K-SPACE FILTER EFFECT IN 3-DIMENSIONAL CONTRAST MR-ANGIOGRAPHY

Purpose. In three-dimensional (3-D) contrast MR angiography, temporal misregistration between the data acquisition period and the arrival of the contrast agent in the target vessels is thought to degrade the qu ality of the reconstructed images. The purpose of this study was to de monstrate and investigate this effect in phantom experiments. Material and Methods: MR images of a phantom tube were evaluated with flowing materials of water or Gd-DTPA solution by changing from water to Gd-DT PA solution halfway through the data acquisition period. Results: Whil e no signal could be acquired with a stream of water in the tube, a cl ear signal was obtained with a flow of Gd-DTPA solution. Blurring and ghost artifacts surrounding the tube along the phase-encoding directio n were observed when the flowing material was changed from water to Gd -DTPA solution halfway through the data acquisition period. Conclusion : K-space filter effect occurs during 3-D contrast MR angiography owin g to the transient passage of the contrast agent, and this effect caus es spatial artifacts in the reconstructed images.