Multilayer and crushed stent visualization using photon- counting detector computed tomography – a proof of concept

Abstract

Abstract Photon‑counting detector CT (PCD‑CT) enables ultra‑high resolution (UHR, 0.2 mm) and may improve visualization of coronary stents compared with standard‑resolution (SR, 0.4 mm). In this ex- vivo study, we utilized a phantom heart model to simulate physiological attenuation and imitated the most common coronary bifurcation stenting techniques by creating multiple stent layers and stent- crush situations (single layer, crushed, two‑ and three‑layer). We compared UHR and SR PCD‑CT using Bv72 and Bv56 kernels. Objective endpoints were in‑stent lumen visibility, signal-to-noise ratio, and percentage change in stent attenuation; subjective image quality was rated on a 5‑point Likert scale (1 = excellent to 5 = non‑diagnostic). Depending on distribution, two‑sided t‑tests (mean ± SD) or Mann–Whitney U tests (median[IQR]) were applied, p‑values were Bonferroni‑corrected for multiple comparisons. In the pooled Crush cohort, UHR Bv72 improved in‑stent lumen visibility when compared with both, SR Bv72 (single-layer: 68.08 ± 4.30% vs. 79.03 ± 3.79%; crushed: 63.62 ± 4.97% vs. 74.73 ± 2.51%) and SR Bv56 (single-layer: 63.63 ± 4.47% vs. 79.03 ± 3.79%; crushed: 62.18 ± 3.55% vs. 74.73 ± 2.51%), all p < 0.01. The effect was even more pronounced in small stents (single‑layer 65.45 ± 1.91% (SR) vs. 77.11 ± 2.55% (UHR) and crushed 60.67 ± 2.67% vs. 74.00 ± 2.67%), both p < 0.01. Regarding subjective image quality, UHR was associated with better sharpness and less blooming, e.g., UHR Bv72 vs. SR Bv56 (multilayer: sharpness 1[0] vs. 2[0], blooming 1[0] vs. 2[0]; crush: sharpness 1[0] vs. 2[0], blooming 1[0] vs. 2[1]; all p ≤ 0.01) and UHR Bv72 vs. SR Bv72 (multilayer: sharpness 1[0] vs. 1[1], blooming 1[0] vs. 1[1]; crush: sharpness 1[0] vs. 1[1]; all p ≤ 0.05). These findings indicate that UHR PCD‑CT with Bv72 might enable assessment of complex stents in a phantom setting; even though clinical studies are warranted.