(99m)Tc-3P(4)-RGD(2) Scintimammography in the Assessment of Breast Lesions: Comparative Study with (99m)Tc-MIBI

PURPOSE: To compare the potential application of (99m)Tc-3P-Arg-Gly-Asp ((99m)Tc-3P(4)-RGD(2)) scintimammography (SMM) and (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SMM for the differentiation of malignant from benign breast lesions. METHOD: Thirty-six patients with breast masses on physical examination and/or suspicious mammography results that required fine needle aspiration cytology biopsy (FNAB) were included in the study. (99m)Tc-3P(4)-RGD(2) and (99m)Tc-MIBI SMM were performed with single photon emission computed tomography (SPECT) at 60 min and 20 min respectively after intravenous injection of 738±86 MBq radiotracers on a separate day. Images were evaluated by the tumor to non-tumor localization ratios (T/NT). Receiver operating characteristic (ROC) curve analysis was performed on each radiotracer to calculate the cut-off values of quantitative indices and to compare the diagnostic performance for the ability to differentiate malignant from benign diseases. RESULTS: The mean T/NT ratio of (99m)Tc-3P(4)-RGD(2) in malignant lesions was significantly higher than that in benign lesions (3.54±1.51 vs. 1.83±0.98, p<0.001). The sensitivity, specificity, and accuracy of (99m)Tc-3P(4)-RGD(2) SMM were 89.3%, 90.9% and 89.7%, respectively, with a T/NT cut-off value of 2.40. The mean T/NT ratio of (99m)Tc-MIBI in malignant lesions was also significantly higher than that in benign lesions (2.86±0.99 vs. 1.51±0.61, p<0.001). The sensitivity, specificity and accuracy of (99m)Tc-MIBI SMM were 87.5%, 72.7% and 82.1%, respectively, with a T/NT cut-off value of 1.45. According to the ROC analysis, the area under the curve for (99m)Tc-3P(4)-RGD(2) SMM (area = 0.851) was higher than that for (99m)Tc-MIBI SMM (area = 0.781), but the statistical difference was not significant. CONCLUSION: (99m)Tc-3P(4)-RGD(2) SMM does not provide any significant advantage over the established (99m)Tc-MIBI SMM for the detection of primary breast cancer. The T/NT ratio of (99m)Tc-3P(4)-RGD(2) SMM was significantly higher than that of (99m)Tc-MIBI SMM. Both tracers could offer an alternative method for elucidating non-diagnostic mammograms.