Chemical exchange saturation transfer and T2 mapping in subjects with intervertebral disc degeneration

Abstract

INTRODUCTION: Intervertebral disk degeneration (IVD) on magnetic resonance imaging (MRI) is an etiological factor associated with low back pain. The (IVD) has been well acknowledged to degenerate as characterized by biochemical and morphological changes. T2 relaxation time has been suggested to be sensitive to changes in collagen and water content in cartilage and in the IVD. In the disk, the investigators have quantified chemical exchange saturation transfer (CEST) and its specificity as well as its correlation capacity for glycosaminoglycan (GAG) content (gagCEST). However, the correlation between conventional qualitative MRI assessment (T2-weighted) and quantitative MRI measurement, such as T2 and CEST, remains unknown. In this study, we aimed to investigate the association between CEST, T2 and degenerative grades in IVD using T2-weighted MRI in human subjects. MATERIALS AND METHODS: Total 21 subjects (8 females, 13 males; median age 34; age range: 24 to 58 years) with no prior spine surgery were recruited. Sagittal T2-weighted, CEST, and T2 MRI of the lumbar spine were obtained. All images of the lumbar spine were acquired using a 3T Achieva scanner. High-resolution T2-weighted disks were qualitatively graded according to Schneiderman's classification (score range: 0 to 3). CEST and T2 maps were quantitatively assessed based on a voxel-by-voxel basis. RESULTS: A decreasing trend of CEST and T2 values with increasing grade of degeneration was noted. The mean CEST values in L3/4, L4/5 and L5/S1 discs with Schneiderman grades 0 (n = 41), 1 (n = 10), 2 (n = 7) and 3 (n = 5) were 7.17 ± 1.10%, 6.00 ± 0.83%, 2.85 ± 0.39%, and 1.84 ± 0.27%, respectively. The mean T2 values in discs with Schneiderman grades 0 (n = 41), 1 (n = 10), 2 (n = 7) and 3 (n = 5) were 109.74 ± 12.40 ms, 83.84 ± 6.19 ms, 71.70 ± 3.44 ms, and 65.16 ± 2.97 ms, respectively. Schneiderman grade was correlated with both CEST (r = -0.67, p < 0.001) and T2 (r = -0.71, p) CONCLUSION: Our results showed that CEST and T2 decreases with increasing grade of disk degeneration and that CEST values significantly correlated with T2. Our findings propose useful quantitative imaging tools with discriminatory capacity to assess early and end-stage IVD degeneration.