Invasive Ductal Breast Carcinoma Response to Neoadjuvant Chemotherapy: Noninvasive Monitoring with Functional MR Imaging— Pilot Study

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Abstract
To investigate if the extraction flow product (EFP), as determined on dynamic contrast material-enhanced magnetic resonance (MR) images, could be a potential marker of tumor response to neoadjuvant chemotherapy in patients with locally advanced breast cancer. Fourteen women with proven breast cancer underwent MR imaging prior to and following neoadjuvant chemotherapy. Dynamic gradient-echo and echo-planar MR images were acquired before and after injection of gadopentetate dimeglumine. Precontrast T1s were measured before EFP maps were calculated by using a multicompartmental model. Mean EFP (EFPmean) and distribution analysis of EFP (EFPcount) were measured in tumors before and after neoadjuvant chemotherapy and were compared with tumor response at MR imaging. The significance of the difference in EFP values between the responders and nonresponders was calculated with a two-tailed Student t test. EFPmean after neoadjuvant chemotherapy in partial responders and nonresponders was 33 mL x 100 g-1 x min-1 +/- 9.8 and 54.2 mL x 100 g-1 x min-1 +/- 10.3, respectively (P <.005). EFPmean decreased after neoadjuvant chemotherapy in the responders and nonresponders by 37% +/- 30 and -5% +/- 35, respectively (P >.05). An increase in EFPmean values was observed only in nonresponders who received taxanes. For regimens without taxanes, EFPmean decreased regardless of the morphologic response. EFPcount decreased for all the responders by 77% +/- 33 and increased for all the nonresponders by 45% +/- 68 (P <.02). EFPcount appears to provide functional information regarding changes in tumor angiogenesis due to neoadjuvant chemotherapy. Functional MR imaging of the breast may be useful in monitoring tumor response to neoadjuvant chemotherapy.