Reducing pulsation artifacts in 3D time-of-flight angiography at 7T using locally-scrambled ordering of the acquisition

Motivation: Non-contrast-enhanced time-of-flight (TOF) at 7T greatly improves the delineation of small vessels but is impaired by pulsation artifacts. Goal(s): Our goal was to reduce pulsation artifacts in 3D TOF to better delineate vessels. Approach: We recently developed “local-scrambling” which generates semi-random acquisition ordering to reduce artifacts from semi-periodic local signal fluctuations. This local-scrambling was tested in 3D TOF to reduce pulsatile blood flow artifacts in human scanning at 7T. Results: Artifacts from pulsatile blood flow were significantly reduced using the new local-scrambling (of the 2D phase encodes), both for line-by-line and center-out acquisitions. The method can be of special interest for high-resolution angiography. Impact: Increased resolution of non-contrast-enhanced time-of-flight (TOF) can provide more accurate vessels delineation. A new local-scrambling acquisition scheme can significantly improve 3D angiography by reducing interference noise and pulsation artifacts without requiring any changes to the reconstruction scheme.