The radio nuclide investigation of cerebrovascular abnormality

The clinical use of cerebral blood flow measurements has been hampered by the lack of equipment designed for use in the hospital environment, and by the wide range of measures or indices for cerebral blood flow that have been proposed. This thesis reviews the available methods for the measurement of cerebral blood flow, and has selected the simple single compartment model as being the most suitable. The errors involved in repeated measurements are investigated using a computer model, and a new method for the correction of residual activity proposed. This new technique allows repeated measurements to be taken within five minutes of each other. A special portable cerebral blood flow measurement system has been built for use in the hospital environment. It is entirely self contained and features a built in microcomputer for the acquisition of data, and the calculation of the results. The system has been used for clinical and research work, and examples of the results are presented. A new cerebral blood flow imaging agent 99mTc labelled Hexamethylpropyleneamine oxime (HM-PAO), suitable for use with tomographic imaging systems, is investigated and compared with standard methods for the measurement of cerebral blood flow in both man and the rat. It was found that the distribution of the agent does not reflect cerebral blood flow. Computer models of the HM-PAO kinetics were developed, and are able to explain the in vivo behaviour of the agent.