# Fully-automated estimation of upper cervical cord cross-sectional area using pontomedullary junction referencing in multiple sclerosis

## TL;DR

This study introduces a fully automated method to measure spinal cord size in multiple sclerosis patients, which is more reliable and correlates with disability levels.

## Contribution

The novel contribution is an automated PMJ-referenced method for cervical cord cross-sectional area measurement in MS.

## Key findings

- CSA PMJ and CSA C2–C3 were highly correlated, but PMJ-based CSA performed better due to vertebral labeling errors.
- CSA PMJ was negatively associated with disability, independent of age and sex.
- The PMJ was correctly identified in all subjects using the automated method.

## Abstract

Spinal cord cross-sectional area (CSA) is a biomarker of disability in multiple sclerosis (MS). Vertebral-based CSA suffers from anatomical variability and positional bias.

To evaluate a fully automated PMJ-referenced approach, as implemented in the open-source Spinal Cord Toolbox, to assess cervical cord CSA at a fixed distance from the pontomedullary junction (PMJ) in MS.

Retrospective study performed at the MS center of Lugano (Switzerland). Inclusion criteria were treatment with natalizumab or ocrelizumab and absence of clinical/radiological disease activity over ≥2 years. CSA at 64 mm caudal to the PMJ (CSA PMJ) and at C2–C3 vertebral level (CSA C2–C3) were calculated using the Spinal Cord Toolbox.

Seventy-five MS patients [females = 44 (58.7%), age = 45.1 (36.7–53.8) years, natalizumab = 36 (48%), ocrelizumab = 39 (52%)] were included. Median CSA PMJ and CSA C2–C3 were 57.7 (53.1–62.1) and 58.1 (53.2–62.6) mm2, respectively. The two measures were highly correlated (rho = 0.95, p < 0.001), with some exceptions related to errors in vertebral labelling in CSA C2–C3 assessments. PMJ was correctly identified in all subjects. CSA PMJ measures were negatively associated with disability (β = −0.08, p = 0.002), independent of age and sex.

Automated measurement of spinal cord CSA at fixed distance from the PMJ is applicable in MS, performs better than vertebral-based CSA, and correlates with neurological disability.