Novel technique used to detect swallowing in volume‐selective turbo spin‐echo (TSE) for carotid artery wall imaging

Abstract

Purpose: To improve three-dimensional (3D) volume-selective turbo spin-echo (TSE) carotid wall imaging by the addition of a novel body surface swallowing detection device. Material and Methods:A 3D volume-selective TSE sequence was used to image the carotid artery. A novel carbon-fiber motion device, positioned over the laryngeal prominence, was used to detect swallowing movement. An electrical output generated by coil movement was used to detect motion, and an algorithm was programmed to reject data acquired during swallowing and for a short period afterwards. Images were acquired with and without the algorithm and scored on a scale of 0 -5 by four independent blinded observers according to the clarity of the vessel wall, e.g., 0 ϭ poor image quality and 5 ϭ excellent quality images with little or no artifact. Results:The scans with the rejection algorithm on were scored higher than the scans without the algorithm. The comparison of scores with the algorithm on vs. the algorithm off were as follows: mean Ϯ standard deviation (SD) ϭ 3.76 Ϯ 0.25, 95% confidence interval (CI) ϭ 3.27-4.25 vs. 2.64 Ϯ 0.25, 95% CI ϭ 2.15-3.13; with good interobserver correlation (Kendall's W score 0.77). Conclusion:Image quality can be improved by the algorithm during acquisition. This can be achieved by a novel, anatomically positioned superficial device. This may help in prolonged 3D scans where a single movement can corrupt the entire acquisition.

Prospective self‐gating for swallowing motion: A feasibility study in carotid artery wall MRI using three‐dimensional variable‐flip‐angle turbo spin‐echo

“…However, it should be pointed out that the image quality obtained from the SPACE SWL + SG scan is slightly inferior to that obtained from the “SPACE STIL” scan and the difference was statistically significant. This could potentially be attributed to heart‐rate variability‐induced artifacts that commonly follows swallowing (14); variable T 1 recovery between echo trains would introduce signal modulation and thus image blurring. Discarding data collected several TRs right before and after the detection of swallowing may help reduce image degradation.…”

“…Navigator echoes acquired from the epiglottis can be used to eliminate data acquired during swallowing, but it requires precise placement of navigator bars and may fail when the epiglottis shifts (13). Recently, Chan et al applied a MR‐safe coil made from carbon fiber to detect swallowing‐related motion at the laryngeal prominence (14). However, additional setup time of up to 15 min for the hardware including coil positioning and preamplifier parameters tune‐up can markedly prolong scanning.…”

Imaging biomarkers of cardiovascular disease

“…Other than navigator based techniques, external coils that can accurately detect neck motion have also been proposed for improved carotid artery image quality. In an in vivo study on five healthy volunteers, the adoption of the external coil was found to significantly improve the image quality and minimize swallowing artifacts (46) (Fig. 3).…”

Advanced Techniques for MRI of Atherosclerotic Plaque

“…The related motion sensitized driven equilibrium (MSDE) technique for blood suppression [45] has also been investigated for use in a 3D protocol because it does not depend on inflow for blood suppression [46]. Mitigation of swallowing artifacts was also proposed by Chan et al [47] using an electrical signal induced by motion of a coil placed on the neck to reject data acquired during swallowing. If the challenges of 3D imaging of artery walls can be overcome, 3D imaging also offers potential time efficiencies for certain imaging geometries.…”