The Value Of Gemstone Spectral Imaging(GSI)in Differentiation Between Benign And Malignant Thyroid Nodules

ObjectiveTo investigate the value of gemstone spectral imaging (GSI) in the differential diagnosis of benign and malignant thyroid nodules.MethodsTotally50patients with thyroid nodules confirmed by pathology underwent gemstone spectral imaging examination from October2012to December2013,range24～79(mean age49.8), and20cervical patients with no thyroid diseases as comparison group, range25～56(mean age42.6). All subjects had signed informed consent. Using spectral CT cervical GSI mode, send images to AW4.5workstation after scan completed. Using GSI Viewer software process images, The solid component of nodules were selected as region of interested, avoiding calcification, cystic region, the artifacts of blood vessels and clavicle. Iodine and water concentration in region of interested were measured in iodine and water based material decomposition images. The spectral curves and Effective-Z in region of interested were measured, and calculate the spectral curve slope:Hu(100keV)-Hu(40keV)/60. In enhanced scan, to minimize the difference of injection speed, contrast agent dose and cycle time of different patients, measured the ratio of iodine concentration in region of interested and carotid artery, that is standardization iodine concentration. Then analyze optimal CNR monochromatic images, spectral curves, iodine-water concentration and Effective-Z. For patients with thyroid cancer and cervical lymph node enlargement, analyze the spectral curves and iodine-water concentration of primary lesions and enlarged lymph nodes, then measure and calculate the iodine concentration and slope of spectral curve. SPSS17.0software was used to statistical analysis, p<0.05was considered differentiation statistically significant.ResultsConfirmed by pathology, among these50patients,25were diagnosed as nodular goiter,22were papillary thyroid carcinoma and3were thyroiditis, there are3papillary thyroid carcinoma combined with nodular goiter and8papillary thyroid carcinoma with cervical lymph node enlargement. Through statistical analysis: 1. The curve slope of normal thyroid and nodular goiter were positive and the slope of nodular goiter was inferior to normal thyroid, the difference between them was statistically significant.2. The curve slope of thyroid carcinoma is negative or small positive. Thyroid carcinoma, nodular goiter and normal thyroid in slope and iodine concentration difference between each two groups were statistically significant.3. There were significant differences between each two groups in iodine concentration while no significant differences in water concentration.4. The difference of Effective-Z between thyroid carcinoma and nodular goiter was statistically significant.5. The spectral curve shape of thyroid carcinoma and part cervical enlarged lymph nodes had better consistency, The difference of curve slope and iodine concentration between them was no statistically significant.ConclusionGSI curve slope and iodine concentration combined CT morphology can help the differential diagnosis of benign and malignant thyroid nodules.