Positron Emission Tomography Group Research Articles

Recommendations for fluorine-18 production

Data for the production of fluorine-18 (t 1/2 = 109.6 min; β + = 100%) are reviewed. The experience of some well-established European centres for positron emission tomography (PET), in the routine production of fluorine-18 for the purpose of labelling radiopharmaceuticals, is described. This experience is evaluated, along with published data, to give practical and technical recommendations to new PET group entering this key area.

The effect of anxiety on cortical cerebral blood flow and metabolism.

The relation between anxiety and cortical activity was compared in two samples of normal volunteers. One group was studied with the noninvasive xenon-133 inhalation technique for measuring cerebral blood flow (CBF) and the other with positron emission tomography (PET) using 18Flurodeoxyglucose (18FDG) for measuring cerebral metabolic rates (CMR) for glucose. The inhalation technique produced less anxiety than the PET procedure, and for low anxiety subjects, there was a linear increase in CBF with anxiety. For higher anxiety subjects, however, there was a linear decrease in CBF with increased anxiety. The PET group manifested a linear decrease in CMR with increased anxiety. The results indicate that anxiety can have systematic effects on cortical activity, and this should be taken into consideration when comparing data from different procedures. They also suggest a physiologic explanation of a fundamental behavioral law that stipulates a curvilinear, inverted-U relationship between anxiety and performance.