESS: 0.307±0.052, fat-subtracted: 0.965±0.101). The mean vessel-to-muscle contrast in opposed-phase TE MRA was significantly lower (p<0.01) than in other MRA images (minimum-TE: 0.526±0.036, opposed-phase TE: 0.419±0.188, CHESS: 0.511±0.023, fat-subtracted: 0.573±0.016). Fat-subtracted MRA by use of the two-point Dixon technique improves the image quality of neck MRA. This technique would be a useful method for MRA, especially in areas with inhomogeneous magnetic fields, such as the neck.