256层CT支气管动脉成像技术优化

Optimization of CT Angiography Technique of Bronchial Artery with 256-slice MSCT

目的：探讨256层CT支气管动脉造影的技术优化。方法：90例拟行常规胸部增强CT（Philips i CT）的患者顺序分成三组：第1～30例纳入A组,采用120k V,Average 100m As（standard）;第31～60例纳入B组,采用100k V,100m As（standard）;第61～90例纳入C组,采用100k V,100m As（high）。0.67mm层厚,0.67mm间隔,i Dose4第4级重建,比较3组图像的主动脉CT值、噪声值（SD）和对比噪声比（CNR）。对三组采集的图像进行MIP和VR重组,并对重组图像上的支气管动脉细节显示进行主观评价。结果：主动脉CT强化值,B、C两组相似且均明显高于A组（P〈0.05）,横断面图像SD值则A,B两组相似且明显低于C组（P〈0.05）,CNR值则A,B两组相似且明显高于C组（P〈0.05）。三维图像上支气管动脉细节显示以C组最佳,优于B组（P〈0.05）,显著优于A组（P〈0.01）,B组稍优于A组（P〈0.05）。结论：低k V、高分辨扫描方式可以更好显示支气管动脉细节,适合256层i CT上应用。

Purpose： To optimize the technique ofMSCT angiography of bronchial artery with a 256-slice CT scanner. Methods： Ninety patients undertaken thoracic contrasted MSCT （Philips iCT） examination were enrolled in our study and divided into three groups according to the exam order： group A （patients 1-30） with protocol A （120kV, Average 100mAs, standard resolution）, group B （patients 31-60） with protocol B （100kV, Average 100mAs, standard resolution）, and group C （patients 61-90） with protocol C （100kV, Average 100mAs, high resolution）. The other parameters included 0.67mm slice-thickness, 0.67ram interval, and iDose4 4 algorithm. The maximum intensity projection （MIP） and volume rendering （VR） images were obtained. The CT value, noise （SD） and contrast-noise-ratio （CNR） of aorta were compared among these three groups. The bronchial artery on MIP and VR images were evaluated by two radiologists. Results： The attenuation of aorta in group B and C was significantly larger than that in group A （P〈0.05）. The SD values in group A and B was significantly smaller than that in group C （P〈0.05）. The CNR in group A and B was significantly larger than that in group C （P〈0.05）. The three-dimensional details of bronchial artery revealed in group C was better than that in group B （P〈0.05） and group A （P〈0.01）. Conclusion： The protocol including low kV and high resolution scan mode would best reveal the details of bronchial artery, which could be applied in Philips iCT scanner.