To evaluate the significance of incidentally discovered breast lesions on 18-fludeoxyglucose (18F-FDG) positron emission tomography (PET)/CT.
6050 18F-FDG PET/CT studies, performed between January 2009 and February 2012, were retrospectively reviewed. 55 lesions in 50 patients were identified. Additional work-up, including mammography, ultrasound, follow-up 18F-FDG PET/CT and biopsy, was available for 39 incidental breast lesions in 36 patients. All patients were female, with mean age 61.5 years (range 36–90 years). The maximum standardised uptake value (SUVmax), CT size and CT Breast Imaging Reporting and Data System (BI-RADS®) scores were compared between the malignant and the benign subgroups, using the unpaired t-test and Fisher’s exact test. Tests were two-sided and a p-value of <0.05 was considered to be significant.
Incidental breast lesions were identified in 50 (0.8%) of 6050 18F-FDG PET/CT studies. 21 (53.8%) of the 39 breast incidentalomas were malignant on biopsy or imaging, of which 15 (38.5%) represented a second primary breast cancer. A statistically significant difference in the mean SUVmax between malignant and benign breast lesions was observed (p=0.021). Malignancy was significantly more common in the CT BI-RADS Category 4 or greater groups (76.2%; p=0.0105).
Incidental breast lesions detected at 18F-FDG PET/CT are uncommon. When detected, however, they may represent malignancy in up to 53.8% of cases.
Advances in knowledge:
SUVmax and CT findings at 18F-FDG PET/CT can assist with differentiating benign and malignant breast conditions, guiding further evaluation with dedicated breast imaging.
Review of 18F-FDG PET/CT-detected breast lesions by a breast radiologist may be helpful in determining the need for and correlation with further breast imaging.
Radiologists and nuclear medicine physicians should be cognisant of breast pathology when reporting 18F-FDG PET/CT image data sets.