Is radiation-free ultrasound accurate for quantitative assessment of spinal deformity in idiopathic scoliosis (IS) : a detailed analysis with EOS radiography on 952 patients

Abstract

Radiation exposure with repeated radiography required at follow-up poses serious health concerns for scoliosis patients. Although spinous process angle (SPA) measurement of spinal curvatures with ultrasound has been reported with promising results, an evidence-based account on its accuracy for translational application remains undefined. This prospective study involved 952 idiopathic scoliosis patients (75.7% female, mean age 16.7 +/- 3.0 y, Cobb 28.7 +/- 11.6 degrees). Among 1432 curves (88.1%) detected by ultrasound, there was good correlation between radiologic Cobb angles measured manually on EOS (E_Cobb) whole-spine radiographs and automatic ultrasound SPA measurement for upper spinal curves (USCs) (r = 0.873, apices T7-T12/L1 intervertebral disc) and lower spinal curves (LSCs) (r = 0.740, apices L1 or below) (p < 0.001). Taller stature was associated with stronger correlation. For E_Cobb <30 degrees, 66.6% USCs and 62.4% LSCs had absolute differences between E_Cobb and predicted Cobb angle calculated from SPA <= 5 degrees. Ultrasound could be a viable option in lieu of radiography for mea- suring coronal curves with apices at T7 or lower and Cobb angle <30 degrees.