Effectiveness of Hounsfield Unit Values in the Differentiation of Malign and Benign Thyroid Nodules

INTRODUCTION: Thyroid nodules are today encountered more frequently due to the advances in imaging methods. Here, we aimed to evaluate the efficacy of computed tomography Hounsfield Unit (HU) values in the differential diagnosis of benign or malignant thyroid nodules.
METHODS: This retrospective study involved 51 patients with thyroid nodules who had thyroid FNAB result and chest CT with or without contrast-enhanced, between January 2018 and September 2020. Circular ROIs (region of interest) were drawn on the section that best demonstrated the thyroid nodule on CT and obtained HU values were averaged. An independent t-test was applied to the HU values for the malign-benign differentiation.
RESULTS: Of the 40 patients who had contrast-enhanced CT, 25 were benign and 15 were malignant. Of the 11 patients who had non-enhanced CT, 6 were benign and 5 were malignant. In contrast-enhanced scans, nodule attenuation was statisticaly significantly higher in malignant nodules (116.26±17.74 HU) when compared with benign nodules (93.84±24.33 HU) (P = 0.004). A ROC analysis revealed an area under the curve of 78.8%. The sensitivity and specificity of the cut-off value of 104.5 for the area under the curve were found to be 80% each. In non-enhanced scans, nodule attenuations were not significantly different in malignant (49±12.14 HU) and benign (67.5±16 HU) nodules (P=0.72).
DISCUSSION AND CONCLUSION: Taking into consideration the possibility of malignancy in thyroid nodules, the thyroid gland should be evaluated carefully through thoracic CT. A sonographic correlation is recommended for nodules with an HU value of 104.5 and above detected on contrast-enhanced tomography images.