title: Effect of menstrual cycle phase on background parenchymal uptake at molecular breast imaging.
abstract: OBJECTIVE
  The level of Tc-99m sestamibi uptake within normal fibroglandular tissue on molecular breast imaging (MBI), termed background parenchymal uptake (BPU), has been anecdotally observed to fluctuate with menstrual cycle. Our objective was to assess the impact of menstrual cycle phase on BPU appearance.
  
  
  METHODS
  Premenopausal volunteers who reported regular menstrual cycles and no exogenous hormone use were recruited to undergo serial MBI examinations during the follicular and luteal phase. A study radiologist, blinded to cycle phase, categorized BPU as photopenic, minimal mild, moderate, or marked. Change in BPU with cycle phase was determined, as well as correlations of BPU with mammographic density and hormone levels.
  
  
  RESULTS
  In 42 analyzable participants, high BPU (moderate or marked) was observed more often in luteal phase compared to follicular (P = .016). BPU did not change with phase in 30 of 42 participants (71%) and increased in the luteal phase compared to follicular in 12 (29%). High BPU was more frequent in dense breasts compared to nondense breasts at both the luteal (58% [15 of 26] vs. 13% [2 of 16], P = .004) and follicular phases (35% [9 of 26] vs. 6% [1 of 16], P = .061). Spearman correlation coefficients did not show any correlation of BPU with hormone levels measured at either cycle phase and suggested a weak correlation between change in BPU and changes in estrone and estradiol between phases.
  
  
  CONCLUSIONS
  We observed variable effects of menstrual cycle on BPU among our cohort of premenopausal women; however, when high BPU was observed, it was most frequently seen during the luteal phase compared to follicular phase and in women with dense breasts compared to nondense breasts.
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Electronic address: hruska.carrie@mayo.edu.
authors.forename: Carrie B
authors.initials: CB
authors.lastname: Hruska
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors.forename: Amy Lynn
authors.initials: AL
authors.lastname: Conners
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Celine M
authors.initials: CM
authors.lastname: Vachon
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors.forename: Michael K
authors.initials: MK
authors.lastname: O'Connor
authors.affiliation: Department of Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Lynne T
authors.initials: LT
authors.lastname: Shuster
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Bartley
authors.affiliation: Department of Medicine, Mayo Clinic, Rochester, Minnesota.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Rhodes
mesh_terms: D000328:Adult; D001940:Breast / Q000000981:diagnostic imaging*; D000071060:Breast Density / Q000502:physiology; D002853:Chromatography, Liquid / Q000379:methods; D015331:Cohort Studies; D004958:Estradiol / Q000097:blood; D004970:Estrone / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000502:physiology*; D006801:Humans; D008183:Luteal Phase / Q000502:physiology*; D008327:Mammography / Q000379:methods; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D017697:Premenopause / Q000502:physiology; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D053719:Tandem Mass Spectrometry / Q000379:methods; D017256:Technetium Tc 99m Sestamibi; D013739:Testosterone / Q000097:blood
chemical_list: D019275:Radiopharmaceuticals; D012738:Sex Hormone-Binding Globulin; D004970:Estrone; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D017256:Technetium Tc 99m Sestamibi
keywords: Molecular breast imaging; background parenchymal uptake; hormones; menstrual cycle