Systematic Review of the Reliability and Reproducibility of Magnetisation Transfer Imaging in Human Cervical Spinal...

Objectives: The objective of magnetisation transfer imaging (MTI) is to quantitatively assess myelin integrity in the cervical spinal cord (CSC) using MRI technology. The magnetisation transfer ratio (MTR) has been extensively studied as a prospective biomarker for identifying microstructural alterations in both healthy and diseased tissue. This systematic review aims to assess the repeatability and reproducibility of MTI-derived MTR studies in human CSC. Methods: A systematic search was performed in PubMed, Scopus, and Web of Science to identify studies evaluating the reliability of MTI, specifically MTR. Studies that met the criteria presented statistical metrics including intraclass correlation coefficient (ICC), coefficient of variation (CV%), or Bland-Altman (BA) analysis. Only peer-reviewed articles in English were included. The review adhered to PRISMA 2020 guidelines, and methodological quality was evaluated using the Quality Assessment with Diverse Studies (QuADS) tool. Results: Thirty studies were identified; following screening, six studies satisfied the inclusion requirements. These investigations assessed the reliability and reproducibility of MTR in both healthy individuals and patients with cervical myelopathy throughout spinal levels C1-C7. The ICC values exhibited considerable variability, spanning from poor agreement to about 0.90%, depending on the region of interest. The CV% values varied from 1.3% to 6.1% in non-healthy populations and from 0.5% to 12.7% in healthy groups. The BA analysis indicated no systematic bias, characterised by relatively minimal mean differences. A quantitative meta-analysis was not conducted due to methodological differences in each study. QuADS ratings demonstrated moderate to high methodological quality (77-96%). Conclusions: MTR exhibits generally low ICC values over different ROIs in most of the included studies and high to medium reproducibility for the evaluation of CSC. Nonetheless, diversity in acquisition procedures, statistical reporting and ROI selection continues to be a significant limitation of our study for not reporting the meta-analysis.