Dual-time-point [18F]-FDG PET/CT in the diagnostic evaluation of suspicious breast lesions.

PURPOSE: The authors sought to evaluate whether the reacquisition of images 3 h after administration of radiotracer improves the sensitivity of fluorine-18 fluorodeoxyglucose positron emission tomography computed tomography ([(18)F]-FDG PET/CT) in patients with suspicious breast lesions.

MATERIALS AND METHODS: Forty-eight patients with 59 breast lesions underwent an [(18)F]-FDG PET/CT study in the prone position with a dual-time-point acquisition performed in the early phase 1 h after FDG administration (PET-1) and in the delayed phase 3 h after FDG administration (PET-2). Both examinations were evaluated qualitatively and semiquantitatively with calculation of the mean percentage variation of the standard uptake values (Delta% SUV(max)) between PET-1 and PET-2. All lesions with an SUV(max) >or=2.5 at PET-1 or a reduction in SUV between PET-1 and PET-2 were considered benign. The definitive histopathological diagnosis was available for all patients included in the study.

RESULTS: The dual-time-point acquisition of [(18)F]-FDG PET/CT displayed an accuracy of 85% for lesions with an SUV(max) >or=2.5 and/or positive Delta% SUV(max), with sensitivity and specificity values of 81% and 100% compared with 69%, 63% (both p<0.001) and 100% (p=n.s.), respectively, for the single-time-point acquisition. Malignant lesions showed an increase in FDG uptake between PET-1 and PET-2, with a Delta% SUV(max) of 10+/-7 (p<0.04). In contrast, benign lesions showed a decrease in SUV between PET-1 and PET-2, with a Delta% SUV(max) of -21+/-7 (p<0.001).

CONCLUSIONS: The delayed repeat acquisition of PET images improves the accuracy of [(18)F]-FDG PET/CT in patients with suspicious breast lesions with respect to the single-time-point acquisition. In addition, malignant breast lesions displayed an increase in FDG uptake over time, whereas benign lesions showed a reduction. These variations in FDG uptake between PET-1 and PET-2 are a reliable parameter that can be used for differentiating between benign and malignant breast lesions.