The Value Of Functional MR Imaging In Evaluating And Predicting The Efficacy Of Neoadjuvant Therapy For Breast Cancer

ObjectiveTo investigate the clinical value of MR functional imaging sequences(DWI,3D-APTWI,IVIM-DWI)in assessing and predicting the efficacy of neoadjuvant therapy(NAT)for breast cancer.MethodsThirty breast cancer patients who underwent NAT at Shandong Provincial Hospital between December 2021 and October 2022 were included in this study.All patients underwent routine MRI and DWI,3D-APTWI,and IVIM-DWI scans before treatment and at the end of four cycles of treatment.All patients had invasive breast cancer confirmed by puncture biopsy,received a complete cycle of NAT and underwent surgery at the end of treatment.Based on the post-operative pathological findings as the gold standard,grades 4-5 on the Miller-Payne pathological grading system were classified as the major histological response(MHR)and grades 1-3 as the non-major histological response(NMHR).The DWI,3D-APTWI and IVIM-DWI images were post-processed,and relevant parameters were measured and recorded,including the apparent diffusion coefficient(ADC),magnetization transfer asymmetry(MTRasym),and tissue diffusion coefficient.(MTRasym),tissue diffusion coefficient(D),pseudo-diffusion coefficient(D*),and perfusion fraction(f).Tumour length and diameter were measured in axial and sagittal enhancement sequences.The values of each parameter at the end of the four-week treatment period minus the pre-treatment period were recorded as changes and expressed as ΔADC,ΔMTRasym,ΔD,Δf,ΔD*,andΔLength diameter,respectively.Paired samples t-test and Wilcoxon test were used to compare the differences between the pre-and post-treatment values of each parameter in the MHR and NMHR groups.Independent samples t-test,Mann-Whitney U rank sum test were used to compare the differences in the values of each parameter and their change values between the MHR and NMHR groups before and after treatment.The parameters with statistically significant differences between the groups were selected to draw receiver operating characteristic(ROC)curves and the diagnostic efficacy of the corresponding parameters was assessed by ROC curve analysis.Results(1)The tumour length diameter and MTRasym values at the end of four cycles of treatment in the MHR group were significantly lower and the ADC and D values were significantly higher than those before treatment,with statistically significant differences(P<0.01).(2)At the end of four cycles of treatment,the tumour length and MTRasym values in the NMHR group were significantly lower than those before treatment,and the ADC and D values were significantly higher than those before treatment,and the difference was statistically significant(P<0.01).(3)The difference between the MHR and NMHR groups before treatment was statistically significant only for MTRasym values,which were higher in the MHR group than in the NMHR group[(2.42± 0.50)%,(1.85 ± 0.55)%,P=0.009].(4)The tumour length diameter in the MHR group was significantly smaller than that in the NMHR group at the end of four cycles of treatment[1.0(0.8,2.9)cm,2.7(2.2,3.7)cm,P=0.008],and the ADC and D values in the MHR group were higher than those in the NMHR group[(1.54 ± 0.20)× 10-3mm2/s,1.26(1.10,1.32)× 10-3mm2/s,P<0.001];[(1.41±0.23)×10-3mm2/s,(1.20 ± 0.13)× 10-3mm2/s,P=0.02],with statistically significant differences.(5)ΔLength diameter,ΔADC,ΔMTRasym,and ΔD values were significantly greater in the MHR group than in the NMHR group before and after treatment[(-2.80±1.54)cm,(-0.82± 0.50)cm,P=0.002];[(0.63 ± 0.33)× 10-3mm2/s,0.24(0.15,0.35)×10-3mm2/s,P=0.003];[(-0.95± 0.46)%,(-0.22±0.35)%,P<0.001];[(0.62±0.26)× 10-3mm2/s,(0.32±0.13)×103mm2/s,P=0.006],with statistically significant differences.(6)ROC analysis of MR functional sequence parameters showed that the diagnostic efficacy of pre-treatment MTRasym values in predicting efficacy was 0.787,with a sensitivity of 90.91%using 1.97%as the threshold;the best diagnostic efficacy of ADC values at the end of four cycles of treatment(AUC=0.885,sensitivity 72.73%,specificity 94.74%),and before and after four cycles of treatment Δ MTRasym had the best diagnostic efficacy(AUC=0.883,sensitivity 63.64%,specificity 100%),with no statistically significant differences between AUCs for any of the Delong tests(P>0.05).ConclusionDWI,3D-APTWI and IVIM-DWI can all be used for the assessment and prediction of NAT efficacy in breast cancer.3D-APTWI-related parameter MTRasym can predict the occurrence of MHR in patients before treatment and is important for the development of clinical treatment plans.Among the MR functional sequence parameters,ADC and ΔMTRasym at the end of the four-week period had high diagnostic efficacy in predicting the efficacy.