Comparison of Tc-99m THY and Tc-99m MIBI scans for diagnosis of breast lesions

Mammoscintigraphy has recently become a useful method for breast cancer diagnosis, mainly in patients whose X-ray mammography is affected by technical problems. Tc-99m MIBI has been used for this purpose. A noninvasive, improved technique to select those who would most benefit from biopsy of the breast and reduce the number of negative biopsies is clearly of value and still desired. Here, we describe the use of Tc-99m THY in breast carcinoma and show the comparative results with Tc-99m MIBI in 29 patients. We studied a total of 39 women, 32 were patients and 7 healthy volunteers. Of the 32 patients, 3 had bilateral pathology. In addition, mammography imaging and histopathologic findings were presented. Twenty three malignant lesions were taken up by labeled thymine. Of the 12 benign cases there was one false-positive uptake with Tc-99m THY. There was no thymine uptake in the breasts of the healthy volunteers. Of the 30 cases treated with both radiopharmaceuticals there were 4 false-positives and 1 false-negative uptake with Tc-99m MIBI. The results confirm that Tc-99m THY breast imaging has a high specificity of 94.73% (18/19), an accuracy of 97.61% (41/42) and a positive predictive value of 95.83% (23/24) when compared with Tc-99m MIBI specificity of 71.42% (10/14), an accuracy of 86.48% (32/37) and a positive predictive value of 84.61% (22/26) in detection of breast carcinoma. Scintimammography using Tc-99m THY could influence the therapeutic strategy and reduce the number of mammographically recommended surgical biopsies that yield benign results.