Nur Neyal1, Jiye Son2, Christopher Schwarz2, Elizabeth Atkinson3, Holly Morrison4, John Port5, Kejal Kantarci2, Orhun Kantarci6, Burcu Zeydan7
1Department of Neurology & Radiology, 2Department of Radiology, 3Department of Quantitative Health Sciences, 4Center for Multiple Sclerosis and Autoimmune Neurology, 5Department of Radiology & Center for Multiple Sclerosis and Autoimmune Neurology, 6Department of Neurology & Center for Multiple Sclerosis and Autoimmune Neurology, 7Department of Neurology & Radiology & Center for Multiple Sclerosis and Autoimmune Neurology, Mayo Clinic
Objective:
Evaluate the association between upper cervical cord (UCC) volume and common brain metrics of MS.
Background:
Based on their higher availability than cord MRIs, UCC atrophy assessed from brain MRIs is frequently used as an imaging biomarker in MS. Compared to the measurements from the whole cervical cord, UCC atrophy may not be as sensitive, but it seems to correlate well with MS disability metrics. UCC may also be associated with other imaging metrics of MS.
Design/Methods:
89 consecutive patients with MS (63F/26M, 72 relapsing/17 progressive) were prospectively enrolled from a single center. For brain structure volumes, automated LesionQuant (Cortechs Labs) was used. For lower brainstem and UCC volumes, a novel automated method was used. To propagate a mask of lower brainstem and UCC regions from the atlas template space to each T1-weighted brain MRI, Advanced Normalization Tools nonlinear registration was utilized. Volumes were calculated as the image's voxel volume multi plied by the sum of voxels in the masks. Automated volumes from each anatomical level (aMedulla, aCervicomedullaryJunction-aCMJ, aC1, aC2) and total volumes from medulla to C2 (aMedulla+UCC) and from CMJ to C2 (aUCC) were identified.
Results:
130 brain MRIs were analyzed. Age at MRI was 46.0±12.3 years. Individual aCMJ, aC1 and aC2 volumes and total volumes (aMedulla+UCC and aUCC) associated with whole brain and thalamus volumes(p<0.05). The strongest correlations were between aMedulla and whole brain (unadjusted r=0.67p<0.001; adjusted for age&sex r=0.59 p<0.001) and thalamus volumes (unadjusted r=0.53 p<0.001; adjusted for age&sex r=0.46 p<0.001).
Conclusions:
Besides the whole brain and thalamus volumes, brain imaging is also used to evaluate UCC atrophy in MS. These common imaging metrics are often considered as independent variables; however, they also seem to interact with each other. Therefore, in MS trials, a composite metric, especially accounting for thalamus and UCC volumes, could serve as a complementary imaging outcome.