SimulScan and Partial Least Squares: Visualizing swallowing through functional and dynamic imaging correlations.

Purpose: Swallowing is a complex function involving the precise coordination of muscles, nerves, and brain areas, and can be disrupted in a variety of neurological conditions. Current imaging studies to visualize the central control of swallowing cannot examine both the biomechanics of the swallow and the brain activity associated with swallow events. An updated version of SimulScan is introduced that provides high-quality and high-speed dynamic imaging, together with fMRI acquisitions, to enable data-driven analysis of swallowing function through a partial least squares correlation (PLSC) analysis. Methods: Integrating updated dynamic imaging approaches, SimulScan can achieve dynamic MRI at 23.75 frames per second and BOLD fMRI at a 1.6 s TR. Five subjects were recruited and scanned with SimulScan twice and with videofluoroscopy to compare the preliminary reliability of measuring swallowing biomechanics and the test-retest relationship in correlated functional and dynamic components of PLSC. Results: High reliability of biomechanical measures of swallowing were achieved across the two SimulScan runs. In addition, these showed moderate correlation with videofluorscopy measures. Correlations between dynamic and functional imaging across runs also showed high reliability indicating that SimulScan with PLSC can extract maps of linked correlations between the brain and the oropharyngeal region. Conclusion: The updated version of SimulScan with PLSC analysis enables the study of central control of swallowing, providing simultaneous biomechanical visualization of the swallow along with brain functional signals.