Performance of Spectral Photon-Counting Coronary CT Angiography and Comparison with Energy-Integrating-Detector CT: Objective Assessment with Model Observer.

David C Rotzinger,Elias Lahoud,Joël Greffier,Damien Racine,Yoad Yagil,Fabio Becce,Reto A Meuli,Pascal Monnin,Loïc Boussel,Salim A Si-Mohamed,Anaïs Viry,Philippe C Douek,Klaus Erhard

doi:10.3390/diagnostics11122376

Abstract

Aims: To evaluate spectral photon-counting CT’s (SPCCT) objective image quality characteristics in vitro, compared with standard-of-care energy-integrating-detector (EID) CT. Methods: We scanned a thorax phantom with a coronary artery module at 10 mGy on a prototype SPCCT and a clinical dual-layer EID-CT under various conditions of simulated patient size (small, medium, and large). We used filtered back-projection with a soft-tissue kernel. We assessed noise and contrast-dependent spatial resolution with noise power spectra (NPS) and target transfer functions (TTF), respectively. Detectability indices (d’) of simulated non-calcified and lipid-rich atherosclerotic plaques were computed using the non-pre-whitening with eye filter model observer. Results: SPCCT provided lower noise magnitude (9–38% lower NPS amplitude) and higher noise frequency peaks (sharper noise texture). Furthermore, SPCCT provided consistently higher spatial resolution (30–33% better TTF10). In the detectability analysis, SPCCT outperformed EID-CT in all investigated conditions, providing superior d’. SPCCT reached almost perfect detectability (AUC ≈ 95%) for simulated 0.5-mm-thick non-calcified plaques (for large-sized patients), whereas EID-CT had lower d’ (AUC ≈ 75%). For lipid-rich atherosclerotic plaques, SPCCT achieved 85% AUC vs. 77.5% with EID-CT. Conclusions: SPCCT outperformed EID-CT in detecting simulated coronary atherosclerosis and might enhance diagnostic accuracy by providing lower noise magnitude, markedly improved spatial resolution, and superior lipid core detectability.

Highlights

Since its inception in 1973, computed tomography (CT) has undergone steady improvements on both the data acquisition and image reconstruction aspects, quickly becoming a key player in cardiovascular imaging and establishing itself as the primary non-invasive coronary artery disease assessment tool [1]
dual-energy CT (DECT) suffers from some fundamental limitations, including the absence of notable improvement in spatial resolution or electronic noise compared with single-energy systems, which could be addressed by photon-counting-detector (PCD) technology [7]
Contrary to conventional energy-integrating detectors (EID)—which are used in single-energy and DECT systems—that measure the total energy deposited in the detector, PCDs quantify the energy of each incident photon according to two or more thresholds called “energy bins” and can be produced with a much smaller detector element size to increase spatial resolution

Summary

Introduction

Since its inception in 1973, computed tomography (CT) has undergone steady improvements on both the data acquisition and image reconstruction aspects, quickly becoming a key player in cardiovascular imaging and establishing itself as the primary non-invasive coronary artery disease assessment tool [1]. Contrary to conventional energy-integrating detectors (EID)—which are used in single-energy and DECT systems—that measure the total energy deposited in the detector, PCDs quantify the energy of each incident photon according to two or more thresholds called “energy bins” and can be produced with a much smaller detector element size to increase spatial resolution. For these reasons, PCD-CT is expected to address some major limitations of EID-based DECT [8,9,10]

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Discussion

Conclusion