Positron emission mammography (PEM): a promising technique for detecting breast cancer

The authors are developing a high specificity technique for detecting the increased metabolic rate of breast tumours. The glucose analog FDG is known to concentrate in breast tumours rendering them easily detectable in conventional PET scans. Since PET is a relatively expensive imaging technique it is not been used routinely in the detection of breast cancer. Positron emission mammography (PEM) will provide a highly efficient, high spatial resolution, and low cost positron imaging system whose metabolic images are co-registered with conventional mammography. Coincidences between two BGO blocks cut into 2×2 mm squares coupled to two 7.5 cm square imaging PMTs are detected and back-projected to form real-time multiple plane images. The design is about 20 times more sensitive than a conventional multi-slice PET body scanner, so much less radiopharmaceutical can be used, reducing the patient dose and cost per scan. Prototype detectors have been made and extensive measurements done. The device is expected to have an in-plane spatial resolution about 2 mm FWHM. Besides the application as a secondary screening tool the device may be beneficial in measuring a tumour´s response to radiotherapy or chemotherapy, as well as aiding the surgeon in optimizing the removal of malignant tissue