多层螺旋CT胸部低剂量扫描对肺结节或肿块的评价

目的评价低剂量螺旋CT扫描对肺结节的临床可行性及合适扫描方案。方法42例病例平扫均采用低剂量全肺螺旋扫描,发现肺结节或肿块病例在病变部位加低剂量及常规剂量薄层轴扫,首次发现者静脉注射造影剂后行常规剂量(200mAs)全肺扫描及病变部位薄层延迟轴扫。全肺扫描采用标准算法分别重建出低剂量7.5mm、5mm及常规剂量5mm横断面图像,同时利用标准算法及高分辨算法分别重建出2种剂量VR图像。比较2种剂量横断面5mm、薄层图像以及低剂量5mm与7.5mm图像对肺结节或肿块的形态特征、大小、测量密度的差别;比较低剂量及不同算法对三维VR图像质量的影响。结果2种剂量图像对肺结节或肿块大小、形态的显示无明显差异,但是低剂量薄层扫描图像部分征象显示不如常规剂量图像。密度测量方面,低剂量薄层扫描图像标准差较大,与常规剂量有明显差异。重建VR图像质量2组剂量无明显差异,标准算法重建好于或等于高分辨算法图像。结论低剂量扫描7.5mm标准算法图像重建,病灶局部加常规剂量薄层轴扫,可以准确显示肺结节或肿块形态、大小、密度特征而且大大降低了病人的辐射剂量,具有较好的临床实用价值。

The Low Dose MSCT in Evaluating the Nodules or Masses of Lung

Objective To evaluate low dose MSCT in displaying lesions characters of nodules or masses. Methods Low-dose chest MSCT was performed in 42 cases with nodule or mass.All patients were undergone low-dose plain scan of whole lung.Additional thin axis scans with low-dose and conventional-dose were obtainned at the level of the lesion when!nodule or mass was detected.Conventional-dose scans were performed after administration of intravenous contrast materials in patients detected nodule or mass firstly.5 mm of the two dose and 7.5 mm of the low-dose images were reconstructed using standardization resolution.And VR images of the two dose were reconstructed using standardization and high resolution separately.The difference in form,size and density of nodule or mass on two dose 5 mm image,thin image,and 7.5 mm low-dose image were compared.The influence on VR image quality in different dose and algorithm was also compared.Results There was no difference between two dose images in showing the size and form of nodule or mass.But the standardization deviation of density measured in low-dose thin image was higher than that of conventional-dose image.There was no difference between two dose image in VR image quality,but standardization resolution image was better than high resolution.Conclusion The form,size and density of lung nodule or mass can be displayed accurately in low-dose scanning with standardization resolution image reconstruction and conventional-dose thin axial scan,and simultaneously the radiated dose of patients is much decreased.