Detection of small-size primary breast cancer: 99mtc-tetrofosmin single photon emission computed tomography

This chapter explains a study demonstrating the use of 99mTc-tetrofosmin single photon emission computed tomography in the detection of small-size primary breast cancer. An intravenous injection of 740 MBq of 99mTc-tetrofosmin is given to all patients in the antecubital vein of the arm contralateral to the mammary lesion. When bilateral disease is suspected, the radiotracer is injected in a pedal vein. Radiolabeling and quality control procedures of the radiotracer are performed according to the manufacturer's instructions. Labeling efficiency is always >95%. Ten minutes after the injection of the radiotracer, planar imaging is acquired in both supine and lateral views followed by single photon emission computed tomography (SPECT), using a rectangular, large field of view, dual-head gamma camera equipped with low-energy, high-resolution, parallel-hole collimators. The anterior planar view is obtained with the patient lying in a supine position with the arms raised over the head and with the chest, both breasts, and axillae included in the field of view. The detector is positioned below and as close as possible to the table with the involved breast and corresponding axilla included in the field of view. Scintigraphy is considered positive when one or more focal areas of increased uptake with a higher activity compared to the surrounding background is identified in the breast in at least one view (either supine anterior or lateral) for planar imaging and in at least two sequential planes (transverse, coronal, or sagittal) for SPECT. The results show that mammography is more sensitive (97.4% sensitivity value) than SPECT, but at the cost of an extremely lower specificity (30%). Moreover, SPECT is more accurate than the radiologic procedure in the assessment of multifocal/bilateral disease.