双能CT成像评价冠状动脉钙化斑块的体模研究

Objective: To analyze the impact of dual energy monochromatic reconstructions (50-160 keV) on coronary calcified plaque stenosis quantification in a cardiac phantom with the real stenosis as standard of reference. Methods: Signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. In conventional 120 kV coronary CT angiography (CCTA) images as well as 12 monochromatic series (50-160 keV), luminal narrowing of calcified plaque was measured and compared to the real stenosis. Bland-Altman plots were performed to analyze the correlation of reference standard with conventional 120 kV and 12 monochromatic series (50-160 keV). The sensitivity, specificity, and accuracy of CCTA for detection of ≥50% stenosis were calculated and receiver operating characteristic (ROC) curve was analyzed with the real stenosis as reference standard. Results: The SNR and CNR were decreased with the increase of keV from 70 keV. The SNR and CNR of monochromatic imaging were lower compared with conventional 120 kV images (SNR: 76.4±16.1;CNR: 274.7±54.1)(P<0.05). The Bland-Altman plots presented a smaller measurement bias towards 90-160 keV than conventional 120 kV, and smallest measurement bias was revealed in 100-130 keV imaging (100-130 keV: bias 17.2% vs 120 kV: 21.4%). Using the stenosis ≥50% as cut-off value, the specificity were higher in the monochromatic series (70-160 keV) than conventional 120 kV CCTA. The specificity (75.0%) were the highest in the 120 keV and 130 keV images. The area under the ROC curve (AUC) of 90-130 keV (0.991-0.995) was higher than that in conventional 120 kV imaging (0.990). Conclusions: The use of monochromatic imaging improves the overall accuracy of stenosis evaluation in coronary calcified plaques. Reconstructions at 100-130 keV for calcified lesions yielded the optimal results.