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

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.

To assess the reliability and agreement of intervertebral disc height measurements between MRI, X-ray, and CT.

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.

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.

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.