Cardiovasc Imaging Asia.  2023 Oct;7(4):39-48. 10.22468/cvia.2023.00073.

Initial Clinical Experience With Coronary CT Angiography Performed on Dual Source Photon Counting CT Using Different Cardiac Scan Modes-Analysis of Image Quality and Radiation Dose

• Hoe J
• Toh KH

• KMID: 2551118
• DOI: http://doi.org/10.22468/cvia.2023.00073

Abstract

Objective
To assess experience with coronary computed tomography angiography (CTA) performed on a dual source photon counting computed tomography scanner during first installation, using different cardiac scan modes.
Materials and Methods
A total of 92 patients (mean body mass index 25.5 kg/m² ) were scanned with either High resolution (UHR) mode, 0.2 mm scan thickness, using 120 kV, and spiral method, or Quantum mode, 0.4 mm scan thickness, using 90 kV with spectral virtual monoenergetic images reconstructed. Signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated. Qualitative assessment of image quality, noise, stent image quality was performed by 2 independent readers.
Results
Overall mean SNR was 25.51±6.78, CNR 29.62±7.92. Qualitative overall mean image quality was assessed as near excellent (3.84 out of 4-point Likert scale; κ=0.85 [near perfect agreement]) and almost no noise on the images (3.63; κ=0.81). Calcium scoring was performed (in 74 patients) with mean radiation dose of 0.37 mSv±0.16 mSv. Overall mean radiation dose of coronary CTA was 5.85 mSv±2.62 mSv (range 0.49–15.09 mSv). Mean radiation dose of UHR scans (in 49 patients or 53.2%) was 7.22 mSv±2.39 mSv. Mean dose for Quantum FLASH (3 patients) was 0.78 mSv±0.26 mSv, Quantum Sequential (36 patients) was 4.29 mSv±1.55 mSv, and Quantum Spiral (4 patients) was 6.25 mSv±1.56 mSv.
Conclusion
Image quality of scans was near excellent with almost no noise. Radiation dose is dependent on the scan mode used. UHR scan mode should not be used for routine cases but reserved for patients with stents and large calcified plaques. Quantum mode using FLASH or sequential method may be the preferred mode for scanning routine cases, as it allows lower radiation dose scans while maintaining image quality.

Keyword

Photon counting CT; Cardiac CT; CT Computed tomography angiography; Radiation dosage