Can Multi-Channel FID Navigators Quantify Head Motion?

This work investigates the ability of free induction decay (FID) navigators to provide information on rigid head motion. FID navigators were incorporated in a gradient-echo sequence. In parallel, optical tracking data was acquired and served as the ground truth. Three subjects were scanned at 3T with a 32-channel head coil while performing complex head movements. A linear model was trained with a subset of the FID and optical tracking data and verified with the remainder by cross-validation. Following the linear assumption, it can be shown that FID signal changes can quantify all six motion parameters with sub-millimeter and sub-degree precision.