Sciatic nerve magnetization transfer ratio was significantly lower in adults with SMA type 3 compared to healthy controls (P<0.0001) and positively correlated with clinical scores.
Case-Control (n=36)
Does sciatic nerve magnetization transfer ratio (MTR) differentiate adults with SMA type 3 from healthy controls and correlate with clinical severity?
Magnetization transfer ratio of the sciatic nerve is a promising quantitative imaging biomarker that differentiates SMA type 3 patients from healthy controls and correlates with clinical severity.
p-value: p=<0.0001
BACKGROUND AND PURPOSE: We quantified peripheral nerve lesions in adults with 5q-linked spinal muscular atrophy (SMA) type 3 by analysing the magnetization transfer ratio (MTR) of the sciatic nerve, and tested its potential as a novel biomarker for macromolecular changes. METHODS: Eighteen adults with SMA 3 (50% SMA 3a, 50% SMA 3b) and 18 age-/sex-matched healthy controls prospectively underwent magnetization transfer contrast imaging in a 3-Tesla magnetic resonance scanner. Two axial three-dimensional gradient echo sequences, with and without an off-resonance saturation rapid frequency pulse, were performed at the right distal thigh. Sciatic nerve regions of interest were manually traced on 10 consecutive axial slices in the images generated without off-resonance saturation, and then transferred to corresponding slices generated by the sequence with the off-resonance saturation pulse. Subsequently, MTR and cross-sectional areas (CSAs) of the sciatic nerve were analysed. In addition, detailed neurologic, physiotherapeutic and electrophysiologic examinations were conducted in all patients. RESULTS: Sciatic nerve MTR and CSA reliably differentiated between healthy controls and SMA 3, 3a or 3b. MTR was lower in the SMA 3 (P < 0.0001), SMA 3a (P < 0.0001) and SMA 3b groups (P = 0.0020) than in respective controls. In patients with SMA 3, MTR correlated with all clinical scores, and arm nerve compound motor action potentials (CMAPs). CSA was lower in the SMA 3 (P < 0.0001), SMA 3a (P < 0.0001) and SMA 3b groups (P = 0.0006) than in controls, but did not correlate with clinical scores or electrophysiologic results. CONCLUSIONS: Magnetization transfer ratio is a novel imaging marker that quantifies macromolecular nerve changes in SMA 3, and positively correlates with clinical scores and CMAPs.
Kollmer et al. (Thu,) conducted a case-control in 5q-linked spinal muscular atrophy (SMA) type 3 (n=36). 5q-linked spinal muscular atrophy (SMA) type 3 vs. Healthy controls was evaluated on Sciatic nerve magnetization transfer ratio (MTR) (p=<0.0001). Sciatic nerve magnetization transfer ratio was significantly lower in adults with SMA type 3 compared to healthy controls (P<0.0001) and positively correlated with clinical scores.