Abstract: ob＜x＞jective To study the value of SUVmax obtained from PET/CT and ADCs obtained from multi b-values DWI in differentiating benign from malignant pulmonary lesions using a trimodality PET/CT-MRI setup and analyze the molecular correlation between SUVmax and ADC. Methods A retrospective study performed in 33 consecutive patients with pathologically or clinically proved diagnosis. All patiants underwent 18F-FDG PET/CT and subsequently MRI examinations using a trimodality PET/CT-MRI setup. SUVmax and different ADCs obtained from multi b-values DWI were acquired，including ADC-fast related to perfusion obtained from low b-values DWI, ADC-slow related to perfusion obtained from middle b-values DWI and ADC-AQP related to AQP obtained from high b-values DWI. Independent-sample t test was used for the comparison of SUVmax and ADCs between benign and malignant pulmonary lesions. ROC curve was used to evaluate the diagnostic performance of SUVmax and ADC. The correlation between SUVmax and ADC was analyzed by Pearson correlationship analysis. Results SUVmax was significantly higher for malignant lesions than for benign lesions (10.30 ± 4.12 vs. 4.83 ± 5.41; t = -3.105, P = 0.004). ADC-slow was significantly lower for malignant lesions than for benign lesions(0.13 ± 0.50 vs. 0.19 ± 0.07; t = 2.688, P = 0.011). The cut-off of SUVmax was 4.95g/ml. The sensitivity and specificity were 95.8% and 77.8%. The cut-off of ADC-slow was 0.15×10-3 mm2/s. The sensitivity and specificity were 77.8% and 66.7%.No significant correlation was found between SUVmax and ADC. Conclusions SUVmax and ADC-slow are helpful to differentiate benign from malignant pulmonary lesions. There is no significant correlation between SUVmax and ADCs and they indicate different biological information separately.