Published in:
01-01-2015 | Cardiac
A new technique for noise reduction at coronary CT angiography with multi-phase data-averaging and non-rigid image registration
Published in: European Radiology | Issue 1/2015
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Objectives
To investigate the feasibility of a newly developed noise reduction technique at coronary CT angiography (CTA) that uses multi-phase data-averaging and non-rigid image registration.
Methods
Sixty-five patients underwent coronary CTA with prospective ECG-triggering. The range of the phase window was set at 70–80 % of the R–R interval. First, three sets of consecutive volume data at 70 %, 75 % and 80 % of the R–R interval were prepared. Second, we applied non-rigid registration to align the 70 % and 80 % images to the 75 % image. Finally, we performed weighted averaging of the three images and generated a de-noised image. The image noise and contrast-to-noise ratio (CNR) in the proximal coronary arteries between the conventional 75 % and the de-noised images were compared. Two radiologists evaluated the image quality using a 5-point scale (1, poor; 5, excellent).
Results
On de-noised images, mean image noise was significantly lower than on conventional 75 % images (18.3 HU ± 2.6 vs. 23.0 HU ± 3.3, P < 0.01) and the CNR was significantly higher (P < 0.01). The mean image quality score for conventional 75 % and de-noised images was 3.9 and 4.4, respectively (P < 0.01).
Conclusions
Our method reduces image noise and improves image quality at coronary CTA.
Key Points
• We introduce a new method for image noise reduction at cardiac CT.
• Multiple data acquisitions of an object and their averaging yield lower noise.
• Our method uses multi-phase images reconstructed from unused redundant imaging data.
• It reduces image noise by averaging multi-phase images transformed by non-rigid registration.
• This method achieves a 20 % image noise reduction at cardiac CT.