Magnetization Transfer Ratio of the Spinal Cord in Multiple Sclerosis: Relationship to Atrophy and Neurologic Disability

Abstract

The authors compare the spinal cord magnetization transfer ratio (MTR) of multiple sclerosis (MS) patients to healthy volunteers, relate MTR to spinal cord atrophy, and relate these and other magnetic resonance (MR) imaging parameters to disability. Sixty-five patients with MS (14 relapsing remitting [RRL 34 secondary progressive [SPL and 17 primary progressive [PP] MS), and 9 healthy volunteers were studied using MR at 1 .0 T. Disability of the patients was assessed using the expanded disability status scale (EDSS). Magnetic resonance parameters were upper spinal cord MTR, number of focal spinal lesions, presence of diffuse abnormalities, and spinal cord cross-sectional area (CSA).Correlations were assessed using Spearman's rank correlation coefficient (r). Magnetization transfer ratio was higher in the controls (median, 33%; range, 30%-38%) than in patients with MS (median, 30%; range, 16-36; p < 0.05). In patients with MS, EDSS correlated with spinal cord MTR, albeit weakly (r = -0.25, p < 0.05). Correlation between EDSS and spinal cord CSA was better (SRCC = -0.40, p < 0.01 ). No correlation was found between MTR and CSA (r = 0.1, p = 0.4). Combining MTR with spinal cord CSA improved correlation with EDSS (r = -0.46, p < 0.001 ), suggesting an independent correlation between disability and these 2 MR parameters. Expanded dis-ability status scale scores were higher in patients who had diffuse spinal cord abnormality regardless of focal lesions (median, 6; range, 1.5-7.5) than in patients without diffuse abnormalities (median, 3.5; range, 0-8; p < 0.01). CSA was lower in patients with diffuse spinal cord abnormality (median, 62; range, 46-89 mm 2 ) than in patients without diffuse abnormalities (median, 73; range, 47-89 mm 2 ; p < 0.01). MTR was slightly lower in patients with diffuse spinal cord abnormalities (median, 29; range, 21 %-33%) than in patients without diffuse abnormalities (median, 31; range, 16-36; t-test, p < 0.05).

Proton Density MRI Increases Detection of Cervical Spinal Cord Multiple Sclerosis Lesions Compared with T2-Weighted Fast Spin-Echo

“…Although statistical comparison was not performed, reported contrast-to-noise ratio values were approximately twice as high for PD-SE imaging as for T2-SE imaging. 11 Conversely, an alternate smaller study found that T2 conventional SE had a greater contrast-to-noise ratio than PD conventional SE imaging at 1.5T in 20 patients with MS. 9 This difference may simply reflect our larger cohort and imaging results on modern 1.5T MR imaging scanners compared with this previous study, which recruited almost 20 years ago.…”

“…7 This was not surprising due to few studies comparing pulse sequences and the disparate study designs in the literature. [8][9][10][11] Perhaps the discrepancy in study designs are related to the marked variability in adherence to guideline recommendations in routine clinical practice. 12 While previous studies have examined the diagnostic benefit of additional STIR imaging, 9,13,14 no previous study has assessed whether there is a diagnostic benefit to the addition of sagittal PD imaging to T2-weighted imaging of the cord.…”

Diffusion tensor imaging of the cervical spinal cord of patients with relapsing-remising multiple sclerosis: a study of 41 cases

“…Currently, spinal cord MR imaging studies focus on the presence of lesions visible on T2, short tau inversion recovery (STIR) or proton density sequences, which are secondary to demyelination 17 . however, previous authors have failed to prove the relation between the spinal cord MR imaging abnormalities on the conventional sequences and the clinical disability 16,18,19 . Advanced MR imaging techniques, such as proton spectroscopy and diffusion tensor imaging, have also been studied with some success when aiming to demonstrate a correlation between the imaging findings and the clinical status 20 .…”

“…Spinal cord lesions demonstrated with MR imaging have been included in revised McDonald criteria of MS 15 , ascertain that these findings can be used to demonstrate disease dissemination in time and space. MS spinal cord abnormalities may consist of focal well-demarcated or diffuse poorly demarcated lesions, and up to 97% of the MS patients demonstrate spinal cord abnormalities on MR imaging 16 . Currently, spinal cord MR imaging studies focus on the presence of lesions visible on T2, short tau inversion recovery (STIR) or proton density sequences, which are secondary to demyelination 17 .…”

Imaging of multiple sclerosis: Role in neurotherapeutics

“…5). The cervical cord 140 and optic nerve 141 also show decreased MTR in MS. The degree of decreased MTR varies among MS phenotypes and is thus related to disease course.…”