Rationale and objectives: [18F]fluorodeoxyglucose positron emission tomography (F-18 FDG PET), a functional imaging modality has opened a new field in clinical imaging that informs about glucose metabolism of tissues. However, increased FDG uptake is not limited to malignant tissues alone. We hypothesize that the intensity of physical FDG uptake in the normal breast tissues would affect the detect ability of breast cancer; therefore, good knowledge of physical FDG uptake in the healthy population is important for the correct interpretation of FDG PET images of pathologic processes. The study aimed to evaluate the relationship between intensity of FDG uptake in the normal breast tissues and menstrual cycle.
Materials and methods: A total of 1,108 charts of healthy females, referred from the department of family medicine of China Medical University Hospital, examined by whole-body FDG PET for health screening examination between June 2002 and June 2006 were reviewed retrospectively and included for analyzing. A total of 524 premenopausal females with regular menstrual cycles over the previous 6 months (length 26-30 days) and 584 menopausal females without current use of exogenous hormones were included in this study. The menstrual cycle was recorded on the day of performing FDG PET in premenopausal women. The breast tissues are diagnosed as normal either by mammary sonography or by mammography. We defined FDG uptake was Grade I when FDG uptake was equal to the pulmonary uptake, Grade II when FDG uptake between pulmonary and liver uptake, and Grade III when FDG uptake equal to or greater than liver uptake.
Results: The FDG uptake in the breast regions shows Grade I in 500 women (45.1%), Grade II in 281 (25.4%) and Grade III in 327 (29.5%). Among the Grade I uptake group, 388 are menopausal, 1 is in flow phase, and 111 are in proliferative phase. Among the Grade II uptake group, 196 are menopausal, 23 are in flow phase, 9 are in proliferative phase, 43 are in the ovulatory phase, and 10 are in the secretory phase. Among Grade III uptake group, 97 are in flow phase, 108 are in the ovulatory phase, and 122 in the secretory phase. The study shows significant correlation between the intensity FDG uptake in the normal breast tissues and menstrual cycle (P < .001).
Conclusions: The physical FDG uptake in the normal breast tissues is generally homogeneous. There is no Grade III FDG uptake in the normal breast tissues in menopause women without using exogenous hormones or in proliferative phase women. In addition, there is no Grade I FDG uptake in the normal breast tissues in the ovulatory phase or secretory phase women.