Dual-energy computed tomography in the diagnosis of mediastinal tumor

Abstract

PURPOSE: The purpose of this study is to investigate the diagnostic utility of dual-energy computed tomography (DECT) in differentiating between mediastinal 1) cystic and solid masses, and 2) benign and malignant tumors. MATERIALS AND METHODS: Our institutional review board approved this study, and patients provided informed consent. We prospectively enrolled 38 patients (18 males; mean age: 46 years) who had suspected mediastinal tumors on chest radiography or chest computed tomography (CT). All patients underwent a DECT using gemstone spectral imaging (GSI) mode (GE HD750). For qualitative analysis, each mass was characterized in terms of its size, location, internal characteristics, and external characteristics. For the quantitative analysis, two reviewers measured the following parameters of the tumors: CT attenuation value in Hounsfield units (HU), iodine-related HU, and iodine concentration (mg/ml). Pathological results were used for a final diagnosis. Statistical analyses were performed using the Fisher’s exact test, independent samples t-test, and Mann-Whitney test.RESULTS: In qualitative analysis, malignant tumors were more likely to be greater in size (p = 0.015), with lobulated or irregular contours (p < 0.001), a necrotic or cystic component (p = 0.025), local invasion (p < 0.001), metastasis (p = 0.016), and lymphadenopathy (p < 0.001) than were benign tumors. In comparison of mediastinal cysts and masses, the mean attenuation values in HU, iodine-related HU, and iodine concentration were higher in mediastinal masses than cysts (all p < 0.001). In comparison of benign and malignant tumors, the iodine related HU was significantly lower in malignant tumors than benign tumors (p = 0.041).CONCLUSION: DECT using a quantitative analytic method based on iodine concentration measurements can be used to evaluate tumor enhancement of medistinal tumors using a single-phase scanning. Therefore, we believe that DECT could be a helpful complementary tool in cases where conventional contrast CT is inconclusive.