Dose optimized computed tomography of the cervical spine in patients with shoulder pull down: Is image quality comparable with a standard dose protocol in an emergency setting?
PURPOSE Superimposing soft tissue and bony structures in computed tomography (CT) of the cervical spine (C spine) is a limiting factor in optimizing radiation exposure maintaining an acceptable image quality. Therefore, we assessed image quality of dose optimized (DO) C spine CT in patients capable of shoulder pull down in an emergency setting. METHODS AND MATERIALS DO CT (105mAs/120 kVp) of the C spine in trauma settings was performed in patients with shoulder pull down if C5 was not superimposed by soft tissue on the lateral topogram, otherwise standard dose (SD) CT (195 mAs/120 kVp) was performed. 34 DO (mean age, 68y 21; BMI, 24.2 kg/m2 3.2) and 34 SD (mean age 70y 19; BMI 25.7 kg/m2 4.4) iterative reconstructed CTs were evaluated at C2/3 and C6/7 by two musculoskeletal radiologists. Qualitative image noise and morphological characteristics of bony structures (cortex, trabeculae) were assessed on a Likert scale. Quantitative image noise was measured and effective dose (ED) was recorded. Parameters were compared using Mann Whitney U test (p 0.05) RESULTS At C2/3, DO CT vs. SD CT yielded comparable qualitative noise (mean, 1.3 vs. 1.0; p 0.18) and morphological characteristics, but higher quantitative noise (27.2 8.8HU vs. 19.6 4.5HU; p 0.001) At C6/7, DO CT yielded lower subjective noise (1.9; SD CT 2.2; p 0.017) and better morphological characteristics with higher visibility scores for cortex (p 0.001) and trabeculae (p 0.03) Quantitative noise did not differ (p 0.24) Radiation dose was 51% lower using DO CT (EDDO CT 0.80 0.1 mSv; EDSD CT 1.63 0.2 mSv; p 0.001) CONCLUSION C spine CT with dose reduction of 51% showed no image quality impairment. Additional pull down of both shoulders allowed better image quality at lower C spine segments as compared to a standard protocol.
European journal of radiology