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

本研究的目的是提高断层局部脑血流量(RCBF)测量的图像质量和可靠性。图像质量主要受脉冲幅度分析器(PHA)窗位的影响。对于Xe-133的81keV光子能量，非对称窗能级应设置为75-110keV。为了避免头部数据与呼吸空气曲线不匹配，对数据采集时间间隔进行了标准化。为了减少Xe-133气体的损失和空气曲线与动脉活动曲线之间的偏差，需要适当的螺旋袋容量设置和吸入系统的呼吸同步控制。对于Xe-133气体吸入，口罩优于面罩，因为鼻腔的散射辐射较少。为了提高rCBF值的可靠性，尝试对呼气末二氧化碳浓度的rCBF数据进行校正。呼气末二氧化碳浓度每增加1%，平均rCBF增加14%。我们介绍了对rCBF数据的校正，将呼气末二氧化碳浓度归一化至约5.8%，对应于41 mm HgPaCO2。经过这些改进后，rCBF图像的质量和测量rCBF值的可靠性显著提高。阿尔茨海默病患者rCBF分布呈顶叶缩小，多发梗死性痴呆患者全脑缩小呈斑块状。痴呆的严重程度与rCBF降低的程度相关，特别是在阿尔茨海默病的情况下，尤其是在颞顶区。我们改进的SPECT的能力使其成为研究或常规检查痴呆症患者的一个有前景的工具。

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.