Predicting Pathological Response to Neoadjuvant Chemotherapy in Breast Cancer With Quantitative H-1 MR Spectroscopy using the External Standard Method

Purpose: To assess the efficacy of quantitative H-1 MR spectroscopy (MRS) using the external standard method to predict the pathological response to neoadjuvant chemotherapy with an anthracycline-based regimen in breast cancer patients. Materials and Methods: Sixteen patients with breast cancer were included. Tumor response to chemotherapy was evaluated after the second cycle using MRI and MRS. Final histopatholov following surgery after four cycles of chemotherapy served as reference. Results: The average normalized choline (Cho) signal was 1.2 (range. 0.40 to 2.8). There were no significant differences in the baseline tumor size and normalized Cho signals between the pathological responders (n = 8) and nonresponders (n = 8). The reduction rates of the normalized Cho signal were statistically significantly different between the pathological responders and nonresponders (P = 0.004). whereas the reduction rates of the lesion size were not significantly different between the two groups. When 40-50% of the reduction rates of the normalized Cho was chosen as the cutoff value. the positive and negative predictive values of MRS were 89%(8/9) and 100% (7/7), respectively. Conclusion: The changes in Cho after the second cycle of chemotherapy as determined by quantitative MRS may be more sensitive than changes in the tumor size to predict the pathological response.