Radionuclede imaging Archives - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: a case-control study comparing two radiocolloids used in scintigraphy to map the sentinel lymph nodes (SLN) in breast cancer patients. METHODS: forty patients were prospectively enrolled between May 2002 and April 2004, after signing an informed consent form. In the present double-blind study, each patient was submitted twice to the same examination, a mammary scintigraphy, one with 99mTc-dextran 500 (dextran) and the other with 99mTc-phytate (phytate), on different days. A volume of 2 ml with 1-1.5 mCi of each radiopharmaceutical, in divided aliquots, was injected in the breast parenchyma in four points around in the tumor and the subcutaneous area superficial to the tumor. The image was obtained 2 h after the injection, using a gamma camera with high-resolution collimator. The lymph nodes were identified by anterior and lateral static scintigraphic images. Statistical analysis was done with the use of McNemar and Z tests. RESULTS: in the analysis of the 40 patients, we had 15 pairs with positive identical images, 4 pairs with negative images and 21 pairs with inconsistent images, either because one of them was negative, or because the SLN numbers were different. When the protocol was opened, we found 35 and 27 positive images and 5 and 13 negative images for dextran and phytate treatment groups, respectively. Among the negative images, 4 were shared by both groups. The McNemar test, used for the statistical analysis, showed p=0.026, odds ratio (OR) = 0.11 with 95% CI 0.01 < OR < 0.85. The accuracy, evaluated by the success ratio of the SLN mapping, was 67.5% for phytate and 87.5% for dextran, with p=0.032. Analysis of variance of the SLN number in lymphoscintigraphy images showed p=0.008. CONCLUSION: these results recommend the use of dextran instead of phytate for the SLN study of breast carcinoma by scintigraphy, when the same methodology is being used.