Vergleich von konventioneller wirbelsäulenganzaufnahme und fluoroskopischer scan-methode bei jungen patienten mit idiopathischer skoliose

Purpose: Evaluation of low-dose full spine radiographs using fluoroscopic images for the assessment of the Cobb angle measurement in patients with scoliosis. Material and Methods: Twenty-one consecutive patients (aged 10-27 years, mean age 14 years) with a conventional full spine examination (film speed class 800) underwent a follow-up exam using digital pulsed fluoroscopy (Multi Diagnost 4, Philips Medical Systems, Eindhoven, The Netherlands). The mean follow-up was 9 months. During a synchronized scan with a C-arm speed of 4 cm/sec fluoroscopic images were stored with a pulsed frequency of 3 images per second. The single images were merged and reconstructed to one image with the software Easy Spine (Philips medical Systems, Eindhoven, The Netherlands). The corresponding dose-area product values (DAP) of both methods were compared. Three independent observers assessed Cobb angles and image quality for each technique. Results: The mean DAP values for conventional imaging was 94.9 cGy × cm² and for fluoroscopy 7.8 cGy × cm², respectively. A significant dose reduction of 91.8% (CI 91% to 95%) was calculated. The average absolute angle difference between the observers was found to be 2.7° for conventional imaging and 2.4° for the fluoroscopic method. Interobserver standard deviation of 2.9° was lower than the 5.3° for conventional images. Image quality was better in the conventional images. Conclusion: Using the scanning method, we could achieve a mean reduction of the radiation dose of 92%, while the accuracy of the Cobb angle measurements was comparable for both techniques despite of reduced image quality of digital fluoroscopy.