| Solitary pulmonary nodule(solitary pulmonary nodule,SPN)refers to single and round nodule with a maximum diameter of not more than 30 mm,surrounded by normal lung tissue,not associated with atelectasis,pneumonia.With the application of chest CT,more and more solitary pulmonary nodules have been found.More than 150,000 patients with SPN were reported annually in the United States by radiographic X-ray or CT examination.Most of the lesions in the SPN were benign,but about 35%of the SPNs were primary malignant tumors and some are metastatic tumors.Because the lesion is of small size and little function,has no specific clinical symptoms and with atypical imaging features,it is easily misdiagnosed or delayed diagnosis.Therefore,to diagnose the SPN earlier is essential to improve the survival rate of patients,and it's a challenge for clinicians.CT is a widely used and most valuable method for diagnosing SPN.High resolution CT(HRCT)can clearly show the interface and the internal structure of nodules and other morphological signs to improve the accuracy of the diagnosis of nodules.However,due to a considerable part of the SPN lack of characteristic CT performance and benign and malignant nodules had overlapped CT morphologic features,the diagnostic accuracy of CT for SPN still needs to be further improved.Invasive examination such as fiberoptic bronchoscopy,thoracic needle aspiration biopsy,video-assisted thoracoscopy and thoracotomy can provide pathological diagnosis.But these methods are invasive examinations,and the accuracy of these methods is relevant with nodule size and nodule location.For small nodules and deep nodules,the diagnostic effectiveness of bronchoscopy is limited and the cost is huge and related to the incidence of disease.Therefore,to find a noninvasive method with high diagnostic efficiency is very important to the management of SPN.Positron emission tomography/CT(PET/CT)can not only show the CT morphological features of nodule but also provide metabolic information at the molecular level to evaluate anatomical and functional changes in SPN.Its application value in SPN has been widely recognized.However,there are few studies reported the diagnostic value of-18F-FDG PET/CT in SPNs with different diameters.This study compared the diagnostic value of 18F-FDG PET/CT in SPNs with different diameter range to verifify the usefulness of PET/CT in SPN patients with different nodule size and it's helpful for the staging of lung cancer.Lung cancers with different pathologic types have various biological characteristics.However,there are few studies focus on the difference of SUVmax and the correlation of 18F-FDG uptake with the lesion size of lung cancer with different pathological types.We compared the difference of 18F-FDG uptake in four major pathological types of lung cancer and analyze the relationship between nodule size and 18F-FDG uptake to further understand the biological characteristics of different pathological types of lung cancer.The mathematical model is based on the objective evaluation by method of statistics with good accuracy and reproducibility.Most of the previously reported SPN mathematical predictive models were established on the basis of the clinical characteristics and morphological features of nodule,such as the widely cited Mayo model and the VA model.But these two models have obvious limitations to diagnose SPN in non-smokers.Therefore,we expect to provide a reliable and accurate SPN diagnostic method by establishing a new mathematical model which can be commonly used.As far as we know,there are few models use the metabolic parameter of 18F-FDG uptake as predictor and the value of this kind of model in diagnosis of SPN is still unconfirmed.Therefore,the other purpose of this study is to establish a new mathematical model that includes the clinical features of nodules,the clinical data of SPN patients and the glucose metabolism of nodules as parameters to further clarifies the predictive efficiency of each clinical risk factor for lung cancer and to improve the diagnostic performance of PET for SPN.Part 1:Diagnostic value of 18F-FDG PET/CT in solitary pulmonary nodulesThis study aimed to evaluate the diagnostic value of PET/CT for SPNs with different diameters,for malignant nodules in different pathological types and for those nodules with SUVmax(maximum standardized uptake value)less than 2.5.The diagnostic value of delayed imaging in patients with SPN with SUVmax<2.5 was also evaluated.Final diagnoses were made according to pathological results or clinical follow-up.Clinical data including the gender,the age of patients and diameter of nodules were collected to determine whether they are differed in benign and malignant nodules.SPNs were divided into three groups according to the size of nodule:Group A consisted of 28 patients with diameters not more than 10mm,Group B consisted of 78 patients with diameters greater than 10mm and not more than 20mm,Group C consisted of 76 patients with diameters greater than 20mm and not more than 30mm.The diagnostic value of PET/CT in each group was evaluated.The cutoff value of SUVmax for different groups was set according to the ROC curves.The malignant nodules were grouped according to different pathological types.The difference of SUVmax between different types and the relationship between SUVmax and nodule size in each type were compared.The early SUVmax(expressed in SUVmax1),delayed SUVmax(expressed in SUVmax2)and RImax(maximum retention index)of the nodules for SUVmax less than 2.5 were evaluated by the delayed imaging.The diagnostic value of delayed imaging and PET/CT imaging in SPNs with SUVmax less than 2.5 were evaluated.Part 2:18F-FDG PET/CT mathematical prediction model for the diagnosis of solitary pulmonary nodulesThe mathematical model is an objective evaluation method based on a statistics,so we aim to provide a more reliable and reproducibile method to diagnose SPN by establishing a more accurate and extensive mathematical model.In this study,19 clinical features including SUVmax calculated by PET/CT,the clinical features such as the age,gender,smoking history,smoking cessation time,tumor history,family history of cancer of SPN patients and CT morpholigic features were used as risk factors.Logistic mathematical model was established by univariate and multivariate logistic regression analysis.The mathematical model established by logistic regression analysis was:y = ex/(1+ex),x =-7.363 +(0.079 × age)+(1.900 × lobulation)+(1.024× vascular convergence)+(1.530 × pleural retraction)+(0.359 × SUVmax).The diagnostic capabilities of the mathematical model,the Mayo model,the VA model?PET/CT and PET for differentiating malignant from benign SPNs were calculated respectively and the areas under the ROC curves(AUC)were compared. |
PDF Full Text Request