This study investigated the relationship between choline by magnetic resonance spectroscopy (MRS) and late enhancement curves by dynamic magnetic resonance imaging (DMRI) in determining therapeutic response to neoadjuvant chemotherapy (NAC) among invasive breast cancer patients. Subjects comprised 21 women (22 breasts) with biopsy-confirmed invasive breast cancer (mean age 54 years) who underwent MRS with choline and gadolinium-enhanced DMRI at 1.5 T before and after NAC. Choline signals on MRS were classified into 2 patterns: choline-positive or choline-negative, while late enhancement curves were classified as ‘plateau’ or ‘washout’ (type A), or ‘persistent’ (type B) according to the consensus of 2 radiologists. Maximum tumor diameters and clinical tumor reduction rates were assessed by MRI. Before NAC, choline-positive results were found in all 22 tumors, 21 of which were type A and 1 of which was type B. After NAC, a change from choline-positive to choline-negative was observed with MRS in 11 tumors, while another 11 remained choline-positive. According to DMRI, enhancement curves changed from type A to type B in 14 tumors, remained type A in 7 tumors, and remained type B in 1 tumor. Tumor reduction rates were significantly greater for choline-negative tumors than for choline-positive tumors after NAC (p=0.0115). Following NAC, no significant correlation was noted between enhancement curves and reduction rates (p=0.1210), although a significant correlation was noted between enhancement curves and choline signals (p=0.0014). Changes in choline signals as noted using MRS might offer advantages over changes in enhancement curves by DMRI when evaluating response to NAC in terms of the tumor reduction rate in invasive breast cancer.

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