Positron Emission Tomography With Multiple Tracers In Pulmonary Abnormalities

ObjectiveTo assess the value of positron emission tomography (PET) with multiple tracers in diagnosis of pulmonary abnormalities and the features of different pulmonary abnormalities in PET. MethodsFrom October 1996 to April 2006, out of the 1532 patients with pulmonary nodules or pulmonary masses confirmed by CT scans received PET scans, 628 patients fitted our research qualification. 594 patients received ¹⁸F-fluorodeoxyglucose(FDG)- PET, 55 patients received ¹¹C-choline(CH)-PET, 16 patients received ¹¹C- methionine (MET)-PET, 15 patients received ¹⁸F-fluorothymidine(FLT)-PET, 4 patients received ¹¹C-acetate-PET. PET data was analyzed by visual method and semiquantitative method with standard uptake value(SUV). Diagnoses were compared with pathology and follow-up survey. ResultsIn FDG-PET, 271 primary lung cancer, 99 pulmonary metastasis, 25 pulmonary tuberculosis, 10 pneumonia, 7 inflammatory pseudotumor, 5 cryptococcosis, 2 sarcoidosis, 2 pulmonary distomiasis, 1 bronchiectasis were visible with SUV equal to or above 2.5; 32 bronchial alveolar carcinoma, 31 adenocarcinoma, 2 squamous cell carcinoma, 14 pulmonary metastases, 93 benign pulmonary abnormality were no more FDG-avid than mediastinum and with SUV lower than 2.5. For identification of pulmonary neoplasms beyond 1.0 centimeter with FDG-PET, the sensitivity, specificity and accuracy were 82.4%(370/449), 64.1%(93/145) and 77.9%(463/594). In 375 patients with solitary pulmonary nodules(SPNs) from 1.0 to 3.0 centimeters, the sensitivity, specificity andaccuracy were 73.7%(188/255), 71.7%(86/120) and 73.1%(274/375). SUV was correlated with tumor size and pathologic type but not correlated with age or gender. SUV of FDG-avid benign pulmonary abnormalities had no relationship with pathologic type or size or age or gender.In CH-PET, 32 malignant neoplasms, 2 pulmonary tuberculosis, 3 inflammatory abnomalities, 1 bronchogenic cyst were CH avid. 4 bronchial alveolar carcinoma, 1 pulmonary metastasis of kidney clear cell carcinoma, 1 pulmonary metastasis of colon cancer, 11 benign abnormalities were not CH avid. For identification of pulmonary neoplasms with CH-PET, the sensitivity, specificity and accuracy were 84.2%(32/38), 64.7%(11/17) and 78.2%(43/55). In cancer cases, SUV has not correlation with tumor size or age or gender. SUV of squamous cell carcinoma was different from that of adenocarcinoma.In MET-PET, 6 primary lung cancer, 1 pulmonary tuberculosis, 2 inflammatory pseudotumor showed MET avid. 1 bronchial alveolar carcinoma and 6 benign abnormalities were normal MET uptake. For identification of pulmonary neoplasms with MET-PET, the sensitivity, specificity and accuracy were 6/7, 6/9 and 75.0%(12/16). In cancer cases, SUV has not correlation with tumor size or age.In FLT-PET, 9 primary lung cancer, 2 inflammatory pseudotumor, 2 pulmonary tuberculosis showed FLT avid. FLT-PET failed to reveal 1 bronchial alveolar carcinoma and 1 adenocarcinoma. For identification of pulmonary neoplasms with FLT-PET, the sensitivity, specificity and accuracy were 81.8% (9/11), 0/4 and 60.0%(9/15). In cancer cases, SUV has not correlation with tumor size or age.In Acetate-PET, only 1 case of pulmonary metastasis of kidney clear cell carcinoma showed acetate avid. 2 squamous cell carcinoma and 1 adenocarcinoma appear nothing abnormal in Acetate-PET.In the 56 cases who received two tracer-PETs, CH-PET, MET-PET, FLT-PET and Acetate-PET have sensitivity no higher than FDG-PET. Even withFLT-PET, all have specificity no higher than FDG-PET. ConclusionsFDG-PET displays features of glucose metabolism in pulmonary abnormalities and shows great value in diagnosis. In diagnosing pulmonary abnormalities above 1.0 centimeter, FDG-PET has the sensitivity and specificity and accuracy of 82.4% and 64.1% and 77.9%. In patients with solitary pulmonary nodules(SPNs) from 1.0 to 3.0 centimeters, the sensitivity and specificity and accuracy were 73.7% and 71.7% and 73.1%.Because FDG is not tumor specific tracer, even with limitation of PET technology and equipment, FDG-PET has false positive and false negative cases in diagnosing pulmonary abnormalities.CH, MET, FLT, Acetate display metabolism of pulmonary abnormalities specifically. Like FDG, these tracers are valuable in diagnosing but also lead to false positive and false negative. And their sensitivity is not superior to that of FDG FDG-PET is the first choice in diagnosing pulmonary abnormalities.PET's combined tracers can complement each other, but can not elevate diagnosing accuracy prominently. It is of great challenge to search more specific tracers.To establish the correct diagnosis, PET must be combined with clinical data. If pulmonary abnormalities are PET positive, unless antibiotic or antituberculosis therapy is effective, operation should be taken. If pulmonary abnormalities are PET negative, clinical appearance such as CT results should be considered as to make treatments of operation or follow-up survey.