Depiction of intracranial vessels with MRA: Utility of magnetization transfer saturation and gadolinium

Purpose: The purpose of this work was to quantitate the individual and comb ined effects of magnetization transfer (MT) saturation and gadolinium (Gd) on the visualization of intracranial vessels with MR angiography (MRA). Method: Thirty-five subjects underwent two three-dimensional time-of-flight MRA sequences without and with MT and/or Gd. There were 14 MR angiograms w ithout Gd or MT, 18 with MT only. 17 with Gd only, and 21 with both Gd and MT. On a projection image, a region of interest was drawn to delineate the arteries in the middle cerebral artery territory. The total area of blood v essels in the region of interest was calculated for each MR angiogram. Mean vessel areas for the four types of MRA were compared with analysis of vari ance. Results: MRA with either MT or Gd alone showed significantly more vessel ar ea than MRA without either (p < 0.05). MRA with MT alone and MRA with Gd al one were not different from each other (p = 0.29). The improvement in vesse l area measured by using MT and Gd together was significantly more than exp ected from the cumulative improvement of adding each alone (p < 0.05). Conclusion: Combining MT and Gd synergistically improved the visualization of intracranial vessels on MRA.