Objective:

The purpose of this study was to investigate differences between measurements of spine on 2D X-ray and 3D CT images taken of adolescent idiopathic scoliosis patients.

Methods:

Standard preoperative CT images and posterior-anterior (PA) and lateral (LA) X-ray images were collected prospectively from 43 AIS patients in whom selective spinal fusions were performed. The parameters of interest were the thoracic Cobb (TC) angle, lumbar Cobb (LC) angle, T4-T12 kyphosis (TK) angle and L1-S1 lordosis (LL) angle. The parameters were measured using three separate methods: 3D measurement of CT images (3D measurement), 2D measurement of X-ray images (2D measurement) and 2D measurement of X-ray images generated by the projection of CT images (2D XP measurement). Significant differences between the results were assessed by comparison T test.

Results:

The mean difference between the 2D and 2D XP measurements for the TC, LC, TK and LL 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) between the spinal parameters measured using the 2D, 2D XP and 3D measurement methods on both the coronal and sagittal plane.

Conclusions:

Significant differences between the 2D, 2D XP and 3D measurement methods were observed on both the sagittal plane and coronal plane of the scoliotic spines due to variations in posture during imaging and differences in measurement methods.