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

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.

Quantum Iterative Reconstruction for Low-Dose Ultra-High-Resolution Photon-Counting Detector CT of the Lung

“…Photon-counting detector computed tomography (PCD-CT) is an emerging technology that enables the direct conversion of incident x-ray photons into an electrical signal. As compared to conventional energy-integrating detector (EID)-CT systems, PCD-CT has shown improved spatial resolution, lower image noise, and higher contrast-to-noise ratio (CNR) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Previous studies on preclinical prototype PCD-CT suggest that these benefits can be translated to an improved diagnosis of pulmonary nodules [ 10 ] and to improvements in shape and texture image information due to the higher spatial resolution of PCD-CT as compared to EID-CT [ 11 , 12 ].…”

Photon Counting CT Angiography of the Head and Neck: Image Quality Assessment of Polyenergetic and Virtual Monoenergetic Reconstructions

“…Recent studies have already investigated the image quality of CT angiographies in photon counting [ 16 , 28 , 29 ], especially with regard to comparison with conventional CT systems with EIDs. Euler et al [ 28 ] investigated the image quality of photon counting CT angiography of the aorta, also comparing PER with a selection of low keV MERs.…”

“…Based on this technological innovation, PCDs are expected to provide spectral data with higher resolution and lower noise [ 15 ]. Initial studies on CT angiographies conducted with prototype PCCTs suggest that image quality, and thus diagnostic accuracy, is superior to CT systems using EIDs [ 16 ].…”

Computed tomography analysis of vulnerable carotid atherosclerotic plaque and relationship to clinical characteristics

“…This technique results in improved spatial resolution, higher contrast-to-noise ratio, correct beam-hardening artifacts, lower radiation exposure and optimized spectral imaging [25]. For these reasons PC-CT may have the potential to overcome most of the current technical demands of plaque imaging associated with high-resolution requirements and image noise.…”

“…Each photon that hits the detector of a PC-CT system produces an electrical pulse with a height proportional to the energy deposited by the photon; therefore, PC-CT can count the number of incoming photons and measure their individual energy [24]. This technique results in improved spatial resolution, higher contrast-to-noise ratio, correct beam-hardening artifacts, lower radiation exposure and optimized spectral imaging [25]. For these reasons PC-CT may have the potential to overcome most of the current technical demands of plaque imaging associated with high-resolution requirements and image noise.…”