Quality Research Of Optimal Mono-energy HDCT With ASIR Reconstruction In Coronary CT Angiography

Objective: To evaluate the difference of polychromatic and mono-energy reconstruction images with ASIR reconstruction in coronary CT angiography and,measured and analyzed objectively index CT value,CNR and noise, and subjective image quality scores. To determine the optimal reconstruction mode.Methods: 30 patients(heart rate <70 bpm)with suspected coronary artery disease underwent CT coronary angiography(CCTA) with dual energy spectral mode(Discovery CT 750 HD, GE healthcare). GSI viewer was used to obtain the ‘optimal CNR’ monochromatic images and reconstructed the optimal CNR monochromatic images with 40%ASi R and polychromatic images(140KVp).The image quality after reconstruction were scored for comparisons and analyses of the objective evaluation indices(CT attenuation value,image noise and contrast-to-noise ratio of proximal portion of aorta, proximal segment of left anterior descending branch, proximal segment of left circumflex artery branch and proximal segment of right coronary artery) for two groups.Results: The optimal monochromatic level was(65.46±0.74 ke V), which had the highest CNR. Compared with polychromatic images, image noise of the optimal monochromatic images(65kev) was reduced by 12.73%, the CT attenuation value and the CNR of optimal monochromatic images was increased by 30.15% and 96.03%.Conclusion: The optimal Mono-energy using the gem spectrum CT coronary artery angiography with 40% blending level of ASi R is able to provide better image quality than using conventional CCTA. Monochromatic imaging at 65 ke V provided the best image quality for cardiac spectral CT imaging. It can be used for clinical diagnosis. 65 ke V monochromatic imaging could be used routinely as a protocol for coronary artery CTA exam.