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Abstract 17178: Adaptive Statistical Iterative Reconstruction V: Impact on Image Quality in Ultra-low-dose Coronary Computed Tomography Angiography


 Introduction:
 To accomplish a further decrease in radiation dose for coronary CT angiography (CCTA), advances in iterative reconstruction (IR) algorithms are necessary. The purpose of the present study was to investigate the impact of a latest generation adaptive statistical IR algorithm (ASiR-V, GE Healthcare) on CCTA signal intensity, noise and image quality (IQ).
 
 
 Methods:
 Sixty-five consecutive patients underwent clinically indicated CCTA using a latest generation 256-slice CT scanner (Revolution CT, GE Healthcare) and an ultra-low-dose CCTA protocol (i.e. a BMI-adapted tube current of 180-310 mA and tube voltage of 80-120 kVp). Datasets from each patient were reconstructed at different levels of ASiR-V (i.e. ASiR-V 0% [= filtered back projection, FBP], 20%, 40%, 60%, 80% and 100%). The signal intensity and noise (i.e. attenuation and its standard deviation [in HU]) were measured in each reconstruction by placing a region of interest in the aortic root as well as the proximal RCA and LMA. Furthermore, IQ was assessed for each coronary segment on a 5-point Likert scale by two blinded readers.
 
 
 Results:
 The ultra-low-dose CCTA protocol resulted in a median radiation dose of 0.49 mSv (IQR 0.40-0.60). Signal intensity in the LMA and RCA slightly but significantly decreased with increasing levels of ASiR-V (Table). Nevertheless, the substantial decrease in image noise resulted in a significant increase in signal-to-noise ratio (SNR) in the RCA and LMA. Correspondingly, IQ significantly increased with higher levels of ASiR-V. Applying ASiR-V at a level of 100% led to a 141-143% increase in SNR and a substantial increase in IQ compared to FBP. Of note, for reconstructions with ASiR-V 100%, a significant increase in IQ was even observed when compared to ASiR-V 80%.
 
 
 Conclusions:
 Increasing ASiR-V levels offer substantial image noise reduction and improved IQ for CCTA datasets acquired at low tube voltage and current, enabling application of ultra-low-dose CCTA protocols.
 
 
 
