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A Hybrid Iterative Reconstruction Algorithm That Improves the Image Quality of Low-Tube-Voltage Coronary CT Angiography
American Journal of Roentgenology, 05/10/2012
Oda S et al. – The hybrid iterative reconstruction (HIR) algorithm can reduce image noise and improve image quality at low–tube–voltage coronary CT angiography (CTA).
Methods- Eighteen patients (seven men, 11 women; mean age, 67.8 years) underwent retrospectively gated coronary CTA at 80 kV with a volume CT dose index (CTDIvol) of 18.8 mGy on a 64-MDCT scanner.
- CT images were reconstructed using only FBP and only HIR.
- For each patient, CT images subjected to the two different reconstructions were reviewed by two observers.
- Quantitative image quality parameters—that is, CT attenuation (HU) of the coronary arteries, image noise, and contrast-to-noise ratio (CNR)—were calculated and compared for the two reconstruction methods and the overall image quality for each reconstruction was visually scored on a 5-point scale.
- The mean estimated effective radiation dose for 80-kV coronary CTA was 4.7 ± 0.4 (SD) mSv.
- The two reconstruction methods did not significantly differ with respect to the CT attenuation of the coronary arteries.
- The image noise was significantly lower with HIR than with FBP (20.3 ± 5.3 vs 49.4 ± 12.0 HU, respectively; p < 0.01), and the CNR was significantly higher with HIR than with FBP (29.8 ± 7.4 vs 12.7 ± 2.9, p < 0.01).
- The visual scores for image quality were higher with HIR than with FBP (p < 0.01).
