Poster No:
1699
Submission Type:
Abstract Submission
Authors:
Olivia Kowalczyk1, Sonia Medina2, Alessandra Venezia3, Dimitra Tsivaka4, Steven Williams3, Jonathan Brooks5, David Lythgoe6, Matthew Howard6
Institutions:
1King's College London / University College London, London, London, 2University of Exeter, Exeter, Devon, 3King's College London, London, London, 4University of Thessaly, Volos, Thessaly, 5School of Psychology, University of East Anglia, Norwich, Norfolk, 6King's College London, London, United Kingdom
First Author:
Olivia Kowalczyk
King's College London / University College London
London, London
Co-Author(s):
Jonathan Brooks
School of Psychology, University of East Anglia
Norwich, Norfolk
Introduction:
Establishing the reliability of spinal fMRI (sfMRI) measurements is critical before employing it to assess experimental or clinical interventions. Previous sfMRI studies have mapped human motor activity primarily to the ipsilateral ventral horn, aligning with myotomal projection patterns (Landelle et al., 2021; Kinany et al., 2022). Despite these insights, the test-retest reliability of the measurement remains under-investigated. We investigated cervical spinal activation during a robust motor paradigm involving hand grasping (squeezing), characterising test-retest reliability within a single session and across multiple days.
Methods:
Thirty healthy right-handed adult volunteers (29±4 years) completed two identical cervical sfMRI sessions while performing a hand squeeze motor task, using a rubberised air-filled ball in their right hand (measuring grip-force). We used a block design comprising eight squeeze/rest block pairs. Each block contained either eight 'squeeze and release' or eight 'rest' instructions (trial duration=2.5s; block duration=20s). Participants completed two 5min 40s runs of the task per session. Functional scans covered the whole cervical spinal cord (38 slices, slice thickness=4mm, slice gap=1mm, TR=2.5s, TE=30ms, flip angle=90°, ASSET factor=2, FOV=180mm, acquisition matrix=96×96). Slicewise x-, y-, and z-shimming including higher-order terms was used to optimise signal integrity (Tsivaka et al., 2023).
Spinal cord functional data were motion-corrected for x- and y-translations and smoothed with a 2D Gaussian kernel of 2mm full width at half maximum. Warping parameters for spatial normalisation were determined by segmenting and registering sfMRI data to the PAM50 template (De Leener et al., 2018) via a subject-specific T2-weighted image. First-level models (FSL FEAT) included explanatory regressors for squeeze trials, along with slice-wise nuisance regressors accounting for physiological noise and in-scan motion. Squeeze trials were contrasted against rest trials to investigate motor activity. Group-level activation maps were created using randomise with threshold-free cluster enhancement (5000 permutations, p<0.05). Intraclass correlation coefficients (ICC) were used to assess test-retest reliability of the data across task runs within-session and between-session.
Results:
Participants followed task instructions correctly, producing consistent hand-grip force during the squeeze blocks (mean maximum squeeze strength across all task runs and sessions, expressed as a percentage of individually thresholded squeeze strength=83.5%, SD=4.1). Averaging across both task runs and both sessions showed ipsilateral motor-related activation in both ventral and dorsal regions of segmental levels C6 and C7, as well as bilateral ventro-dorsal activation at levels C1-C3 (p<0.05). Despite the reliability of the behavioural data being good within session (ICC=0.7) and excellent between sessions (ICC=0.8), reliability estimates of imaging data were poor for both within- and between-session comparisons (ICC<0.4).
Conclusions:
Our findings reveal motor-related activation in ipsilateral ventro-dorsal regions of the cervical spinal cord, mapping to dermatomal projections of the hand and forearm, and myotomal projections associated with wrist flexion and extension. These activation patterns align with the established neuroanatomical organisation of motor circuits and corroborate existing spinal fMRI literature demonstrating that motor-related activity in the spinal cord corresponds to myotome-to-cord projections (Kinany et al., 2022; Landelle et al., 2021). However, while task performance reliability was good-to-excellent, the reliability of spinal cord activation was poor, both within and between sessions. These results indicate caution in the interpretation of spinal fMRI results and highlight the need for further refinement of acquisition and analysis protocols to improve the reproducibility of the technique.
Motor Behavior:
Motor Planning and Execution 1
Novel Imaging Acquisition Methods:
BOLD fMRI 2
Keywords:
FUNCTIONAL MRI
Motor
Spinal Cord
Other - Reliability
1|2Indicates the priority used for review
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Please indicate below if your study was a "resting state" or "task-activation” study.
Task-activation
Healthy subjects only or patients (note that patient studies may also involve healthy subjects):
Healthy subjects
Was this research conducted in the United States?
No
Were any human subjects research approved by the relevant Institutional Review Board or ethics panel?
NOTE: Any human subjects studies without IRB approval will be automatically rejected.
Yes
Were any animal research approved by the relevant IACUC or other animal research panel?
NOTE: Any animal studies without IACUC approval will be automatically rejected.
Not applicable
Please indicate which methods were used in your research:
Functional MRI
For human MRI, what field strength scanner do you use?
3.0T
Which processing packages did you use for your study?
AFNI
SPM
FSL
Provide references using APA citation style.
De Leener, B., Fonov, V. S., Collins, D. L., Callot, V., Stikov, N., & Cohen-Adad, J. (2018). PAM50: Unbiased multimodal template of the brainstem and spinal cord aligned with the ICBM152 space. NeuroImage, 165, 170–179.
Kinany, N., Pirondini, E., Micera, S., & Van De Ville, D. (2022). Spinal Cord fMRI: A New Window into the Central Nervous System. The Neuroscientist, 10738584221101827.
Landelle, C., Lungu, O., Vahdat, S., Kavounoudias, A., Marchand-Pauvert, V., De Leener, B., & Doyon, J. (2021). Investigating the human spinal sensorimotor pathways through functional magnetic resonance imaging. NeuroImage, 245, 118684.
Tsivaka, D., Williams, S. C. R., Medina, S., Kowalczyk, O. S., Brooks, J. C. W., Howard, M. A., ... & Tsougos, I. (2023). A second-order and slice-specific linear shimming technique to improve spinal cord fMRI. Magnetic Resonance Imaging, 102, 151-163.
No