The respiratory movement reduces the sensitivity in the detection of pulmonary lesions. The synchronized acquisition of PET with respiratory movement (4D) can reduce this inconvenient. Our objective was assess the effect of 4D PET-CT in the metabolic activity of (18)F FDG and final classification of pulmonary lesions.
Material and methods: 12 patients with 18 pulmonary lesions with sizes within 0.8-4cm were assessed. The maximum SUV was obtained in the imaging acquired in standard conditions (3D) and the obtained in the respiratory period with higher metabolic activity in 4D images. The difference of percentage between both values was calculated. Moreover were evaluated the changes of the classification of pulmonary nodes (benign or malignant) obtained from the assessment of 4D and 3D PET images.
Results: 17/18 pulmonary lesions showed an increase in the SUV(max) value in the 4D with respect to 3D image. 5 lesions showed SUV(max) values >2.5 in 4D image and <2.5 in 3D image. From these 3 were correctly catalogued as malignant with 4D although the number of false positive increased to 2.
Conclusion: (18)F-FDG 4D PET-CT shows values of metabolic activity more realistic allowing the correct classification reducing the false negative although increasing the false positive.