Development of 3-D ultrasound system for assessment of adolescent idiopathic scoliosis (AIS): and system validation.

Adolescent idiopathic scoliosis (AIS) is a common spinal disease and the prevalence of AIS is 2 to 4 % of the youngsters in the United States. Radiograph based Cobb's method is regarded as the gold standard. AIS patients normally have to undergo regular X-ray assessment every 4 to 6 months until skeletal maturity is reached. Because of radiation hazard, X-ray images cannot be taken frequently, and thus it is difficult to perform close monitoring for the disease progression and treatment outcomes. In this study, a free-hand 3D ultrasound imaging system has been successfully developed for the radiation-free assessment of AIS. A series of B-mode ultrasound images with their spatial information were exploited to form a spine model for measuring the spine curvature. Sixteen spine phantoms with different simulated deformity were scanned by both conventional X-ray imaging and the 3D ultrasound system. The results showed that there was a strong correlation (R(2) = 0.759) between the Cobb's angles obtained by the two methods. The results also demonstrated a very good intra- and inter-observer reproducibility with ICC of 0.99 and 0.89, repectively. The findings suggest that it is feasible to use 3D ultrasound imaging for the assessment of scoliosis and deserves further clinical tests on patients with spine deformity.