Inter-Evaluator Reliability of Sagittal and Rotational Spinal Measurements from 3D Ultrasound Imaging of Healthy Females in Standing with Varying Arm Positions

Spinal alignment can be assessed without radiation using three-dimensional ultrasound imaging (3DUS). Reliable measurements could inform the ideal arm position for scoliosis radiographs. This study determined the inter-evaluator reliability of axial vertebral rotation (AVR) measurements and sagittal curve angles in healthy females from 3DUS spinal images in standing with two common radiograph arm positions: Chin and abduction (Abd). Three novice evaluators (R1, R2, and R3) measured images once. The Bland–Altman bias and limits of agreement (LOA) were calculated. T5-T12 kyphosis measurements met our bias and LOA error threshold only for R1 vs R2 in the Chin position [−0.53° (−10.7,9.7)]. The distance between the bias and the LOA also met our acceptable threshold of 5° for all mean AVRTwist, and all but one AVRTwist measurements (R1-R2_Chin = 5.9°). Three lordosis measurements did not meet our acceptable threshold (R1-R2_Chin, R1-R3_Chin, and R2-R3_Abd). The inter-evaluator reliability of novice evaluators was adequate and did not differ significantly between positions.