The effect of adaptive iterative dose reduction on image quality in 320-detector row CT coronary angiography

Objective: To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA). Methods: 50 patients (14 females, mean age 68 +/- 9 years) who underwent CTCA (100 kV or 120 kV, 400-580mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent). Results: All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4 +/- 3.1 HU vs 36.9 +/- 4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75 +/- 0.38 vs 4.24 +/- 0.38; p<0.001). Conclusion: The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA.