PET在阿尔茨海默病临床与研究中的应用

阿尔茨海默病(Alzheimer‘s Disease,AD）又称老年性痴呆，是一种多发于老年人，以进行性认知障碍和记忆能力损害为主的中枢神经系统退行性疾病。其典型的组织病理学改变是老年斑和神经纤维缠结。本文就PET在AD诊断、疾病预测、药物疗效观察、神经递质功能评价等方面的应用作一简要阐述。     

~(133)Xe吸入法测定局部脑血流量的临床应用

局部脑血流量(rCBF)的测定对脑部疾病,特别是对缺血性脑血管病的诊断、病情估计、疗效观察及预后判断等都具有重要意义。~(133)Xe吸入法测定rCBF具有无创伤性、安全、操作简便并可多次重复测定等优点。本法首先由Mallett及Veall提出,后经Obrist等诸多作者的研究与改进,方法已日臻完善。我们在完成~(133)Xe吸入测定rCBF方法学研究的基础上,对临     

硝基咪唑类PET肿瘤乏氧显像剂的研究总结和展望

乏氧显像剂能选择性的滞留在乏氧组织或细胞中。随着正电子发射计算机断层显像(PET)技术的发展,PET肿瘤乏氧显像可无创性评估实体瘤的乏氧状态,对肿瘤的治疗指导、疗效评价和预后判断具有重要的临床应用价值。~(18)F-硝基咪唑(~(18)F-FMISO)是目前广泛用于临床研究的硝基咪唑类乏氧显像剂,然而其存在某些缺点,新的硝基咪唑类乏氧显像剂正在广泛研究。本文就近年来正电子核素标记的硝基咪唑类肿瘤乏氧显像剂的研究进展进行简要概述。     

18F标记的脑受体PET显像剂的制备研究进展

脑受体的PET显像剂制备研究具有重要意义 ,其中以18F标记的药物研究最多。介绍了18F标记的脑受体PET显像剂制备的一般方法 ,对亲核取代法进行了较为详细的讨论 ,分析了主要影响因素 ;按照脑受体功能进行分类 ,回顾了近年来脑受体的PET显像剂制备研究的一些进展。     

脑专用PET显像探测器自由结构符合与初步实验测试

采用脑PET进行人脑功能的研究对生物医学起到至关重要的作用,为了显著提高脑PET显像质量,增加探测效率、实时显示图像,本文设计一种脑专用PET显像大面积平板型探测系统,该探测系统由两个大面积探头组成,每个大面积探头包含3×3阵列的位置灵敏光电倍增管和多个紧密排布的硅酸钇镥闪烁晶体（Ce：LYSO)阵列。并利用1 μCi的²²Na点源对晶格大小为0.7 mm×0.7 mm等六种LYSO晶体阵列进行晶体性能测试,并选用两块晶格大小为1.5 mm×1.5 mm的LYSO晶体阵列进行一对一符合探测初步断层显像。结果显示,各种晶格大小的LYSO晶体阵列的位置区分轮廓的半高宽平均值在0.38~0.49 mm之间,平均能量分辨率（半高宽）在17.61%~30.40%之间;在对²²Na点源的初步图像断层扫描实验测试中,通过滤波反投影算法获得重建图像的空间分辨率为1.5 mm,验证了大面积平板型探测系统的可行性。     

PET心肌血流量测定

介绍了以15O-H2O和13N-NH3作为显像剂，应用PET和示踪动力学原理进行无创性局部心肌血流量（RMBF）测定的方法，并对RMBF测定中的技术问题，如输入函数校正、部分容积校正和心肌血容积校正等进行了简述     

CEREBRAL BLOOD FLOW AND METABOLISM EVALUATION IN COMATOSE PATIENTS BY DYNAMIC SPECT

Thirty patients in coma state underwent dynamic SPECT with 133Xe, a validated technique for the quantitation of CBF by SPECT, using a new brain dedicated tomograph: CERTO-96. CMRO2 was computed by multiplying the mean CBF by AVDO2 according to the Fick's principle. The mean values of CBF, AVDO2 and CMRO2 in patients with good outcome were significantly different from those with worse outcome. On the basis of the best "discriminant threshold", CBF and AVDO2 demonstrated an intermediate accuracy in separating the two groups, while CMRO2 showed a satisfactory accuracy.     

~(133)Xe吸入法双探头测量局部大脑血流量的简易装置

目前,国外用吸入~(133)Xe测量局部大脑血流量(rCBF)的方法已日趋完善,由多探头、多道分析器及电子计算机组成的测量装置已应用于临床。测量大脑各功能区的血流量,对缺血性脑血管病的诊断、病情估计及疗效观察都有重要意义。我们利用现有仪器和设备,组装一台可以同时测量大脑左右两个部位的血流量的简易装置,进行了吸入~(133)Xe测量rCBF方法的研究,并对106例正常健康人、22例功能性头痛患者及22例缺血性脑血管病人的rCBF值进行了检查,取得了有一定参考价值的数据。本装置组成简单,操作方便,在我国现有条件下有     

Control of Oxygen Partial Pressure with Stabilized Zirconia Cell

A study was made on the method of controlling oxygen partial pressure in the range of 10^?4~10^?8 atm by the addition of oxygen into purified argon gas through stabilized zirconia cell. The oxygen partial pressures obtained by controlling the electric current passed through the cell and the feed rate of the carrier gas were found to agree well with theoretical values in the range of 10^?4 to 10^?6 atm oxygen partial pressure. Below 10^?6 atm, however, some discrepancy appeared between the theoretical and observed values, due to the oxygen partial pressure being reduced by the reaction with impurity gases such as hydrogen present in the argon. A discussion is also presented on the measured polarization curves for the anode and cathode of the stabilized zirconia cell.     

Effect of Liquid Flow Rate on Film Boiling Heat Transfer during Reflood in Rod Bundle

An experiment was performed in a wide range of core flooding rate to study the effect of liquid flow rate on the film boiling heat transfer during reflood using a 6 × 6 heater rod bundle with a full-height heated length. The flooding rate was in the range of 2–30cm/s. The obtained data were evaluated through assessment and improvement of Murao-Sugimoto heat transfer coefficient correlation, which predicted well the heat transfer coefficient under the core flooding rate up to 10 cm/s, but underestimated the heat transfer coefficient in the range of the flooding rate higher than 10 cm/s. An empirical correction factor for the Murao-Sugimoto correlation was proposed based on the present experimental data. The proposed correction factor was confirmed to be applicable to another large scale tests.     

非稳定流场中的大流量测量

本文介绍了非稳定流场中的大流量测量的一种方法。由于管道布置的限制,只能在φ700的管子弯头后1D的位置采用φ12的五孔球形测针作多点测量,再用等环面面积积分方法来确定其流量。此方法进行了实验室验证,并对反应堆主热交换器流量(2000—4000m~3/h)进行了实测。证明此方法是稳妥可靠的,误差为±5%。测量结果已为工程所采用。     

Evaluation of Steam Generation Rate from Falling Film on Heater Rod

The electric charges to enhance the localized in-pile corrosion are estimated quantitatively by a model analogous to an electric circuit. The model is more detailed than that reported in the previous papers. It is applied to the cases of a fuel cladding near platinum in the Halden experiments and a fuel channel near a control blade. As a result, respecting the electric charges to enhance the localized oxidation, both cases investigated in this work are explained quantitatively by the total amount of electric current, from all the localized electrochemical cells between the surface of zirconium oxide adjacent to and facing to bare and grounded metals such as platinum or stainless steel and its neighboring parts, introduced by the “β-induced electric fields” on zirconium oxide.

The electric potential of the electrochemical cell concerned decreases in the course of oxidation, and therefore, the retardation of oxidation during the growth of the oxide film can be explained by the fact that the electric current by the above electrochemical cell becomes insufficient to enhance the localized oxidation.     

Investigation of Pre- and Post-Dryout Heat Transfer in Upward Steam-Water Two-Phase Flow at Low Flow Rate

A heat transfer experiment was performed on steam-water two-phase flow in an annular flow path with a uniformly heated rod under the conditions of the mass flow rates from 0.2xlO⁶ to l.Ox 10⁶ kg/m²-h, inlet qualities from 0.5 to 1.0, heat fluxes below 4.7x 10⁵ W/m² and pressure of 31 bar. Dryout of the heater rod surface was observed resulting in the sharp rise of the heater rod surface temperature. Measured heat transfer coefficients were compared with the several empirical and semi-empirical correlations with the emphasis on the applicability of the correlations to the present test conditions being important in the analysis of the thermal hydraulic behavior during a LOCA of a nuclear reactor. The measured heat transfer coefficient in the pre-dryout region is lower than the existing correlations. The cooling of the heat transfer surface by the liquid phase in the post-dryout region is significant, which is neglected in the existing correlations. The heat transfer coefficients calculated for the post-dryout region by the Groeneveld correlation show good agreement with the presently measured results within the accuracy of 0~27%.