METHODS: Extracorporeal perfusion of the upper leg was established in one fresh-frozen human cadaver via inguinal and popliteal accesses using a peristaltic pump. Seven peripheral stents were deployed in the SFA. Photon-counting CTAs were performed under contrast perfusion in SR and UHR mode with dose-equivalent 120kVp acquisition protocols (low-/ medium-/ high-dose: CTDIVol=3, 5, 10 mGy) and reconstructed with four vascular convolution kernels. Lumen visibility and contrast-to-noise ratio were compared using analyses of variance. Subjective image quality was assessed using a pairwise, forced-choice comparison software.
RESULTS: Lumen visibility was equal for SR and UHR at the used dose levels. CNR increase by UHR was significant for (ultra-)sharp convolution kernels BV60 (3 mGy; UHR vs. SR, 19.9 ± 1.9 vs. 15.7 ± 1.6, p < 0.046) and BV76 (8.0 ± 0.6 vs. 5.4 ± 0.3, p < 0.001). The relative CNR increase was higher for low-dose than high-dose scans (BV76: 48% vs. 36% at high dose, p < 0.033). The CNR of the low-dose scan in UHR mode was comparable to the high-dose scan in SR mode when the ultra-sharp kernel was used (8.0 ± 0.6 vs. 9.1 ± 1.1, p > 0.760). Among UHR examinations, a significant increase in CNR could only be measured in BV76 (8.0 ± 0.6 (3 mGy) vs. 12.4 ± 0.9 (10 mGy), p < 0.001). Readers preferred subjective image quality of UHR for all kernels with BV76 being ranked highest.
CONCLUSIONS: The CNR increase in UHR mode is highest when combining low radiation dose and ultra-sharp reconstructions. Meanwhile, the subjective image quality in UHR mode generally supersedes SR images, suggesting further dose reduction potential.
方法:使用蠕动泵通过腹股沟和pop入路在一个新鲜冷冻的人尸体中建立了上腿的体外灌注。在SFA中部署了七个外周支架。光子计数CTA在SR和UHR模式下使用剂量等效120kVp采集协议(低/中/高剂量:CTDIVol=3、5、10mGy)在造影剂灌注下进行,并用四个血管卷积核进行重建。使用方差分析比较了管腔能见度和对比度噪声比。使用成对评估主观图像质量,强制选择比较软件。
结果:在使用的剂量水平下,SR和UHR的管腔能见度相等。对于(超)尖锐卷积核BV60(3mGy;UHRvs.SR,19.9±1.9vs.15.7±1.6,p<0.046)和BV76(8.0±0.6vs.5.4±0.3,p<0.001)。低剂量扫描的相对CNR增加高于高剂量扫描(BV76:48%vs.高剂量时36%,p<0.033)。当使用超尖锐内核时,UHR模式下低剂量扫描的CNR与SR模式下的高剂量扫描相当(8.0±0.6与9.1±1.1,p>0.760)。在UHR考试中,仅在BV76中可以测量到CNR的显着增加(8.0±0.6(3mGy)与12.4±0.9(10mGy),p<0.001)。读者更喜欢所有内核的UHR主观图像质量,其中BV76排名最高。
结论:当结合低辐射剂量和超尖锐重建时,UHR模式的CNR增加最高。同时,UHR模式下的主观图像质量通常取代SR图像,提示进一步的剂量减少潜力。