Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA, 02114, USA.
Department of Radiology, University of Washington, Seattle, WA, USA.
Abdom Radiol (NY). 2020 Sep;45(9):2902-2909. doi: 10.1007/s00261-020-02416-7.
To assess the diagnostic image quality and material decomposition characteristics of portal venous phase abdominal CT scans performed on rapid kVp-switching DECT (rsDECT) in patients with large body habitus.
We retrospectively included consecutive patients with large body habitus (≥ 90 kg) undergoing portal venous phase abdominal CT scans on rsDECT scanners between Sep 2014 and March 2018. Qualitative and quantitative assessment of the DECT data sets [65 keV monoenergetic, material density iodine (MD-I) and material density water (MD-W) images] was performed for determination of image quality (IQ) and image noise. Correlation of qualitative assessment scores with weight, BMI and patients' diameter were calculated using Pearson correlation test. Optimal thresholds were calculated using AUC and Youden index to define most appropriate size cut off, below which the IQ of material density images is largely acceptable.
The 65 keV monoenergetic images were of diagnostic quality (diagnostic acceptability, DA ≥ 3) in 97.8% of patients (n = 91/93). However, there was significant IQ degradation of MD-I images in 20.4% (n = 19/93, DA < 3) of patients. Similarly, there was significant degradation (DA < 3) of MD-W images in 26.9% (25/92). Clinically significant artifacts (PA ≥ 3/4) were seen in 31% (n = 29/93) and 32.3% (30/93) of MD-I and MD-W images respectively. Optimal threshold for diagnostic acceptability of MD-I images were 110 kg for weight and 33.5 kg/m for BMI.
Rapid kVp-switching DECT provides diagnostically acceptable monoenergetic images for patients with large body habitus (≥ 90 kg). There is degradation of IQ in the material density specific images particularly in patients weighing > 110 kg and with BMI > 33.5 kg/m, due to higher number of artifacts.
评估体型较大（≥90kg）患者行快速千伏切换能谱 CT（rsDECT）门静脉期腹部 CT 扫描的诊断图像质量和物质分解特征。
我们回顾性纳入了 2014 年 9 月至 2018 年 3 月期间在 rsDECT 扫描仪上行门静脉期腹部 CT 扫描的体型较大（≥90kg）连续患者。对 DECT 数据集（65keV 单能量、碘物质密度（MD-I）和水物质密度（MD-W）图像）进行定性和定量评估，以确定图像质量（IQ）和图像噪声。使用 Pearson 相关检验计算定性评估评分与体重、BMI 和患者直径的相关性。使用 AUC 和 Youden 指数计算最佳阈值，以定义最合适的大小截止值，低于该值，物质密度图像的 IQ 基本可以接受。
65keV 单能量图像在 97.8%（91/93）的患者中具有诊断质量（诊断可接受性，DA≥3）。然而，在 20.4%（93 例中有 19 例，DA<3）的患者中，MD-I 图像的 IQ 显著降低。同样，在 26.9%（92 例中有 25 例）的 MD-W 图像中也存在显著的 IQ 降低。在 31%（93 例中有 29 例）和 32.3%（93 例中有 30 例）的 MD-I 和 MD-W 图像中分别观察到临床显著伪影（PA≥3/4）。MD-I 图像诊断可接受性的最佳阈值为体重 110kg 和 BMI 33.5kg/m。
快速千伏切换能谱 CT 可为体型较大（≥90kg）患者提供具有诊断可接受性的单能量图像。在物质密度特定图像中，IQ 会降低，特别是在体重>110kg 和 BMI>33.5kg/m 的患者中，由于伪影数量增加，IQ 降低更为明显。
