[Assessment of flexibility in adolescent idiopathic scoliosis by curved planar reformation using multi-slice spiral CT scanning].

Objective: To investigate the role of curved planar reformation (CPR) using multi-slice spiral CT scanning to evaluate the coronal and sagittal plane in scoliosis so as to affirm the features of supine coronal and sagittal plane in idiopathic scoliosis.
Methods: Thoracic and lumbar spine multi-slice spiral CT scanning was undertaken on 45 patients with adolescent idiopathic scoliosis (AIS), all female, age 10 - 18. CPR was used to reconstruct the spine coronal and sagittal planes respectively. The values of main curve and compensate curve Cobb angles were obtained and compared with those obtained by X-ray films.
Results: The average CPR coronal main curve Cobb angle was smaller by 10.17 degrees than that obtained by standing position film. The average CPR coronal compensate curve Cobb angle was smaller by 6.97 degrees than that obtained by standing position film. For scoliosis coronal flexibility assessment, fulcrum-bending method offered better surgical correction result than other methods. Only the post-operational Cobb angle was different between the 10 - 14 year-old group and 15 - 18 year-old group. Bending film showed differences in correction rate and flexibility rate between the main thoracic group and main lumbar/thoracolumbar group. The correction rate and flexibility rate of main curve and compensate curve of the 10 - 14 year-old group were significantly higher than those of the 15 - 18 year-old group. In the sagittal plane, the CPR thoracic kyphotic angle (T5-T12) and upper thoracic curve kyphosis of the main thoracic group were both smaller than those of the main lumbar/thoracolumbar group. The CPR thoracic kyphotic angle (T5-T12) of the 10 - 14 year-old group was significantly smaller than that of the 15 - 18 year-old group. Correlation analysis showed that the CPR main curve flexibility and bending film flexibility were positively corrected with the surgical correction rate.
Conclusion: CPR using multi-slice spiral CT scanning is able to obtain multiple three-dimensional assessment by one scanning and is helpful in scoliosis curve type diagnosis and scoliosis 3D analysis.