Development of 3-D ultrasound system for assessment of Adolescent Idiopathic Scoliosis (AIS)

AIS is defined as deformity of the spine in coronal plane with more than 10 degrees of Cobb's angle. Cobb's Method is the gold standard in monitoring patients that are susceptible to scoliosis development. The patients need to conduct an X-ray examination of the patient's whole spine regularly every 4 to 6 months until skeletal maturity is reached. However, there are less than 1% of the screened population and less than 10% of those with curves greater than 10 degrees warrant treatment. This previous finding implies that more than 90% of patients are subject to unnecessary radiation. It is clearly necessary to have a system that can provide AIS mass screening system and longitudinal follow-up for children without the hazard of radiation. The investigators successfully developed a 3D ultrasound system specifically for the assessment of AIS, which is a nonradiation assessment system. This system consists of a portable ultrasound scanner, a frame, an electromagnetic spatial sensing device, and a PC with a customized program. The images collected from subjects are displayed in 3D space corresponding to the spatial information collected. The frames which consist of spinous or traverse processes are selected for marking the processes' position. The tip of each process is manually assigned with a marker. A 3D model of spine which is formed by markers is exploited to measure spine deformity angle and rotation. In our phantom study, the phantoms were deformed to simulate AIS with different severities. These phantoms were taken coronal X-ray and 3D ultrasound imaging. The results obtained by the two methods were very close. This system not only provides a new way to assess AIS without radiation hazard but also provides additional new information on spine's 3D geometrical information. The system evidently indicates its potential as a complementary tool for X-ray Cobb's method.