Ultrasound Imaging of Spinal Vertebrae to Study Scoliosis

Scoliosis is a musculoskeletal disorder manifested as a three-dimensional spinal deformity. It affects 2% 3% of the adolescent population. The conventional method to diagnose scoliosis is to measure the Cobb angle from posteroanterior radiograph. Since radiation exposure is not desirable for patients, other non-ionizing methods have been explored. Among all the non-ionization methods, ultrasound (US) is a potential cost-effective method. However, our understanding of US interaction with the vertebrae or the spine is limited. The purpose of this study was to demonstrate the ability of US to identify bony landmarks for measuring spinal deformity. This study used a phased array US system with a 5 MHz transducer and a position encoder. In-vitro experiment on a cadaver vertebra and a pilot clinical study were carried out. The in-vitro experimental results showed that the lamina and spinous process were strong reflectors from the single vertebra. Less than 4% of error occurred on the dimension measurements. The pilot study was performed on a healthy subject and a scoliotic patient. The results indicated the lamina and spinous process could be identified and the curvature of the spine could be estimated using the reflectors. The difference of the curvature angle of the spine measured from the radiograph and the US images was 2 ̊. These results have illustrated that US is a promising tool to measure curvature of spinal deformity and study scoliosis.