With the approval of the first disease modifying treatments for SMA, there is an increasing need for biomarkers that allow easy to perform, reliable, and valid disease course- and therapeutic response monitoring. The novel rAMIRA method enables high in-plane resolution MR-imaging with improved contrast of SC GM in clinically feasible acquisition times at 3 Tesla.

Using axial 2D rAMIRA imaging, we prospectively investigated 21 patients with 5q-SMA, types 2 and 3 (mean age/SD 41.3/11.6y, 9 women) and 21 age- and sex-matched healthy controls (HC) (mean age/SD 41.7/11.4y, 9 women) at the intervertebral disc levels C2/C3-C5/C6 perpendicular to the cord. SC GM areas were determined using a semi-automated approach. The associations between SC GM area and Revised Upper Limb Module (RULM), an established measure of upper limb disability in SMA, were assessed using multivariable regression analysis covarying for age.

Cervical SC GM atrophy is detectable in patients with 5q SMA compared to HC and correlates with clinical measures of upper limb function, namely RULM. Further longitudinal investigations are necessary next steps to evaluate the potential of this novel and easy to assess imaging marker for monitoring the disease course and therapeutic response.