Assessing the effects of subject motion on T relaxation under spin tagging (TRUST) cerebral oxygenation measurements using volume navigators.

PURPOSE

Subject motion may cause errors in estimates of blood T when using the T -relaxation under spin tagging (TRUST) technique on noncompliant subjects like neonates. By incorporating 3D volume navigators (vNavs) into the TRUST pulse sequence, independent measurements of motion during scanning permit evaluation of these errors.

METHODS

The effects of integrated vNavs on TRUST-based T estimates were evaluated using simulations and in vivo subject data. Two subjects were scanned with the TRUST+vNav sequence during prescribed movements. Mean motion scores were derived from vNavs and TRUST images, along with a metric of exponential fit quality. Regression analysis was performed between T estimates and mean motion scores. Also, motion scores were determined from independent neonatal scans.

RESULTS

vNavs negligibly affected venous blood T estimates and better detected subject motion than fit quality metrics. Regression analysis showed that T is biased upward by 4.1 ms per 1 mm of mean motion score. During neonatal scans, mean motion scores of 0.6 to 2.0 mm were detected.

CONCLUSION

Motion during TRUST causes an overestimate of T , which suggests a cautious approach when comparing TRUST-based cerebral oxygenation measurements of noncompliant subjects. Magn Reson Med 78:2283-2289, 2017. © 2017 International Society for Magnetic Resonance in Medicine.