Concordant uptake of Tc-99m sestamibi and Tl-201 in unsuspected breast tumor.

An unsuspected breast tumor was discovered in a 65-year-old woman referred for evaluation of possible ischemic heart disease. Marked tumor uptake of Tl-201 and concordant but less intense uptake of Tc-99m sestamibi (Tc-99m MIBI) was observed after both planar and SPECT imaging post treadmill exercise. Although many reports in the literature document Tl-201 tumor uptake, this is much less frequently reported with Tc-99m MIBI at this time. To the authors' knowledge, Tc-99m MIBI breast tumor uptake has not been reported to date. Tc-99m MIBI might prove useful in the detection of primary and metastatic breast carcinoma, and warrants further investigation.