Affiliation:
1. Department of Neuroimaging, Institute of Psychology, Psychiatry & Neuroscience King's College London London UK
2. The Wellcome Centre for Human Neuroimaging, Queen Square Institute of Neurology University College London London UK
3. Medical Physics Department, Medical School University of Thessaly Larisa Greece
4. Wolfson Centre for Age Related Diseases King's College London London UK
5. School of Psychology University of East Anglia Norwich UK
Abstract
AbstractResting functional magnetic resonance imaging (fMRI) studies have identified intrinsic spinal cord activity, which forms organised motor (ventral) and sensory (dorsal) resting‐state networks. However, to facilitate the use of spinal fMRI in, for example, clinical studies, it is crucial to first assess the reliability of the method, particularly given the unique anatomical, physiological, and methodological challenges associated with acquiring the data. Here, we characterise functional connectivity relationships in the cervical cord and assess their between‐session test–retest reliability in 23 young healthy volunteers. Resting‐state networks were estimated in two ways (1) by estimating seed‐to‐voxel connectivity maps and (2) by calculating seed‐to‐seed correlations. Seed regions corresponded to the four grey matter horns (ventral/dorsal and left/right) of C5–C8 segmental levels. Test–retest reliability was assessed using the intraclass correlation coefficient. Spatial overlap of clusters derived from seed‐to‐voxel analysis between sessions was examined using Dice coefficients. Following seed‐to‐voxel analysis, we observed distinct unilateral dorsal and ventral organisation of cervical spinal resting‐state networks that was largely confined in the rostro–caudal extent to each spinal segmental level, with more sparse connections observed between segments. Additionally, strongest correlations were observed between within‐segment ipsilateral dorsal–ventral connections, followed by within‐segment dorso–dorsal and ventro–ventral connections. Test–retest reliability of these networks was mixed. Reliability was poor when assessed on a voxelwise level, with more promising indications of reliability when examining the average signal within clusters. Reliability of correlation strength between seeds was highly variable, with the highest reliability achieved in ipsilateral dorsal–ventral and dorso‐dorsal/ventro–ventral connectivity. However, the spatial overlap of networks between sessions was excellent. We demonstrate that while test–retest reliability of cervical spinal resting‐state networks is mixed, their spatial extent is similar across sessions, suggesting that these networks are characterised by a consistent spatial representation over time.
Funder
NIHR Maudsley Biomedical Research Centre
Medical Research Council
University of Thessaly
Subject
Neurology (clinical),Neurology,Radiology, Nuclear Medicine and imaging,Radiological and Ultrasound Technology,Anatomy