Demonstration of the ability of MRI to capture the motion of swallowing. 2D FLASH images acquired with parallel imaging (a) and without parallel imaging (b). Increases in oropharynx and superior larynx signal intensity are caused by anatomy containing fully relaxed spins that move into the imaging plane during deglutition.
MR images depicting resting [(a) and (d)] and swallowing [(b) and (e)] states for two patients included in the study. The time series data on the left [(a)–(c)] were acquired with parallel imaging. The time series data on the right [(d)–(f)] were acquired without parallel imaging. The peaks in the corresponding voxel time series [(c) and (f)] mark the occurrence of a swallowing event.
Illustration of GTV displacement (red contours) and corresponding percent change in GTV area during one resting and one swallowing event for a representative patient. In comparison to resting-induced GTV displacement (a) and percent change in GTV area (b), deglutition-induced GTV displacement (c) and percent change in GTV area (d) exhibit greater magnitude and variability. However, the nonzero changes in GTV displacement (a) and percent change in GTV area (b) demonstrated during rest indicates there is always some degree of baseline motion. The thin, solid, horizontal line in (b) and (d) denotes the mean percent change in GTV area during resting and swallowing events, respectively.
Deglutition frequency and mean duration calculated from long time series acquisition.
Maximal deglutition-induced GTV displacement results.
Maximal resting-induced GTV displacement results.
Resting- and deglutition-induced percent change in GTV area results.
Systematic and random components of variation due to swallowing and resting.
Asymmetric internal margins calculated from data in Tables II and VI and Eq. (5).
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