Abstract
We propose a novel intersection profile method for a four-dimensional magnetic resonance image (4DMRI) to analyze thoracic motion from time-sequential images of two-dimensional (2D) MR images acquired under free breathing. Using the proposed method, first, time-sequential MR images in many coronal planes that are set to cover the lung area widely are acquired as data slices. Second, the timesequential MR images in a proper sagittal plane are acquired as navigator slices. Then 2D spatio-temporal images (2DSTI), constituting a time-sequential array of profiles along the intersection of slices of two kinds, are generated for both the navigator slice and the data slices. After a proper respiratory pattern (template) is extracted from 2DSTI of the navigator slice, template matching by normalized cross-correlation is conducted to identify a similar respiratory pattern from the 2DSTI of the data slices. Then 4DMRI is reconstructed by application of this process to each data slice. Additionally, to evaluate diaphragmatic motion quantitatively, we constructed a diaphragmatic function map using 4DMRI reconstructed using the proposed method. The diaphragmatic function map was able to visualize diaphragmatic function of spontaneous breathing.
