Aim: This prospective study was designed to assess the utility of the dual time point imaging technique using 2-[(18)F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) to detect primary breast cancer and to determine whether it is useful for the detection of small and non-invasive cancers, as well as cancers in dense breast tissue.
Methods: One hundred and eleven patients with newly diagnosed breast cancer underwent two sequential PET/CT examinations (dual time point imaging) for preoperative staging. The maximum standardized uptake value (SUVmax) of FDG was measured from both time points. The percentage change in SUVmax (DeltaSUVmax%) between time points 1 (SUVmax1) and 2 (SUVmax2) was calculated. The patients were divided into groups: invasive (n=82), non invasive (n=29); large (>10mm; n=80), small (<or=10mm; n=31); tumours in dense breasts (n=61), and tumours in non-dense breasts (n=50). The tumour:background (T:B) ratios at both time points were measured and the DeltaSUVmax%, DeltaT:B% values were calculated. All PET study results were correlated with the histopathology results.
Results: Of the 111 cancer lesions, 88 (79.3%) showed an increase and 23 (20.7%) showed either no change [10 (9%)] or a decrease [13 (11.7%)] in the SUVmax over time. Of the 111 contralateral normal breasts, nine (8.1%) showed an increase and 102 (91.9%) showed either no change [17 (15.3%)] or a decrease [85 (76.6%)] in the SUVmax over time. The mean+/-SD of SUVmax1, SUVmax2, Delta%SUVmax were 4.9+/-3.6, 6.0+/-4.5, and 22.6+/-13.1% for invasive cancers, 4.1+/-3.8, 4.4+/-4.8, and -2.4+/-18.5% for non-invasive cancers, 2.3+/-1.9, 2.7+/-2.3, and 12.9+/-21.1% for small cancers, 5.6+/-3.7, 6.8+/-4.8, and 17.3+/-17.1% for large cancers, 4.9+/-3.7, 5.8+/-4.8, and 15.1+/-17.6% for cancers in dense breast, and 4.5+/-3.6, 5.4+/-4.5, and 17.2+/-19.2% for cancers in non-dense breast. The receiver-operating characteristic (ROC) analysis suggested DeltaSUVmax% of 8% as the only significant cut-off for discrimination between invasive and non-invasive cancer (sensitivity 84.1%, specificity 75.9%, p<0.0001).
Conclusion: Dual time point FDG-PET/CT improves the discrimination between non-invasive and invasive cancers, and provided superior sensitivity for the detection of small cancers and cancers in dense breast.