Changes of Water and Muscle Content in Paraspinal Muscle Degeneration and Gender Differences During Aging Using Dual-Energy CT

Objectives To quantitatively assess paraspinal muscle degeneration and gender-related differences during aging in adults using rapid kVp switching dual-energy computed tomography (DECT). Methods A total of 156 healthy adults underwent lumbar DECT scans and were prospectively grouped into young (20–39 years), middle-aged (40–59 years), and elderly (60–79 years) groups. Muscle density (MD), cross-sectional area (CSA), muscle content (MC), and water content (WC) were measured using muscle-water decomposition images for the bilateral erector spinae (ES) at the L1/2 to L4/5 levels and bilateral multifidus (MF) and psoas (PS) at the L2/3 to L5/S1 levels. Results Across age groups, significant differences in paraspinal muscle MD and WC were observed ( P  < 0.01), with MD negatively and WC positively correlated with age at lower lumbar levels for both MF and ES ( P  < 0.001). In females, except for the L5/S1 PS, WC differences between the middle-aged and elderly groups were significant (P < 0.05), but not between the young and middle-aged groups ( P  > 0.05). In males, multifidus MC at L4/5 decreased with age ( P  < 0.05), while in females, multifidus MC at L3/4 and L5/S1 was higher in the middle-aged group and lowest in the elderly group ( P  < 0.05). PS CSA at L4/5-L5/S1 showed a moderate negative correlation with age ( P  < 0.001). Conclusions The muscle-water decomposition technique using rapid kVp switching DECT provides a noninvasive quantitative assessment of paraspinal muscle degeneration by evaluating changes in muscle and water content, potentially reflecting alterations in the extracellular matrix. This method highlights age- and gender-related differences, aiding in the differentiation between physiological aging and pathological degeneration.