^{18 F-FDG PET / CT Imaging In Diagnosis Of Mouth Before Surgery In Patients With Non-small Cell Lung Cancer}

Background:Lymph node staging determines the treatment strategy for NSCLC. PET/CT has become an essential examination for the staging of NSCLC,and it is widely used for the staging of NSCLC providing useful anatomical and metabolic information to characterize tumoral lesions and to detect unsuspected metastatic disease. PET/CT has become an essential examination for preoperative assessment in patients with NSCLC.Objective:1) To evaluate the diagnostic Sensitivity, specificity, negative predictive value,positive predictive value and accuracy of PET/CT in preoperative intrathoracic lymph node staging in patients with NSCLC. To analysis the causes of the false-negative and false-positive results.2) To evaluate the accuracy of PET/CT on preoperative lymph node staging of NSCLC.3) To explore the risk factors for malignant lymph nodes in non-small cell lung cancer.Method:Consecutive patients with pathologically proven NSCLC who underwent staging using PET/CT6weeks prior to lung resection from July2008to Febrary2012were evaluated retrospectively. Lymph node staging was pathologically confirmed on tissue specimens obtained at thoracotomy. The sensitivity, specificity, positive predictive value,negative predictive value and accuracy of PET/CT in the assessment of intrathoracic lymph node involvement were determined by using histological results as reference standard.Logistic regression was used to define the causes of the false-negative and false-positive results,and to determine the factors affecting the presence or absence of nodal metastases. Statistical significance was set to a value ofp<0.05.Results:A total of101patients with pathologically proven NSCLCs were enrolled in this study.59.4%males, with a mean age of61±11(31-79) years.A total of528lymph stations were evaluated in101patients. Nodes were positive for malignancy in101(19.2%) out of528lymph stations. The mean interval between PET/CT and surgery was14.9±10.2days (range:1-42days).1) The overall sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT for detecting metastatic lymph nodes were51.5%、95.8%、74.3%、89.3%and87.3%, while the corresponding data by CT were45.5%、87.1%、45.5%、87.1%、79.2%. PET/CT confers significantly higher specificity, positive predictive value and accuracy than CT scan in detecting nodal metastasis.2) The false positive rate and false negative rate of PET/CT for detecting metastatic lymph nodes were4.2%and48.5%, while the corresponding data by CT were12.9%and54.5%, PET/CT confers significantly lower false positive rate than CT scan.3) PET/CT staged the disease correctly in73out of101patients (72.3%),comparing with64.4%of CT scan.4) Multivariate analysis demonstrated that SUVmax of primary tumor≥4.0,lymph node size≥1cm,low differentiation and adenocarcinoma were significant factors for predicting the presence of nodal metastasis.Conclusions:1) The specificity and negative predictive value of PET/CT for mediastinal lymph node staging in patients with NSCLC are high,patients with negative PET/CT can be operated without invasive mediastinal lymph node staging. On the other hand, the sensitivity and positive predictive value are low, when positive mediastinal lymph nodes are detected, invasive mediastinal lymph node staging should be performed. PET/CT confers significantly higher specificity, positive predictive value and accuracy than CT scan in detecting nodal metastasis.2) The false-positive results are significately associated with lymph node size, the presence or absence of combined infective disorders. The false-negative results aresignificately associated with lymph node size.3) PET/CT confers significantly higher accuracy than CT scan in lymph node staging.4) SUVmax of primary tumor≥4.0,lymph node size>3cm,low differentiation and adenocarcinoma are significant factors for predicting the presence or absence of nodal metastasis. Patients with nodal metastasis risk factors need to perform further examination.