能谱CT下肢静脉成像优化:模体研究
Optimization of Dual-energy Spectral Lower-extremity Computed Tomography Venography Scanning Protocol:Phantom Study
王诗耕 1浦仁旺 1刘义军 1方鑫 1魏巍 1李贝贝1
作者信息
- 1. 大连医科大学附属第一医院放射科,辽宁 大连 116011
- 折叠
摘要
目的:基于模体研究优化能谱下肢CT静脉成像(CTV)方案.方法:在能量CT质控模体的内部孔洞中放置测试插件以模拟临床场景.使用 4mgI/mL碘棒模拟下肢静脉增强;将大小不同的鸭血块放入 4mgI/mL的碘溶液试管中,模拟下肢静脉内的大小血栓.采用Revolution CT对置入碘棒和试管的模体进行CT常规成像(A组)和能谱成像(B组).A组成像参数:管电压 120kVp,管电流自动调节技术(100～600mA),噪声指数(NI)为 10,采用后置 40%的多模型自适应统计迭代重建算法(ASIR-V)进行图像重建;B组成像参数:能谱成像(GSI)模式,管电压 80/140kVp瞬切,管电流采用GSI Assist技术,并根据NI=10、11、12设置 3个扫描组.在每个扫描组中重建 40～70keV间隔 10keV的单能量图像,每个单能量图像分别结合后置 40%、60%、80%ASIR-V进行图像重建,共得到 36组图像.A组和B组其他成像参数均一致.扫描完成后记录A组和B组有效辐射剂量(ED),计算两组碘棒对比噪声比(CNR),评估两组主观图像质量以及识别血栓的真阳性率和假阳性率.结果:B组NI设置为 11和 12的ED分别比A组低 21.5%和 32.2%.B组NI为 10和 11的扫描组中,除了 70keV结合 40%ASIR-V和 60keV结合 40%ASIR-V的图像外,其余图像的碘棒CNR均高于A组.B组碘棒边缘锐利度得分最高的组别是NI为 10的扫描组中,50keV结合 40%、60%ASIR-V的图像,以及NI为 11的扫描组中,50keV结合 60%ASIR-V的图像,这 3组图像得分均为 5(4,5)且优于A组得分 3(3,4).A组图像识别大血栓的真阳性率和假阳性率分别为 65.0%和 30.0%;识别小血栓的真阳性率和假阳性率分别为55.0%和 50.0%.B组NI为 10和 11的扫描组中,50keV结合 60%ASIR-V图像识别血栓的效能最佳并优于A组,其中识别大血栓的真阳性率和假阳性率分别为 90.0%和 5.0%,识别小血栓的真阳性率和假阳性率分别为 80.0%和 5.0%.结论:将NI设置为 11,并重建 50keV结合 60%ASIR-V的单能量图像是能谱下肢CTV的最佳成像方案,可在模体研究中实现图像质量与辐射剂量之间的平衡.
Abstract
Objective:To optimize a scanning protocol for dual-energy spectral lower-extremity computed tomography venography(CTV)based on a phantom study.Methods:Test plugs were placed in the cavities of an energy CT quality-control phantom to simulate clinical scenarios.A 4 mgI/mL iodine rod was used to mimic venous enhancement in the lower extremities,and duck blood clots of various sizes were placed in test tubes containing 4 mgI/mL of iodine solution to simulate thrombi of different sizes in the lower-extremity veins.Revolution CT was used to perform standard CT imaging(Group A)and spectral imaging(Group B)on phantoms containing iodine rods and test tubes.The imaging parameters for Group A were as follows:tube voltage of 120 kVp,auto tube-current technology(100～600 mA),noise index(NI)of 10,and image reconstruction using 40%posterior multimodel adaptive statistical iterative reconstruction(ASIR-V).The imaging parameters for Group B were spectral imaging(GSI)mode,instantaneous dual tube voltage of 80/140 kVp,tube current with GSI Assist technology,and three scan groups based on NI values of 10,11,and 12.For each scan group,monoenergetic images at 40～70 keV with 10 keV intervals were reconstructed,each combined with 40%,60%,and 80%posterior ASIR-V,which resulted in 36 image sets.Other imaging parameters for Groups A and B were consistent.The effective radiation doses(ED)for Groups A and B were recorded after scanning,and the contrast-to-noise ratio(CNR)of the iodine rods was calculated.Subjective image quality and true-and false-positive rates for thrombus identification were assessed.Results:The EDs for Group B,with NI values of 11 and 12,were 21.5%and 32.2%lower than those for Group A,respectively.In Group B,for the scan groups with NI values of 10 and 11,except for the images at 70 keV combined with 40%ASIR-V and at 60 keV combined with 40%ASIR-V,the CNR of the iodine rods was higher than that in Group A.The highest edge-sharpness scores for the iodine rods in Group B were observed in the scan group with an NI value of 10 for images at 50 keV combined with 40%and 60%ASIR-V,and in the scan group with an NI value of 11 for images at 50 keV combined with 60%ASIR-V.These three image sets scored 5(4,5)compared with Group A's score of 3(3,4).The true-and false-positive rates for large-thrombus identification in Group A were 65.0%and 30.0%,respectively,whereas those for small-thrombus identification were 55.0%and 50.0%,respectively.In Group B,the best thrombus-identification efficacy was observed in the scan groups,with NI values of 10 and 11 for images at 50 keV combined with 60%ASIR-V.The true-and false-positive rates for large-thrombus identification were 90.0%and 5.0%,respectively,whereas those for small-thrombus identification were 80.0%and 5.0%,respectively.Conclusions:Setting the NI to 11 and reconstructing monoener-getic images at 50 keV combined with 60%ASIR-V is the optimal imaging strategy for dual-energy spectral lower-extremity CTV,which balances between image quality and radiation dose in the current phantom study.
关键词
体层摄影术/X线计算机/能谱CT/静脉血栓形成/图像质量Key words
tomography/X-ray computed/dual energy computed tomography/venous thrombosis/image quality引用本文复制引用
出版年
2025
国家科技期刊平台
NSTL
万方数据