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)(P<0.05);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(P<0.05);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)(P<0.05);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)(P<0.05)。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。
Objective To evaluate the feasibility of the artifact suppressed-large neighborhood nonlocal means for improving the quality of low dose abdominal CT images. Methods With institutional review board approval 26 pa- tients who underwent routine-dose and low-dose abdominal CT examination were enrolled. The routine dose and low dose abdominal raw data were reconstructed with FBP,40% ASIR respectively, and the reconstructed thickness of image was 0. 625 ram. Two reconstruction algorithms of low dose data were processed the artifact suppressed large neighborhood nonlocal means. The application of processing station was used to analyze the CT images. The image noises were measured, and the noise, contrast to noise ratio(CNR) and the signal to noise ratio(SNR) of the liv- er, spleen and abdominal aorta were compared. The subjective evaluation was described for the abdominal image quality. Radiation dose by CT dose index volumes(CTDIvol) and dose length product(DLP) were recorded, and effective dose(ED) and the average reduction rate was calculated. Results For the image quality of the abdomi- nal, the AS-LNLM low dose images had lower noise values, higher CNR and SNR than conventional and low dose images without using this technique(P 〈 0.05 ). The conventional dose images had lower noise values, higher CNR and SNR than low-dose images (P 〈 0. 05). For the FBP reconstruction algorithm, the subjective scores of low dose images used AS-LNLM technology and low dose images without using this technique were approximately (4. 23 ± 0. 43) and (1.95±0. 72) (P 〈0.05). For the 40% ASIR reconstruction algorithm, the subjective scores of low dose images used AS-LNLM technology and low dose images without using this technique were approximately (4.36 ±0. 49) and (2. 18 ± 0. 66)(P 〈0.05). The subjective scores of conventional dose images of FBP and 40% ASIR were approximately (4.73 ±0.46) and (4. 82 ±0.40), respectively. CTDIvol,DLP and ED of low-dose CT images were ( 1.84 ±0. 01 ) mGy, (4. 96 ±2. 63 ) mGy/cm and (0. 74 ±0. 04) mSv, and for conventional dose CT images were (7.61 ±0. 03) mGy, (204. 18 ± 11.19) mGy/cm and (3.06 ±0. 17) mSv, respectively. Conclusion Compared with conventional scanning, AS-LNLM can significantly reduce the scanning dose and improve the im- age CNR and SNR, and the quality of image can meet the diagnostic requirements. Key words X-ray computed tomography;artifact suppressed large neighborhood nonlocal means;low dose scan; filtered back projection;adaptive statistical iterative reconstruction ;artifacts suppressed
出处
《安徽医科大学学报》
CAS
北大核心
2017年第6期887-891,共5页
Acta Universitatis Medicinalis Anhui
基金
安徽省科技计划项目(编号:1604a0802079)
关键词
体层摄影技术
X线计算机
大尺度非局部均值伪影抑制
低剂量扫描
滤波反投影法
自适应统计迭代重建
伪影抑制
X-ray computed tomography
artifact suppressed large neighborhood nonlocal means
low dose scan
filtered back projection
adaptive statistical iterative reconstruction
artifacts suppressed