A Retrospective Study on the Evaluation of True Cervical Lordosis Based on the Scout Image of Carotid Computed Tomography Angiography in Korea

Objective In clinical settings, older adults presenting with headaches often undergo brain or carotid computed tomography (CT) to evaluate whether intracranial pathology is present. However, cervical spine conditions may be underrecognized. The scout image from carotid CT angiography may reveal incidental spinal findings, such as loss of cervical lordosis. This study aimed to evaluate whether cervical alignment, specifically C1-7 lordosis, can be reliably assessed using the scout image from carotid CT angiography. Methods We retrospectively reviewed 153 patients who underwent both carotid CT angiography and cervical spine plain radiographs, excluding those with atlantoaxial fusion. The C1-7 cervical lordosis angle was measured on both the CT scout image and a plain radiograph. In a subgroup of 34 patients with cervical spine CT, the angle was also measured using the scout image from the cervical CT. Results The scout angle from carotid CT showed a moderate correlation with the true cervical lordosis angle on radiographs (r=0.382, P<0.001), with a median difference of 16.22° (interquartile range, 8.94°-23.11°). A strong correlation was noted between the carotid CT scout image and the cervical CT scout image (r=0.857, P<0.001). Receiver operating characteristic curve analysis identified a cutoff of <21.725° for predicting lordosis loss (area under the curve=0.733). Despite a significant difference between scout and radiograph angles (P<0.001), the association remained moderate (r=0.397, P=0.020). Conclusion The scout angle can indicate a loss of cervical lordosis before plain radiograph evaluation. CT scout images are valuable for screening, but are subject to measurement limitations.