Intra-individual comparison of coronary calcium scoring between photon counting detector- and energy integrating detector-CT: Effects on risk reclassification

Elias V Wolf; Moritz C Halfmann; U Joseph Schoepf; Emese Zsarnoczay; Nicola Fink; Joseph P Griffith 3rd; Gilberto J Aquino; Martin J Willemink; Jim O'Doherty; Michaela M Hell; Pal Suranyi; Ismael M Kabakus; Dhiraj Baruah; Akos Varga-Szemes; Tilman Emrich

doi:10.3389/fcvm.2022.1053398

Intra-individual comparison of coronary calcium scoring between photon counting detector- and energy integrating detector-CT: Effects on risk reclassification

Front Cardiovasc Med. 2023 Jan 19:9:1053398. doi: 10.3389/fcvm.2022.1053398. eCollection 2022.

Authors

Elias V Wolf^{1

2}, Moritz C Halfmann^{1

3}, U Joseph Schoepf², Emese Zsarnoczay^{2

4}, Nicola Fink^{2

5}, Joseph P Griffith 3rd², Gilberto J Aquino², Martin J Willemink^{6

7}, Jim O'Doherty^{2

8}, Michaela M Hell⁹, Pal Suranyi², Ismael M Kabakus², Dhiraj Baruah², Akos Varga-Szemes², Tilman Emrich^{1

2

3}

Affiliations

¹ Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
² Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States.
³ German Centre for Cardiovascular Research, Partner Site Rhine-Main, Mainz, Germany.
⁴ MTA-SE Cardiovascular Imaging Research Group, Medical Imaging Center, Semmelweis University, Budapest, Hungary.
⁵ Department of Radiology, University Hospital Munich, LMU Munich, Munich, Germany.
⁶ Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States.
⁷ Segmed, Inc., Palo Alto, CA, United States.
⁸ Siemens Medical Solutions USA, Inc., Malvern, PA, United States.
⁹ Department of Cardiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.

Abstract

Purpose: To compare coronary artery calcium volume and score (CACS) between photon-counting detector (PCD) and conventional energy integrating detector (EID) computed tomography (CT) in a phantom and prospective patient study.

Methods: A commercially available CACS phantom was scanned with a standard CACS protocol (120 kVp, slice thickness/increment 3/1.5 mm, and a quantitative Qr36 kernel), with filtered back projection on the EID-CT, and with monoenergetic reconstruction at 70 keV and quantum iterative reconstruction off on the PCD-CT. The same settings were used to prospectively acquire data in patients (n = 23, 65 ± 12.1 years), who underwent PCD- and EID-CT scans with a median of 5.5 (3.0-12.5) days between the two scans in the period from August 2021 to March 2022. CACS was quantified using a commercially available software solution. A regression formula was obtained from the aforementioned comparison and applied to simulate risk reclassification in a pre-existing cohort of 514 patients who underwent a cardiac EID-CT between January and December 2021.

Results: Based on the phantom experiment, CACS _PCD-CT showed a more accurate measurement of the reference CAC volumes (overestimation of physical volumes: PCD-CT 66.1 ± 1.6% vs. EID-CT: 77.2 ± 0.5%). CACS _EID-CT and CACS _PCD-CT were strongly correlated, however, the latter measured significantly lower values in the phantom (CACS _PCD-CT : 60.5 (30.2-170.3) vs CACS _EID-CT 74.7 (34.6-180.8), p = 0.0015, r = 0.99, mean bias -9.7, Limits of Agreement (LoA) -36.6/17.3) and in patients (non-significant) (CACS _PCD-CT : 174.3 (11.1-872.7) vs CACS _EID-CT 218.2 (18.5-876.4), p = 0.10, r = 0.94, mean bias -41.1, LoA -315.3/232.5). The systematic lower measurements of Agatston score on PCD-CT system led to reclassification of 5.25% of our simulated patient cohort to a lower classification class.

Conclusion: CACS _PCD-CT is feasible and correlates strongly with CACS _EID-CT , however, leads to lower CACS values. PCD-CT may provide results that are more accurate for CACS than EID-CT.

Keywords: coronary artery calcium scoring (CACS); coronary artery disease; energy-integrating detector computed tomography; photon-counting detector computed tomography; risk stratification.

Grants and funding

This work was supported by a research grant from Siemens Healthineers. The MAInz-DOC Doctoral College and the Kaltenbach Doctoral Scholarship of the German Heart Foundation supported EVW.