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. 2021 Jan;11(1):392-401.
doi: 10.21037/qims-20-626.

Deep learning reconstruction versus iterative reconstruction for cardiac CT angiography in a stroke imaging protocol: reduced radiation dose and improved image quality

Angélique Bernard  1 , Pierre-Olivier Comby  1 , Brivaël Lemogne  1 , Karim Haioun  2 , Frédéric Ricolfi  1 , Olivier Chevallier  3 , Romaric Loffroy  3
Affiliations

Deep learning reconstruction versus iterative reconstruction for cardiac CT angiography in a stroke imaging protocol: reduced radiation dose and improved image quality

Angélique Bernard et al. Quant Imaging Med Surg. 2021 Jan.

Abstract

Background: To assess the radiation dose and image quality of cardiac computed tomography angiography (CCTA) in an acute stroke imaging protocol using a deep learning reconstruction (DLR) method compared to a hybrid iterative reconstruction algorithm.

Methods: Retrospective analysis of 296 consecutive patients admitted to the emergency department for stroke suspicion. All patients underwent a stroke CT imaging protocol including a non-enhanced brain CT, a brain perfusion CT imaging if necessary, a CT angiography (CTA) of the supra-aortic vessels, a CCTA and a post-contrast brain CT. The CCTA was performed with a prospectively ECG-gated volume acquisition. Among all CT scans performed, 143 were reconstructed with an iterative reconstruction algorithm (AIDR 3D, adaptive iterative dose reduction three dimensional) and 146 with a DLR algorithm (AiCE, advanced intelligent clear-IQ engine). Image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality (IQ) scored from 1 to 4 were assessed. Dose-length product (DLP), volume CT dose index (CTDIvol) and effective dose (ED) were obtained.

Results: The radiation dose was significantly lower with AiCE than with AIDR 3D (DLP =106.4±50.0 vs. 176.1±37.1 mGy·cm, CTDIvol =6.9±3.2 vs. 11.5±2.2 mGy, and ED =1.5±0.7 vs. 2.5±0.5 mSv) (P<0.001). The median SNR and CNR were higher [9.9 (IQR, 8.1-12.3); and 12.6 (IQR, 10.5-15.5), respectively], with AiCE than with AIDR 3D [6.5 (IQR, 5.2-8.5); and 8.4 (IQR, 6.7-11.0), respectively] (P<0.001). SNR and CNR were increased by 51% and 49%, respectively, with AiCE compared to AIDR 3D. The image quality was significantly better with AiCE (mean IQ score =3.4±0.7) than with AIDR 3D (mean IQ score =3±0.9) (P<0.001).

Conclusions: The use of a DLR algorithm for cardiac CTA in an acute stroke imaging protocol reduced the radiation dose by about 40% and improved the image quality by about 50% compared to an iterative reconstruction algorithm.

Keywords: Computed tomography angiography (CTA); artificial intelligence; cardiac imaging; deep learning; image reconstruction.

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Conflict of interest statement

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-626). KH works as a CT Clinical Research Scientist for Canon Medical Systems Europe. RL serves as an unpaid Deputy Editor for Quantitative Imaging in Medicine and Surgery. The other authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Scan plan protocol for the carotid (blue box) and the cardiac (yellow box) computed tomography acquisition.
Figure 2
Figure 2
Flow chart of the population study.
Figure 3
Figure 3
Examples of cardiac computed tomography scans in two patients with same weight of 60 kg. (A) AIDR 3D with a DLP of 202.1 mGy·cm and CTDIvol of 12.6 mGy, and (B) AiCE with a DLP of 23.3 mGy·cm and CTDIvol of 1.7 mGy. AIDR 3D, adaptive iterative dose reduction three dimensional; DLP, dose-length product; AiCE, advanced intelligent clear-IQ engine.
Figure 4
Figure 4
Left atrial appendage thrombus on cardiac computed tomography in two patients with same weight of 60 kg. (A) AIDR 3D with a DLP of 177.3 mGy·cm and CTDIvol of 11.1 mGy, and (B) AiCE with a DLP of 42.1 mGy·cm and CTDIvol of 2.6 mGy. AIDR 3D, adaptive iterative dose reduction three dimensional; DLP, dose-length product; AiCE, advanced intelligent clear-IQ engine.
Figure 5
Figure 5
Box-plots comparing AIDR 3D and AiCE algorithms. (A) Dose-length product (DLP) (mGy·cm), (B) volume computed tomography dose index (CTDIvol) (mGy), (C) effective dose (ED) (mSv). AIDR 3D, adaptive iterative dose reduction three dimensional; AiCE, advanced intelligent clear-IQ engine.
See this image and copyright information in PMC

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