Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
Department of Diagnostic Radiology, Yokohama City University Hospital, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
Eur Radiol. 2020 Jan;30(1):394-403. doi: 10.1007/s00330-019-06337-y. Epub 2019 Jul 16.
To evaluate the image quality and optimal energies of virtual monoenergetic images (VMIs) from dual-layer spectral detector computed tomography (DLCT) in multiphasic pancreatic CT and investigate whether low-keV VMI at the portal venous phase (PVP) provides sufficient tumor conspicuity and arterial depiction relative to conventional pancreatic parenchymal phase (PPP) images.
Forty-eight patients with pancreatic ductal adenocarcinoma (PDAC) underwent contrast-enhanced DLCT during PPP and PVP. Conventional polyenergetic images (PEIs) and VMI at 40-100 keV (VMI, 10-keV increments) were reconstructed at each enhancement phase. Image noise and the contrast-to-noise ratio (CNR) of the pancreas, tumors, arteries, and veins were quantified. Two radiologists independently assessed tumor conspicuity, margin delineation, image noise, sharpness of pancreatic duct, and depiction of arteries and veins on a five-point scale. Size-specific dose estimate (SSDE) was calculated.
Image noise for VMI was significantly lower than that for PEI (p < 0.01). The CNR in VMI increased gradually with decreasing energy; CNRs for VMI were significantly greater than that for PEI (p < 0.01). All subjective VMI scores were maximized at VMI, followed by VMI, all of which were significantly better than of PEI (p < 0.01). Objective and subjective image qualities of VMI at the PVP were equivalent to or even better compared with conventional PPP images. No significant difference in SSDE was observed between phases (p = 0.10).
DLCT-VMI improved the subjective and objective image quality in multiphasic pancreatic CT for patients with PDAC. Low-keV PVP imaging may yield diagnostically adequate tumor conspicuity and arterial assessment compared with polyenergetic PPP images.
• Low-keV VMI from DLCT yields better subjective and objective image quality of multiphasic pancreas CT in comparison with conventional PEI for the assessment of pancreatic ductal adenocarcinoma. • Tumor conspicuity and depiction of peripancreatic vasculature were maximized at VMI without an increase in the image noise. • Low-keV VMI of the portal venous phase provides sufficient tumor conspicuity and arterial depiction, potentially allowing the early detection and local staging of PDAC on routine abdominal CT performed for various clinical indications.
评估双层光谱探测器 CT（DLCT）在多期胰腺 CT 中的虚拟单能量图像（VMI）的图像质量和最佳能量，并探讨门静脉期（PVP）的低 keV VMI 是否能提供与常规胰腺实质期（PPP）图像相比足够的肿瘤显著性和动脉显影。
48 例胰腺导管腺癌（PDAC）患者在 PPP 和 PVP 期间行对比增强 DLCT。在每个增强阶段重建常规多能量图像（PEI）和 40-100keV 的 VMI（VMI，每 10keV 递增）。量化图像噪声和胰腺、肿瘤、动脉和静脉的对比噪声比（CNR）。两位放射科医生独立评估肿瘤显著性、边缘描绘、图像噪声、胰管清晰度以及动脉和静脉的显示情况，采用五分制评分。计算大小特异性剂量估计值（SSDE）。
VMI 的图像噪声明显低于 PEI（p<0.01）。VMI 的 CNR 随能量降低而逐渐升高；VMI 的 CNR 明显大于 PEI（p<0.01）。所有主观 VMI 评分在 VMI 时达到最大值，其次是 VMI，均明显优于 PEI（p<0.01）。PVP 时 VMI 的客观和主观图像质量与常规 PPP 图像相当或更好。各期 SSDE 无显著差异（p=0.10）。
DLCT-VMI 改善了 PDAC 患者多期胰腺 CT 的主观和客观图像质量。与多能量 PPP 图像相比，低 keV PVP 成像可能具有足够的肿瘤显著性和动脉评估能力。
与常规 PEI 相比，DLCT 产生的低 keV VMI 可改善多期胰腺 CT 的主观和客观图像质量，用于评估胰腺导管腺癌。
肿瘤显著性和胰周血管的显示在 VMI 时达到最大值，而图像噪声没有增加。
门静脉期的低 keV VMI 可提供足够的肿瘤显著性和动脉显影，有可能在常规腹部 CT 上实现各种临床适应证的早期检测和局部分期。
