Participant Sample

Our study was approved by our local institutional review board and was performed in full accordance with the Health Insurance Portability and Accountability Act. Written informed consent was obtained from each participant enrolled in the study. A total of 51 participants with stage I–III TNBC were enrolled in our prospective clinical trial (DCE-MRI and MBI in Assessing Tumor Response to Chemotherapy in Patients With Triple Negative Breast Cancer [{"type":"clinical-trial","attrs":{"text":"NCT02744053","term_id":"NCT02744053"}}NCT02744053]) at our institution from January 31, 2019, through November 11, 2019. These participants met the inclusion criteria of having a primary tumor measuring 1.0–5.0 cm in diameter as diagnosed by anatomic MRI; an estimated glomerular filtration rate of greater than or equal to 60 mL/min and without a history of renal disease; age 18 years or older; not pregnant; and a body mass index lower than 35 kg/m². These participants underwent CEST MRI before treatment (baseline, n = 51), after two cycles (C2, n = 35), and after four cycles (C4, n = 42) of NAST. The NAST regimen consisted of doxorubicin and cyclophosphamide for four cycles followed by paclitaxel every 2 weeks for four cycles or weekly for 12 doses, followed by surgery.

The results from all 51 participants were used to evaluate combinations of the CEST saturation power levels and the analysis methods. Of the 51 participants, 30 underwent CEST MRI at all three time points. The C2 time point was optional per protocol. The missed scans at C4 occurred primarily because of participant discomfort caused by the disease and/or treatment. Pathology reports following surgery were available for 26 of the 30 participants. Of these 26 participants, 15 had pCR, and 11 had non-pCR. pCR was defined as no residual invasive disease in the breast or resected nodal tissue. The results from these 26 participants who had known outcomes and had undergone CEST MRI at all time points were used to evaluate whether APT_W CEST MRI can evaluate the early response to NAST to predict pCR or non-pCR.