Absolute quantitation of regional myocardial blood flow of rats using dynamic pinhole SPECT
Absolute quantitation of regional myocardial blood flow of rats using dynamic pinhole SPECT
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使用动态针孔 SPECT 对大鼠局部心肌血流进行绝对定量
DOI：
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发表时间：
2002
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通讯作者：
Hidehiro Iida
中科院分区：
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作者：
T. Aoi;Hiroshi Watabe;H. M. Deloar;M. Ogawa;N. Teramoto;Nobuyuki Kudomi;Toshihiro Oota;Kyeong;Tetsuya Matsuda;Hidehiro Iida
PET和SPECT已被广泛应用于动物体内生理功能的研究。然而，在估计小动物的绝对生理参数，即血流方面所做的工作却很少。本研究旨在利用配备针孔准直器的动态SPECT，仔细测定动脉输入功能(IF)，对大鼠心肌血流量进行绝对定量。旋转中心小心翼翼地对准了精度为0.05 mm的固定伽马相机的视场中心。一只老鼠被放在一个旋转装置上，该装置将老鼠固定在站立位置。经常采集动脉血样本，并使用与SPECT图像交叉校准的井式计数器测量其放射性浓度。尾静脉注射~(201)Tl后5min开始动态SPECT扫描(步射模式)。每个旋转角度的采集周期为10s，获得了120个视角投影数据。以大约20分钟的间隔获得360度完整数据集，持续5个时间帧。图像重建采用滤波反投影技术和Feldkamp算法。交叉校准因子是用一个直径5厘米的圆柱形模体填充201TlCl溶液来测定的。在左室壁上放置感兴趣区，以生成组织时间活动曲线(TTAC)。TTAC和IF符合先前验证的单组织室模型，以估计局部心肌血流量(RMBF)和铊的分布体积(Vd)。该系统提供了清晰的心肌摄取~(201)Tl的图像，以及组织放射性浓度随时间变化的区域性基础，这在统计学上足以应用房室模型分析。动力学分析得到的rMBF约为0.77ml/min/g，考虑到部分体积效应和其他误差源的贡献，这似乎是一个可接受的值。Vd约为91.9ml/ml，与细胞膜上钾电势的已知值一致。这些结果有力地表明了动态针孔SPECT作为一种绝对定量小动物生理参数的工具的潜力。
PET and SPECT have been widely used to investigate the physiological function of animals in vivo. However, little efforts have been done to estimate absolute physiological parameters, i.e. blood flow of small animals. The present study was aimed at the absolute quantitation of myocardial blood flow of rats by means of the dynamic SPECT fitted with a pinhole collimator with a careful determination of the arterial input function (IF). The center-of-rotation was carefully aligned to the center of the field-of-view of a fixed gamma camera with the accuracy < 0.05 mm. A rat was placed on a rotating device that fixes the rat in a stand position. The arterial blood samples were frequently collected and their radioactivity concentration was measured using a well counter cross-calibrated to the SPECT images. Dynamic SPECT (the step-and-shoot mode) was initiated at 5 min after the injection of 201TlCl into the tail vein. Acquisition period was 10 sec at each rotation angle, and 120 view projection data were obtained. The 360-degree complete data sets were obtained at approximately 20 min interval for 5 time frames. Images were reconstructed by filtered-back projection technique with Feldkamp algorithm. The cross-calibration factor was determined using a cylindrical phantom of 5 cm diameter filled with the 201TlCl solution. Regions-of-interest were placed on the left ventricular wall to generate the tissue time activity curve (TTAC). TTAC and IF were fitted to the previously validated single-tissue compartment model to estimate the regional myocardial blood flow (rMBF) and volume of distribution (Vd) of thallium. The present system provided clear images of myocardial uptake of 201TlCl, and the time-dependent change of the tissue radioactivity concentration in regional basis, which was statistically sufficient for applying the compartment model analysis. The kinetic analysis yielded the rMBF of approximately 0.77 ml/min/g, which appeared to be an acceptable value with a consideration of contribution of partial volume effect and other error sources. Vd of approximately 91.9 ml/ml was also consistent with the know value of the potassium potential across the cell membrane. These results strongly suggested the potential of the dynamic pinhole SPECT as a tool for absolute quantitation of physiological parameters in small animals.