THE APPLICATION OF POSITRON EMISSION TOMOGRAPHY TO THE STUDY OF THE NORMAL MENSTRUAL-CYCLE

Positron emission tomography (PET) was used to investigate regions of the brain that are selectively affected during different phases of the normal menstrual cycle. A total of 10 healthy 18-29 year old female v olunteers had PET measurements of brain glucose metabolism between day s 5 and 9 of the follicular phase when plasma concentrations of oestra diol and progesterone were relatively low and between days 5 and 8 of the luteal phase when plasma concentrations of oestradiol and progeste rone were relatively high, Automated algorithms were used to align the PET images in each individual, transform them into the coordinates of a brain atlas, control for variations in whole brain measurements and compute t-score maps of phase-related differences in regional glucose metabolism. The mid-follicular phase was associated with significantl y higher glucose metabolism in thalamic, prefrontal, temporoparietal a nd inferior temporal regions, The mid-luteal phase was associated with significantly higher glucose metabolism in superior temporal, anterio r temporal, occipital, cerebellar, cingulate and anterior insular regi ons. While this study should be considered to be exploratory, it provi des normative data for future studies and illustrates how PET can be u sed to help characterize relationships between phases of the female li fe cycle, temporally related disorders and local functions of the livi ng human brain.