低剂量CT扫描结合模型迭代重建术前评估乳腺癌的图像质量研究

Image Quality of Low Dose Computed Tomography Combined with Iterative Model Reconstruction Technique in Preoperative Evaluation of Breast Cancer

目的探讨低剂量CT扫描结合模型迭代重建(IMR)技术对乳腺癌及胸部转移病灶评估的价值,比较IMR、混合迭代重建(HIR)和滤波反投影重建(FBP)对图像质量的影响。资料与方法收集2016年1月-5月海军总医院经乳腺X线和(或)超声检查发现孤立肿块,且乳腺影像报告与数据系统4级及以上的患者21例。所有患者行变化管电流的乳腺CT动态增强扫描(6 min内6次扫描)和胸部扫描,即注药后2 min时相采用常规管电流(61 mAs),其他5个时相采用低管电流(10 mAs)。分别采用FBP、HIR和IMR进行图像重建。对2 min时相图像行乳腺病灶及胸部图像的主客观质量评估。结果平均有效辐射剂量为(2.15±0.39)mSv。2 min时相3种重建技术比较,IMR图像的图像噪声最低、对比噪声比最优,差异有统计学意义(P<0.05);主观评估3种重建图像均达到可接受的质量,其中IMR优于HIR及FBP,差异有统计学意义(P<0.05)。结论低剂量CT扫描结合IMR技术可达到2 mSv的低辐射剂量,同时保持良好的图像质量,在乳腺癌术前评估中可同时评估乳腺病灶以及胸部转移情况。

Purpose To investigate the value of low dose CT combined with iterative model reconstruction （IMR） technique for evaluation of both breast lesion and pulnaonary metastasis in patients with breast cancer, and compare the effects of IMR, hybrid iterativc reconstruction （HIR） and filtered back projection （FBP） techniques on image quality. Materials and Methods Twenty-one patients with solitary tumor confirmed by mammography and/or ultrasonography at Navy General Hospital from January to May in 2016 were enrolled, and the related breast imaging reporting and data system reached to level 4 and above. All patients underwent dynamic contrast-enhanced CT with difli^rent tube current for breast （scanning 6 times within 6 minutes） and chest scans： the conventional tube current （61 mAs） was used at the 2 minutes phase alter injection, and the low tube current （10 mAs） was used at the other 5 phases. CT images were reconstructed with FBP, HIR and IMR techniques, respectively. The images of breast lesions and chest in 2 minutes scans were evaluated objectively and subjectively. Results Tile mean effective radiation dose was （2.15 ± 0.39） mSv. The images of 3 reconstruction techniques at the 2 minutes phase were compared, and the IMR images showed the lowest image noise and the optimal contrast to noise ratio （P〈0.05）. The images quality of 3 kinds of reconstruction techniques was acceptable, of which IMR was better than HIR and FBP （P〈0.051. Conclusion Low dose CT scan combined with IMR technique can remain low radiation with dose of 2 mSv, while maintaining good image quality, which can be used for preoperative evaluation of both breast lesion and pulmonary metastasis in patients with breast cancer.