Almutairi Abdulrahman, Al Safran Zakariya, AlZaabi Saif A, Sun Zhonghua
Department of Medical Radiation Sciences, Curtin University, Perth, Western Australia, Australia.
Department of Medical Imaging, King Fahad Specialist Hospital, Dammam, Saudi Arabia.
Quant Imaging Med Surg. 2017 Oct;7(5):520-531. doi: 10.21037/qims.2017.10.07.
To determine the optimal scanning protocols of dual energy computed tomography angiography (DECTA) in terms of radiation dose and image quality assessment at different keV levels, and compare it with conventional computed tomography angiography (CTA) in patients treated with peripheral arterial stents.
Twenty-nine patients with previous stent placement in peripheral arteries were evaluated with DECTA. Images were reconstructed with virtual monochromatic spectral imaging (VMS) at 65, 68, 70 and 72 keV and adaptive statistical iterative reconstruction (ASIR) at 50% compared with CTA. Image quality comprising image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed, and radiation dose was compared. Effects of different type of peripheral arterial stents on image quality were also evaluated. Fifty-six uniquely identified stents that were located in common iliac arteries (CIA), external iliac arteries (EIA) and superficial femoral arteries (SFA) were evaluated.
Within subjects, the results showed that DECTA images (VMS) had less noise than the CTA images for CIA, EIA and SFA stents, with the lowest noise at 72 keV. Also, the VMS images had greater SNR than the CTA images for the EIA stents (P<0.05); and the VMS images had greater CNR than the CTA images for CIA, EIA, and SFA stents (P<0.001). Also, on CT attenuation, VMS continued to outperform CTA, but to a lesser extent. Between subjects, average VMS noise varied significantly with the type of the stent used (P=0.025) for CIA stents. Radiation dose was highly significant between DECTA and conventional CTA scans (6.98 7.40 mSv, P=0.047).
We conclude that an optimal scanning protocol consisting of 72 keV and 50% ASIR leads to better image quality for DECTA in peripheral arterial stenting when compared to conventional CTA.
为了在不同keV水平下，根据辐射剂量和图像质量评估来确定双能计算机断层血管造影（DECTA）的最佳扫描方案，并将其与接受外周动脉支架治疗患者的传统计算机断层血管造影（CTA）进行比较。
对29例既往在外周动脉置入支架的患者进行DECTA评估。与CTA相比，图像采用65、68、70和72keV的虚拟单色光谱成像（VMS）以及50%的自适应统计迭代重建（ASIR）进行重建。评估包括图像噪声、信噪比（SNR）和对比噪声比（CNR）在内的图像质量，并比较辐射剂量。还评估了不同类型外周动脉支架对图像质量的影响。对位于髂总动脉（CIA）、髂外动脉（EIA）和股浅动脉（SFA）的56个唯一识别的支架进行了评估。
在受试者内部，结果显示，对于CIA、EIA和SFA支架，DECTA图像（VMS）的噪声低于CTA图像，在72keV时噪声最低。此外，对于EIA支架，VMS图像的SNR高于CTA图像（P<0.05）；对于CIA、EIA和SFA支架，VMS图像的CNR高于CTA图像（P<0.001）。此外，在CT衰减方面，VMS继续优于CTA，但程度较小。在受试者之间，CIA支架的平均VMS噪声因所用支架类型而异（P=0.025）。DECTA和传统CTA扫描之间的辐射剂量差异具有高度统计学意义（6.98±7.40mSv，P=0.047）。
我们得出结论，与传统CTA相比，由72keV和50%ASIR组成的最佳扫描方案可使外周动脉支架置入术中DECTA的图像质量更好。
