Purpose: To perform intra-individual comparison of CT parameters, image quality, and radiation exposure between standard computed tomography angiography (CTA) and high-pitch dual source CTA, in subjects undergoing serial CTA of thoraco-abdominal aorta.
Methods: Eighteen subjects with thoraco-abdominal CTA by standard CTA (single source) and high-pitch DS-CTA technique within 6 months of each other were retrieved for intra-individual comparison of image quality in thoracic and abdominal aorta. Quantitative analysis was performed by comparison of mean aortic attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative analysis was performed by visual assessment of motion artifacts (MA) and diagnostic confidence (DC). Radiation exposure was quantified by effective dose (ED). Image quality was apportioned to radiation exposure by means of figure of merit (FOM). Wilcoxon paired rank test and chi-square test were used for comparison between the two CTA techniques, a p < 0.05 was deemed statistically significant.
Results: Mean aortic attenuation and noise were higher in high-pitch DS-CTA of thoraco-abdominal aorta, whereas SNR and CNR were similar in thoracic aorta and significantly lower in high-pitch DS-CTA of abdominal aorta (p=0.024 and p=0.016). High-pitch DS-CTA was significantly better in the first segment of thoracic aorta. ED was reduced by 72% in high-pitch DS-CTA.
Conclusion: High-pitch DS-CTA without ECG-gating is an effective technique for imaging aorta with very low radiation exposure and with significant reduction of motion artifacts in ascending aorta, however the overall quality of high-pitch DS-CTA in abdominal aorta is lower than standard CTA.