Utility of PET-CT in differentiation between the malignant and benign lung lesions over than 2 cm

To characterize 18F-FDG accumulation with PET-CT for differentiation between benign and malignant lung lesions over than 2cm. Sixty-three patients with pulmonary mass over than 2 cm on combined FDG PET-CT, histologically confirmed, were retrospectively reviewed. The peak SUV of mass was measured and the FDG uptake pattern was analyzed. FDG uptake pattern was divided into two groups as homogenous and inhomogeneous ones. Inhomogeneous group was further classified as ring like uptake, peripheral nodular uptake and homogenous uptake with peripheral nodular photon defect. It was included in the evaluation whether the peritumoral opacity without FDG accumulation around mass was or not. The statistical significance of differences among benign and malignant lesions was determined (unpaired T test). Forty one masses were histologically confirmed to be malignant, whereas twenty two were benign. On PET-CT, malignant lesions showed higher SUV levels (malignancy vs benign : 9.22 vs. 3.28, p<0.0001). Twenty six malignant masses (63%) were inhomogeneous in FDG distribution and 24 cases of them (92%) showed ring like uptake pattern. Otherwise, 6 benign masses, the peritumoral opacities without FDG uptake were present. In benign lesions, only two cases had these opacities. The peak SUV level is the most available method in differentiation between benign and malignant lesions over 2 cm in lungs. The inhomogenous FDG accumulation of the mass may support the mass to be malignant. Moreover, peritumoral opacity without FDG uptake may also support the malignancy