Ability of the Positron Emission Mammography system, PEMi, in detection of millimeter-sized lesions

A new polygon Positron Emission Mammography imaging system called PEMi with the ability to detect millimeter-sized lesions has been developed in 2009 by Institute of High Energy Physics (IHEP), Chinese Academy of Sciences. The system is constructed in a polygon structure with a design of LYSO crystal arrays mounted on position sensitive photomultiplier (PSPMT). The diameter of the detector ring is 166 mm and the axial length is 128 mm. Transaxial field of view (FOV) of PEMi is 110 mm. Reconstructed image resolution at the center of FOV is 1.58 mm in radial direction, 1.41 mm in tangential direction and 1.31 mm in axial direction. An ongoing clinical experiment has been performed to verify its ability in practical applications, especially in detecting small tumors (<;1 cm). Our preliminary results indicate that PEMi has a high consistency with conventional PET in detection of the primary tumor with a size larger than 1 cm. But PEMi has a better resolution in detection of millimeter-sized breast tumors. The smallest lesion detected by PEMi is 3mm. Furthermore, PEMi has a number of advantages over conventional PET screening, such as detection of minute lesions, accurate lesion localization and biopsy guidance.