Sasada S, Masumoto N, Kimura Y, et al. - A total of 826 patients with breast cancer were retrospectively assessed by the experts in order to evaluate the diagnostic performance of dual-phase 18F-FDG PET/CT in identifying axillary lymph node metastasis in patients with breast cancer. PET/CT scans were performed 1 hour and 2 hours following FDG administration prior to the treatment. In 285 of 826 patients, axillary lymph node metastasis was identified. In patients with nodal metastasis vs patients without metastasis the median axillary standardized uptake value (SUV_max)1, SUV_max2, and retention index (RI) were higher. The diagnostic exactitude of axillary SUV_max1 and SUV_max2 was comparable, and the sensitivity of SUV_max1 was 74.7% and specificity was 83.4%. Both the SUV_max and the RI were independent predictors of nodal metastasis, however, the performance of the axillary RI was lower to that of SUV_max1 and SUV_max2 and when the SUV_max1 was significantly high, a positive RI inferred axillary lymph node involvement. One hundred and one out of 533 patients with category T1–2 breast cancer without lymph node swelling, had pathologic lymph node involvement and the negative predictive value of axillary SUV_max1 was 86.8%. Hence, postponed phase imaging recognized axillary lymph node metastasis as accurately as standard PET/CT. For the detection of nodal metastasis, a high negative predictive value of PET/CT was concluded to be beneficial by the researchers in order to avoid surgical axillary evaluation in patients with category T1–2 breast cancer without lymph node swelling.