Çift Enerjili Kardiyak Bilgisayarlı Tomografi ile Farklı Kontrast Madde Protokollerinin Görüntü Kalitesinin Karşılaştırılması
Özet
The purpose of this study was to compare the quality of dual-energy cardiac CT images applied with different protocols created by varying the amount of contrast agent and injection rate, according to polyenergetic and virtual monochromatic energy levels.
Patients referred for cardiac CT for the diagnosis or follow-up of coronary artery disease between January 1, 2022, and September 15, 2022, were included in our study. The study included four contrast protocol groups and 50 patients in each group, a total of 200 patients and 200 examinations. All acquisitions were made with a dual-source dual-energy CT device that allows the creation of monoenergetic images between 40-140 keV (10 keV intervals). Contrast attenuation (HU) and noise from the aortic root; HU, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) measurements were made from mid-distal parts of the left anterior descending, circumflex and right coronary arteries in all patients. A 5-point Likert scale was used for the subjective assessment of image quality.
In monoenergetic images, in all contrast groups, in the aorta, the highest contrast attenuation was at 40 keV, and the lowest contrast attenuation was at 140 keV; the highest noise was at 40 keV, and the lowest noise was at 110 keV. Additionally, in monoenergetic images, in all contrast groups, the highest contrast attenuation was at 40 keV, and the lowest was at 140 keV in all three coronary arteries. Furthermore, in monoenergetic images, while the highest CNR value was reached at 90 keV in all three coronary arteries in all contrast groups, the highest SNR values were at different energy levels for all three arteries in different groups.
Additional analyses involving patients who achieved diagnostic coronary attenuation (200-750 HU) in monoenergetic images, were performed only at the 40, 50, and 60 keV levels, where the sufficient number of patients were reached for statistically significant comparison. In all three coronary arteries, the highest SNR and CNR values in all contrast groups were at 60 keV, and the lowest values were at 40 keV. The differences in contrast attenuation and CNR values among the energy levels were significant in all three coronary arteries in all groups. On the other hand, in SNR values, the differences among the energy levels were statistically significant except for the difference between 50 and 60 keV for all three coronary arteries in group 3, and between 40 and 50 keV for the circumflex artery in group 2.
In conclusion, with different contrast agent protocols, adequate diagnostic enhancement in coronary arteries can be obtained in dual-energy cardiac CT at monoenergetic 40-60 keV levels.While evaluating the coronary arteries with monoenergetic imaging, starting the examination with 60 keV images will provide the ideal and most rapid result.
