[Attempt to Improve MIP Image of Cerebrovascular MRA by Subtraction Method: Efficient Acquisition of Mask Images...

The aim of this study was to investigate imaging conditions that allow for the rapid acquisition of mask images used in the subtraction method, one of the depiction improvement methods for brain magnetic resonance angiography, by employing compressed sensing (CS) combined with segmented time-of-flight (TOF).

The experiment was performed on healthy volunteers using 3.0T-MRI. We examined the blood flow signal suppression effects in arteries and veins at different numbers of segments. We determined the flip angle at which the signal value of fat in the mask image became equivalent to that in the angio image. We visually assessed the impact of mask images with varying CS factors on subtraction images and determined the optimal CS factor.

Effective blood flow signal suppression in arteries and veins was achieved with segment numbers of 12 or fewer, and a flip angle of 18° resulted in equivalent fat signal values. Even with a CS factor set to its maximum value of 12, no degradation in image quality was observed in the maximum intensity projection images.

Using segmented TOF with CS, optimal imaging conditions for acquiring mask images for the subtraction method were determined to be segment number 9, flip angle 18°, and CS factor 12.