Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto, 862-0976, Japan.
Eur Radiol. 2018 Apr;28(4):1719-1730. doi: 10.1007/s00330-017-5114-3. Epub 2017 Oct 23.
To evaluate the image quality and lesion conspicuity of virtual-monochromatic-imaging (VMI) with dual-layer DECT (DL-DECT) for reduced-iodine-load multiphasic-hepatic CT.
Forty-five adults with renal dysfunction who had undergone hepatic DL-DECT with 300-mgI/kg were included. VMI (40-70-keV, DL-DECT-VMI) was generated at each enhancement phase. As controls, 45 matched patients undergoing standard 120-kVp protocol (120-kVp, 600-mgI/kg, and iterative reconstruction) were included. We compared the size-specific dose estimate (SSDE), image noise, CT attenuation, and contrast-to-noise ratio (CNR) between protocols. Two radiologists scored the image quality and lesion conspicuity.
SSDE was significantly lower in DL-DECT group (p < 0.01). Image noise of DL-DECT-VMI was almost constant at each keV (differences of ≤15%) and equivalent to or lower than of 120-kVp. As the energy decreased, CT attenuation and CNR gradually increased; the values of 55-60 keV images were almost equivalent to those of standard 120-kVp. The highest scores for overall quality and lesion conspicuity were assigned at 40-keV followed by 45 to 55-keV, all of which were similar to or better than of 120-kVp.
For multiphasic-hepatic CT with 50% iodine-load, DL-DECT-VMI at 40- to 55-keV provides equivalent or better image quality and lesion conspicuity without increasing radiation dose compared with standard 120-kVp protocol.
• 40-55-keV yields optimal image quality for half-iodine-load multiphasic-hepatic CT with DL-DECT. • DL-DECT protocol decreases radiation exposure compared with 120-kVp scans with iterative reconstruction. • 40-keV images maximise conspicuity of hepatocellular carcinoma especially at hepatic-arterial phase.
评估双能量 CT （DECT）降低碘负荷多期肝 CT 中虚拟单能量成像（VMI）的图像质量和病变显示能力。
纳入 45 例因肾功能障碍行肝 DECT 检查的成年人，管电流 300mAs/kg。在每个增强期生成 VMI（40-70keV，DECT-VMI）。作为对照，纳入 45 例匹配的 120kVp 协议（120kVp，600mAs/kg，迭代重建）患者。比较两种方案的大小特异性剂量估计值（SSDE）、图像噪声、CT 衰减和对比噪声比（CNR）。两位放射科医生对图像质量和病变显示进行评分。
DECT 组的 SSDE 明显更低（p<0.01）。DECT-VMI 的图像噪声在每个 keV 时几乎不变（差异≤15%），与 120kVp 相当或更低。随着能量降低，CT 衰减和 CNR 逐渐增加；55-60keV 图像的值几乎与标准 120kVp 相当。总体质量和病变显示的最高评分均为 40keV，其次是 45-55keV，均与 120kVp 相当或更好。
对于碘负荷 50%的多期肝 CT，DECT-VMI 在 40-55keV 时可提供与标准 120kVp 协议相同或更好的图像质量和病变显示能力，而不会增加辐射剂量。
40-55keV 可获得 DECT 半碘负荷多期肝 CT 的最佳图像质量。
与迭代重建的 120kVp 扫描相比，DECT 方案可降低辐射暴露。
40keV 图像可最大限度地提高肝细胞癌的显示能力，特别是在肝动脉期。
