Differentiation between malignant and benign solitary pulmonary nodules with proton density weighted and ECG-gated magnetic resonance imaging

Objective: To estimate performance of MRI for differentiating malignant from benign solitary pulmonary nodules (SPN) using morphological characteristics. Material and Methods: MRI in 46 patients with SPN (mean diameter: 19mm) was carried out on 1.0 Tesla scanner using ECG-gated, gradient echo sequence. Morphological signs of SPN were determined and compared with previously performed helical-CT, where final diagnosis served as reference with 52% frequency of malignancy. Furthermore, three observers evaluated all images. Results: Significant differences between the two groups were found for nodules shape, margin, inhomogeneity and the vessel-sign in MRI, nodules shape, margin, the vessel-sign, and presence of spicules in CT. Using these signs, AUC were 0.746 for MRI and 0.765 for CT. The mean sensitivity, specificity, and accuracy of observers for MRI/CT were 89%/ 95%, 42%/41%, 66%/68%, respectively. Conclusions: Despite discrepancies in morphologic appearance, no significant difference of accuracy between MRI and CT was determined. Further investigations are necessary to demonstrate the clinical use in combination with functional parameters, establishing MRI as a comprehensive diagnostic modality for SPN.