| Objective: This study is to assess the feasibility and clinical values of multiparameterquantitative measurement solitary pulmonary nodules (SPN) by Gemstone SpectralImaging(GSI) high-definition computed tomography and find the characteristics of spectralHU curve, iodine concentration of SPN with different pathologic types, by which we canprovide new morphological and functional information for the diagnosis of SPN andpromote the sensitivity and specificity for distinguishing SPN.Materials And Methods:86patients with SPN were examined by a single-sourcedual-energy Spectral CT (sDECT, GE Discovery CT750HD，HDCT；GE Healthcare,Milwaukee Wis) during the arterial phase (AP) and venous phase (VP). The images of SPNin venous phase were evaluated by Gemstone Spectral Imaging, a post-processing softwarefrom Gemstone Spectral CT. Iodine-based material-decomposition images, Water-basedmaterial-decomposition images and101sets of monochromatic images with photon energiesfrom40to140keV were reconstructed. The CT values of SPN in11different sequences ofmonochromatic images from40keV to140keV with an interval of10keV, iodineconcentrations, water concentrations in SPN were measured. The HU curve slope (λHU) inthe target SPN was calculated respectively. Results were correlated with pathologicalfindings. Ratio of λHU, iodine and water concentrations were studied among differentpathologic types. The results were analyzed with ANOVA or Rank sun test.Results: Of the86patients who met the inclusion criteria, we excluded23patients becauseof the absence of adequate follow-up or definite pathologic diagnosis (n=16),6cases ofmetastatic tumor,3cases of hamartoma and the last one was pleomorphic adenoma.Therefore,63patients (30men,33women; mean age,53.67years) were ultimately includedin the present analysis. All of the63SPN`s pathologic types were identified by operation,needle biopsy or follow-up, among which there were12cases of lung squamous cellcarcinoma (SCCL),21cases of lung adenocarcinoma(AC),10cases of small cell lungcarcinoma(SCLC),5cases of lung adenosquamous carcinoma(ASC),10cases oftuberculosis and5cases of inflammatory nodules. On the same monochromatic keV level,there were significant difference in CT values of low monochromatic level betweenmalignancies and tuberculosis, between adenocarcinoma and squamous cell carcinoma,between adenocarcinoma and small cell lung carcinoma, between adenocarcinoma andtuberculosis, between squamous cell carcinoma and tuberculosis, between inflammatorynodules and tuberculosis. The λHU and iodine concentrations of SCLC, AC, SCCL, ASC,tuberculosis and inflammatory nodules were (-1.93±0.37),(-2.52±0.53),(-1.95±0.57),(-1.93±0.48),(-1.59±0.50),(-2.73±0.79) and (1.633±0.308),(2.136±0.452),(1.644±0.483),(1.641±0.407),(1.350±0.480),(2.299±0.657) mg/mL, respectively. The λHU and iodineconcentrations were significantly different between adenocarcinoma and squamous cell carcinoma, between adenocarcinoma and small cell lung carcinoma, betweenadenocarcinoma and tuberculosis, between squamous cell carcinoma and inflammatorynodules, between inflammatory nodules and tuberculosis. There was no difference in waterconcentrations among these groups.The correlation analysis between the average iodineconcentrations and the CT numbers in70keV of each group showed there was positivecorrelation in all the six groups, and there was high correlation in groups of small cell lungcarcinoma,tuberculosis and inflammatory nodules. There were also some difference inEffective-Z among six groups.Conclusion: Spectral CT imaging was of great importance to evaluate SPN, especially todistinguish benign and malignant SPN by CT values in the monochromatic images on lowenergy levels, quantitative iodine-based material decomposition and HU curve of spectralCT imaging. Spectral CT imaging provides a quantitative approach for distinguishing SPNand can establish the relationship between radiologic imaging and postoperative pathology. |
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