Slice-selective fat saturation in MR angiography using spatial-spectral selective prepulses

Presaturation of fat signals by frequency-selective radiofrequency (RF) pul ses is often applied in MR angiography to improve the visualization of the blood vessels. Unfortunately, standard fat saturation methods might cause a considerable reduction of the blood signal in the measured slices. This ef fect is caused by an attenuation of blood magnetization in remote tissue re gions with water protons showing a similar Larmor frequency as the fat prot ons in the recorded slice. The affected blood water protons subsequently no w into the recorded slice and provide low signal intensity. Suitable spatia l-spectral selective methods for slice-selective fat saturation were develo ped to avoid this unwanted effect. A spatial-spectral fat saturation techni que was compared with a corresponding only spectrally selective approach, B oth saturation techniques were included in a standard two-dimensional (2D) cine sequence and applied in angiographic examinations of the thighs. The r esults indicate that spatial-spectral saturation (acting slice selectively) leads to a clearly higher blood signal intensity in fat-suppressed MR angi ography compared with standard techniques, especially in measurements perfo rmed during the systolic phase of the cardiac cycle.