A Study of Image Quality and Radiation Dose in Lower Extremity Computed Tomography Angiography Using Caudo-cranial Flash Scanning

Objective: We conducted a comparative study of image quality and radiation dose in CTA angiography of lower extremity arteries with single-source CT cranio-cauda and dual-source CT cranio-cauda Flash scans. Methods: This prospective study enrolled 50 patients with suspected peripheral occlusive arterial disease which required CTA imaging of the lower extremities. Patients were randomly assigned to a control group (P1) or an experimental group (P2). Group P1 was scanned with protocol 1: single-source CT cranio-cauda direction, Group P2 was scanned with protocol 2: dual-source CT cranio-cauda direction Flash. Intravascular CT values, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were compared as a group. Image quality was assessed by two radiologists. CT volume dose index (CTDI_VOI) and dose length product (DLP) were compared as well. Results: Statistical differences were observed between P1 and P2 groups in intravascular CT values, SNR, and CNR at the aorta, external iliac artery, popliteal artery, and anterior tibial artery. No statistically significant difference was seen in intravascular CT values, SNR, or CNR at the femoral artery. The mean intravascular CT value in the P2 group was higher than that in the P1 group ((534.4±25.2) vs. (480.6±143.4)), and showed better consistency in each part. In the subjective evaluation, significant differences were found in image quality scores for the aorta and inferior knee arteries between P1 and P2 groups, but no significant differences between groups were found in image quality scores for the femoral artery and popliteal artery The radiation dose in the P2 group was significantly lower than that in the P1 group, including a 64.0% reduction in CTDIvol ((0.9±0.3) mGy to (0.5±0.3) mGy) and a 63.4% reduction in DLP ((113.5±33.4) mGy·cm to (310.1±53.5) mGy·cm). Conclusion: Lower extremity CTA combined with dual-source CT caudo-cranial Flash scanning yields better quality images in the small arterial system below the knee with higher CT values, SNR, and CNR, and better consistency than single-source CT cranio-cauda scanning. This method also reduces the radiation dose for lower extremity CTA examinations.