In addition, tumors presenting initially as nonmass enhancement more likely presented as scattered foci within an area of fibrosis on posttreatment MRI, making prediction of residual disease challenging [34,84]. Finally, there is some evidence that certain chemotherapeutic agents, such as ER modulators, antiangiogenic agents, and taxane-based therapies, may alter perfusion to the breasts, limiting the ability of MRI to accurately predict residual tumor after chemotherapy, most often leading to disease underestimation [85,86]. MRI Breast Without IV Contrast A small study of 71 patients with MRI before and after treatment found no significant difference in lesion size interpretation on unenhanced versus enhanced MRI sequences [39]. However, there is insufficient literature to support the use of MRI without IV contrast of the breast in initial imaging evaluation of tumor size and extent in the breast after initiation or completion of chemotherapy. Sestamibi MBI In a study of 20 patients who underwent imaging with Tc-99m sestamibi, reduction in tumor size correlated reliably with size on MRI, but tumor to background ratio after chemotherapy did not correlate with treatment response [95]. Monitoring Response to Neoadjuvant Chemotherapy A small study of 62 patients also showed that high uptake after chemotherapy predicts poor survival [96]. In one study of 122 patients, breast-specific gamma imaging had sensitivity of 74% and specificity of 72% for detection of residual tumor after chemotherapy, but it underestimated the amount of residual disease for tumors of luminal subtype [97]. In a small study of 49 patients with locally advanced breast cancer, MBI did not accurately predict response to therapy [98]. In a prospective study of 90 patients, posttreatment MBI had a higher false-negative rate than MRI (41% versus 18%) for predicting pathologic response [41].
Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer. In addition, tumors presenting initially as nonmass enhancement more likely presented as scattered foci within an area of fibrosis on posttreatment MRI, making prediction of residual disease challenging [34,84]. Finally, there is some evidence that certain chemotherapeutic agents, such as ER modulators, antiangiogenic agents, and taxane-based therapies, may alter perfusion to the breasts, limiting the ability of MRI to accurately predict residual tumor after chemotherapy, most often leading to disease underestimation [85,86]. MRI Breast Without IV Contrast A small study of 71 patients with MRI before and after treatment found no significant difference in lesion size interpretation on unenhanced versus enhanced MRI sequences [39]. However, there is insufficient literature to support the use of MRI without IV contrast of the breast in initial imaging evaluation of tumor size and extent in the breast after initiation or completion of chemotherapy. Sestamibi MBI In a study of 20 patients who underwent imaging with Tc-99m sestamibi, reduction in tumor size correlated reliably with size on MRI, but tumor to background ratio after chemotherapy did not correlate with treatment response [95]. Monitoring Response to Neoadjuvant Chemotherapy A small study of 62 patients also showed that high uptake after chemotherapy predicts poor survival [96]. In one study of 122 patients, breast-specific gamma imaging had sensitivity of 74% and specificity of 72% for detection of residual tumor after chemotherapy, but it underestimated the amount of residual disease for tumors of luminal subtype [97]. In a small study of 49 patients with locally advanced breast cancer, MBI did not accurately predict response to therapy [98]. In a prospective study of 90 patients, posttreatment MBI had a higher false-negative rate than MRI (41% versus 18%) for predicting pathologic response [41].