Prediction of pathological complete response of breast cancer patients undergoing neoadjuvant chemotherapy: usefulness of breast MRI computer-aided detection

Abstract

Objective: To evaluate the usefulness of MR computer-aided detection (CAD) in patients undergoing neoadjuvant chemotherapy for prediction of the pathological complete response of tumours.

Methods: 148 patients with breast cancer (mean age, 47.3 years; range, 29-72 years) who underwent neoadjuvant chemotherapy were included in our study. They underwent MRI before and after neoadjuvant chemotherapy, and we reviewed the pathological result as the gold standard. The computer-generated kinetic features for each lesion were recorded, and the features analysed included "threshold enhancement" at 50% and 100% minimum thresholds; degree of initial peak enhancement; and enhancement profiles comprising lesion percentages of washout, plateau and persistent enhancement. The final pathological size and character of tumours were correlated with post-chemotherapy mammography, ultrasonography and MR CAD findings. Kruskal-Wallis test and intraclass correlation coefficient were used to analyse the findings.

Results: We divided the 148 patients into complete pathological response and non-complete pathological response groups. A complete pathological response was defined as no histopathological evidence of any residual invasive cancer cells in the breast or axillary lymph nodes. 39 patients showed complete pathological response, and 109 patients showed non-complete pathological response. Between enhancement profiles of MR CAD, plateau proportion of tumours was significantly correlated with the pathological response of tumours (mean proportion of plateau on complete pathological response group was 27%, p = 0.007).

Conclusion: When plateau proportion of tumours is high, we can predict non-complete pathological response of neoadjuvant chemotherapy.

Advances in knowledge: MR CAD can be a useful tool for the assessment of response to neoadjuvant chemotherapy and prediction of pathological results.

Figure 1.

Definition of computer-assisted diagnosis-generated variabls.

Figure 2.

Demonstration of the kinetic features of tumour on a report from MR computer-aided detection (CAD). The tumour location, distance from the nipple, size and angio volume are present in the standardized report of the CAD system. It also shows kinetic parameters of the tumour with a colour-coded image. For breast studies, it is only able to show the washout map. Radiologists can manually add information about the morphology of the tumour and the final assessment in the report. For colour images see online: www.birpublications.org/doi/abs/10.1259/bjr.20140142.

Figure 3.

MR computer-aided detection (CAD) images of a 51-year-old patient with invasive ductal carcinoma. Before chemotherapy, there is a well enhancing mass with internal non-enhancing area in the inner portion of the right breast (a). The colour-coded kinetic pattern was overlaid in the MR CAD image (b), delayed plateau enhancement component was 15% of the total tumour angio volume (c). After chemotherapy, the previously noted malignant mass markedly decreased and a subtle enhancing parenchymal lesion remained (d). The kinetic curve showed predominant progressive enhancing pattern on MR CAD (e, f). After a breast conserving operation, there was 1 cm of focal ductal carcinoma in situ on the final pathology. Ax, axial; CC, craniocaudal; Cor, coronal; Lat, lateral; L1, lesion 1; LO, lower outer; Med, medial; ML, mediolateral; Sag, sagittal. For colour images see online: www.birpublications.org/doi/abs/10.1259/bjr.20140142.

Figure 4.

MR computer-aided detection (CAD) images of a 48-year-old patient with invasive ductal carcinoma. Before chemotherapy, there was a large well enhancing mass in the left breast on breast MRI (a). The colour-coded kinetic pattern was overlaid in the MR CAD image (b), plateau enhancement component was 38% of the total tumour angio volume (c). After chemotherapy, the size of the large mass significantly decreased (d), but there was still an enhancing parenchymal lesion on MRI of about 8 cm. The colour-coded kinetic pattern on MR CAD was also significantly improved from the previous study (e, f). There was 10 cm of residual invasive ductal carcinoma on final pathological result after modified radical mastectomy. For colour images see online: www.birpublications.org/doi/abs/10.1259/bjr.20140142.

Figure 5.

MR computer-aided detection (CAD) images of a 52-year-old invasive ductal carcinoma patient. In breast MRI, there was a well enhancing large mass in the right breast (a). The colour-coded kinetic pattern was overlaid in the MR CAD image with calculated tumour size (b). After chemotherapy, the size of the tumour markedly decreased (c, d). After modified radical mastectomy, there was 2.0 cm of residual invasive ductal carcinoma on the final pathology. FOV, field of view; L, length; W, width. For colour images see online: www.birpublications.org/doi/abs/10.1259/bjr.20140142.