Diffusion weighted imaging of the normal breast: reproducibility of apparent diffusion coefficient measurements and variation with menstrual cycle and menopausal status

Objectives To establish the reproducibility of apparent diffusion coefficient (ADC) measurements in normal fibroglandular breast tissue and to assess variation in ADC values with phase of the menstrual cycle and menopausal status. Methods Thirty-one volunteers (13 premenopausal, 18 postmenopausal) underwent magnetic resonance twice (interval 11–22 days) using diffusion-weighted MRI. ADC total and a perfusion-insensitive ADC high (omitting b = 0) were calculated. Reproducibility and inter-observer variability of mean ADC values were assessed. The difference in mean ADC values between the two phases of the menstrual cycle and the postmenopausal breast were evaluated. Results ADC total and ADC high showed good reproducibility ( r % = 17.6, 22.4). ADC high showed very good inter-observer agreement ( kappa = 0.83). The intraclass correlation coefficients (ICC) were 0.93 and 0.91. Mean ADC values were significantly lower in the postmenopausal breast (ADC total 1.46 ± 0.3 × 10 -3 mm 2 /s, ADC high 1.33 ± 0.3 × 10 -3 mm 2 /s) compared with the premenopausal breast (ADC total 1.84 ± 0.26 × 10 -3 mm 2 /s, ADC high 1.77 ± 0.26 × 10 -3 mm 2 /s; both P