Gruschwitz P, Petritsch B, Schmid A, Schmidt A M A, Grunz J-P, Kuhl P J, Heidenreich J F, Huflage H, Bley T A, Kosmala A
Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany; Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
Radiography (Lond). 2023 Jan;29(1):19-27. doi: 10.1016/j.radi.2022.09.002. Epub 2022 Oct 6.
The aim of this study was to evaluate the influence of a noise optimized virtual monoenergetic reconstruction algorithm (VMI+) on the image quality and assessability of dual energy (DE) computed tomography angiography (CTA) of the lower extremity runoff.
A total of 118 lower extremity runoff CTA performed on a 3rd generation DE-CT scanner in 109 patients (54 females; 75.6 ± 9.5 years) were included in this retrospective study. Axial image stacks were reconstructed with a standard 120 kV setting and VMI+ of different keV levels. Objective image quality criteria (contrast attenuation, signal-to-noise [SNR] and contrast-to-noise ratio [CNR]) were measured. Two radiologists evaluated subjective image quality regarding intraluminal attenuation and image noise using a 5-point Likert scale. Diagnostic accuracy for significant stenosis (>75%) and vessel occlusion was assessed for 120 kV and 50 keV VMI+ images rated by two radiologists. In all patients, a digital subtraction angiography (DSA) rated by on board-certified radiologist served as the standard of reference.
Intraluminal attenuation was highest in 40/50 keV VMI+ while SNR were similar to 120 kV images. In subjective assessment, intraluminal contrast of 50 keV images was deemed superior compared to 120 kV despite higher image noise. Sensitivity, specificity, and accuracy for detection of a vessel occlusion were similar in 50 keV VMI+ compared to 120 kV (70%/92%/84%; 70%/91%/83%; p < 0.001) but 13 of 118 (11%) lower leg runoffs were only assessable with 50 keV VMI+.
VMI+ reconstructions improve assessability of DE-CTA by increased luminal attenuation with consistent image noise, also allowing the evaluation of lower leg arterial segments inassessable with standard reconstructions.
Providing higher intraluminal attenuation and similar image noise compared with conventional reconstructions, 50 keV VMI+ may be appropriate for routine evaluation of DE-CTA.
本研究旨在评估噪声优化的虚拟单能量重建算法（VMI+）对下肢血管CTA图像质量和可评估性的影响。
本回顾性研究纳入了109例患者（54例女性；年龄75.6±9.5岁）在第三代双能量CT扫描仪上进行的118次下肢血管CTA检查。轴向图像堆栈采用标准120 kV设置和不同keV水平的VMI+进行重建。测量客观图像质量标准（对比剂衰减、信噪比[SNR]和对比噪声比[CNR]）。两名放射科医生使用5分李克特量表评估腔内衰减和图像噪声方面的主观图像质量。对两名放射科医生评定的120 kV和50 keV VMI+图像评估显著狭窄（>75%）和血管闭塞的诊断准确性。在所有患者中，由经委员会认证的放射科医生评定的数字减影血管造影（DSA）作为参考标准。
40/50 keV VMI+的腔内衰减最高，而SNR与120 kV图像相似。在主观评估中，尽管50 keV图像的图像噪声较高，但腔内对比度被认为优于120 kV图像。与120 kV相比，50 keV VMI+检测血管闭塞的敏感性、特异性和准确性相似（70%/92%/84%；70%/91%/83%；p<0.001），但118例下肢血管CTA中有13例（11%）仅使用50 keV VMI+可评估。
VMI+重建通过增加管腔衰减并保持一致的图像噪声，提高了双能量CTA的可评估性，还能对标准重建无法评估的小腿动脉节段进行评估。
与传统重建相比，50 keV VMI+提供了更高的腔内衰减和相似的图像噪声，可能适用于双能量CTA的常规评估。
