Assessment of Glycosaminoglycan Content of Lumbar Intervertebral Discs in Patients with Radiculopathy

Objective: To assess glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVDs) in patients with radiculopathy compared with healthy volunteers with glycosaminoglycan chemical exchange saturation transfer (gagCEST). Methods: The lumbar spines of 15 patients with radiculopathy (9 women, 6 men; mean age 45 years; range: 19 - 80 years) and 13 healthy controls (10 women, 3 men; mean age 29 years; range: 19 - 38 years) without lumbar back pain or previous spine surgery were examined at a 3 Tesla (T) magnetic resonance imaging (MRI) scanner in this prospective study. The MRI protocol included standard morphological, sagittal, and transverse T2-weighted (T2w) images of the five lumbar IVDs (L1-S1) to assess Pfirrmann score and to detect disc disorders according to the Combined Task Force classification. To analyze biochemically the lumbar IVDs, a gagCEST sequence was applied to measure the GAG content of the nucleus pulposus (NP) and annulus fibrosus (AF). Results: Patients with radiculopathy indicated significantly lower gagCEST values in NP than healthy volunteers (2.82% ± 3.12% vs. 4.09% ± 2.25%, P = 0.017). The GAG content of AF showed no significant difference between volunteers and patients (2.66% ± 2.01% vs. 1.92% ± 2.56%; P = 0.175). Conclusions. Patients with radiculopathy presented with lower GAG values than healthy volunteers in NP, indicating an association between pain and IVD degeneration. gagCEST of lumbar IVDs is a powerful, non-invasive tool to investigate early disc degeneration, which we could demonstrate in the NP in our study collective.