Lesion T₂ relaxation times and volumes predict the response of malignant breast lesions to neoadjuvant chemotherapy

Abstract 

The aim of this study was to investigate the utility of the water T₂ values of malignant breast lesions in predicting response after the first and second cycles of neoadjuvant chemotherapy (NAC), both alone and in combination with lesion volumes. Thirty-five patients were scanned before the commencement of chemotherapy and again after the first, second and final treatment cycles. Two methods of obtaining lesion T₂ were used: imaging, where a series of T₂-weighted images was acquired (T_R/T_E=1000/30, 60, 90 and 120 ms), and spectroscopy, where the T₂ value of unsuppressed water signal was determined with a multiecho sequence (T_R=1.5 s; initial T_E=35 ms; 64 steps of 2.5 ms; 2 unsuppressed acquisitions per T_E). Lesion volumes were computed from contrast-enhanced 3D fat-suppressed images. The study found that, using the imaging method of obtaining T₂, the ratio of the product of lesion T₂ and volume after the second cycle of NAC to pretreatment value is a good predictor of ultimate lesion response, defined as a ≥65% reduction in tumor volume after the final treatment cycle, with positive and negative predictive values of 95.5% and 84.6%, respectively.

Keywords: Breast cancer, Chemotherapy, Magnetic resonance imaging, Magnetic resonance spectroscopy, Water T₂