Fully automated segmentation of the cervical cord from T1-weighted MRI using PropSeg: Application to multiple sclerosis.

Marios C Yiannakas,Olga Ciccarelli,Benjamin De Leener,Carmen Tur,Floriana De Angelis,Julien Cohen-Adad,Daniel R Altmann,David H Miller,Hugh Kearney,Ahmed M Mustafa,Claudia A.M Gandini Wheeler-Kingshott,Domenico Plantone

doi:10.1016/j.nicl.2015.11.001

Abstract

Spinal cord (SC) atrophy, i.e. a reduction in the SC cross-sectional area (CSA) over time, can be measured by means of image segmentation using magnetic resonance imaging (MRI). However, segmentation methods have been limited by factors relating to reproducibility or sensitivity to change. The purpose of this study was to evaluate a fully automated SC segmentation method (PropSeg), and compare this to a semi-automated active surface (AS) method, in healthy controls (HC) and people with multiple sclerosis (MS). MRI data from 120 people were retrospectively analysed; 26 HC, 21 with clinically isolated syndrome, 26 relapsing remitting MS, 26 primary and 21 secondary progressive MS. MRI data from 40 people returning after one year were also analysed. CSA measurements were obtained within the cervical SC. Reproducibility of the measurements was assessed using the intraclass correlation coefficient (ICC). A comparison between mean CSA changes obtained with the two methods over time was performed using multivariate structural equation regression models. Associations between CSA measures and clinical scores were investigated using linear regression models. Compared to the AS method, the reproducibility of CSA measurements obtained with PropSeg was high, both in patients and in HC, with ICC > 0.98 in all cases. There was no significant difference between PropSeg and AS in terms of detecting change over time. Furthermore, PropSeg provided measures that correlated with physical disability, similar to the AS method. PropSeg is a time-efficient and reliable segmentation method, which requires no manual intervention, and may facilitate large multi-centre neuroprotective trials in progressive MS.

Highlights

Neuropathological and magnetic resonance imaging (MRI) studies have demonstrated the involvement of the spinal cord (SC) in multiple sclerosis (MS); neurodegeneration in the Spinal cord (SC) is thought to represent the main pathological substrate of irreversible locomotor disability (Abdel-Aziz et al, 2015; DeLuca et al, 2006; Ganter et al, 1999)
In this study we evaluate PropSeg, as compared to the widely used semi-automated active surface (AS) method (Horsfield et al, 2010), in a large cohort of healthy controls and people with MS, in order to test the following hypotheses: (i) PropSeg provides reproducible cross-sectional area (CSA) measurements in the cervical SC
Out of 160 scans processed in total, PropSeg failed to correctly segment the cord only in 3 cases (1 healthy control and 2 RRMS), and these cases were manually processed by inserting seed points in the centre of the cord prior to the segmentation; the presence of MS lesions had no obvious effect on the performance of the segmentation method

Summary

Introduction

Neuropathological and magnetic resonance imaging (MRI) studies have demonstrated the involvement of the spinal cord (SC) in multiple sclerosis (MS); neurodegeneration in the SC is thought to represent the main pathological substrate of irreversible locomotor disability (Abdel-Aziz et al, 2015; DeLuca et al, 2006; Ganter et al, 1999). SC MRI has provided indirect evidence of axonal degeneration.

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