Positron emission mammography-guided breast biopsy

Positron emission mammography (PEM) is a technique to obtain planar images of the breast for detection of potentially cancerous, radiotracer-avid tumo rs. To increase the diagnostic accuracy of this method, use of minimally in vasive methods (e,g., core biopsy) may be desirable for obtaining tissue sa mples from lesions detected with PEM. The purpose of this study was to test the capabilities of a novel method for performing PEM-guided stereotactic breast biopsies. Methods: The PEM system consisted of 2 square (10 x 10 cm) arrays of discrete scintillator crystals. The detectors were mounted on a stereotactic biopsy table. The stereotactic technique used 2 PEM images acq uired at +/- 15 degrees and a new trigonometric algorithm. The accuracy and precision of the guidance method was tested by placement of small point so urces of F-18 at known locations within the field of view of the imager. Th e calculated positions of the sources were compared with the known location s. In addition, simulated stereotactic biopsies of a breast phantom consist ing of a 10-mm-diameter gelatin sphere containing a concentration of F-18-F DG consistent with that reported for breast cancer were performed. The simu lated lesion was embedded in a 4-cm-thick slab of gelatin containing a comm only reported concentration of FDG, simulating a compressed breast (target- to-background ratio, approximately 8.5:1). An anthropomorphic torso phantom was used to simulate tracer uptake in the organs of a patient 1 h after a 370-MBq injection of FDG. Five trials of the biopsy procedure were performe d to assess repeatability. Finally, a method for verifying needle positioni ng was tested. Results: The positions of the point sources were successfull y calculated to within 0.6 mm of their true positions with a mean error of +/-0.4 mm. The biopsy procedures, including the method for verification of needle position, were successful in all 5 trials in acquiring samples from the simulated lesions. Conclusion: The success of this new technique shows its potential for guiding the biopsy of breast lesions optimally detected w ith PEM.