Objective: The purpose of our study was to compare dual-time-point (18)F-FDG PET/CT, performed with the patient in the prone position, and contrast-enhanced MRI in patients with suspected breast malignancy.
Subjects and methods: Forty-four patients with 55 breast lesions underwent two PET/CT scans (dual-time-point imaging) in the prone position and breast MRI. Sensitivity, specificity, and overall accuracy were calculated. In addition, the average percentage of change in standard uptake values (Delta%SUV(max)) between time point 1 and time point 2 was calculated for PET/CT. A final histopathologic diagnosis was available for all patients.
Results: MRI showed an overall accuracy of 95%, with sensitivity and specificity of 98% and 80%. Conversely, dual-time-point PET/CT showed an accuracy of 84% for lesions with an SUV(max) > or = 2.5 or with a positive Delta%SUV(max), with sensitivity and specificity of 80% and 100% versus 69% accuracy, 62% sensitivity (both, p < 0.001), and 100% specificity (p not significant) for single-time-point PET/CT. On PET/CT, malignant lesions showed an increase in FDG between time points 1 and 2, with a Delta%SUV(max) of 11 +/- 24. Benign lesions showed either no change or a decrease in SUV(max) between time points 1 and 2, with a Delta%SUV(max) of -21 +/- 7.
Conclusion: A dual time point improves PET/CT accuracy in patients with a suspected breast malignancy over single-time-point PET/CT. On PET/CT, FDG is increasingly taken up over time in breast tumors; conversely, benign lesions show a decrease in FDG uptake over time. These changes in SUV might represent a reliable parameter that can be used to differentiate benign from malignant lesions of the breast on PET/CT examination.