Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D).

Hesong Shen,Guochao Dai,Dan Liang,Chaijie Duan,Wenli Cai,Dongyun Zhu,Jianping Qiu,Xinhua Wang,Mingyue Luo,Wenru Li,Qinghui Zhang

doi:10.1371/journal.pone.0142185

Abstract

PurposeTo investigate image quality and radiation dose of CT coronary angiography (CTCA) scanned using automatic tube current modulation (ATCM) and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D).MethodsEighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP) respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product.ResultsCompared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05); compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001). Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%), 486 (96.4%), and 394 (93.8%) in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%), 472 (93.7%), 378 (90.0%), respectively; those for FBP were 217 (64.6%), 173 (34.3%), 114 (27.1%), respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5%) were higher than those of standard AIDR3D (1182, 93.8%) and FBP (504, 40.0%); the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001). The mean effective radiation dose was (2.55±1.21) mSv.ConclusionCompared with standard AIDR3D and FBP, CTCA with ATCM and strong AIDR3D could significantly improve both quantitative and qualitative image quality.

Highlights

CT coronary angiography (CTCA) has become the primary noninvasive imaging modality that enables accurate diagnosis or exclusion of coronary artery disease
Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), their differences were all statistically significant (P
Adaptive iterative dose reduction threedimensional (AIDR3D) is an iterative reconstruction method developed by Toshiba Medical Systems, which incorporates the statistical and scanner models for projection data, and multiple cycles of iteration for noise reduction until the desired noise level is achieved [8,9,10,11]

Summary

Introduction

CT coronary angiography (CTCA) has become the primary noninvasive imaging modality that enables accurate diagnosis or exclusion of coronary artery disease. To reduce the radiation dose in CTCA imaging while maintaining diagnostic image quality, a number of approaches were developed including prospective electrocardiogram-triggered acquisition, heart rate reduction, denoising, high-pitch helical scanning, minimized z-axis scan range, tube voltage reduction, electrocardiogram-based tube current modulation, automatic tube current modulation (ATCM), and new iterative reconstruction methods [4,5,6,7]. Adaptive iterative dose reduction threedimensional (AIDR3D) is an iterative reconstruction method developed by Toshiba Medical Systems, which incorporates the statistical and scanner models for projection data, and multiple cycles of iteration for noise reduction until the desired noise level is achieved [8,9,10,11]. AIDR3D is expected to overcome the intrinsic limitations of conventional filtered back-projection (FBP) reconstruction, reduce image noise and improve image quality [12,13,14]. AIDR3D has three predetermined strength modes: mild, standard and strong, which define different blending ratio of AIDR3D and FBP in the iterative reconstruction process

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Conclusion