Study On The WHO Classification And Masaoka-Koga Staging Of Thymic Epithelial Tumors By Energy Spectral CT

Objective: To investigate the CT characteristics,spectral CT parameters,single-energy CT value,iodine concentration,and slope of the energy spectrum curve for the diagnosis of WHO classification of TETs and the value of Masaoka-Koga staging.Materials and Method: 1.A total of 109 thymic epithelial tumors diagnosed surgically and pathologically in our hospital were retrospectively collected,including 59 males and 50 females,with an average age of 51.87 ± 10.78 years.The clinical data of patients,pathological data and CT image data were collected.The pathological data were classified by two pathologists according to WHO classification.Staging based on surgery and postoperative pathology;CT features were double-blinded evaluated by two radiologists.Record tumor size,morphology,margin,density,calcification,cystic necrosis,density of the fat layer around the tumor,invasion of surrounding tissues,mediastinal lymph node enlargement,pleural effusion / pericardial effusion,distant metastasis,CT plain scan and enhanced two-phase CT value were measured.2.A total of 38 patients who underwent spectral CT imaging examination were collected,24 males and 14 females,aged 34 to 70 years,with an average age of 52.78 ± 9.11 years,including19 cases of low-risk type,12 cases of high-risk type,and thymic cancer 7 cases.According to Masaoka-koga staging,17 cases were in stage I,9 cases in stage II,6 cases in stage III,and 6cases in stage IV.The 38 patients were divided into 3 groups,non-invasive group(stage I),surrounding fat group(stage II),surrounding structure and distant metastasis group(stage III and IV).The energy spectrum CT image was drawn by a radiologist on the AW 4.6 workstation GSIviewer software to draw a region of interest(ROI)in the area of uniform lesion density,the thoracic aorta at the same level of the lesion,the extracapsular fat of the lesion,and the anterior chest wall fat layer.Single-energy CT values of 40-140 keV and iodine(water)-based substance concentrations in the region of interest were obtained.Calculate the slope of the energy spectrum curve and the normalized iodine concentration.Result: 1.1 109 patients with TETs,57 low-risk thymoma,34 high-risk thymoma,and 18 thymic carcinoma;about 76%(26/34)of patients with high-risk thymoma have rough edges and obscure surrounding fat tissue,about 47% with surrounding tissue invasion,and about 62%(21/34)of patients with mediastinal lymphadenopathy.The difference between the above high-risk thymoma signs and low-risk thymoma patients was statistically significant(P <0.05);Patients with thymic carcinoma have irregular morphology(17/18),irregular edge(16/18),obscurity of fat around the lesion(18/18),associated tissue invasion,pleural effusion(6/18)and distant metastasis2/18),the CT value of the arterial phase is about 66 HU,the enhancement is about 24 HU,The difference between the above signs and low-risk thymoma is statistically significant(P <0.05).1.2109 patients with TETs in the non-invasive group(stage I)37 cases,the surrounding fat group(stage II)32 cases,the surrounding structures and distant metastasis group(stage III and IV)40cases;The diameter of stage Ⅰ lesion is the smallest,about 5.98 cm,and the diameter of stage Ⅲand stage Ⅳ is the largest,about 7.73 cm.Irregular morphology(35/40),irregular edge(35/40),peripheral fat blur(39/40),peripheral blood vessels,pericardial and lung tissue invasion,and lymphadenopathy(27/40)),with pleural and pericardial effusion,The differences between the above signs and non-invasive groups were statistically significant(P <0.05).2.Spectral CT parameters,arterial phase 40KeV-100 keV single energy CT values were statistically significant in low-risk,high-risk thymoma and thymoma(P <0.05),low-risk thymoma,high-risk thymoma and thymoma NIC is 0.15,0.11 and 0.11 respectively,the difference between the three groups is statistically significant(H = 16.154,P = 0.000),the slope of the energy spectrum curve of the three groups is-2.22,-1.75 and-1.57 respectively,the difference between the groups is Statistical significance(H = 8.751,P = 0.013),the slopes of NIC and spectrum curve of low-risk thymoma were higher than those of high-risk thymoma and thymoma.The venous phase 40KeV-140 keV single energy CT value was statistically significant in low-risk,high-risk thymoma and thymic carcinoma(P <0.05),the NIC of low-risk thymoma,high-risk thymoma and thymic carcinoma were 0.47,0.39 and 0.32 respectively,the difference between the three groups is statistically significant(F = 9.330,P = 0.001),the slope of the energy spectrum curve of the three groups is-2.24,-2.01 and-1.60,respectively,and the difference between the groups is statistically significant(F = 5.374,P = 0.009);The NIC and spectral curve slopes of low-risk thymoma are higher than those of high-risk thymoma and thymoma.Among the studied energy spectrum CT parameters,NIC has high specificity and sensitivity.The AUC of the arterial phase is 0.878,and the AUC of the vein phase is 0.816.3.The slopes of the energy spectrum curves of stage Ⅰ lesions and extra-lesion fat are respectively-2.00 and 1.96 in arterial stage,-1.88 and 1.55 in venous stage,and the curves are reversed,the difference is statistically significant(P = 0.000);The slope of the energy spectrumcurve is-1.81 and-1.21 in the arterial phase,-2.20 and-1.47 in the venous phase,and the curves are consistent,and there is no statistically significant difference;The slopes of the curves are-2.05,-1.79 and-1.40 in the arterial phase,-1.67,-1.54 and-1.32 in the venous phase,respectively.The difference was not statistically significant(P> 0.05).Conclusion:1.CT features have different performance in different types and stages.Analysis of CT features before surgery can make preliminary classification and stage diagnosis of TETs.2.Spectral CT parameters the single-energy CT value,the slope of the spectral curve,and the iodine concentration are of pre-evaluation value for TETs before surgery.Especially the standardized iodine concentration is of great value in typing,and can be used for the classification and differential diagnosis of different types of thymoma and thymic cancer before surgery.3.Energy spectrum the spectral curve and slope of CT parameters are valuable to evaluate TETs before operation.In particular,the energy spectrum curve and slope of the fatty tissue around the lesion can be better distinguished between stage Ⅰ and stage Ⅱ lesions before surgery;the energy spectrum curve and slope,iodine concentration of enlarged lymph nodes,intravascular emboli and lesions can be the same Source judgment,and then diagnose the stageⅣ lesions.