Semiautomatic quantification of abdominal wall muscles deformations based on dynamic MRI image registration
Résumé
in the diagnosis of abdominal muscle deficiency. Here, we
present a dedicated semiautomatic dynamic MRI postprocessing method enabling
the quantification of spatial and temporal deformations of the antero-lateral abdominal
wall muscles. Ten healthy participants were imaged during a controlled breathing
session at the L3–L4 disc level using real-time dynamic MRI at 3 T. A coarse featuretracking
step allowed the selection of the inhalation cycle of maximum abdominal
excursion. Over this image series, the described method combines (1) a supervised
2D+t segmentation procedure of the abdominal wall muscles, (2) the quantification
of muscle deformations based on masks registration, and (3) the mapping of deformations
within muscle subzones leveraging a dedicated automatic parcellation. The
supervised 2D+t segmentation (1) provided an accurate segmentation of the abdominal
wall muscles throughout maximum inhalation with a 0.95 ± 0.03 Dice similarity
coefficient (DSC) value and a 2.3 ± 0.7 mm Hausdorff distance value while requiring
only manual segmentation of 20% of the data. The robustness of the deformation
quantification (2) was indicated by high indices of correspondence between the registered
source mask and the target mask (0.98 ± 0.01 DSC value and 2.1 ± 1.5 mm
Hausdorff distance value). Parcellation (3) enabled the distinction of muscle substructures
that are anatomically relevant but could not be distinguished based on image
contrast. The present genuine postprocessing method provides a quantitative analytical
frame that could be used in further studies for a better understanding of abdominal
wall deformations in physiological and pathological situations.
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