多层螺旋CT胸部低剂量扫描对气道三维重建的应用研究

Low-dose MSCT:Application to Three-dimension Imaging of Central Airways

目的:比较低剂量与常规剂量条件下中央气道三维重建图像的差别,探讨低剂量螺旋CT扫描进行中央气道三维重建的可行性。材料和方法:32例病例行低剂量(50mAs)平扫及常规剂量(195mAs)平扫(1例)及增强扫描(31例),将两组原始数据分别普通算法及高分辨算法重叠重建出4组横断面图像,并进行气道SSD及VR重建,由两名放射科医师分析4组图像的质量、支气管显示情况、支气管病变检出情况,将结果进行统计学分析。结果:①图像质量:两组剂量间SSD图像质量无明显差异,高分辨重建图像质量≥普通算法重建图像质量;VR图像质量两种剂量之间无明显差异,高分辨算法图像质量≥标准算法重建图像质量。②支气管显示:两名医生评价结果均表明对段以上支气管显示方面无论SSD图像还是VR图像,低剂量与常规剂量组以及两种算法图像之间均无明显差异。③病变检出:无论SSD还是VR图像4组图像对支气管病变的检出无差异。④剂量差别:低剂量扫描比常规剂量扫描辐射剂量大大降低(13.6～3.6mGy)。结论:与常规剂量扫描相比,低剂量薄层扫描气道三维重建图像质量、对中央气道显示及病变检出都无明显差异,而病人接受的辐射剂量却大大降低,因此低剂量薄层扫描气道三维重建可以代替常规剂量重建图像应用于临床气道病变显示。

Purpose： Comparing of low and conventional dose MSCT of difference of reconstructive imaging quality of the central airway , then assess the utility of low - dose MSCT for three - dimensional imaging of the central airway. Materials and Methods： MSCT was performed in 32 patients using two tube currents （50 and 195mAs）. 4 groups SSD and VR images were reconstructed with standard and high resolution . They were assessed by 2 radiologists for image quality and results were analysed statistically. Results： ①image quality： SSD images of low - dose were better or as well as conventional - dose, and images of high- resolution were better than standard- resolution. No significant difference in image qualiyy was note with two dose VR images. VR images of high - resolution were better than standard - resolution. ②bronchia display： there were no significant difference in SSD and VR images with 50 and 195mAs for displaying bronchi.③lesion detection： there were no significant difference in SSD and VR images of two dose. Odose difference： dose can be decreased greatly with 50 mAs （13.6-3.6mGy）. Conclusion： There is no difference of three - dimensional images of the central airway of low - dose thin MSCT and thoses of conventional - dose. Three - demensional images of the central airway with low - dose thin MSCT can be used clinically.