OBJECTIVE: To explore the utility of dual-energy spectral computed tomography (CT) in the differential diagnosis of focal organizing pneumonia (FOP) and solitary bronchioloalveolar carcinoma (S-BAC).
METHODS: The institutional review board approved this study and waived the requirement for informed consent. It is a retrospective study. A total of 105 patients (62 with FOP and 43 with S-BAC) enrolled and all patients have contrast enhanced spectral CT including the arterial phase (AP) and venous phase (VP). During AP and VP, CT40 keV, CT70 keV, and CT100 keV values, iodine concentration (IC), water concentration (WC), and effective atomic number (Zeff) were measured on monochromatic and iodine-based material decomposition images, and the slope of the spectral curve (λHu) was calculated. The two-sample t-test was used to compare quantitative parameters, and receiver operating characteristic (ROC) curves were generated to calculate diagnostic efficacies.
RESULTS: For AP, CT40 keV and CT70 keV values, IC, WC, Zeff, λ70 keV, and λ100 keV measurements, there were significantly higher in patients with S-BAC than in those with FOP (P < 0.05). However, these quantitative parameters of VP were significantly lower in patients with S-BAC than in those with FOP (P < 0.05). ROC curve analysis revealed that the combination of all quantitative parameters in AP and VP provided the best diagnostic performance in distinguishing S-BAC from FOP (area under the ROC curve, 93.1%; sensitivity, 95.3%; specificity, 77.4%).
CONCLUSIONS: Dual-energy spectral CT has the potential to identify S-BAC and FOP.