Kazuhito Nozu MD, Presenter: Nothing to Disclose

Yasuyuki Kobayashi MD, PhD, Abstract Co-Author: Nothing to Disclose

Sou Oode MD, Abstract Co-Author: Nothing to Disclose

Yasuyoshi Ogawa RT, Abstract Co-Author: Nothing to Disclose

Kiyoko Tateishi, Abstract Co-Author: Nothing to Disclose

Yukihisa Ogawa, Abstract Co-Author: Nothing to Disclose

Yasuo Nakajima MD, Abstract Co-Author: Nothing to Disclose

Coronary computed tomography angiography (CTA) is useful for detecting coronary disease and is clinically performed worldwide. However, the radiation dose is crucial. The application of an iterative reconstruction (IR) algorithm can help decrease the noise, result in radiation dose reduction. However, IR has been reported to have a noise-free appearance with an unusually homogeneous attenuation. This study aimed to investigate the effect of IR on visual and quantitative evaluation of lumen stenosis and diameter with known dimensions using coronary CTA by 320-slice area detector CT.

We used the pulsating heart phantom (HR 40bpm) with acrylic coronary vessel phantoms (FUYO,Tokyo,Japan) and 320 slice CT(Toshiba, Nasu, Japan). Acrylic coronary vessel phantoms with precisely drilled stenosis of mild (25%), moderate (50%), and severe (75%) grades were studied using 320-slice MDCT. Image acquisition was optimized, and images were reconstructed by using filtered back projection (FBP) and AIDR 3D (weak/mild/standard/strong). Stenosis was evaluated visually by blinded expert readers using a four-grade image quality score (IQS), and lumen diameter was quantitatively assessed by using automated lumen contour detection software (Ziosoft, Tokyo, Japan).

IQS was significantly increased in AIDR 3D compared with FBP. AIDR 3D algorithms improved the image quality to a diagnosable level when the SD was less than 45HU in FBP. With quantitative assessment, the error between the real and measured diameter using automated software in AIDR 3D was significantly smaller than that in FBP (AIDR 3D mild; p=0.028, standard; p=0.004, strong; p<0.001). The association between the error and strengthen of AIDR 3D was significant (p<0.001).

AIDR 3D algorithms can reduce a noise, and improve image quality and quantitative accuracy, compared with FBP. 

AIDR 3D algorithms can reduce a noise, and improve image quality and quantitative accuracy, compared with FBP, results in radiation dose reduction. 

Nozu, K, Kobayashi, Y, Oode, S, Ogawa, Y, Tateishi, K, Ogawa, Y, Nakajima, Y, Visual and Quantitative Evaluation of Lumen Stenosis and Diameter with Known Dimensions Using Coronary Computed Tomography Angiography by 320-row Detector CT: Effect of Iterative Reconstruction Assessed By Pulsating Cardiac Phantom.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14005522.html