大尺度非局部均值伪影抑制技术对提高低剂量腹部CT图像质量的价值研究

发布时间：2018-08-25 13:52

【摘要】：目的评价大尺度非局部均值伪影抑制(AS-LNLM)技术对提高低剂量腹部CT图像质量的价值。方法对腹部检查的26例患者采用GE Discovery CT750 HD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)、40%自适应统计迭代重建(ASIR)技术对常规剂量及低剂量腹部原始数据进行0.625 mm薄层重建,并将两种重建算法的低剂量数据进行AS-LNLM技术处理,应用后处理站对图像进行质量评价分析,测量并比较肝脏、脾脏及腹主动脉的噪声、对比噪声比和信噪比,并对腹部图像质量进行主观评分。记录每例患者每次检查的剂量长度乘积(DLP)和CT剂量指数(CTDIvo1),并计算有效剂量(ED)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、更高对比噪声比(CNR)及信噪比(SNR)(P0.05);常规剂量图像较低剂量图像有更低噪声值以及更高的CNR及SNR(P0.05);对于FBP重建算法,低剂量+AS-LNLM技术及未用此技术低剂量图像的主观评分分别为(3.36±0.69)和(1.95±0.72)(P0.05);对于40%ASIR重建算法,低剂量+ASLNLM技术及未用此技术低剂量图像的主观评分分别为(3.68±0.48)和(2.18±0.66)(P0.05)。常规剂量图像用FBP及40%ASIR两种算法重建后的图像主观评分分别为(4.73±0.46)和(4.82±0.40)。低剂量扫描的CTDIvol值、DLP值及ED值分别为(1.84±0.01)m Gy、(49.60±2.63)m Gy/cm和(0.74±0.04)m Sv;常规剂量扫描的CTDIvol值、DLP值及ED值分别为(7.61±0.03)m Gy、(204.18±11.19)m Gy/cm和(3.06±0.17)m Sv。结论AS-LNLM低剂量图像较常规扫描不但可以明显降低扫描剂量,并可以明显提高图像CNR及SNR,图像质量能够满足诊断要求。
[Abstract]:Objective to evaluate the value of large scale nonlocal mean artifact suppression (AS-LNLM) in improving the quality of low dose abdominal CT images. Methods 26 patients with abdominal examination were examined with GE Discovery CT750 HD, routine and low dose CT scans were performed. The conventional and low-dose abdominal raw data were reconstructed with 0.625 mm thin-layer reconstruction using 40% adaptive statistical iterative reconstruction of (ASIR) with filter backprojection (FBP), respectively, and the low-dose data of two reconstruction algorithms were processed by AS-LNLM technique. The post-processing station was used to evaluate the image quality, to measure and compare the noise of liver, spleen and abdominal aorta, to compare the noise ratio and signal-to-noise ratio, and to evaluate the quality of abdominal image. The dose length product (DLP) and CT dose index (CTDIvo1) of each patient were recorded, and the effective dose (ED) and the average dose reduction rate were calculated. Results for abdominal image quality AS-LNLM low dose images had lower noise values than conventional and low dose images without this technique. Higher contrast noise ratio (CNR) and signal-to-noise ratio (SNR) (P0.05); conventional dose images have lower noise value and higher CNR and SNR (P0.05); for FBP reconstruction algorithm, The subjective scores of low-dose AS-LNLM and low-dose images were (3.36 卤0.69) and (1.95 卤0.72) (P0.05), respectively, and the subjective scores of low-dose ASLNLM and low-dose images were (3.68 卤0.48) and (2.18 卤0.66) (P0.05), respectively. The subjective scores of conventional dose images reconstructed by FBP and 40%ASIR were (4.73 卤0.46) and (4.82 卤0.40), respectively. The CTDIvol values and ED values of low-dose scans were (1.84 卤0.01) m Gy, (49.60 卤2.63) m Gy/cm and (0.74 卤0.04) m Sv;) CTDIvol values and ED values were (7.61 卤0.03) m Gy, (204.18 卤11.19) m Gy/cm and (3.06 卤0.17) m Sv.), respectively. Conclusion the low dose AS-LNLM images can not only reduce the scanning dose, but also improve the image quality of CNR and SNR, images.
【作者单位】：安徽医科大学第一附属医院放射科;东南大学影像科学与技术实验室;
【基金】：安徽省科技计划项目(编号:1604a0802079)
【分类号】：R816.5

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