| Objective:To investigate the value of 3.0T multimodality magnetic resonance imaging,including dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI）,diffusion weighted imaging（DWI）and diffusion kurtosis imaging（DKI）,in evaluating the efficacy of neoadjuvant chemotherapy（NAC）for breast cancer.Methods:（1）Thirty-eight breast cancer patients underwent neoadjuvant chemotherapy between October 1st,2016 and December 30th,2017 in Affiliated Hospital of Zunyi Medical College were collected.Age ranged from 30 to 65 years old and mean age was 47 years old.All of the patients with breast cancer were confirmed by histological biopsy,including 30cases of invasive ductal carcinoma,6 cases of invasive ductal carcinoma with ductal carcinoma in situ,1 case of infiltrative solid papillary carcinoma with cribriform carcinoma and 1 case of invasive lobular carcinoma.All patients underwent surgical treatment within 4 weeks after 6-8 courses of NAC treatment.（2）All patients were examined by conventional MRI,DWI,DKI and DCE before chemotherapy,after 34 cycles of chemotherapy and after chemotherapy.The maximum diameter of the tumor was measured to observe the changes of the size of the tumor before and after NAC.The correlation between the maximum diameter of the MR measurement and the maximum diameter of the postoperative pathological measurement was analyzed.The value of apparent diffusion coefficient（ADC）,mean kurtosis（MK）and mean diffusivity（MD）were measured before and after NAC.The changes of ADC value（△ADC1%、△ADC2%）,MK value（△MK1%、△MK2%）and MD value（△MD1%、△MD2%）were calculated.The changes of time-signal intensity curve（TIC）type were observed.All of patients were divided into major histological response（MHR）group and non–major histological response（NMHR）group according to postoperative pathological results.Statistical software SPSS17.0 was used to analyze data and to determine differences（P<0.05 was defined as statistical significance）.Measurement data were compared between two groups by using t test or Mann-Whitney U test,and counting data were compared by usingχ2 test.The receiver–operating characteristic curve（ROC）was used to analyze the diagnostic efficacy of the three methods for the assessment of pathological response and to obtain the diagnostic cut-off point.Result:（1）The maximum diameter of tumors had no significant difference between MHR groupand NMHR group before and after 34 cycles of NAC（P>0.05）,but after NAC it showed significantly different between the two groups.The medium-term reduction ratio（△D1%）and preoperative reduction ratio（△D2%）of tumor diameter were（43.22±5.24）%and（78.88±5.45）%in MHR group,which was significantly higher than those in NMHR group[（16.57±5.22）%and（34.17±6.23）%].（2）After NAC,the mean maximum diameter of the tumor measured by MRI was significantly correlated with the pathological measurement（r=0.919,P<0.01）.（3）There was no significant difference in the three types of TIC curves of residual lesions after 34 cycles of NAC between MHR group and NMHR group,but there was a significant difference in TIC types between the two groups after chemotherapy in breast cancer（P<0.05）.The TIC curve types generally have the transition from typeⅢto type I.TypeⅠwas defined as the standard to distinguish between responders and non-responders and its sensitivity and specificity were 73.3%and 82.6%,respectively.（4）Before NAC,the ADC values of NMHR group and MHR group were（0.90±0.14）×10-3mm2/s and（0.94±0.15）×10-3mm2/s,respectively,with no significant difference.After NAC,the ADC values of MHR group were（1.26±0.21）×10-3mm2/s and（1.54±0.28）×10-3mm2/s respectively,which were significantly higher than those of NMHR[（1.04±0.18）×10-3mm2/s,（1.16±0.21）×10-3mm2/s].The△ADC2%of MHR group was（65.60±34.21）%,which was higher than that of NMHR group[（31.30±25.68）%],the difference was statistically significant（P<0.05）.（5）Mean ADCT22 values were positively correlated to changes in tumor diameter after NAC（r=0.734,P<0.01）,as well as changes in mean ADC values（r=0.593,P<0.01）.（6）Before NAC,the values of MD and MK in NMHR group and MHR group were（1.14±0.20）×10-3mm2/s and 0.93±0.18,（1.22±0.20）×10-3mm2/s and 0.85±0.15respectively,with no significant difference.After NAC,the values of MD in MHR group were（1.55±0.32）×10-3mm2/s and（1.77±0.28）×10-3mm2/s respectively,which were significantly higher than those in NMHR[（1.36±0.24）×10-3mm2/s,（1.45±0.25）×10-3mm2/s].The values of MK in MHR group were 0.66±0.14 and 0.59±0.12respectively,which were significantly lower than those in NMHR[0.77±0.14,0.71±0.12].The△MD2%of MHR group was（48.07±31.99）%,which was higher than that of NMHR group[（28.13±24.58）%],the difference was statistically significant（P<0.05）.（7）Using 1.13×10-3mm2/s of ADCT1,1.40×10-3mm2/s of ADCT2,55%of△ADC2%after NAC as the cut off value to predict MHR,the sensitivity were 80%,86.7%,73.3%respectively and specificity were 73.9%,95.7%,91.3%,respectively.Using1.53×10-3mm2/s of MDT1,1.66×10-3mm2/s of MDT2,21.5%of△MD2%after NAC as the cut off value to predict MHR,the sensitivity were 33.3%,93.3%,93.3%and specificity were 95.7%,65.2%,39.1%,respectively.Conclusion:（1）After NAC,the maximum diameter of tumor decreased compared with that before treatment,and there was a significant change in the middle of chemotherapy,but there was no value in the diagnosis of MHR.The rate of change of tumor size can effectively assess the pathological response.（2）The maximum diameter measured with MRI measurement is significantly correlated to that of pathological results,and assessment of residual tumor size in high congruence with pathology evaluation,but the phenomenon may be overestimated or underestimated.（3）ADC,MK value and△ADC%can effectively evaluate the pathological response of tumor.△D%showed a moderate positive correlation with ADC value and△ADC2%.（4）MD vaule and△MD2%have high sensitivity to the assessment of NAC pathological response in breast cancer.（5）The type of TIC curve can well assess NAC effect.The type I curve has high sensitivity and specificity for the classification of pathological reaction. |
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