Optimization of energy level for coronary angiography with dual-energy and dual-source computed tomography

Dual-energy computed tomography (DE-CT) uses polyenergetic X-rays at 100- and 140-kVp tube energy, and generates 120-kVp composite images that are referred to as polyenergetic images (PEIs). Moreover, DE-CT can produce monoenergetic images (MEIs) at any effective energy level. We evaluated whether the image quality of coronary angiography is improved by optimizing the energy levels of DE-CT. We retrospectively evaluated data sets obtained from 24 consecutive patients using cardiac DE-CT at 100- and 140-kVp tube energy with a dual-source scanner. Signal-to-noise ratios (SNRs) were evaluated in the left ascending coronary artery in PEIs, and in MEIs reconstructed at 40, 50, 60, 70, 80, 90, 100, 130, 160 and 190 keV. Energy levels of 100, 120 and 140 kVp generated the highest SNRs in PEIs from 10, 12 and 2 patients, respectively, at 60, 70 and 80 keV in MEIs from 2, 10 and 10 patients, respectively, and at 90 and 100 keV in those from one patient each. Optimization of the energy level for each patient increased the SNR by 16.6% in PEIs (P < 0.0001) and by 18.2% in MEIs (P < 0.05), compared with 120-kVp composite images. The image quality of coronary angiography using DE-CT can be improved by optimizing the energy level for individual patients.