The role of 18F-FDG uptake features in the differential diagnosis of solitary pulmonary lesions with PET/CT

BACKGROUND The aim of this study is to evaluate the value of (18)F-FDG uptake features in the diagnosis of solitary pulmonary lesions. METHODS One hundred thirty-nine patients with solitary pulmonary lesions were divided into full uptake, circular uptake, multi-focus uptake, mild uptake, and no-uptake groups according to the uptake features of (18)F-FDG in solitary pulmonary lesions. The incidence of benign and malignant lesions and the false-positive and false-negative rates in each group were analyzed. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the method using (18)F-FDG uptake features combined with maximum standard uptake value (SUVmax) (SUV method) in the differential diagnosis of solitary pulmonary lesions were evaluated. RESULTS There were 89 malignant and 50 benign lesions. (1) The malignant incidence of the full uptake group was 84.0% (63/75), and there were significant differences when compared with the other groups except the circular uptake group (16/23) (all P = 0.0001). The benign incidence of the multi-focus and no-uptake groups was 83.3% (10/12) and 82.4% (14/17), respectively, and there were significant differences when compared with the full uptake and the circular uptake groups, respectively (all P < 0.05). The benign incidence of the mild uptake group was 58.3% (7/12), and there were no significant differences when compared with the others except the full uptake group (all P > 0.05). No statistical significance was found between either two of the no-uptake, mild uptake, and multi-focus uptake groups (all P > 0.05). (2) In cases with SUVmax ≥2.5, the false-positive rate in the multi-focus uptake group was 83.3% (10/12), which was significantly higher than in the full uptake (12/75) or circular uptake group (7/23) (all P < 0.05). In cases with SUVmax <2.5, the false-negative rates in the mild and no-uptake groups were 41.7 and 17.6% (P = 0.218). (3) The sensitivity, specificity, accuracy, PPV, and NPV of the method using (18)F-FDG uptake features combined with SUVmax and the single SUV method were 88.7%/91.0%, 62.0%/42.0%, 79.1%/73.4%, 80.6%/73.6%, and 75.6%/72.4%, respectively. CONCLUSIONS The method using uptake features of (18)F-FDG combined with SUVmax can improve the diagnostic specificity and accuracy of solitary pulmonary lesions. The multi-focus uptake feature maybe a benign sign, which still needs more researches to confirm.