Role of the intravoxel incoherent motion diffusion weighted imaging in the pre-treatment prediction and early response monitoring to neoadjuvant chemotherapy in locally advanced breast Cancer

Abstract

The aim of this study was to explore whether intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) can probe pre-treatment differences ormonitor early response in patientswith locally advanced breast cancer receiving neoadjuvant chemotherapy (NAC). Thirty-six patients with locally advanced breast cancer were imaged usingmultiple-bDWIwith 12 b values ranging from0 to 1000 s/mm2 at the baseline, and 28 patientswere repeatedly scanned after the second cycle of NAC. Subjectswere divided into pathologic complete response (pCR) and nonpathologic complete response (non-pCR) groups according to the surgical pathologic specimen.Parameters (D,D, f,maximumdiameter [MD] and volume [V]) before and after 2 cycles ofNAC and their corresponding change (Dparameter) between pCR and non-pCR groups were compared using the Student t test or nonparametric test. The diagnostic performance of different parameters was judged by the receiver-operating characteristic curve analysis. Before NAC, the f value of pCR group was significantly higher than that of non-pCR (32.40% vs 24.40%, P=0.048). At the end of the second cycle of NAC, the D value was significantly higher and the f value was significantly lower in pCR than that in non-pCR (P=0.001; P=0.015, respectively), whereas the D value and V of the pCR group was slightly lower than that of the non-pCR group (P=0.507; P=0.676, respectively). DD was higher in pCR (0.4510-3mm2/s) than that in non-pCR (0.07103mm2/s) after 2 cycles of NAC (P0.001). Df value in the pCR group was significantly higher than that in the non-pCR group (17.30% vs 5.30%, P=0.001). There was no significant difference in DD between the pCR and nonpCR group (P=0.456). The prediction performance of DD value was the highest (AUC [area under the curve]=0.924, 95% CI [95% confidence interval]=0.759-0.990). When the optimal cut-off was set at 0.163103mm2/s, the values for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were up to 100% (95% CI=66.4-100), 73.7% (95% CI=48.8-90.9), 64.3% (95% CI=35.6-86.0), and 100% (95% CI=73.2-99.3), respectively. IVIM-derived parameters, especially the D and f value, showed potential value in the pre-treatment prediction and early response monitoring to NAC in locally advanced breast cancer. DD value had the best prediction performance for pathologic response after NAC.