单色能量CTA成像结合锐利迭代重建技术评价支架术后再狭窄的效果

Application of CTA with monoenergetic imaging combined with iterative reconstruction using a sharp convolution kernel in the evaluation of in-stent restenosis

目的:研究下肢CTA单色能量成像结合中等锐利迭代重建(B60f,SAFIRE)技术在下肢血管支架植入术后再狭窄(instent restenosis,ISR)诊断中的应用价值。方法:对72例(男37,女35)股动脉植入支架的患者行下肢动脉CT血管造影(computer tomography angiography,CTA)。25例采用双能量扫描,中等锐利迭代重建(B60f SAFIRE),分离出2组(70 keV_锐,80 keV_锐)单色能量图像。47例采用100 kV扫描,其中23例(100 kV标组)标准平滑迭代重建(50%ASIR),24例(100 kV锐组)中等锐利迭代重建(B60f SAFIRE)。比较图像噪声(SD)、信噪比(SNR)、对比噪声比(CNR)、支架-血管密度差(SV_D)、测量-实际支架壁厚差(MAD),结合血管超声或DSA,评价ISR的诊断准确率。结果:①不同重建同能级:SD,100 k V_标<100 kV_锐,SNR、CNR之间无统计学差异(P>0.05)。②不同能级同重建比较:SD,70 keV_锐<80 keV_锐<100 kV_锐,各组间差异有统计学意义(P<0.05)。腔内SNR和CNR:100 kV_锐<70 keV_锐<80 keV_锐,组间差异有统计学意义(P<0.05)。③支架-血管密度差(SV_D):70 keV_锐<80 keV_锐<100 kV_锐<100 kV_标,测量-真实支架壁厚差(MAD):80 keV_锐<100 kV_锐<70 keV_锐<100 k V_标,组间差异有统计学意义(P<0.05)。④主观图像质量评分:70 keV_锐<100 kV_标<100 k V_锐<80 keV_锐(P<0.05),支架内再狭窄的诊断准确率:70 keV_锐(71.04%)<100 kV_标(86.19%)<100 kV_锐(91.27%)<80 keV_锐(95.8%),(χ^2=9.95,P=0.019),κ=0.743(P<0.05)。结论:80 keV_锐单色能量结合中等锐利迭代重建(B60f SAFIRE)成像有助于优化支架血管CTA的图像质量,提高ISR的诊断准确率。

Objective:To study the practical value of computed tomography angiography(CTA)with monoenergetic imaging combined with iterative reconstruction using a medium-sharp convolution kernel(B60f,SAFIRE)in the diagnosis of in-stent restenosis(ISR)of the lower extremities. Methods:CTA of the lower extremity arteries was performed in 72 patients(37 males and 35 females)with a stent implanted in the femoral artery. Among the above patients,25 underwent dual-energy scanning combined with iterative reconstruction using a medium-sharp convolution kernel(B60 f,SAFIRE) and were subdivided into two monoenergetic imaging groups(70 keVsharpand 80 keVsharp);47 underwent 100-kV scanning and were subdivided into 100 k Vstandardgroup(23 cases,using adaptive statistical iterative reconstruction [50% ASIR]) and 100 k Vsharpgroup(24 cases,using iterative reconstruction with a medium-sharp convolution kernel[B60 f,SAFIRE]). These groups were compared for image noise(standard deviation [SD]),signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR),stent-vessel deviation(SVD),and measured-actual deviation(MAD);the diagnostic accuracy for ISR was evaluated by taking into account the results of vascular ultrasound or digital subtraction angiography. Results:In groups of the same energy level and processed with different reconstruction methods,the image noise(SD)was significantly lower in the 100 kVstandardgroup than in the 100 kVsharpgroup;there were no significant differences between groups in SNR or CNR(P>0.05). Between groups of different energy levels and processed with the same reconstruction method,there were significant differences in image noise(SD)(70 keVsharp<80 keVsharp<100 kVsharp,P<0.05)and intraluminal SNR and CNR(100 kV sharp<70 keVsharp<80 keVsharp,P<0.05). There were significant differences between groups in SVD(70 keVsharp<80 keVsharp<100 kVsharp<100 kVstandard,P<0.05),MAD(80 keVsharp<100 k Vsharp<70 keVsharp<100 kVstandard,P<0.05),subjective image quality score(70 keVsharp<100 kVstandard<100 k Vsharp<80 keVsharp,P<0.05),and diagnostic accuracy for ISR(70 keVsharp(71.04%)<100 kVstandard(86.19%)<100 kVsharp(91.27%)<80 keVsharp(95.8%),(χ2=9.95,P=0.019),κ=0.743,P<0.05). Conclusion:Monoenergetic imaging combined with iterative reconstruction using a medium-sharp convolution kernel(B60 f,SAFIRE)in the 80 keVsharp group can help optimize the image quality of CTA for stent-implanted vessels and improve the diagnostic accuracy for ISR.