1H-magnetic resonance spectroscopy in diffuse and focal cervical cord lesions in multiple sclerosis

Objectives: To investigate differences between focal and diffuse cervical lesions in multiple sclerosis (MS) by proton magnetic resonance spectroscopy (¹H-MRS) at 1.5 T in comparison to quantitative MR imaging of the upper cervical cord area and T2 relaxometry at baseline and follow-up. Methods: Including 22 MS patients with persistent spinal cord symptoms by either diffuse or focal lesions and 17 controls, we acquired MRS, the mean cord area and the water T2 relaxation time and disability at baseline and follow-up. Cross-sectional analyses included group-level comparisons and correlation studies. Follow-up studies covered assessment of reproducibility and progression of the baseline results. Results: Compared with focal lesions, diffuse lesions were attended by more cord atrophy, longer T2, elevated levels of creatine (Cre) and reduced N-acetyl aspartate (NAA)/Cre (focal/diffuse: 83 ± 9/73 ± 15 mm², 121 ± 21/104 ± 13 ms, 3.6 ± 1.1/5.1 ± 2.4 mM, 2.4 ± 1.1/2.0 ± 0.9). NAA/Cre at baseline was associated significantly with cord atrophy and with clinical progression during follow-up. Baseline MRS results were not significantly correlated to the clinical disability parameters. The reproducibility of MRS was 0.17-0.30. Longitudinal changes of the MRS results were not statistically significant. Conclusions: MRS indicated differences in demyelination and gliosis between diffuse and focal cervical lesions in MS. Although longitudinal spectral and clinical changes were sparse, NAA/Cre turned out to be the most sensitive spectral parameter. Key Points: • MR spectroscopy shows differences between focal and diffuse spinal cord MS lesions. • MRS indicates axonal degeneration and gliosis in MS compared with controls. • MRS results are associated with cervical cord atrophy. • MRS may help clinicians to monitor spinal cord damage in MS.