Spectral CT Imaging Of Thyroid Nodules

Iodine content analysis by gemstone spectral imaging:phantom studyObjective:To evaluate the confidence and accuracy of GSI in analyzing the iodine content of different phantoms.Methods:Iodine solution with varying iodine concentrations (mg/ml) were dissolved in distilled water into18different groups in50ml tubes. The iodine concentration of these tubes were0.35mg/ml、0.53mg/ml、0.70mg/ml、0.88mg/ml、1.05mg/ml、1.23mg/ml、1.40mg/ml、1.58mg/ml、1.75mg/ml、1.75mg/ml、3.50mg/ml、5.25mg/ml、7.00mg/ml、8.75mg/ml、10.50mg/ml、12.25mg/ml、14.00mg/ml、15.75mg/ml in order. GSI scans were acquired on a Discovery CT750HD scanner with a small field of view (FOV=25cm) and thin slices (1.25mm). Tube rotation speed was0.8s/rotate. Image processing was performed on GSI Viewer browser. To measure Ⅰ the iodine content of the solution., II Slope of spectral HU curve,Ⅲ Mean HU value.Results:Positive correlation was found between the iodine concentrations and the reference standard concentration of iodine(r=0.998, P=0.000)were found. There was no significant difference between the measurements and the true value of iodine content (P=0.73>0.05).ConclusionsGSI mode can generate MD images for analyzing the material contents, GSI mode can accurately reflect the content of iodine in different concentrations and be used for further quantitative analysis. Spectral CT imaging of thyroid nodule specimensObjective:To study the imaging characteristics of thyroid nodules in spectral CT imaging and to investigate the clinical values of spectral CT in differentiating benign and malignant thyroid lesions and different ingredients of intra-nodules through imaging thyroid nodular specimens.Material and methods:One hundred and eight fresh specimens of thyroid nodules underwent CT scans with Gemstone Spectral Imaging (GSI) scan mode before pathologic examinations. Of all patients,39were male (18～75years, mean42.3years),68were female (17-71years, mean43.5years). The iodine and water-based material decomposition images and101sets of monochromatic images were reconstructed. Spectral CT image analysis:These images were reviewed with the GSI-viewer analysis software for image analysis and data measurement. The measurements included:(Ⅰ) the iodine and water contents of nodules and surrounding thyroid tissues and different components of nodules in material decomposition images,(Ⅱ) the characterization of the spectral HU curve (CT number as function of photon energy) for nodules and surrounding thyroid tissues and different components of nodules by calculating the slopes of the curves generated from the101sets of monochromatic images. The slope was calculated as the CT value difference at two energy levels (40keV and100keV) divided by the energy difference (60keV) from the spectral HU curve:Slope=(HU40kev-HU100kev)/60;(Ⅲ) the effective atomic number (Effective-Z) of nodules and surrounding thyroid tissues and different components of nodules; and (Ⅳ) the CT value of nodules and surrounding thyroid tissues and different components of nodules.Results:Pathologic results:180nodules were confirmed in all108specimens into4lesion groups:104nodules were nodular goiter,46were follicular adenoma,16were papillary carcinoma and14were thyroid cyst.(1) Spectral imaging analysis of benign and malignant nodulesIodine content:There was no difference for the iodine concentration in lesions between groups NG and FA(P=0.931), and between groups PTC and TC (P=0.953). There were statistically significant differences for iodine concentrations between groups PTC and NG(P=0.000), PTC and FA(P=0.000), NG and TC(P=0.000), and FA and TC (P=0.000). In all4groups, there was no statistically significant difference for the iodine concentrations for the surrounding thyroid tissues (p=0.924).Water content:There was no difference for the iodine concentration in lesions among all groups. There was statistically significant differences for water concentrations between groups PTC and TC(P=0.044), and there was no statistically significant difference for the water concentrations for the other surrounding thyroid tissues.Slope of spectral HU curve:There was no difference for the slope of spectral HU curve in lesions between groups NG and FA(P=0.997), and between groups PTC and TC (P=0.980). There was statistically significant differences for the slope of spectral HU curve between groups PTC and NG(P=0.000), PTC and FA(P=0.000), NG and TC(P=0.000), and FA and TC (P=0.000). In all4groups, there was no statistically significant difference for the slope of spectral HU curve for the surrounding thyroid tissues.CT value:There was statistically significant differences for the CT value between groups PTC and NG(P=0.000), PTC and FA(P=0.000), and FA and TC (P=0.01), and TC and NG(P=0.000).There was no difference for the CT value in lesions between groups NG and FA(P=0.397), and between groups PTC and TC (P=0.976). In all4groups, there was no statistically significant difference for the CT value for the surrounding thyroid tissues.Effective-Z:There was no difference for the Effective-Z in lesions between groups NG and FA(P=0.898), and between groups PTC and TC (P=0.999). There was statistically significant differences for the Effective-Z between groups PTC and NG(P=0.000), PTC and FA(P=0.000), and FA and TC (P=0.000), and TC and NG(P=0.000). In all4groups, there was no statistically significant difference for the Effective-Z for the surrounding thyroid tissues.(2) Spectral CT image analysis of components of nodulesThere were40nodules with hemorrhage confirmed by gross pathological examination,14of them were FA nodules and26nodules were NG. One hundred and seven nodules had cystic degeneration. One hundred and eighty surrounding thyroid tissues (BG, background),104nodules were nodular goiter,46were follicular adenoma,16were papillary carcinoma.Iodine content:There was no difference for the iodine concentration in components between groups HEMO and CD(P=0.074), and between groups PTC and HEMO (P=0.500), and CD and PTC(P=1.000), and NG and FA(P=1.000).There were statistically significant differences for iodine concentrations between groups HEMO and BG(P=0.000), HEMO and NG(P=0.000), HEMO and FA(P=0.000), and CD and BG (P=0.000), CD and NG(P=0.000), CD and FA(P=0.000), BG and PTC(P=0.000), BG and NG(P=0.000), BG and FA(P=0.000), PTC and NG(P=0.000), PTC and FA(P=0.000).Water content:There was statistically significant differences for water concentrations between groups HEMO and other groups (P=0.000). There were statistically significant differences for water concentrations between CD and BG(P=0.000), BG and PTC(P=0.026), and BG and NG(P=0.002), BG and FA(P=0.000). There was no statistically significant difference for the water concentrations between CD and PTC(P=1.000), CD and NG(P=0.087), CD and FA(P=1.000), PTC and NG(P=1.000), PTC and FA(P=1.000), NG and FA(P=0.119).Slope of spectral HU curve:There were statistically significant differences for the slope of spectral HU curve between groups BG and other groups(P=0.000), HEMO and CD(P=0.001), HEMO and NG(P=0.000), HEMO and FA(P=0.000), CD and NG(P=0.000), CD and FA(P=0.000), PTC and NG(P=0.000), PTC and FA(P=0.000).There was no difference for the slope of spectral HU curve between groups HEMO and PTC(P=0.211), and between groups PTC and TC (P=1.000), NG and FA(P=1.000). CT value:There were statistically significant differences for the CT value between groups BG and other groups(P=0.000).There were statistically significant differences for the CT value between groups HEMO and CD(P=0.000), PTC and HEMO(P=0.000), and FA and HEMO(P=0.006), and TC and NG(P=0.000), and CD and FA(P=0.000), PTC and NG(P=0.000), PTC and FA(P=0.010).There was no difference for the CT value in lesions between groups NG and HEMO(P=0.369), and between groups PTC and TC (P=1.000), NG and FA (P=0.711).Effective-Z:There were statistically significant differences for the Effective-Z between groups BG and other groups(P=0.000). There were statistically significant differences for the Effective-Z between HEMO and CD(P=0.000), HEMO and NG(P=0.000), HEMO and FA(P=0.000), HEMO and PTC(P=0.026), PTC and NG(P=0.000), PTC and FA(P=0.000).There was no difference for the Effective-Z in lesions between groups CD and PTC(P=1.000), and between groups NG and FA(P=1.000).(3) Different parameters of spectral CT imaging in differential diagnosis(DD) of different componentsHEMO versus CDThere were high value of CT value and water content for DD between HEMO and CD(AUC>0.90), and no significant value of slope of spectral HU curve, iodine content and Effective-Z for DD between HEMO and CD(AUC<0.50).HEMO versus BGThere was high value of water content were valuable for DD between HEMO and BG(AUC=0.9862), and no significant value of CT value, slope of spectral HU curve, iodine content and Effective-Z for DD between HEMO and CD(AUC<0.50).HEMO versus PTCThere were high value of CT value and water content for DD between HEMO and PTC(AUC=1.000). There were no significant value slope of spectral HU curve, iodine content and Effective-Z for DD between HEMO and PTC(AUC<0.50).HEMO versus NGThere was high value of water content for DD between HEMO and NG(AUC=0.9868). There was lower value of CT value for DD between HEMO and NG(AUC=0.6547),and no significant value slope of spectral HU curve, iodine content and Effective-Z were for DD between HEMO and NG(AUC<0.50).HEMO versus FAThere was high value of water content for DD between HEMO and FA(AUC=0.9995). There was medium value of CT value for DD between HEMO and FA(AUC=0.7304). There were no significant value of slope of spectral HU curve, iodine content and Effective-Z for DD between HEMO and FA(AUC<0.50).CD versus BGThere were high value of CT value, Slope of spectral HU curve, iodine content and Effective-Z for DD between CD and BG(AUC>0.90), and lower value of water content was statistically lower value for DD between CD and BG(0.50<AUC<0.70).CD versus PTCThere were lower value of CT value, water content, iodine content and Effective-Z for DD between CD and PTC(0.50<AUC<0.70). There was no significant value of slope of spectral HU curve for DD between HEMO and NG(AUC<0.50).CD versus NGThere were no significant value of CT value, water content, slope of spectral HU curve, iodine content and Effective-Z for DD between HEMO and NG(AUC<0.50).CD versus FAThere was lower value of water content for DD between CD and FA(0.50<AUC<0.70). There were no significant value of CT value, slope of spectral HU curve, iodine content and Effective-Z for DD between CD and FA(AUC<0.50).PTC versus BGThere was lower value of water content for DD between PTC and BG(0.50<AUC<0.70).There were higher value of CT value, slope of spectral HU curve, iodine content and Effective-Z for DD between PTC and BG(AUC>0.90).NG versus BGThere was lower value of water content for DD between PTC and BG(0.50<AUC<0.70).There were higher value of CT value, slope of spectral HU curve, iodine content and Effective-Z for DD between PTC and BG(AUC>0.90).FA versus BGThere were medium value of CT value, water content, slope of spectral HU curve, iodine content and Effective-Z for DD between PTC and BG(0.70<AUC<0.90).PTC versus NGThere were higher value of slope of spectral HU curve, iodine content and Effective-Z for DD between PTC and NG(AUC>0.90).There were medium value of CT value for DD between PTC and NG(0.70<AUC<0.90), and lower value of water content for DD between PTC and NG(0.50<AUC<0.70).PTC versus FAThere were higher value of slope of spectral HU curve, iodine content and Effective-Z for DD between PTC and FA(AUC>0.90). There were medium value of CT value for DD between PTC and FA(0.70<AUC<0.90), there was lower value of water content for DD between PTC and FA(0.50<AUC<0.70).NG versus FAThere were no significant value of CT value, water content, slope of spectral HU curve, iodine content and Effective-Z for DD between NG and FA(AUC<0.50).Conclusion(1) Spectral CT imaging provided material decomposition images that made the quantitative measurement for the iodine concentration and effective atomic number in the thyroid nodules and tissue possible. Spectral CT imaging may provide us a new way for differential diagnosis for thyroid nodules.(2) It was Spectral CT imaging which could analysis the components of thyroid nodules, such as hemorrhage and cystic degeneration.(3) It was different value that different parameters of spectral CT imaging for DD the components of thyroid nodules. Spectral CT imaging of thyroid noduleObjective:To study the imaging characteristics of thyroid nodules in spectral CT imaging and to investigate the clinical values of spectral CT in differentiating benign and malignant thyroid lesions through imaging thyroid nodules.Material and methods:Fifty-four patients of thyroid nodules underwent CT scans with Gemstone Spectral Imaging (GSI) scan mode before pathologic examinations. Of all patients,24were male (21～72years, mean50.6years),28were female (18-69years, mean47.7years)Spectral CT image analysis:These images were reviewed with the GSI-viewer analysis software for image analysis and data measurement. The measurements included:(Ⅰ) the iodine and water contents of nodules and surrounding thyroid tissues in material decomposition images,(Ⅱ) the characterization of the spectral HU curve (CT number as function of photon energy) for nodules and surrounding thyroid tissues by calculating the slopes of the curves generated from the101sets of monochromatic images. The slope was calculated as the CT value difference at two energy levels (40keV and100keV) divided by the energy difference (60keV) from the spectral HU curve:Slope=(HU40kev-HU100kev)/60;(Ⅲ) the effective atomic number (Effective-Z) of nodules and surrounding thyroid tissues; and (Ⅳ) the CT value of nodules and surrounding thyroid tissues.Results:Pathologic results:67nodules were confirmed in all52patients into4lesion groups:30nodules were nodular goiter,24were follicular adenoma,7were papillary carcinoma and6were thyroid cyst.Spectral imaging analysisCT value:The CT value of CD was lower than other lesions. The CT value of PTC was lower than NG and FA lesions. There was not significant difference of CT value between NG and FA lesions. The CT value of surrounding thyroid tissues of CD was lower that other groups’. There was not significant difference of CT value among other groups of surrounding thyroid tissues.Iodine content:The iodine content of CD was lower than other lesions. The iodine content of PTC was lower than NG and FA lesions. There was not significant difference of iodine content between NG and FA lesions. The iodine content of surrounding thyroid tissues of CD was lower that other groups’. There was not significant difference of iodine content among other groups of surrounding thyroid tissues.Water content:There was no difference for water content in lesions and surrounding thyroid tissues among all groups.Slope of spectral HU curve:The slope of spectral HU curve of CD was lower than other lesions. The slope of spectral HU curve of PTC was lower than NG and FA lesions. There was not significant difference of slope of spectral HU curve between NG and FA lesions. The slope of spectral HU curve of surrounding thyroid tissues of CD was lower than other groups’. There was not significant difference of slope of spectral HU curve among other groups of surrounding thyroid tissues.Effective-Z:There was no significant difference for the Effective-Z in lesions between groups CD and PTC. There was not significant difference of Effective-Z between lesions of NG and FA. The Effective-Z of surrounding thyroid tissues of CD was lower than other groups’. In other groups, there was no significant difference for the Effective-Z for the surrounding thyroid tissues.Conclusion(1)Spectral CT imaging may provide us a new way for differential diagnosis for thyroid nodules.(2) It was which value needs further research to verify the value of spectral CT imaging for DD of thyroid nodules.