Impact of arm position on low dose dual-source CT one-step aortic and cerebral-carotid artery angiography image quality and radiation dose.

Background: Although one-stop cerebral carotid aortic CTA is useful for diagnosing and treating type A aortic dissection, the radiation dose is increased due to the wider scanning range. The impact of varying arm positions on radiation dose and image quality is unknown when optimizing the scan protocol. This study aims to determine the best scanning protocol to minimize radiation dose while maintaining image quality, as well as how arm position impacts radiation dose and image quality of low dose one-stop cerebral carotid aortic CTA.

Methods: Between January 2022 and August 2023,a total of 185 patients were enrolled in the study and underwent low-dose one-stop cerebral carotid aortic CTA. Two groups were randomly assigned to the patients: Rising arm group (group A) and drooping arm group (group B). Two radiologists assessed the subjective image quality using a 5-point scale, and kappa test was performed to evaluate the consistency between observers. Regions of interest (ROI) were set up in target vessels, and the objective image quality was evaluated by attenuation, noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR). Tube current, volumetric CT dose index (CTDIvol) and dose length product (DLP) and the effective radiation dose (E) were compared between the two groups. The comparison was performed using t test.

Results: Subjective image quality of group B was significantly higher than group A (p < 0.05), and the patient characteristics of the two groups did not differ significantly (P > 0.05). The consistency between observers (κ = 0.84 for group A and κ = 0.89 for group B) were excellent. Group B showed lower overall noise level, higher SNR, CNR, and higher vascular attenuation level than group A. Furthermore, group B showed reduced DLP, E, tube current, and CTDIvol, and higher aortic noise and decreased cerebral and carotid vascular noise (all p < 0.05).

Conclusion: Low-dose dual-source one-stop cerebral carotid aortic CTA radiation dose can be minimized and image quality can be improved by positioning both arms on the body side.

Clinical trial number: Not applicable.