Ek Tsoon Tan1, John III Huston1, Stephen J. Riederer1
1Radiology, Mayo Clinic, Rochester, MN, USA
A non-contrast-enhanced MRA technique for imaging the intracranial arteries is described. The complex difference between selective and non-selective cycles of inversion-prepared gradient echo subtracts out static tissue, leaving only the vascular signal from proximal blood flow during the inversion interval. Each cycle also produces T1-weighted tissue contrast, which may be fused with the angiogram-only image for anatomical reference. A two-slab FIR-MRA acquisition is compared against a three-slab standard 3D time-of-flight sequence. FIR-MRA has significantly improved vessel conspicuity, background and artifact suppression but has a longer scan time (11 min vs. 6.5 min).