Difference and Correlation Between Standing and Supine Cervical Sagittal Alignment: DTS vs MRI

Study designRetrospective study.ObjectivesThis study aimed to measure cervical sagittal alignment parameters on upright digital tomosynthesis (DTS) and supine magnetic resonance imaging (MRI) in patients with cervical spondylotic myelopathy (CSM) and evaluate the difference and correlation of cervical curvature in different postures.Methods101 CSM patients underwent both standing DTS and supine MRI. Parameters including O-C2 angle, cervical lordosis (CL), C2-7 sagittal vertical axis (C2-7 SVA), neck tilt (NT), T1 slope (T1S), thoracic inlet angle (TIA), cervical tilt, and cranial tilt were measured. Intraclass correlation coefficients (ICC) was used to assess inter-observer reliability. Paired <i>t</i>-tests and Pearson correlation analyses were applied to investigate the difference and correlation of parameters in standing and supine position.ResultsAll parameters measured on DTS and MRI showed excellent reliability (ICC >0.8). Significant differences were observed in O-C2 (DTS: -24.2 ± 11.2° vs MRI: -14.3 ± 6.6°, <i>P</i> < 0.001), CL (DTS: -15.2° ± 4.4° vs MRI: -8.1° ± 3.6°, <i>P</i> < 0.001), C2-7 SVA (DTS: 23.6 ± 11.0 mm vs MRI: 16.5 ± 8.5 mm, <i>P</i> < 0.001), T1S (DTS: 26.3° ± 8.4° vs MRI: 18.2° ± 6.6°, <i>P</i> < 0.001), Cervical tilt (DTS: 16.4° ± 5.6° vs MRI: 11.9° ± 6.5°, <i>P</i> < 0.001), and cranial tilt (DTS: 9.8° ± 9.3° vs MRI: 6.6° ± 8.3°, <i>P</i> = 0.015). Strong correlations existed for O-C2 (r = 0.834, <i>P</i> < 0.001), CL (r = 0.870, <i>P</i> < 0.001), and T1S (r = 0.875, <i>P</i> < 0.001).ConclusionsDTS reliably quantifies standing cervical alignment, particularly for cervicothoracic junction (CTJ) parameters obscured on radiography. Positional variations between standing and supine postures significantly impact cervical sagittal alignment. O-C2, CL and T1S obtained in supine position are considered meaningful parameters for evaluating cervical alignment in standing position.