自动预置技术结合噪声指数及迭代重建算法在腹壁下动脉CT血管成像中的应用

Application of auto⁃prescription technique combined with noise index and iterative reconstruction algorithm to the computed tomographic angiography of deep inferior epigastric artery

目的探究自动预置技术(Auto⁃prescription)结合噪声指数(NI)和重建算法(ASIR⁃V)对腹壁下动脉CTA成像辐射剂量和图像质量的影响。方法前瞻性收集于大连医科大学附属第一医院行腹壁下动脉CT血管成像检查的患者150例,并随机数字表法分为3组。A组(50例)管电压120 kVp,NI 10,图像采用40%的ASIR⁃V重建;B组(50例)管电压采用自动预置技术,NI 10,图像分别采用40%、60%、80%ASIR⁃V重建,获得B1~B33个亚组。C组(50例)管电压采用Auto⁃prescription技术,NI 13,图像分别采用40%、60%、80%ASIR⁃V重建,获得C1~C33个亚组。在各组轴位图像上测量腹壁下动脉起始水平股动脉及同层面腹直肌的CT值和SD值,计算信噪比(SNR)及对比噪声比(CNR),记录3组辐射剂量。由2名观察者采用盲法独立对各组腹壁下动脉显示情况和图像噪声行主观评分。结果B、C组股动脉CT值均高于A组(t=-5.18、-5.17、-5.06、-6.08、-6.08、-6.07,P<0.05);B、C组内随着ASIR⁃V等级的提高,图像SNR、CNR逐渐升高(F=55.45、49.70、53.47、68.89,P<0.05),且均优于A组(P<0.05)。2名观察者主观评价一致性较好(Kappa=0.76~0.92,P<0.05)。B、C组图像在腹壁下动脉穿支、穿出点显示、肌内走行的主观评分方面均优于A组。B2、B3和C2组在图像噪声主观评分方面与A组差异无统计学意义(P>0.05)。B、C组辐射剂量与A组相比分别降低15.10%和52.85%(H=75.21,P<0.05)。结论自动预置技术结合NI=13和60%ASIR⁃V的成像方案可在保证腹壁下动脉清晰显示的同时降低52.85%的辐射剂量。

Objective To explore the effects of the auto⁃prescription technique combined with noise index(NI)and adaptive statistical iterative reconstruction algorithm⁃veo(ASIR⁃V)on the radiation dose and image quality in the computed tomographic angiography(CTA)of the deep inferior epigastric artery(DIEA).Methods The data of 150 cases who underwent DIEP CTA in the First Affiliated Hospital of Dalian Medical University were prospectively collected,and were randomized into groups A,B,and C,with 50 cases in each group.For group A,the conventional tube voltage was 120 kVp,and images were reconstructed using 40%ASIR⁃V.For group B,the tube voltage based on the auto⁃prescription technique was adopted,and images were reconstructed using 40%,60%,and 80%ASIR⁃V(corresponding to the three subgroups B1-B3,respectively).For group C,the tube voltage based on the auto⁃prescription technique was employed,NI=13,and images were reconstructed by 40%,60%,and 80%ASIR⁃V(corresponding to subgroups C1,C2,and C3,respectively).Subsequently,the CT and SD values of the originating femoral artery of DIEA and the rectus abdominis at the same level as DIEA were measured on axial images of each group,the signal⁃to⁃noise ratio(SNR)and contrast⁃to⁃noise ratio(CNR)were calculated,and the radiation doses of the three groups were recorded.Finally,the image quality and noise of DIEA in each group were independently and subjectively scored by two radiologists in a blinded manner.Results Compared to group A,groups B and C exhibited higher CT values of femoral artery(t=-5.18,-5.17,-5.06,-6.08,-6.08,-6.07,P<0.05)and higher image SNR and CNR(P<0.05),which increased gradually with the upgrading of ASIR⁃V(F=55.45,49.70,53.47,68.89,P<0.05).The two radiologists offered consistent subjective evaluations(Kappa=0.76-0.92,P<0.05).The images of groups B and C displayed more distinct perforating branches and emerging points of DIEA and received higher subjective scores of intramuscular course compared to those of group A.The subjective scores of image noise in subgroups B2,B3,and C2 were not significantly different from those in group A.The radiation doses in groups B and C decreased by 15.10%and 52.85%,respectively compared to those in group A(H=75.21,P<0.05).Conclusion The combination of the auto⁃prescription technique with NI=13 and 60%ASIR⁃V can reduce the radiation dose by 52.85%while ensuring a clear display of DIEA.