Clinical Validation of the Differences Between Two-Dimensional Radiography and Three-Dimensional Computed Tomography Image Measurements of the Spine in Adolescent Idiopathic Scoliosis.

Abstract

The purpose of this study was to investigate differences between measurements of spine on two-dimensional (2D) radiography and three-dimensional (3D) computed tomography (CT) images taken of patients with adolescent idiopathic scoliosis. Standard preoperative CT images and posteroanterior (PA) and lateral radiography images were collected prospectively from 43 patients with adolescent idiopathic scoliosis in whom selective spinal fusions were performed. The parameters of interest were the thoracic Cobb angle, lumbar Cobb angle, T4-T12 kyphosis angle, and L1-S1 lordosis (LL) angle. The parameters were measured using 3 separate methods: 3D measurement of CT images (3D measurement), 2D measurement of radiography images (2D measurement), and 2D measurement of radiography images generated by the projection of CT images (2D XP measurement). Significant differences among the results were assessed by comparison T test. The mean difference between the 2D and 2D XP measurements for the thoracic Cobb, lumbar Cobb, T4-T12 kyphotic, and L1-S1 lordotic angles was 8.38°, 7.67°, 8.77°, and 10.18°, respectively. The mean difference between the 2D XP and 3D measurements was -2.81°, -2.78°, -1.29°, and -2.36°, respectively. The mean difference between the 2D and 3D measurements was 5.16°, 4.51°, 6.49°, and 7.37°, respectively. The results showed significant differences (P < 0.05) among the spinal parameters measured using the 2D, 2D XP, and 3D measurement methods on both the coronal and sagittal plane. Significant differences among the 2D, 2D XP, and 3D measurement methods were observed on both the sagittal plane and coronal plane of the scoliotic spines as a result of variations in posture during imaging and differences in measurement methods.