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. 2023 Apr 25;13(9):1540.
doi: 10.3390/diagnostics13091540.

Radiation Dose Reduction for Coronary Artery Calcium Scoring Using a Virtual Noniodine Algorithm on Photon-Counting Detector Computed-Tomography Phantom Data

Nicola Fink  1   2 , Emese Zsarnoczay  1   3 , U Joseph Schoepf  1 , Jim O'Doherty  1   4 , Joseph P Griffith 3rd  1 , Daniel Pinos  1 , Christian Tesche  1   5 , Jens Ricke  2 , Martin J Willemink  6 , Akos Varga-Szemes  1 , Tilman Emrich  1   7   8
Affiliations

Radiation Dose Reduction for Coronary Artery Calcium Scoring Using a Virtual Noniodine Algorithm on Photon-Counting Detector Computed-Tomography Phantom Data

Nicola Fink et al. Diagnostics (Basel). .

Abstract

Background: On the basis of the hypothesis that virtual noniodine (VNI)-based coronary artery calcium scoring (CACS) is feasible at reduced radiation doses, this study assesses the impact of radiation dose reduction on the accuracy of this VNI algorithm on a photon-counting detector (PCD)-CT. Methods: In a systematic in vitro setting, a phantom for CACS simulating three chest sizes was scanned on a clinical PCD-CT. The standard radiation dose was chosen at volumetric CT dose indices (CTDIVol) of 1.5, 3.3, 7.0 mGy for small, medium-sized, and large phantoms, and was gradually reduced by adjusting the tube current resulting in 100, 75, 50, and 25%, respectively. VNI images were reconstructed at 55 keV, quantum iterative reconstruction (QIR)1, and at 60 keV/QIR4, and evaluated regarding image quality (image noise (IN), contrast-to-noise ratio (CNR)), and CACS. All VNI results were compared to true noncontrast (TNC)-based CACS at 70 keV and standard radiation dose (reference). Results: INTNC was significantly higher than INVNI, and INVNI at 55 keV/QIR1 higher than at 60 keV/QIR4 (100% dose: 16.7 ± 1.9 vs. 12.8 ± 1.7 vs. 7.7 ± 0.9; p < 0.001 for every radiation dose). CNRTNC was higher than CNRVNI, but it was better to use 60 keV/QIR4 (p < 0.001). CACSVNI showed strong correlation and agreement at every radiation dose (p < 0.001, r > 0.9, intraclass correlation coefficient > 0.9). The coefficients of the variation in root-mean squared error were less than 10% and thus clinically nonrelevant for the CACSVNI of every radiation dose. Conclusion: This phantom study suggests that CACSVNI is feasible on PCD-CT, even at reduced radiation dose while maintaining image quality and CACS accuracy.

Keywords: calcium scoring; computed tomography; coronary artery disease; photon-counting detector; radiation dose; virtual noniodine.

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Conflict of interest statement

U.J.S. receives institutional research support and/or personal fees from Bayer, Bracco, Elucid Bioimaging, Guerbet, HeartFlow, Inc., Keya Medical, and Siemens. A.V.-S. receives institutional research support and/or personal fees from Bayer, Elucid Bioimaging and Siemens. T.E. received a speaker fee and travel support from Siemens Medical Solutions USA Inc. J.O. is an employee of Siemens Medical Solutions USA Inc. C.T. has received speaker’s fees from Siemens Healthineers, Heartflow Inc., and AstraZeneca.

Figures

Figure 1
Figure 1
Comparison of (A) image noise levels (SD background) and (B) contrast-to-noise ratio between VNI (55 keV, QIR 1 and 60 keV, QIR 4, respectively) and TNC (70 keV, QIR off) reconstructions. Range of INTNC and CNRTNC at dose level 100 to 25% highlighted in green. Recommended Image Noise Target: 20 HU in small/medium phantoms (T1) and 23 HU in large phantoms (T2), respectively [33]. **** p < 0.0001. CNR = contrast-to-noise ratio; HU = Hounsfield units; IN = image noise; QIR = quantum iterative reconstruction; SD = standard deviation; VNI = virtual noniodine.
Figure 2
Figure 2
Comparison of Agatston scores between CACSVNI (55 keV, QIR 1 and 60 keV, QIR 4, respectively) at different radiation dose levels and CACSTNC (70 keV, QIR off) at standard radiation dose. ns = not significant; QIR = quantum iterative reconstruction; TNC = true noncontrast; VNI = virtual noniodine.
See this image and copyright information in PMC

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