Differentiated thyroid carcinomas - Prediction of tumor invasion with MR imaging

Purpose: To assess diagnostic accuracy for tumor invasion of surrounding organs by measurement of tumor circumferences on MR images in patients with differentiated thyroid carcinomas. Material and Methods. Surgical and MR imaging findings in 50 patients with differentiated thyroid carcinoma (43 primary, 7 recurrent lesions) were retrospectively reviewed. The degrees of circumference of tumor encroachment to the organs were measured, and the measurements and morphologic diagnosis of tumor invasion made by a head and neck radiologist were compared with surgical and pathologic findings using receiver operating characteristic curves. Results: Diagnosis of tumor invasion by the radiologist was superior to the measurements of the carotid artery and cartilage, while the reverse was true for the trachea and esophagus. However, no statistical differences were noted between them for each structure. Optimal thresholds for tumor invasion were 90 degrees or more for the cartilage (94% accuracy) and esophagus (86% accuracy), 135 degrees or more for the trachea (86% accuracy), and 225 degrees or more for the carotid artery (90% accuracy). Conclusion. Tumor invasion was more accurately diagnosed by measurement of tumor circumferences of each organ on MR images.