Low-dose High-resolution 18 F-FDG-PET/CT Using Time-of-flight and Point-spread Function Reconstructions: A Role in the Detection of Breast Carcinoma Axillary Lymph Node Metastases.

Aim: to evaluate the performance of N-staging assessment in clinically-proven T1 breast carcinoma by high-resolution F-18-fluorodeoxyglucose-positron-emission tomography/computed tomography (F-18-FDG-PETICT) using time-of-flight with point-spread function reconstruction. Patients and Methods: In 30 women with clinically proven T1 breast carcinoma, imaging before surgery was performed using F-18-FDG-PETICT. The results of PET/CT in detection of lymph node metastases were compared with those obtained after pathological investigation of axillary biopsy. A four-ring PET subsystem with image reconstruction using time-of-flight and point-spread function was used with the radiopharmaceutical dose reduction to 2.5 MBq/kg. Results: Axillary lymph node metastasis was confirmed by histology in 13 patients, but metastasis was suspected based on PET/CT in 12 of those patients, the absence of metastasis was surgically confirmed in 17 women, 15 of which were suspected based on PET/CT. The sensitivity for detection of axillary lymph node metastasis was 93.3%, with a specificity of 88.2% in the whole patient cohort. Additionally, distant metastatic spread was found in 13.3% of patients. Conclusion: The reconstruction of PET images with time-of-flight and point-spread function enabled the improvement of diagnostic performance in N-staging of breast carcinoma, even when the dose of radiopharmaceutical was reduced to 2.5 MBq/kg