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Optimization of the monochromatic energy in imaging the celiac artery with dual energy spectral CT angiography

Xiaoping Yin, Ziwei Zuo, Huaijun Liu, Yingjin Xu, Xiao Tian, Huan Zhou

To identify the optimal monochromatic energy of the dual energy spectral CT Angiography (CTA) of celiac artery with high image quality. 32 patients were tested by the contrast-enhanced CT with the dual energy spectral imaging mode. Based on the polychromatic data, images of celiac artery were reconstructed at the optimal monochromatic energy, 70 keV monochromatic energy level and the 140 kVp tube voltage. Object evaluation depending on the Contrast-to-Noise Ratio (CNR), the Signal-to- Noise Ratio (SNR), and the Image Noise (IN) for celiac artery, and the subjective evaluation have been used to rank image quality of the above three reconstruction groups. The optimal energy level was determined at 51 keV which gives the highest CNR of 18.74 ± 7.91, while the CNR values for celiac artery in the 70 keV group and the 140 kVp tube voltage group were 13.89 ± 6.27 and 13.14 ± 6.25, respectively. The corresponding SNR values were 21.38 ± 8.39, 17.50 ± 7.12 and 17.19 ± 7.90. The IN values were 27.49 ± 7.48 HU, 17.53 ± 4.56 HU, 15.75 ± 5.34 HU. The subjective score were 4.69 ± 0.24, 4.14 ± 0.24 and 3.71 ± 0.27 for the above 3 groups. CNR, SNR and subjective score for images in the optimal energy group were significantly superior to those in the 70 keV group and the 140 kVp tube voltage group. The optimal monochromatic energy is identified at 51 keV in dual energy spectral CT Angiography (CTA), which significantly improves the image quality of the celiac artery.