Comparison of strain and shear-wave ultrasounic elastography in predicting the pathological response to neoadjuvant chemotherapy in breast cancers.

OBJECTIVE: To compare the diagnostic performances of strain elastography (SE) and shear-wave elastography (SWE) for predicting response to neoadjuvant chemotherapy (NACT) in patients with breast cancer.

METHODS: This prospective study recruited 71 eligible patients from June 2014 to May 2016. All patients provided written informed consent. Tumour stiffness was assessed by the SE strain ratio (R), SWE maximum elasticity (Emax ) and SWE mean elasticity (Emean ). Ultrasonic elastography (UE) assessments were performed at each NACT cycle (t1 - t6). For the purpose of predicting, the relative changes in elastographic parameters after the first and second NACT cycles were considered as the variables [Δ(t1) and Δ(t2)]. The area under the receiver operating characteristics (AUC) curve was compared.

RESULTS: ΔEmean (t2) and R2 displayed the best diagnostic performances within their own modalities (AUC = 0.93 and 0.90 for predicting favourable response to NACT; AUC = 0.92 and 0.78 for predicting NACT resistance, respectively). There were no significant differences in AUCs for ΔEmean (t2) and some UE parameters (P > 0.05). By contrast, ΔEmean (t2) was significantly superior to all other SE parameters for predicting resistance (P < 0.05).

CONCLUSIONS: SE and SWE exhibited similar performances for predicting favourable NACT responses; SWE was better than SE for predicting NACT resistance.

KEY POINTS: • Elastography parameters after the second NACT cycle showed the best diagnostic performances. • SWE and SE yielded similar diagnostic performances in predicting favourable responses. • SWE performed better than SE in predicting the pathological resistance to NACT. • Discrepant results may be due to the breast thickness and lesion depth.