Early change of MR diffusion weighted imaging parameters of breast cancer after neoadjuvant chemotherapy and the relationship of the change with therapy response

Abstract

Objective To investigate the early change of MR DWI parameters of breast cancer after neoadjuvant chemotherapy (NAC) and assess the relationship between the changes of the NAC response. Methods Patients with local advanced breast cancer diagnosed by biopsy were enrolled in the prospective study. They received DWI examination before NAC and then received DWI examination at 24 h after the first cycle of NAC. The pathological results of breast cancers were recorded after NAC finished. 14 patients (15 lesions) were enrolled in this study.The minimum ADC values of breast cancer before NAC and after the first cycle of NAC were recorded, and their change rates were calculated. Two weeks after NAC,all cases were divided into clinical complete response (cCR) and non-clinical complete response group according to clinical NAC response evaluation. Then lesions were divided into pathological complete response (pCR) and non-pathological complete response group according to pathological NAC response evaluation. Using the Paired samples t test,we analysed the change of ADC values 24 h after the first cycle of NAC. The ADC values and change rates were compared between cCR and non-cCR group using Mann-Whitney U test. The ADC values and change rates were also compared between pCR and non-pCR group using Mann-Whitney U test. Results The 15 cases were all invasive ductal carcinoma patients. According to clinical NAC response evaluation, 5 cases were cCR and 10 cases were non-cCR. According to pathological NAC response evaluation, 6 cases were pCR and 9 cases were non-pCR. Before NAC, the minimum ADC value of breast cancer was(0.78±0.15)×10-3 mm2/s. After the first cycle of NAC, the minimum ADC value of breast cancer was(0.91±0.16)×10-3 mm2/s. The minimum ADC value of breast cancer significantly increased 24 h after the first cycle of NAC (t=-2.954,P=0.010). But ADC value and its change rate were not significantly different between cCR and non-cCR groups, also between pCR and non-pCR groups (P>0.05). Conclusion Significant change in the minimum ADC value of breast cancer could be observed 24 h after the first cycle of NAC, but the change do not relate to clinical and pathological NAC response in this study. Key words: Breast neoplasms; Magnetic resonance imaging; Treatment outcome