TECHNETIUM-99M-METHYLENE DIPHOSPHONATE SCINTIMAMMOGRAPHY TO IMAGE PRIMARY BREAST-CANCER

Technetium-99m-methylene diphosphonate (MDP) uptake within breast lesi ons was investigated during routine presurgical bone scintigraphy in a cohort of women at high risk for cancer who were candidates for surge ry or excisional biopsy. The aim was twofold: (a) to demonstrate posit ive Tc-99m-MDP uptake in primary breast cancer and (b) to differentiat e malignant from benign lesions. Methods: Anterior and oblique lateral views of the breasts were acquired 0-4 min, 10-20 min and 2 hr after intravenous injection of 740 MBq of Tc-99m-MDP in 200 women with eleva ted suspicion or proven diagnosis of breast cancer (Group 1) and in 80 women with other solid tumor types (Group 2). Results: Physical exami nation and mammography revealed breast abnormalities in all Group 1 su bjects. The mammographic findings were definitely positive for carcino ma in 120 patients, highly suspicious in 27 and indeterminate in 53. B reast cancer was later histologically diagnosed in 172 women (86%) and benign disease found in 28 women (14%). Of these patients, 158 (92%) showed focal uptake of Tc-99m-MDP in the images collected 10-20 min af ter injection. This was found to be the best timing for imaging, with tumor-to-background ratios as high as 4.3 (mean +/- s.d. = 3.8 +/- 0.4 ). Two hr after injection, only 61 of the 158 (38%) malignant lesions were clearly detectable. Conclusion: Technetium-99m-MDP is concentrate d by primary breast carcinoma 10-20 min after injection, enabling succ essful external gamma imaging. Scintimammography with Tc-99m-MDP is an accurate test that differentiates malignant from benign breast lesion s, particularly in patients with indeterminate mammograms.