Age-dependency of glycosaminoglycan content in lumbar discs: A 3t gagcEST study

Abstract

Purpose To analyze age-dependency of glycosaminoglycan content using gagCEST (glycosaminoglycan chemical exchange saturation transfer) imaging in lumbar intervertebral discs of healthy volunteers. Materials and Methods In all, 70 volunteers without low back pain (mean age 44 ± 14 years, range: 21-69 years) were examined with T2-weighted and gagCEST imaging with a 3T MR scanner, with approval of the local Ethics Committee after written informed consent was obtained. Pfirrmann grading and classification into discs without bulging and herniation, discs with bulging, and discs with herniation were performed. Only intervertebral discs without bulging and herniation were analyzed. A region-of-interest-based gagCEST analysis of nucleus pulposus (NP) and annulus fibrosus (AF) was performed. Correlation between age and gagCEST was tested within groups of equal Pfirrmann score. Results GagCEST effects decreased significantly from 3.09 ± 1.12% in 20-29 years old volunteers to -0.24 ± 1.36% in 50-59 years old volunteers (P < 0.001). In the case of Pfirrmann scores 2 and 3, a significant correlation was observed between gagCEST effect and age (Pfirrmann score 2, NP: ρ = -0.558, P < 0.001; Pfirrmann score 3, NP: ρ = -0.337, P = 0.048). For Pfirrmann scores 1 and 4, no significant correlation was obtained (Pfirrmann score 1, NP: ρ = -0.046, P = 0.824; Pfirrmann score 4, NP: ρ = -0.316, P = 0.188). Conclusion We show a decreased gagCEST effect likely corresponding to decreasing glycosaminoglycans with aging. Hence, age-matched analysis of gagCEST imaging may be necessary in future studies.