Pseudo‐gating: Elimination of periodic motion artifacts in magnetic resonance imaging without gating

Abstract

This note explains and illustrates a technique of reducing artifacts produced by periodic motion without using physiologic gating. The method is simple and can be applied on any standard MRI unit. For periodic motion, effective gating can be attained by setting the product of the number of acquisitions (at each phase-encoding step), N, times the repeat time, TR, equal to the period of the motion, T. This pseudo-gating can be used with any TR but, if changes in the period occur, is most robust with short TR values. The method is also applicable to multislice and volume imaging. For fast field echo methods, the above rule can be used if the period of the motion is smaller than the total scan time. Otherwise, the scan need only be repeated N times to avoid artifacts and improve signal-to-noise. The method has been implemented to remove both respiratory and/or cardiac motion artifacts.

Optimization of realtime adaptive navigator correction for 3D magnetic resonance coronary angiography

“…However, low spatial resolution and image blurring from cardiac and respiratory motion are major limitations. To reduce breathing artifacts, images can either be acquired by using breath-holding breathing schemes (4) or by gating techniques (5,6). Breath-holding techniques are most frequently applied, however, slice misalignment, limited spatial resolution, and long sampling windows per heartbeat have to be accepted.…”

Dynamic imaging by model estimation

“…, (12) which can be solved using any of the existing linear system system can be solved in a least-squares sense. It is worthwhile DIME exhibited no obvious blurring or ghosting artifacts, as shown in the example snapshot in Figure 8(d).…”

“…A partial list includes to traverse the entirety of k-space instantaneously, as shown in phase-encoding ordering methods [3,4], averaging methods [5- Figure 1(a). In practice, it takes a finite time (say, Dt) from 7], gating methods [8][9][10][11][12], navigator-based bulk motion correccollecting one k-space data point to another, and (k, t)-space is tion methods [13,14], fluoroscopic imaging methods [15,16], effectively sampled as in Figure 1(b). The motion artifacts which and (k, t)-space methods [17][18][19].…”

The Effect of Respiration on the Contrast and Sharpness of Liver Lesions in MRI

“…It was assumed that T,-weighted imaging was performed, and that the signal measured as a function of the phase encoding view n was given by, (4) where p is the percentage of the voxel taken up by the lesion. This value p depended on the lesion size, the slice thickness (assumed to be 1 cm), and the location of the lesion within the slice for each view.…”