Dynamic contrast-enhanced MRI versus 18F-FDG PET/CT: Which is better in differentiation between malignant and benign solitary pulmonary nodules?

Objective: To prospectively compare the discriminative capacity of dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) with that of F-18-fluorodeoxyglucose (F-18-FDG) positron emission tomography/computed tomography (PET/CT) in the differentiation of malignant and benign solitary pulmonary nodules (SPNs). Methods: Forty-nine patients with SPNs were included in this prospective study. Thirty-two of the patients had malignant SPNs, while the other 17 had benign SPNs. All these patients underwent DCE-MRI and 18F-FDG PET/CT examinations. The quantitative MRI pharmacokinetic parameters, including the trans-endothelial transfer constant (Ktrans), redistribution rate constant (Kep), and fractional volume (Ve), were calculated using the Extended-Tofts Linear two-compartment model. The F-18-FDG PET/CT parameter, maximum standardized uptake value (SUVmax), was also measured. Spearman's correlations were calculated between the MRI pharmacokinetic parameters and the SUVmax of each SPN. These parameters were statistically compared between the malignant and benign nodules. Receiver operating characteristic (ROC) analyses were used to compare the diagnostic capability between the DCE-MRI and F-18-FDG PET/CT indexes. Results: Positive correlations were found between Ktrans and SUVmax, and between Kep and SUVmax (P< 0.05). There were significant differences between the malignant and benign nodules in terms of the Ktrans, Kep and SUVmax values (P< 0.05). The areas under the ROC curve (AUC) of K-trans, Kep and SUVmax between the malignant and benign nodules were 0.909, 0.838 and 0.759, respectively. The sensitivity and specificity in differentiating malignant from benign SPNs were 90.6% and 82.4% for K-trans; 87.5% and 76.5% for K-ep; and 75.0% and 70.6% for SUVmax, respectively. The sensitivity and specificity of Ktrans and Kep were higher than those of SUVmax, but there was no significant difference between them (P> 0.05). Conclusions: DCE-MRI can be used to differentiate between benign and malignant SPNs and has the advantage of being radiation free.