Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA.
Department of Radiology and Radiological Science, Division of Medical Physics, Medical University of South Carolina, Charleston, SC 29407, USA.
Clin Imaging. 2023 Dec;104:110008. doi: 10.1016/j.clinimag.2023.110008. Epub 2023 Oct 14.
Photon-counting-detector computed tomography (PCD-CT) offers enhanced noise reduction, spatial resolution, and image quality in comparison to energy-integrated-detectors CT (EID-CT). These hypothesized improvements were compared using PCD-CT ultra-high (UHR) and standard-resolution (SR) scan-modes.
Phantom scans were obtained with both EID-CT and PCD-CT (UHR, SR) on an adult body-phantom. Radiation dose was measured and noise levels were compared at a minimum achievable slice thickness of 0.5 mm for EID-CT, 0.2 mm for PCD-CT-UHR and 0.4 mm for PCD-CT-SR. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated for five tissue densities. Additionally, data from 25 patients who had PCD-CT of chest were reconstructed at 1 mm and 0.2 mm (UHR) slice-thickness and compared quantitatively (SNR) and qualitatively (noise, quality, sharpness, bone details).
Phantom PCD-CT-UHR and PCD-CT-SR scans had similar measured radiation dose (16.0mGy vs 15.8 mGy). Phantom PCD-CT-SR (0.4 mm) had lower noise level in comparison to EID-CT (0.5 mm) (9.0HU vs 9.6HU). PCD-CT-UHR (0.2 mm) had slightly higher noise level (11.1HU). Phantom PCD-CT-SR (0.4 mm) had higher SNR in comparison to EID-CT (0.5 mm) while achieving higher resolution (Bone 115 vs 96, Acrylic 14 vs 14, Polyethylene 11 vs 10). SNR was slightly lower across all densities for PCD-CT UHR (0.2 mm). Interestingly, CNR was highest in the 0.2 mm PCD-CT group; PCD-CT CNR was 2.45 and 2.88 times the CNR for 0.5 mm EID-CT for acrylic and poly densities. Clinical comparison of SNR showed predictably higher SNR for 1 mm (30.3 ± 10.7 vs 14.2 ± 7, p = 0.02). Median subjective ratings were higher for 0.2 mm UHR vs 1 mm PCD-CT for nodule contour (4.6 ± 0.3 vs 3.6 ± 0.1, p = 0.02), bone detail (5 ± 0 vs 4 ± 0.1, p = 0.001), image quality (5 ± 0.1 vs 4.6 ± 0.4, p = 0.001), and sharpness (5 ± 0.1 vs 4 ± 0.2).
Both UHR and SR PCD-CT result in similar radiation dose levels. PCD-CT can achieve higher resolution with lower noise level in comparison to EID-CT.
与能量积分探测器 CT（EID-CT）相比，光子计数探测器 CT（PCD-CT）在噪声降低、空间分辨率和图像质量方面具有优势。本研究比较了 PCD-CT 超高（UHR）和标准分辨率（SR）扫描模式的这些假设改进。
在成人体模上对 EID-CT 和 PCD-CT（UHR、SR）进行了扫描。测量辐射剂量，并在最小可实现的切片厚度为 0.5mm 时比较 EID-CT、0.2mm 时比较 PCD-CT-UHR 和 0.4mm 时比较 PCD-CT-SR 的噪声水平。为五种组织密度计算了信噪比（SNR）和对比噪声比（CNR）。此外，对 25 例接受 PCD-CT 胸部扫描的患者进行了 1mm 和 0.2mm（UHR）层厚的重建，并进行了定量（SNR）和定性（噪声、质量、锐度、骨细节）比较。
体模 PCD-CT-UHR 和 PCD-CT-SR 扫描的辐射剂量相似（16.0mGy 与 15.8mGy）。与 EID-CT（0.5mm）相比，PCD-CT-SR（0.4mm）的噪声水平较低（9.0HU 与 9.6HU）。PCD-CT-UHR（0.2mm）的噪声水平略高（11.1HU）。与 EID-CT（0.5mm）相比，PCD-CT-SR（0.4mm）的 SNR 更高，同时分辨率更高（骨 115 与 96、有机玻璃 14 与 14、聚乙烯 11 与 10）。所有密度的 PCD-CT UHR（0.2mm）的 SNR 略低。有趣的是，0.2mm PCD-CT 组的 CNR 最高；PCD-CT 的 CNR 是 0.5mm EID-CT 的亚克力和聚乙烯密度 CNR 的 2.45 倍和 2.88 倍。SNR 的临床比较显示，1mm 时 SNR 可预测性更高（30.3±10.7 与 14.2±7，p=0.02）。0.2mm UHR 的中位数主观评分明显高于 1mm PCD-CT 组的结节轮廓（4.6±0.3 与 3.6±0.1，p=0.02）、骨细节（5±0 与 4±0.1，p=0.001）、图像质量（5±0.1 与 4.6±0.4，p=0.001）和锐度（5±0.1 与 4±0.2）。
UHR 和 SR PCD-CT 的辐射剂量水平相似。与 EID-CT 相比，PCD-CT 可以实现更高的分辨率和更低的噪声水平。
