大尺度非局部均值伪影抑制技术在临床低剂量腹部CT图像质量的价值研究

发布时间：2018-06-18 11:29

本文选题：体层摄影技术 + X线计算机　；参考：《安徽医科大学》2017年硕士论文

【摘要】：目的前瞻性探讨大尺度非局部均值伪影抑制(AS-LNLM)技术在处理低剂量腹部CT图像的临床价值。方法采用GE Discovery CT750 HD扫描仪对临床需要接受腹部检查的26例患者进行腹部常规剂量及低剂量CT扫描。分别采用滤波反投影(FBP)技术、40%自适应统计迭代重建(ASIR)两种重建技术分别对常规剂量及低剂量采集的腹部原始数据进行0.625 mm薄层重建,并将两种重建算法所得的两组低剂量图像数据分别进行AS-LNLM技术处理,之后应用GE后处理工作站分别测量并比较肝脏、脾脏、胰腺、肾脏及腹主动脉的噪声(SD)、对比噪声比(CNR)和信噪比(SNR),并对腹部的图像质量进行主观评分。然后记录每例患者每次检查所需要的剂量长度乘积(DLP)及CT剂量指数(CTDIvo1),最后计算其平均有效剂量(ED)以及剂量平均减低率。结果对于腹部图像质量,AS-LNLM低剂量图像比未使用此技术的常规剂量及低剂量图像有更低噪声值(SD)、更高信噪比(SNR)及对比噪声比(CNR)(P0.05);对于FBP重建算法,低剂量+AS-LNLM技术图像、常规剂量图像及低剂量未用此技术图像的主观评分分别约为(3.36±0.69)、(4.73±0.46)和(1.95±0.72)(P0.05);对于40%ASIR重建算法,低剂量+AS-LNLM技术图像、常规剂量图像及低剂量未用此技术图像的主观评分分别约为(3.68±0.48)、(4.82±0.40)和(2.18±0.66)(P0.05)。患者低剂量扫描的CTDIvol值、DLP值及ED值分别为(1.84±0.01)mGy、(49.60±2.63)mGy·cm和(0.74±0.04)mSv;常规剂量扫描的CTDIvol值、DLP值及ED值分别为(7.61±0.03)mGy、(204.18±11.19)mGy·cm和(3.06±0.17)mSv。结论在降低扫描剂量情况下,大尺度非局部均值伪影抑技术可以明显提高低剂量图像的SNR及CNR使其能够满足临床诊断要求。
[Abstract]:Objective to explore the clinical value of large scale non-local mean artifact suppression (AS-LNLM) technique in the treatment of low dose abdominal CT images. Methods 26 patients who needed abdominal examination were examined with GE Discovery CT750 HD scanner. The conventional and low-dose abdominal raw data were reconstructed by 40% adaptive statistical iterative reconstruction (40%) and 0.625 mm thin layer reconstruction, respectively. Two groups of low-dose image data from two reconstruction algorithms were processed by AS-LNLM technique, and then the liver, spleen and pancreas were measured and compared with each other by GE post-processing workstation. The noise of kidney and abdominal aorta was compared with the noise ratio (CNR) and SNR, and the image quality of abdomen was evaluated subjectively. Then the dose length product (DLP) and CT dose index (CTD Ivo 1) of each patient were recorded, and the average effective dose (EDD) and the average dose reduction rate were calculated. Results for abdominal image quality, AS-LNLM low dose image had lower noise value, higher SNR and higher SNR than conventional and low dose images without this technique, and the contrast noise ratio (CNR) was 0.05%. For FBP reconstruction algorithm, low dose AS-LNLM image was obtained. The subjective scores of conventional and low dose images were about 3.36 卤0.69 卤4.73 卤0.46) and 1.95 卤0.72% (P 0.05), respectively. For the reconstruction algorithm of 40ASIR, the subjective scores of conventional and low-dose AS-LNLM images were about 3.68 卤0.48 卤4.82 卤0.40) and 2.18 卤0.66P _ (0.05), respectively, for the reconstruction of 40ASIR, the subjective scores of conventional and low-dose AS-LNLM images were about 3.68 卤0.48 卤0.40) and 2.18 卤0.66P _ (0.05), respectively. The values of DLP and Ed in low dose scan were 1.84 卤0.01mGy and 0.74 卤0.04mSv.The DLP and Ed values were 7.61 卤0.03mGy 204.18 卤11.19mGy and 3.06 卤0.17mSv, respectively. Conclusion large scale nonlocal mean artifact suppression technique can significantly improve the SNR and CNR of low dose images under the condition of reducing scanning dose so that they can meet the requirements of clinical diagnosis.
【学位授予单位】：安徽医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R816.5

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