Fmdamentl alld Cliuical investigation of rCBF Measurement by single Photou Emission CTg (HEADTOME)

本研究旨在提高局部脑血流量（rCBF）测量的图像质量和可靠性。图像质量主要受脉冲高度分析器（PHA）的窗位影响。由于不对称窗口水平应设置为75-110 KeV，因此81 KeV光子能量的133 -133应设置为75-110 KeV。为了避免头部数据和呼吸空气曲线之间的不匹配，对数据采集时间间隔进行了标准化。为了最大限度地减少吸入133气体的损失和空气曲线与动脉活动曲线之间的差异，需要适当的呼吸袋容量设置和吸入系统的呼吸同步控制。对于吸入氚-133气体，吸嘴上级优于面罩，因为鼻腔散射辐射较少。为了提高rCBF值的可靠性，尝试用潮气末CO2浓度对rCBF数据进行校正。潮气末CO2浓度每增加1%，平均rCBF增加14%。我们通过将潮气末CO2浓度归一化为5.8%（对应于41 mmHg PaCO 2），对rCBF数据进行了校正。改进后的rCBF图像质量和rCBF测量值的可靠性明显提高。检测到阿尔茨海默病的rCBF特征分布的颞顶叶减少和多发性梗死性痴呆的斑片状全脑减少特征。痴呆的严重程度与rCBF减少的程度相关，特别是在阿尔茨海默病的情况下，在颞顶叶区域。我们改进的SPECT的能力使其成为一个有前途的工具，用于研究或常规检查痴呆症患者。

The purpose of our stude was to improve image quality and reliability in measurement of tomographic regional cerebral blood flow (rCBF). Image quality was mostly affected by the window level of the pulse height analyzer (PHA). As asymmetric window level should be set as 75-110 KeV for 81 KeV photon energy of Xe-133. To avoid mismatching between the head data and the respiratory air curve, the interval of data acquisition timing was standardized. To minimize loss of Xe-133 gas and discrepancy between the air curve and the arterial activity curve, suitable volume setting of spiro- bag and breath-synchronized control of the inhalation system were required. For the Xe-133 gas inhalation, a mouthpiece was superior to a face mask because of less scattered radiation from the nasal cavity. to improve the reliability of the rCBF value, a correction of the rCBF data for end- tidal CO2 concentration was attempted. Mean rCBF increased by 14% for each 1% increase in end-tidal CO2 concentration. We introduced the correction of rCBF data by normalizing the end-tidal CO2 concentration around 5.8% corresponding to 41mmHg PaCO2. After these improvements, the quality of the rCBF image and the reliability of measured rCBF value were markedly elevated.As a clinical application, demented patiensts were examined. A temporo-parietal reduction in the distribution of the rCBF characteristic in the Alzheimer's disease and a patchy whole brain reduction characteristic in the multi infarct dementia were detected. The severity of dementia correlated with the degree of rCBF reduction especially at the temporo-parietal region in the case of Alzheimer's disease. The ability of our improved SPECT makes it a promising tool for research or routine examination of demented patients.