Assessing cervical intervertebral disc height on MRI and X-ray versus CT; a single center retrospective cohort study.

Introduction: Cervical intervertebral disc height is often used to score cervical degenerative disc disease (CDDD) and can also aid in pre-operative surgical planning. For this purpose, MRI and X-ray imaging are routinely used. However, the reliability and agreement with computed tomography (CT), the gold standard for linear measurements, remain unknown. Research question: To assess the reliability and agreement of intervertebral disc height measurements between MRI, X-ray, and CT. Material and methods: Data was collected from all patients that received an MRI, X-ray, and CT within a timeframe of 6 months at Zuyderland Medical Center (ZMC) between 2014 and 2024. Mid, anterior, and posterior cervical intervertebral disc heights were measured from C2-C3 to C6-C7 in all three imaging modalities. 120 patients were included. The intraclass correlation coefficient (ICC) was calculated for the inter- and intraobserver reliability. A linear mixed model with Bonferroni correction was used to compare outcomes. Results: ICCs ranged from moderate to excellent for X-ray. ICCs ranged from good to excellent for MRI and CT after sensitivity analysis for equal slice selection. Mean difference in disc height was .1 mm (p = 0.163) between MRI and X-ray, 1.3 mm (p < 0.001) between MRI and CT, and 1.3 mm (p < 0.001) between X-ray and CT. Discussion and conclusion: MRI and X-ray exhibit a systematic bias in the measurement of cervical intervertebral disc height when compared to CT. CT should be considered for the assessment of disc height. The mid-disc measurement is recommended to ensure high reliability.