Influence of Menstrual Cycle Timing on Screening Breast MRI Background Parenchymal Enhancement and Diagnostic Performance in Premenopausal Women.

PURPOSE: To assess the influence of menstrual cycle timing on background parenchymal enhancement (BPE) and performance on screening breast magnetic resonance imaging (MRI) in premenopausal women at high risk for developing breast cancer.
METHODS: After Institutional Review Board approval, all screening breast MRIs performed from January 2007 through November 2010 in premenopausal women in whom day from last menstrual period was recorded were identified. Prospectively recorded BPE levels and Breast Imaging Reporting and Data System MRI assessments were extracted from our database. Subject outcomes were determined by using biopsy, imaging follow-up, and linkage with the regional tumor registry (minimum 12-month follow-up). Associations of BPE levels (minimal/mild versus moderate/marked) with menstrual cycle phase (follicular [day 0-15] versus luteal [day 16-35]) and week (1, 2, 3, or 4) were compared. Differences in MRI performance metrics, including abnormal interpretation rate (AIR), positive biopsy rate (PBR), cancer yield, sensitivity, and specificity, were compared between menstrual cycle phase and menstrual cycle week.
RESULTS: Three-hundred twenty examinations in 244 premenopausal women met inclusion criteria with nine cancers diagnosed. BPE levels were not associated with menstrual cycle phase or week (P > 0.05). MRI performance metrics (ie, AIR, PBR, cancer yield, sensitivity, or specificity) did not differ significantly based on menstrual cycle phase or menstrual cycle week (P > 0.05).
CONCLUSIONS: Obtaining screening breast MRI exams during specific phases or weeks of the menstrual cycle in premenopausal women does not reliably produce MRI examinations with lower BPE levels or improved performance.