18F-FDG PET/CT and respiratory synchronization: effect in the detection and classification of pulmonary lesions

Abstract

Respiratory movement reduces sensitivity in the detection of pulmonary lesions. This disadvantage can be reduced with synchronized acquisition of PET with respiratory movement (4D). Our objective was to assess the effect of 4D PET/CT in the metabolic activity of 18F FDG and the final classification of pulmonary lesions. Material and Methods 12 patients with 18 pulmonary lesions whose sizes were within 0.8-4 cm were assessed. Maximum SUV was obtained in the image acquired under standard conditions (3D) and that obtained in the respiratory period with higher metabolic activity in 4D images. The percentage of difference between both values was calculated. Furthermore, changes in classification of pulmonary nodes (benign or malignant) obtained from the assessment of 4D and 3D PET images were evaluated. Results 17/18 pulmonary lesions showed an increase in the SUV max value in the 4D in regards to 3D image. Five lesions showed SUV max values > 2.5 in 4D image and <2.5 in 3D image. Of these, 3 were correctly classified as malignant with 4D, although the number of false positives increased to 2. Conclusion 18F-FDG 4D PET/CT shows values of metabolic activity that are more in accordance with the correct classification of malignant lesions, thus reducing the false negatives although the false positives increase.