Study Of The Evaluation Of ～(18)F-FDG PET/CT In The Differentiating Diagnosis Of Solitary Pulmonary Nodule

Background and purpose: The lung cancer is one of the most familiar malignant tumors of international community currently. In many developed countries, the lung cancer rows the first among malignant tumors of the male, and the second or third among the female. It has already become the main cause of death of malignant tumors in these countries. There are about 600,000 peoples die of lung cancer in China every year, and the number will raise gradually. Owing to smoking cigarette and the influence of the air pollution, it was estimated that the number of lung cancer in our country will over 1000,000 to the year 2025.At that time the incidence of lung cancer in China will become the most highest in the world. The mortality of the lung cancer is nearly equal to the incidence, so it's one of the most malignant tumors. The earlier the operation is performed, the higher the cure rate is. The stage IA has the best five years survival rate which can be above 70%. The stage III A is about 25%, and stage IIIB and IV is lower than 5%. So it's the key for the lung cancer to be checkup, diagnosed and treated in early stage in order to promote cure rate.The solitary pulmonary nodule is familiar in clinic, which is difficulty to be identified as malignant or benign. Most malignant solitary pulmonary nodules are primary lung cancers, the minority are metastatic tumors from other organs. The benign solitary pulmonary nodules mainly include tuberculoma, inflammatory pseudotumor and hamartoma. In recent years with the advance of the idea about health and the gradual universality of the physical checkup, the incidence of solitary pulmonary nodule rises gradually. According to the collecting data, there are about 170,000 new solitary pulmonary nodules be examined in the world every year. Therefore, if there is a kind of diagnosis method with high accuracy to differentiate a solitary pulmonary nodule to be a benign one or malignant one, the clinical surgeries will feel relaxed in work.The old non-invasive examine methods used in solitary pulmonary nodule includes common X-ray chest film, CT etc., their accuracies are lower. Invasive examine methods such as fine needle aspiration biopsy, lung or pleural biopsy and thoracotomy have the advantage of higher accuracy, but they will take some disadvantages, for example, they are more painful and more dangerous in a high risk of accident. And they are not fit for all patients. In recent years along with use of new equipments and techniques such as the high resolution CT, PET and PET/CT etc, the accuracy of diagnosis of solitary pulmonary nodule with non-invasive examine method before operation are promoted greatly, which has reduced the quantity of thoracotomy in patients with a benign pulmonary nodule.The positron emission tomography and computer tomography (PET/CT) is a kind of new technique and new equipment invented in the last few years. It blends PET function pictures with the dissection information that the CT provide accurately in order to attain the aim of promoting the accuracy of diagnosis.¹⁸F-FDG has been extensively applied in the imaging of PET/CT as imaging agent for the following purpose,for example differentiating diagnosis of a solitary pulmonary nodule or staging the lung cancer and oesophagus cancer before the operation is performed correctly. In fact huge success is obtained. This research's aim is to study the value of ¹⁸F-FDG PET/CT in the differentiating diagnosis of solitary pulmonary nodule and applied foreground.Method: 76 cases with solitary pulmonary nodules between October 2004 and December 2006 at Shandong provincial hospital are retrospective analyzed. All the cases have the CT, the ¹⁸F-FDG PET(call PET as follows) and ¹⁸F-FDG PET/CT(call PET/CT as follows) images to learn data and all are confirmed finally by pathology obtained by operation or needle aspiration biopsy. In the study pathology is the gold standard of diagnosis. Calculate the diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of CT, PET and PET/CT respectively. The statistic difference in sensitivity, specificity and accuracy of CT,PET and PET/CT was compared by x² test.Result: Of all 76 cases of solitary pulmonary nodules, 57 cases were correctly diagnosed with CT alone, 61 cases with PET alone, 70 cases with PET/CT. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of CT,PET and PET/CT were 80.4%, 66.7%, 75.0%, 78.7%, 70.0%;82.6%, 76.7%, 80.3%, 84.4%, 74.2%;95.7%, 86.7%, 92.1%, 91.7%, 92.9% respectively. There was a significant difference between CT and PET/CT in accuracy (x² =8.091;P=0.004)and sensitivity (x² =5.059; P=0.024), but there was no significant difference in specificity (x² =3.354; P=0.067). At the same time, There was a significant difference between PET and PET/CT in accuracy (x² =4.475; P=0.034) and sensitivity (x² =4.039; P=0.044), but there was no significant difference in specificity (x² =1.002; P=0.317).Conclusion: PET/CT has higher accuracy and sensitivity than CT and PET when diagnose a solitary pulmonary nodule. At present it is the best non-invasive examine method to differentiate a solitary pulmonary nodule is malignant or benign. But there are no significant difference in specificity between CT PET and PET/CT, a further improvement are necessary. The high accuracy of PET/CT can reduce the quantity of fine needle aspiration biopsy and thoracotomy in patients with a benign pulmonary nodule. It can reduce the patient's pain and save the cost, so the PET/CT should have a better application in future.