Prospective respiratory motion correction for coronary MR angiography using a 2D image navigator

Abstract

Respiratory motion remains the major impediment in a substantial amount of patients undergoing coronary magnetic resonance angiography. Motion correction in coronary magnetic resonance angiography is typically performed with a diaphragmatic 1D navigator (1Dnav) assuming a constant linear relationship between diaphragmatic and cardiac respiratory motion. In this work, a novel 2D navigator (2Dnav) is proposed, which prospectively corrects for translational motion in foot-head and left-right direction. First, 1Dnav- and 2Dnav-based motion correction are compared in 2D real time imaging experiments, by evaluating the residual respiratory motion in 10 healthy subjects as well as in a moving vessel phantom. Subsequently, 1Dnav and 2Dnav corrected high-resolution 3D coronary MR angiograms were acquired, and both objective and subjective image quality were assessed. For a gating window of 10 mm, 1Dnav and 2Dnav performed equally well; however, without any respiratory gating, the 1Dnav had a lower visual score for all coronary arteries compared with 10 mm gating, whereas the 2Dnav without gating performed similar to 1Dnav with 10 mm gating.

Free‐breathing phase contrast MRI with near 100% respiratory navigator efficiency using k‐space‐dependent respiratory gating

“…Several approaches have been proposed to improve the NAV gating efficiency by using additional information, such as two‐dimensional or 3D NAVs (), binning strategies based on NAV data (), or self‐navigating approaches () in coronary MRI, as well as in 4D flow imaging (). Although close to 100% gating efficiency may be achieved, these methods mostly rely on non‐Cartesian acquisitions and motion correction based on parametric models.…”

Cardiac MR Assessment of Coronary Arteries

“…The technique was further developed to iterative self-navigation that does not require the choice of a respiratory reference position [44]. The image-based navigator technique is another method that uses a spatially encoded, low-resolution, 2D image acquired just before the acquisition of k-space data to correct the high-resolution data [45,46]. Fig.…”

Advanced Respiratory Motion Compensation for Coronary MR Angiography

“…In image-based navigation single 2D [57,58], orthogonal 2D [59], or 3D [60] real-time images are acquired in every heart-beat prior to CMRA acquisition. The main advantage of this approach is that the moving heart can be spatially isolated from surrounding static tissues, which allows for improved respiratory motion estimation.…”

“…However, this approach is incompatible with prospective respiratory gating and correction. The feasibility of prospective image-based motion correction has recently been demonstrated [57,58], although compared to 1D navigation such as the diaphragmatic navigator or self-navigation the increased computational complexity of multi-dimensional image reconstruction, registration and correction makes real-time implementations more challenging. A solution to this problem could be to implement the navigator image post-processing on graphics processing units [62,63] as most of the steps can be parallelized.…”