Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, the Netherlands.
Br J Radiol. 2023 Mar;96(1143):20220466. doi: 10.1259/bjr.20220466. Epub 2023 Jan 12.
To assess the impact of low kilo-electronvolt (keV) virtual monoenergetic image (VMI) energies and iterative reconstruction on image quality of clinical photon-counting detector coronary CT angiography (CCTA).
CCTA with PCD-CT (prospective ECG-triggering, 120 kVp, automatic tube current modulation) was performed in a high-end cardiovascular phantom with dynamic flow, pulsatile heart motion, and including different calcified plaques with various stenosis grades and in 10 consecutive patients. VMI at 40,50,60 and 70 keV were reconstructed without (QIR-off) and with all quantum iterative reconstruction (QIR) levels (QIR-1 to 4). In the phantom, noise power spectrum, vessel attenuation, contrast-to-noise-ratio (CNR), and vessel sharpness were measured. Two readers graded stenoses in the phantom and graded overall image quality, subjective noise, vessel sharpness, vascular contrast, and coronary artery plaque delineation on 5-point Likert scales in patients.
In the phantom, noise texture was only slightly affected by keV and QIR while noise increased by 69% from 70 keV QIR-4 to 40 keV QIR-off. Reconstructions at 40 keV QIR-4 exhibited the highest CNR (46.1 ± 1.8), vessel sharpness (425 ± 42 ∆HU/mm), and vessel attenuation (1098 ± 14 HU). Stenosis measurements were not affected by keV or QIR level ( > 0.12) with an average error of 3%/6% for reader 1/reader 2, respectively. In patients, across all subjective categories and both readers, 40 keV QIR-3 and QIR-4 images received the best scores ( < 0.001).
Forty keV VMI with QIR-4 significantly improved image quality of CCTA with PCD-CT.
PCD-CT at 40 keV and QIR-4 improves image quality of CCTA.
评估低千伏（keV）虚拟单能量图像（VMI）能量和迭代重建对临床光子计数探测器冠状动脉 CT 血管造影（CCTA）图像质量的影响。
使用高端心血管体模进行前瞻性 ECG 触发的 CCTA 检查，体模中包含动态血流、脉动心脏运动以及不同狭窄程度的钙化斑块，共 10 名连续患者纳入研究。在体模中，不使用（QIR-off）和使用全量子迭代重建（QIR）各水平（QIR-1 到 4）对 40、50、60 和 70 keV 的 VMI 进行重建。测量噪声功率谱、血管衰减、对比噪声比（CNR）和血管锐利度。两位读者对体模中的狭窄程度进行分级，并对患者的整体图像质量、主观噪声、血管锐利度、血管对比度和冠状动脉斑块描绘进行 5 分李克特量表分级。
在体模中，keV 和 QIR 仅对噪声纹理略有影响，而噪声从 70 keV QIR-4 增加到 40 keV QIR-off 增加了 69%。40 keV QIR-4 重建的 CNR（46.1 ± 1.8）、血管锐利度（425 ± 42 ∆HU/mm）和血管衰减（1098 ± 14 HU）最高。两位读者的狭窄程度测量均不受 keV 或 QIR 水平影响（>0.12），平均误差分别为 3%/6%。在患者中，在所有主观类别和两位读者中，40 keV QIR-3 和 QIR-4 图像的评分均最佳（<0.001）。
使用 QIR-4 的 40 keV VMI 可显著改善 PCD-CT 冠状动脉 CT 血管造影的图像质量。
PCD-CT 在 40 keV 和 QIR-4 可改善 CCTA 图像质量。
