Potential of dual-time-point imaging to improve breast cancer diagnosis with 18F-FDG PET

The purpose of this study was to assess the utility of dual-time-point imaging for identifying malignant lesions in the breast by F-18-FDG PET. Methods: Fifty-four breast cancer patients with 57 breast lesions underwent 2 sequential PET scans (dual-time-point imaging). The average percent change in standardized uptake values (SUVs) between time point 1 and time point 2 was calculated. All PET study results were correlated with follow-up surgical pathology results. Results: Of the 57 breast lesions, 39 were invasive carcinoma and 18 were postbiopsy inflammation. Among the invasive carcinoma lesions, 33 (85%) showed an increase and 6 (15%) showed either no change or a decrease in SUVs over time. The percent change in SUVs from time point 1 to time point 2 (mean +/- SD) was + 12.6% +/- 11.4% (P = 0.003). Of the 18 inflammatory lesions, 3 (17%) showed an increase and 15 (83%) showed either no change or a decrease in SUVs. The percent change in SUVs from time point 1 to time point 2 (mean +/- SD) was -10.2% +/- 16.5% (P = 0.03). Of the 57 normal contralateral breasts, 2 (3.5%) showed an increase and 55 (96.5%) showed either no change or a decrease in SUVs. The percent change in SUVs from time point 1 to time point 2 (mean +/- SD) was -15.8% +/- 17% (P = 0.005). Conclusion: There is increasing uptake of 18F-FDG over time in breast malignancies, whereas the uptake of 18F-FDG in inflammatory lesions and normal breast tissues decreases over time. A percent change of +3.75 or more in SUVs over time is highly sensitive and specific in differentiating inflammatory lesions from malignant lesions.