RESUMO
OBJECTIVE: This study aimed to quantitatively evaluate the effects of age, mammographic density, menopausal status, and menstrual cycle on background parenchymal uptake (BPU) using ring-shaped dedicated breast positron emission tomography (dbPET). METHODS: This study included 186 adult women who underwent mammography and dbPET on the same day and had no abnormalities classified as Breast Imaging Reporting and Data System (BI-RADS) category 1 on both examinations. The volume of interest (VOI) was placed in the glandular tissue of both breasts, and the maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), and metabolic breast volume (MBV) were measured as indicators of BPU. We analyzed the correlation between BPU and age, mammographic density, menopausal status, and menstrual cycle. RESULTS: The SUVmax and SUVmean for normal breast tissue were inversely correlated with age (both p < 0.001). The SUVmax, SUVmean, and MBV of mammographically dense breast tissues were significantly higher than those of non-dense breast tissues (all p < 0.001). The SUVmax, SUVmean, and MBV of normal breast tissue in premenopausal women were significantly higher than those in postmenopausal women (p < 0.001, p < 0.001, p = 0.002, respectively). In the study, 59 premenopausal women, the SUVmax of normal breast tissue in the menstrual-follicular phase was significantly lower than that in the periovulatory-luteal phase (p = 0.02). When we sorted the premenopausal women by mammographic breast composition, the SUVmax and SUVmean of normal breast tissues in the menstrual-follicular phase were significantly lower than those in the periovulatory-luteal phase in the 44 premenopausal women with dense breasts (p = 0.007, and p = 0.038, respectively), whereas no statistically significant difference was found between the menstrual-follicular phase and the periovulatory-luteal phase in the 15 premenopausal women with non-dense breasts. CONCLUSIONS: BPU in normal breast tissues assessed using ring-shaped dbPET was associated with mammographic density, menopausal status, and women's menstrual cycle. The menstrual cycle was significantly associated with BPU in premenopausal women with dense breasts but not in women with non-dense breasts.