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目的实验研究三维自适应迭代剂量降低(AIDR3D)重建算法超低剂量640层CT结肠成像的息肉检出能力。方法制作10段猪结肠息肉模型,每段模型上有30枚1~15mm模拟息肉。所有模型用640层CT机扫描,球管电压120kVp,电流剂量分别为10、20、30、40、50mAs。滤波反投影(FBP)和AIDR3D算法重建后获得CT结肠成像的图像。两位不知道扫描电流剂量及重建算法的影像科医生独立分析图像。每位影像科医生的息肉检出信心分5个等级,用Kappa分析评价2位影像科医生息肉检出信心的一致性。根据剂量长度乘积计算辐射剂量。统计分析5种扫描电流剂量、2种重建算法的图像检出息肉的敏感性。结果两位影像科医生对3 000枚息肉检出信心一致性好(κ=0.740)。20mAs扫描并AIDR3D重建对1~<6、6~<11、11~15mm息肉检出敏感性与50mAs扫描并FBP重建相同,均达100%;有效辐射剂量1.62mSv较50mAs扫描并FBP重建的4.04mSv降低60.00%,差异有统计学意义(P<0.05)。10mAs扫描并AIDR3D重建对1~<6mm息肉检出敏感性77%低于50mAs扫描并FBP重建的100%,差异有统计学意义(P<0.05),对6~<11mm息肉检出敏感性98%也低于50mAs扫描并FBP重建的100%。结论超低剂量20mAs扫描并AIDR3D重建640层CT结肠成像息肉检出能力能够与标准低剂量50mAs扫描并FBP重建媲美,检出敏感性达100%;而且有效辐射剂量降低60.0%,只有1.62mSv。
AIM: To study the polyp detection ability of ultra-low-dose 640-slice CT colonography in three-dimensional adaptive iterative dose reduction (AIDR3D) reconstruction. Methods 10 sections of pig colon polyps model were made. There were 30 pieces of 1-15mm simulated polyps on each section. All models were scanned with a 640-slice CT scanner with a bulb voltage of 120 kVp and current doses of 10, 20, 30, 40 and 50 mAs, respectively. Filtered back projection (FBP) and AIDR3D algorithm reconstruction of CT colon imaging images obtained. Two independent analysis images by imaging doctors who did not know the scan current dose and reconstruction algorithm. Each imaging physician’s confidence in detecting polyps was divided into five grades. Kappa analysis was used to evaluate the confidence of the two imaging doctors in detecting polyps. The radiation dose is calculated from the dose length product. Statistical analysis of five scanning current dose, two kinds of reconstruction algorithm image detection of polyps sensitivity. Results The two radiologists had good confidence in detecting 3,000 polyps (κ = 0.740). The detection sensitivity of 20mAs and AIDR3D in 1 ~ <6,6 ~ <11,11 ~ 15mm polyps was the same as that of 50mAs scan and FBP reconstruction, both reaching 100%; the effective radiation dose was 1.62mSv, which was 4.04 mSv decreased 60.00%, the difference was statistically significant (P <0.05). 10mAs scan and AIDR3D reconstruction of 1 ~ <6mm polyps detection sensitivity of 77% lower than 50mAs scan and FBP reconstruction of 100%, the difference was statistically significant (P <0.05), 6 ~ <11mm polyps detection sensitivity 98 % Is also lower than 100% of 50mAs scans and FBP reconstruction. Conclusions Ultrathin dose 20mAs scanning and AIDR3D reconstruction of 640-slice CT colon polyp can detect the polyp with the standard low-dose 50mAs scanning and FBP reconstruction, the detection sensitivity is up to 100%, and the effective radiation dose is reduced by 60.0% with only 1.62mSv.