Comparison of dual-head coincidence gamma camera FDG imaging with FDG PET in detection of breast cancer and axillary lymph node metastasis

Dual-head coincidence gamma camera F-18-fluorodeoxyglucose (FDG) imaging wa s compared with FDG PET in the detection of breast cancer and axillary lymp h node metastasis. Methods: Both coincidence gamma camera FDG imaging and F DG PET were performed in a cylindrical phantom containing spheres of differ ent sizes and activity ratios (5:1, 10:1 and 15:1) and in 30 women (age ran ge 32-78 y) with suspected breast cancer. Biopsies or mastectomies were per formed in all patients. Images were visually assessed, and the count ratio between tumor and normal tissue (T/N ratio) was calculated. Results: In the phantom studies, coincidence gamma camera imaging visualized the smallest sphere (1.0 cm) at a ratio of 15:1 but not at ratios of 5:1 and 10:1. Coinc idence gamma camera imaging visualized the other spheres (greater than or e qual to 1.3 cm) at all ratios. PET visualized all spheres at all ratios. In the clinical studies, 22 of 26 breast carcinomas detected by PET were also detected by coincidence gamma camera imaging. Coincidence gamma camera ima ging detected all of the carcinomas greater than or equal to 2 cm in diamet er (n = 10) and 12 of 16 carcinomas < 2 cm. In breast carcinomas detected b y both PET and coincidence gamma camera imaging, the T/N ratio in non-atten uation-corrected PET (7.12 +/- 7.13) was significantly higher than in coinc idence gamma camera imaging (2.90 +/- 1.47, P < 0.005). Four of 8 axillary lymph node metastases detected by PET were detected by coincidence gamma ca mera imaging. Of 9 axillary lymph node metastases < 1.0 cm in diameter, 7 a nd 3 were detected by PET and coincidence gamma camera imaging, respectivel y. Conclusion: Coincidence gamma camera imaging is useful in detecting brea st carcinoma greater than or equal to 2 cm in diameter but is not reliable for breast carcinoma < 2 cm in diameter. Coincidence gamma camera imaging m ay be useless or even dangerous in the detection of axillary lymph node met astasis.