Breast Incidental Lesions at 18 F FDG PET/CT: Diagnostic Performance of PET-derived Metabolic Parameters

Background: Breast incidental lesion at 18 F FDG PET/CT are occasionally encountered in cancer patients, which may represent a second primary malignancy. The aim of the present study was to investigate the diagnostic performance of PET metabolic parameters to characterize breast incidentaloma. Materials and Methods: All the images of patients with cancers other than breast with breast incidental lesion underwent PET/CT scan at Masih Daneshvari Hospital between May 2012 and May 2016 were retrieved and reviewed. SUVmax, SUVmean, MTV and TLG in addition to associated morphologic features on CT and demographics were recorded and correlated with final diagnosis defined by histophatologic confirmation or an at least 1-year clinical formal follow up. Results: Of a total 58 from 51 patients (51/5029, 1.01%), 10 (19.60%) were histopathologically verified as second primary breast cancers. There was a statistically significant difference in SUVmax, SUVmean, MTV and TLG between benign and malignant group (1.64 vs. 5.32 (p=0.009), 1.34 vs. 3.69 (p=0.027), 0.96 vs. 2.62 (p=0.035), 1.54 vs 8.89 (p=0.006). Using cut off 2, 1.35, 1.16 and 1.75, sensitivity and specificity of SUVmax, SUVmean, MTV and TLG were calculated as 77% and 62%, 92% and 66.5%, 77% and 75% 77% and 67%, respectively. Conclusion: Despite a significantly higher value in malignant breast incidental lesion, PET-derivative metabolic parameters provided only modest sensitivity and specificity and hence may not be considered as the sole criteria for risk stratification in this clinical setting