Differentiation of FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer with dual-time point F-18-fluorodeoxy-glucose PET/CT scan.

OBJECTIVE: To evaluate the ability of dual-time point F-18-fluorodeoxy-glucose (FDG) PET/CT scans to differentiate FDG-avid loco-regional recurrent and compromised benign lesions after surgery for breast cancer.

METHODS: A total of 64 FDG-avid recurrent lesions (local tumor recurrence or lymph node metastases) in 52 patients and 38 FDG-avid compromised benign lesions after surgery in 37 patients were included in the study. FDG PET/CT study was performed at 60 and 120 min after intravenous injection of 3.5 MBq/kg FDG. The maximum SUV (SUVmax) on the early and delayed scans and the percent change of SUVmax (%DeltaSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis.

RESULTS: The average early SUVmax, delayed SUVmax and DeltaSUVmax% were 4.9 +/- 2.6, 6.0 +/- 3.6 and 18.2% +/- 18.8 in FDG-avid recurrent lesions, and 2.1 +/- 0.8, 1.8 +/- 1.0 and -17.8% +/- 21.3 in FDG-avid benign lesions, respectively. Delayed SUVmax was significantly increased compared with early SUVmax in recurrent lesions (P < 0.0001), while it was decreased in benign lesions (P < 0.0001). All the three parameters in recurrent lesions were significantly higher than those in benign lesions (P < 0.0001). The highest diagnostic accuracy of the differentiation was achieved by the combined use of the optimal parameter of delayed SUVmax > 2.5 and %DeltaSUVmax > 0%, with a sensitivity of 90.6%, specificity of 81.5%, accuracy of 87.2%, NPV of 89.2%, and PPV of 83.7%, which were better than the respective values obtained with the use of delayed SUVmax > 2.5 alone or %DeltaSUVmax > 0% alone (P < 0.005 and P < 0.05, respectively), and the use of the traditional parameter of early SUVmax > 2.5 (P < 0.005).

CONCLUSIONS: This approach with SUVmax estimation appears to improve the differentiation between FDG-avid loco-regional recurrent of breast cancer and compromised benign lesions after surgery, since delayed scanning significantly enhances the difference in FDG uptake between these lesions.