Aim: The aim of the present study was to evaluate the diagnostic performance of semi-quantitative metabolic parameters on 18F-FDG PET/CT; maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), tumor to liver ratio (TLR), and tumor to mediastinum ratio (TMR) in the axillary staging of breast cancer (BC) patients. Patients and methods: One hundred fifty female patients with initially diagnosed BC were recruited in this retrospective study. A 3-D volume of interest (VOI) was drawn over the primary lesion to obtain metabolic PET parameters: SUVmax, SUVmean, MTV, TLG, TLR, and TMR. Additionally, the size and the SUVmax of the axillary lymph node (ALN) were measured. Histopathological examination of the ALN was considered the gold standard.
Results: One-hundred fifty female patients with mean age; 50.6 ± 12 years (range: 19 - 88 years). On a patient basis, histopathological examination revealed metastatic ALNs in 101 patients while 49 cases were negative for metastases, PET/CT successfully identified 74/101 “true positive" and 46/49 “true negative lesions" giving a sensitivity of 73.7 %, 93.9 % specificity with an overall accuracy of 80% (P<0.001). The mean age of patients with negative ALNs was insignificantly higher than that of the positive one. The median values of the aforementioned PET parameters were significantly higher in the ALN positive group. Apart from MTV the areas under the curve (AUCs) of all the PET parameters were superior to the AUC of the primary SUVmax and mean; so these parameters were better to predict ALN metastases. Conclusion: The median values of the PET parameters; SUVmax, SUVmean, MTV, TLG, TLR, and TMR were significantly higher in patients with ALN metastases. Apart from MTV the rest of the PET parameters were superior to the primary SUVmax and mean in predicting ALN metastases.