FIGURE 1. Pretherapy (A and B) and posttherapy (C and D) 99mTc-sestamibi studies (lateral views of right breast in prone position) of patient 30, who showed no response to chemotherapy at pathologic examination. Pretherapy study (A, early image; B, delayed image) evidenced high 99mTc-sestamibi WOR (51%), predicting high MDR expression. Early posttherapy image (C) confirmed negative response to chemotherapy, because tracer uptake persisted in tumoral region. Corresponding delayed image (D) showed evident decrease in tracer uptake, confirming high WOR and high MDR expression.
