Mourits M M, Nijhof W H, van Leuken M H, Jager G J, Rutten M J C M
Department of Radiology, Jeroen Bosch Hospital, Henri Dunantstraat 1, 5223 GZ's-Hertogenbosch, The Netherlands.
University of Twente, MIRA-Institute for Biomedical Technology and Technical Medicine P.O. Box 21 7500 AE Enschede, The Netherlands.
Clin Radiol. 2016 Jun;71(6):615.e7-615.e13. doi: 10.1016/j.crad.2016.03.005. Epub 2016 Apr 6.
To evaluate image quality after contrast medium (CM) and tube voltage reduction in computed tomography angiography (CTA) of the pulmonary artery.
Thirty-three patients referred for CTA of the pulmonary artery for suspected pulmonary embolism were included. Patients were randomly assigned to Protocol I (100 ml of 350 mg iodine/ml iodinated CM; n=16) or Protocol II (50 ml of 350 mg iodine/ml iodinated CM; n=17). Dual-energy CT (80 kV and 140 kV) was performed in all patients. An averaged weighted series equivalent to a 120 kV image acquisition was reconstructed. The mean attenuation value of CM was measured at eight positions in the pulmonary trunk and pulmonary arteries. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Qualitative assessment of the vascular enhancement was performed independently by two experienced radiologists using a three-point scale. Mean attenuation values, image noise, CNR, and SNR of images with 50 ml CM and images with 100 ml CM were compared and mean attenuation values, image noise, CNR, and SNR in 80 kV images and 120 kV images were compared. For qualitative analysis, interobserver variability was analysed using Cohen's kappa statistics.
The mean attenuation values in Protocol I and Protocol II were not significantly different at 80 kV (634.6±168.3 versus 537.9±146.7 HU; p=0.088) and 120 kV (482.8±127.7 versus 410.4±106.0 HU; p=0.085). The mean attenuation value at 80 kV was significantly higher than the mean attenuation value at 120 kV in Protocols I and II (p<0.001). The CNR and SNR were higher at 120 kV than at 80 kV in both protocols (p=0.000-0.019); however, there were no significant differences in the CNR and SNR between both protocols (p=0.600-0.952). Qualitative (subjective) analysis showed no statistical significant difference between Protocols I and II (p=0.524-1.000).
Low tube voltage (80 kV) CTA using 50 ml CM is not inferior to CTA at 120 kV using 100 ml CM.
评估肺动脉计算机断层血管造影（CTA）中使用对比剂（CM）和降低管电压后的图像质量。
纳入33例因疑似肺栓塞而接受肺动脉CTA检查的患者。患者被随机分为方案I组（100 ml含碘量为350 mg碘/ml的碘化CM；n = 16）或方案II组（50 ml含碘量为350 mg碘/ml的碘化CM；n = 17）。所有患者均行双能CT（80 kV和140 kV）检查。重建出相当于120 kV图像采集的平均加权序列。在肺动脉主干和肺动脉的八个位置测量CM的平均衰减值。计算信噪比（SNR）和对比噪声比（CNR）。由两名经验丰富的放射科医生使用三分制独立对血管强化进行定性评估。比较50 ml CM图像和100 ml CM图像的平均衰减值、图像噪声、CNR和SNR，以及80 kV图像和120 kV图像的平均衰减值、图像噪声、CNR和SNR。对于定性分析，使用Cohen's kappa统计分析观察者间的变异性。
在80 kV时，方案I组和方案II组的平均衰减值无显著差异（分别为634.6±168.3 HU和537.9±146.7 HU；p = 0.088），在120 kV时也无显著差异（分别为482.8±127.7 HU和410.4±106.0 HU；p = 0.085）。在方案I组和方案II组中，80 kV时的平均衰减值均显著高于120 kV时的平均衰减值（p<0.001）。在两个方案中，120 kV时的CNR和SNR均高于80 kV时（p = 0.000 - 0.019）；然而，两个方案之间的CNR和SNR无显著差异（p = 0.600 - 0.952）。定性（主观）分析显示方案I组和方案II组之间无统计学显著差异（p = 0.524 - 1.000）。
使用50 ml CM的低管电压（80 kV）CTA并不逊色于使用100 ml CM的120 kV CTA。
