Is radiation-free diagnostic monitoring of adolescent idiopathic scoliosis feasible using upright positional magnetic resonance imaging?

Prospective clinical trial. The purpose of this study was to determine if an upright positional magnetic resonance imaging (MRI) protocol could produce reliable spinal curvature images and measurements compared with traditional radiograph. Concerns about the oncological potential from cumulative doses of ionizing radiation in children and adolescents being monitored for adolescent idiopathic scoliosis (AIS) initiated a search for radiation-free diagnostic imaging modalities, including MRI. We submit that upright, positional MRI (uMRI) produces reliable spinal curvature images compared with traditional radiograph. Twenty-five consecutive patients (16 female; 9 male; average age, 14.6 yr; range, 12-18 yr) with a diagnosis of AIS were enrolled. Average major curve magnitude was 30° (range, 6°-70°). Subjects received anterior-posterior and lateral plain radiographical scoliosis imaging followed within 1 week by uMRI. MRI data acquisition was performed in less than 7 minutes. Two independent observers performed all Cobb angle, T5-T12 kyphosis, and vertebral rotation measurements for comparison. The Pearson correlation method was performed to compare radiograph to uMRI measurements, while inter-rater and intrarater correlations were performed to assess reliability. We found outstanding correlation between all plain film radiography and uMRI measurements (P = 0.01); major Cobb angles (R = 0.901), minor Cobb angles (R = 0.838), and kyphosis (R = 0.943). Inter-rater reliability for both radiographical and MRI measurements of major Cobb angles (R = 0.959, 0.896, respectively), minor Cobb angles (R = 0.951, 0.857, respectively), and vertebral rotation (R = 0.945) were outstanding. Intrarater reliability for both radiographical and MRI measurements of major Cobb angles (R = 0.966, 0.966, respectively) and minor Cobb angles (R = 0.945, 0.943, respectively) were also outstanding. Our results show that uMRI is capable of producing coronal and sagittal plane measurements that highly correlate with traditional plain film radiographical measurements. This, in addition to reliable vertebral rotation measurements, makes uMRI a valuable, radiation-free alternative/substitute for diagnostic evaluation in AIS.