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在评估缺血性心脏病的无创性方法中,SPECT心肌灌注显像(myocardial perfusion imaging,MPI)是大家公认的显像方法,MPI可为医生诊治怀疑或确定冠状动脉疾病(coronary artery disease,CAD)患者提供定量和高效的信息。在临床实践中,静息和负荷MPI能可靠评估局部心肌血流量和心肌的活性:一是明确CAD的诊断;二是对CAD确诊的患者进行预后评估[1]。事实上,MPI为临床医生提供相关信息的优势在于:①对CAD患者进行危险分层;②评估CAD确诊患者的远期预后;③指导临床做出最适当的治疗决策。然而MPI仍受一些因素的影响,如固有的低光子通量、组织不均一性导致的衰减、长时间扫描(无论使用201Tl还是99Tcm标记的放射性同位素,检查过程都很长,且运动和静息扫描时间大概为40 min,但中间的间隔时间约需3 h)产生的运动伪影和辐射等[2]。因此,如果想要保持MPI在可疑或诊断明确CAD患者管理中的重要作用,则应在不降低图像质量的情况下,缩短采集时间和减少放射剂量。
近年来出现的D-SPECT心脏扫描仪包括Spectrum Dynamics和Discovery NM530c(GE Healthcare)。D-SPECT心脏扫描仪具有先进的探头、采集方法以及重建算法[1-4]。带有9组碲化镉锌(cadmium zinc telluride,CZT)晶体和广角钨准直器的像素化固态探头,像素化的CZT探测器阵列集成在9组垂直的模块中,并放置在互相垂直的机架中。9组探测器模块中的每组都配有钨平行孔方形准直器,图像数据采集时同步旋转这几组模块,9组探测器阵列同时采集心脏的数据并成像。在定位扫描后1 min开始获取图像,定位扫描的目的是让9组探测器确定心脏位置从而设定每组探测器的扇扫移动范围,之后用改良的迭代算法重建图像,该重建算法模拟了采集和准直器的几何形态[5]。在扫描过程中,探头和准直器不移动,多个CZT探测器同时进行图像采集。该设备结构紧凑,占地仅需177 cm×170 cm。日常质控仅需57Co放射源采集10 min行均匀性和探测器稳定性检验。该设备利用患者的原始数据进行采集,与传统γ相机相比,计数率提高8倍;CZT晶体使140 keV光子的能量分辨率由5%提高至10%;且与采用滤波反投影重建算法的传统SPECT相比,空间分辨率显著提高[1, 3-5]。心脏专用CZT相机极大地优化了多种放射性核素MPI同时采集的过程,并提高了静息及负荷图像间的精确配准,因此出现了心脏专用CZT相机同步双核素显像。
心脏专用碲化镉锌相机的相关临床应用新进展
The new progress of clinical application of cardiac dedicated cadmium-zinc-telluride camera
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摘要: 在评估缺血性心脏病的无创性方法中,SPECT心肌灌注显像(MPI)是大家公认的显像方法,但MPI受到一些因素的影响,如组织不均一性导致的衰减、扫描时间长、辐射等。近年来出现的心脏专用碲化镉锌(CZT)相机越来越受到人们的广泛关注,该设备有先进的CZT探测器、采集方法及重建算法。心脏专用CZT相机的计数率、空间分辨率和能量分辨率较传统SPECT显著提高。该文就心脏专用CZT相机的相关临床应用进展进行综述。
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关键词:
- 心肌灌注显像 /
- 体层摄影术, 发射型计算机, 单光子 /
- 碲化镉锌 /
- 心脏专用相机
Abstract: Among non-invasive methods for the assessment of ischaemic heart disease, myocardial perfusion imaging(MPI) using SPECT tracers is firmly established and well-known by physician and patients. However, MPI is still affected by several drawbacks such as attenuation due to non-uniform tissue, motion artefacts due to time-consuming scan and radiation exposure. The dedicated solid-state cardiac camera using cadmium zinc telluride(CZT) solid-state detectors emerged in recent years. The camera has gotten more and more attention. The camera has advanced CZT detector, acquisition and reconstruction method. The count rate, spatial resolution and energy resolution of the CZT SPECT have been enhanced significantly. This paper would review the clinical application progress of CZT SPECT. -
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