Clinical Application Of ¹¹C-AC And ¹⁸F-FDG PET In Diagnosis Of Pulmonary Tumour

Object iveThe purpose is to study the feasibility of using 11C-acetate(11C-AC) PET for detecting pulmonary tumour and evaluate the clinical effect of 11OAC used as a complement of 18F-FDG.Materials and Methods18 patients suspicious of pulmonary malignancy tumor were collected between 11/2009-04/2011, which includes 5 well-differentiated adenocarcinoma,3 moderately-differentiated adenocarcinoma, 1 Lymphoepithelioma-like carcinoma, all of them were confirmed by histopathologically;1 mycotic granuloma was confirmed by puncture;1 tuberculosis and 1 pulmonary abscess were confirmed by bronchofiberscop; The rest part of them were confirmed by clinical follow-up(>6 months); 18 patients underwent whole-body18F-FDG PET/CT scan and chest 11C-acetate PET/CT scan in one weeks, and 7 of them underwent CT enhancement scanning.For semiquantitative analysis, SUVmax were calculaed by ROI mothed, the diagnoses of malignant pulmonary tumour in PET images were made by two nuclear medicine doctors with a criterion of standardized uptake value (SUVmax≥2.5), a lesion is calssif ied "+" by both visual assessment and a semi-quantitative SUVmax≥2.5, "-" when its activity is same as that in nontumor tissue and SUVmax<2.5. Imaging information were interpreted and compared with the histopathology findings or with clinical follow-up results. The sensitivity, specificity and accuracy of 11C-acetate and 18F-FDG PET/CT scan were calculated. The matching chi-square test was used to analyze the date.Results1. The sensitivity and accuracy of 11C-acetate PET/CT scan in diagnosis of pulmonary well-differentiated adenocarcinoma are obviously higher than that of 18F-FDG PET/CT, the differences between these two groups are statistically significant; (The sensitivity and accuracy of 11C-acetate PET/CT scan is respectively 80% and 77.8%,18F-FDG PET/CT is respectively 40% and 22.2%).2. In ten cases of pulmonary malignancy tumor, one case of Lymphoepithelioma-like carcinoma in lung with increased 18F-FDG metabolism but no abnormal 11C-acetate metabolism, however the biggest metastatic lymphadenopathy in the mediastinum with increased 11C-acetate metabolism but no abnormal 18F-FDG metabolism;one case of single pulmonary metastatic tumor of hepatic carcinoma with slightly increased 11C-acetate metabolism but no abnormal 18F-FDG metabolism.3. In eight cases of pulmonary benign lesions, four tuberculosis with increased 18F-FDG metabolism, three of them with no abnormal 11C-acetate metabolism, but one case of tuberculosis with slightly increased 11C-acetate metabolism; one case of mycotic granuloma with obviously increased 18F-FDG metabolism but no abnormal 11C-acetate metabolism; one case of pulmonary abscess with all circular increased 18F-FDG and 11C-acetate metabolism, and centrally 18F-FDG and 11C-acetate avid defect in this lesion.4. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of 11C-acetate PET/CT scan in diagnosis of metastatic lymphadenopathy are obviously higher than that of 18F-FDG PET/CT, but there are also more false positive results in 11C-acetate PET/CT scan.Conclusion1. Combination of 11C-acetate and 18F-FDG PET/CT scan can useful in increasing sensitivity and accuracy of diagnosis of lung cancer.2. 11C-acetate PET/CT scan shows better detection rate than do18F-FDG PET/CT scan for diagnosis of pulmonary well-differentiated adenocarcinoma, which can complement the insufficient of 18F-FDG PET/CT scan in diagnosis of pulmonary well-differentiated adenocarcinoma, but 18F-FDG can not be replaced by 11C-acetate, the relationship between "C-acetate and 18F-FDG is complementary to each other. 3. Combination of 11C-acetate and 18F-FDG PET/CT scan can more useful in distinguishing benign lesion with malignant occupying lesion in the lung; but when in diagnosis of lung cancer, some benign lesions (tuberculosis, mycotic granuloma and pulmonary abscess) must be distinguished.4. Combination of 11C-acetate and 18F-FDG PET/CT scan can useful in diagnosis of metastatic lymphadenopathy of lung cancer and tumor staging.