Can quantitative diffusion-weighted imaging (DWI) predict elevated MIB-1 proliferation index in invasive breast cancer?

Purpose: To investigate whether quantitative Diffusion-Weighted Imaging (DWI) parameters predict elevated levels of MIB-1 proliferation index in patients with breast cancer. Methods and Materials: We retrospectively enrolled 52 patients with biopsyand surgically-proven invasive cancers (n=52), who underwent preoperative breast Magnetic Resonance imaging (MRI) on a 1.5 T magnet. MRI examination included a Single Shot Echoplanar DWI sequence with b values of 0 and 1000s/mm2. For each lesion, two experienced readers in consensus measured the apparent diffusion coefficient (ADC) (on the ADC maps) and lesion-to-background-ratio (LBGR) (on b=1000 s/mm2 images). Based on immunohistochemistry results, we then compared mean ADC and LBGR values between MIB-1-positive (> 14%) and MIB-1-negative (14%) patients using the unpaired T-test. Results: Patients were assessed as MIB-1-positive and MIB-1-negative in 23/52 (44.2%) and 29/52 (55.8%), respectively. ADC values were significantly (p < 0.05) lower in MIB-1-positive patients (0.86x10-3 s/mm2; 95%IC 0.80 - 0.92) compared to MIB-1-negative ones (1.01x10-3 s/mm2; 95%IC 0.91-1.11). On the contrary, we showed no significant difference in LBGR between MIB-1- positive (6.73; 95%IC 4.15-9.32) and MIB-1-negative (9.14; 95%IC 4.45-12.82) women. Conclusion: Lower ADC values at DWI are associated with elevated MIB-1 proliferation index in patients with invasive breast cancer.