Fuzuki Yano - Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine
Masatoshi Itoh - Sendai Medical Imaging Clinic (Gazo Kenshin)
Hisashi Hirakawa - Department of Breast Surgery, Tohoku Kosai Hospital
Seiichi Yamamoto - Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan

Objective(s): To investigate the diagnostic accuracy of positron emission mammography (PEM) and positron emission tomography/computed tomography (PET/CT) for small breast tumors of less than 20 mm in size.Methods: The study was conducted on a total of 100 subjects (i.e., 50 patients with pathologically proven breast cancer and 50 normal cases of medical screening). The total number of tumors was 54 (mean size: 11±5.1 mm, range:4-20 mm). The diagnostic accuracy of PEM alone, PET/CT alone, and combined PET/CT and PEM was evaluated by two nuclear medicine physicians based on visual inspection. The two groups (i.e., tumors of ≤ 10 mm and > 10-20 mm) werecompared in terms of the diagnostic capability of the three modalities (PEM alone, PET/CT alone, and PET/CT+PEM).Results: The sensitivities of PEM alone, PET/CT alone, and combined PET/CT and PEM were 72%, 60%, and 76%, respectively. The specificities of these tests were 98%, 100%, and 98%, respectively. Furthermore, the accuracies of these diagnostic modalities were 85%, 79%, and 87%, respectively. The combined PET/CT and PEM showed significantly higher sensitivity and accuracy than PET/CT alone (P=0.005 and P=0.02, respectively). In addition, PEM demonstrated asignificantly higher sensitivity than PET/CT in the ≤ 10 mm group (P=0.03); however, no difference was observed between the two modalities in the > 10 mm group in terms of sensitivity.Conclusion: 18F-fluorodeoxyglucose PET had limited capability for the detection of small breast cancers of < 10 mm. Combined PET/CT and PEM showed higher sensitivity and accuracy, compared to PET/CT alone.

positron emission mammography, PEM, PET/CT, Breast Cancer, diagnostic accuracy