Reliability of EOS-3D reconstruction for scoliosis associated with Chiari malformation

English Keywords:EOS imaging system  Scoliosis  Chiari malformation  Reproducibility of results

English Abstract:

  【Abstract】 Objectives: To investigate the reliability and accuracy of three-dimensional reconstruction by EOS imaging system in patients with Chiari deformity with scoliosis. Methods: Between July 2017 and April 2018, EOS images from 14 Chiari malformation associated with scoliosis patients(5 males, 9 females, 9-18 years old, mean age 13.4±2.9 years old) were collected. Ster-EOS software was used to perform 3D reconstruction of the spine to obtain a set of measurements, including Cobb angle, apical vertebral rotation(AVR), T1-T12 kyphosis angle(T1-T12 TK), T4-T12 kyphosis angle(T4-T12 TK), L1-L5 lordosis angle(L1-L5 LL), L1-S1 lordosis angle(L1-S1 LL), pelvic incidence(PI), sacral slope(SS), and pelvic tilt(PT). Two spinal surgeons independently reconstructed the vertebrae and evaluated the interobserver variability by using the interobserver coefficient of variation. Doctor A measured the above parameters obtained after first EOS-3D modeling and the parameters in the traditional full spine image. And then consistency analysis of them was performed by calculating the intraclass correlation coefficient(ICC) value. Then two doctors studied the retest reliability of the above parameters. In addition, the patients were divided into three groups according to the size of scoliosis Cobb angle: the first group of Cobb angle <40°, a total of 3 cases; the second group of Cobb angle 40° to 60°, a total of 7 cases; the third group of Cobb angle >60°, a total of 4 cases. The three groups were compared in pairs to observe the application of the system in patients with different cob angle sizes. After that, the retest reliability of the above parameters was studied by two doctors. Results: The ICC values were 0.980, 0.990, 0.987, 0.945, 0.990 and 0.963(P<0.01) for Cobb angle, AVR, T1-T12 TK, T4-T12 TK, L1-L5 LL, and L1-S1 LL, respectively. The ICC values were 0.962, 0.821 and 0.895(P<0.01) for PI, SS and PT. For fit score, there was no significant difference between group 1 and group 2, group 2 and group 3(P>0.05), while there was a significant difference between group 1 and group 3(P<0.05). In consistency analysis, the ICC values of Cobb angle, T1-T12 TK, T4-T12 TK, L1-L5 LL, L1-S1 LL, PI, PT and SS were as follows 0.981, 0.991, 0.843, 0.975, 0.972, 0.997, 0.998 and 0.996. The reliability of retesting the parameters by the two physicians was very high, and 2 doctors both showed a minimum value of 0.883 and 0.807 at the pelvic tilt, respectively. Conclusions: The 3D modeling of Chiari deformity with scoliosis by using EOS system and sterEOS post-processing software can obtain good reliability and accuracy of measurement, which adds a new method for the evaluation of scoliosis.