Can 18F-FDG PET improve the evaluation of suspicious breast lesions on MRI?

OBJECTIVE: To evaluate the impact of adding 18F-fluorine-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in the evaluation of suspicious breast lesions on magnetic resonance imaging (MRI). METHODS: Sixty patients with suspicious breast lesions on MRI were selected to perform a PET-CT in prone position, dedicated to the evaluation of the breasts. The areas with increased 18F-FDG concentration relative to normal parenchyma were considered positive on PET-CT. Fusion of PET and MRI images (PET-MRI) was performed on a dedicated workstation to better locate corresponding lesions, and its findings were compared with histological results. RESULTS: 76 lesions were evaluated, including 64 mass lesions (84.2%) and 12 non-mass lesions (15.8%). Lesions' mean diameter on MRI was 29.6 ± 19.2 mm (range 6-94 mm). PET-CT showed increased metabolically activity on 57 lesions (75.0%), with mean maximum SUV of 5.7 ± 5.0 (range 0.8-23.1). On histopathology, there were 17 (22.4%) benign and 59 (79.7%) malignant lesions. Considering all lesions, PET-MRI fusion provided 89.8% sensitivity, 76.5% specificity and 86.8% accuracy. Considering only mass lesions higher than 10mm, PET-MRI fusion provided 95.8% sensitivity, 83.3% specificity and 93.3% accuracy. CONCLUSION: The inclusion of 18F-FDG PET on the evaluation of suspicious breast lesions on MRI helped to differentiate benign from malignant breast lesions, especially for mass lesions with a diameter higher than 10 mm.