RESUMO
<p><b>OBJECTIVE</b>To investigate the value of multi-slice helical CT in the differentiation of benign from malignant thyroid lesions.</p><p><b>METHODS</b>The multi-slice helical CT images of 72 patients with 82 thyroid lesions were prospectively studied. The CT features including the margin, density of the lesion and cervical lymph node enlargement were evaluated double-blindly. All the image findings were compared with the pathological results, and analyzed statistically using the Chi-square test.</p><p><b>RESULTS</b>Of 42 benign lesions, 38 (90.5 % ) showed well-defined margin, 13 (30. 9% ) contained low density nodular areas, 3 (7. 1% ) showed granular calcifications, and 2 (4. 8% ) had cervical lymph node enlargement. Of 40 thyroid carcinomas, 37 lesions(92.5% ) had irregular border, no lesion contained low density nodular areas, 14 (35. 0%) showed granular calcifications, and 31 (77. 5% ) had enlarged cervical lymph nodes. Nineteen lesions (55. 9% ) from 34 thyroid carcinoma patients who had undergone contrast enhanced CT scan showed complex density, while only 2(6. 3% ) of 32 benign lesions showed such findings on contrast enhancement. There were statistically significant differences between benign and malignant lesion in margin, low density nodular area, granular calcification, cervical lymph node enlargement and complex density( P <0.01).</p><p><b>CONCLUSION</b>The findings of well-defined margin and low density nodular area in CT image may suggest benign thyroid lesions, whereas the presence of irregular border, granular calcifications and cervical lymph node enlargement as well as complex density may indicate thyroid malignancy.</p>