3D TOF Angiography using Real Time Optical Motion Correction with a geometric encoded marker

INTRODUCTION: Correction of motion artifacts is an ongoing challenge in MRI. Sadly, motion is often worst in patients that are acutely ill and in which time cannot be afforded to repeat failed exams. This is the case, for example, in patients suffering from acute ischemic stroke or intracranial hemorrhages. In these patients 3D Time of Flight (TOF) angiograms are often performed, but their image quality is often technically borderline or even inadequate due to profound patient motion. This, in turn, makes it often difficult to assess vessel occlusion or recanalization with sufficient confidence. Another group of patients in which TOF MRAs often fail are children. To mitigate motion artifacts different retrospective and prospective approaches have been suggested, thus far. However, these approaches rely frequently on the need to acquire extra MR navigator data, which can substantially increase sequence TR or require ample time before/after the contrast preparation period/readout segment to accommodate these navigators. This is particularly challenging for short-TR SPGR sequences that are typically used for TOF MRAs. Here, a radically different approach is proposed in which external pose information is used which allows one to keep the short-TR features of the TOF intact. Specifically, first in-vivo results of a study will be presented that uses a prospective motion-correction approach which adapts scan geometry to patient pose changes in real-time and which extract these pose data from an MR-compatible optical motion correction system [1,2].