Technetium-99m-methylene diphosphonate scintimammography to image primary breast cancer

Technetium-99m-methylene diphosphonate (MDP) uptake within breast lesions was investigated during routine presurgical bone scintigraphy in a cohort of women at high risk for cancer who were candidates for surgery or excisional biopsy. The aim was twofold: (a) to demonstrate positive 99mTc-MDP uptake in primary breast cancer and (b) to differentiate malignant from benign lesions.

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 99mTc-MDP in 200 women with elevated suspicion or proven diagnosis of breast cancer (Group 1) and in 80 women with other solid tumor types (Group 2).

Physical examination and mammography revealed breast abnormalities in all Group 1 subjects. The mammographic findings were definitely positive for carcinoma in 120 patients, highly suspicious in 27 and indeterminate in 53. Breast 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 99mTc-MDP in the images collected 10-20 min after 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.

Technetium-99m-MDP is concentrated by primary breast carcinoma 10-20 min after injection, enabling successful external gamma imaging. Scintimammography with 99mTc-MDP is an accurate test that differentiates malignant from benign breast lesions, particularly in patients with indeterminate mammograms.