The limited spatial resolution of gamma-cameras is commonly considered the main reason for the low sensitivity of scintimammography in the detection of small carcinomas. The present study assessed whether uptake of (99m)Tc-sestambi is affected by certain tissue-specific parameters besides the size of the tumor.
Methods: Surgical specimens from 75 patients (30 benign lesions, 8 of which had shown false-positive scintigraphic findings, and 45 carcinomas, 8 of which had shown false-negative scintigraphic findings) were subjected to a distinct histopathologic/immunohistochemical reevaluation. Tissue-specific parameters (lesion size, cellular density, vascularity, signs of inflammation, proliferative activity, multidrug resistance expression, and receptor status) were visually scored and correlated with the sestamibi uptake on scintimammograms.
Results: A clear relationship was found between sestamibi uptake and tumor size. As previously assumed, a lesion size of less than 1 cm in diameter was found to be one reason for false-negative scintigraphic diagnoses. In addition, a low cell count, low vascularity, and absence of inflammation in carcinomas had a negative effect on uptake of the radiopharmaceutical. The decisive factor for increased tracer uptake by benign lesions was the presence of inflammatory changes. No correlation could be found between sestamibi uptake and proliferative cellular activity, multidrug resistance expression, or the receptor status of the tumor.
Conclusion: Because all mentioned findings were statistically significant only in part, it is to be supposed that uptake of (99m)Tc-sestambi by breast lesions is determined by various tissue parameters in interaction.