Fig. 3.

Cluster locations derived from SPM show muscle specific FI distribution patterns in relation to presence and severity of degenerative IVD pathology SPM t-tests were conducted to compare FI distributions between subgroups of patients and controls stratified by: the presence of CEP damage, high (> 3) or low ( ≤ 3) Pfirrmann grade, and the presence of MC. For each analysis, the locations of the regions of significance (clusters) were identified using SPM t-tests and are listed numerically and shown graphically to depict muscle-specific trends. Each cluster location represents the region within the muscle where there is a significant difference in fat infiltration found between groups. In the multifidus fat-maps (top), significance clusters are most present in the deep to intermediate regions of the muscle, while, in the erector spinae and psoas fat-maps, significance clusters are most present in the intermediate to superficial regions of the muscle. Spatial patterns of FI in the PSMs are thus associated with the presence and severity of degenerative IVD pathology. Associated differences in FI are localized in unique regions of each paraspinal muscle