Role of DWI assessing nodal involvement and response to neoadjuvant chemotherapy in advanced breast cancer

OBJECTIVE: To explore the role of diffusion-weighted imaging (DWI) in the staging of axillary lymph nodes and the restaging after neoadjuvant chemotherapy (NAD) in advanced breast cancer. PATIENTS AND METHODS: MRI examinations of forty-two patients diagnosed with advanced breast cancer addressed to NAD and axillary lymph node dissection (ALND) were reviewed. Apparent diffusion coefficients (ADC) of each visible node in DWI in the pathologic axilla (PA) and healthy axilla (HA) were measured at the time of diagnosis (t0) and after chemotherapy (t1); mean values of the ADC were calculated. Patients were classified as responders (R), non-responders (NR), macrometastasis (MA), micrometastasis (Mi). RESULTS: Mean ADC was 0.92 ± 0.07 x 10-3 mm2/sec at t0 and 0.97 ± 0.06 x 10-3 mm2/sec at t1 (p = 0.284) in PA, 0.89 ± 0.06 x 10-3 mm2/sec at t0 and 0.92 ± 0.06 x 10-3 mm2/sec at t1 (p = 0.403) in HA, 0.95 ± 0.111 x 10-3 mm2/sec at t0 and 0.95 ± 0.14 x 10-3 mm2/sec at t1 (p = 0.954) in R group, 0.90 ± 0.09 x 10-3 mm2/sec at t0 and 0.97 ± 0.07 x 10-3 mm2/sec at t1 (p = 0.085) in NR group, 0.86 ± 0.10 x 10-3 mm2/sec at t0 and 0.99 ± 0.09 x 10-3 mm2/sec at t1 (p = 0.055) in MA, and 0.99 ± 0.23 x 10-3 mm2/sec at t0 and 0.95 ± 0.15 x 10-3 mm2/sec at t1 in Mi (p = 0.667). CONCLUSIONS: Mean ADC between PA and HA, R and NR, MA and Mi did not significantly differ at t0 and t1 (p > 0.05). Variation in mean ADC between t0 and t1 was not significant in all groups (p > 0.05), except for a trend toward significance (p = 0.055) in MA. DWI has a potential role in restaging of macrometastatic axillary nodes after NAD.