Current methods to evaluate lung tuberculosis include chest radiography and computed tomography. Nuclear medicine imaging techniques are performed after administration of specific radiopharmaceuticals that accumulate in the organs of interest. Alterations of glucose metabolism can be observed by positron-emission tomography, using 18F-fluorodeoxyglucose (18F-FDG PET). These findings are present in the neoplasms, but also in inflammatory and infectious diseases. Tuberculosis is a granulomatous disease caused by Mycobacterium tuberculosis, that uses glucose as an energy source. Purpose: The study of glucose metabolism in lung tuberculosis by PET and the comparison of this results to CT scan findings. Material and methods: Twenty patients with active lung tuberculosis were evaluated. The 18F-FDG PET and computed tomography were performed in all patients, after the diagnosis and until 30 days of treatment. Results of both methods were compared. Results: All patients showed 18F-FDG positive uptake. On the computed tomography, all patients showed signs compatible with tuberculosis. The sensitivity of both methods was of 100%. There was significant concordance between the two methods (K = 0.27). Conclusions: The study concludes that glucose metabolism is modified in lung tuberculosis. There was concordance in the anatomic changes observed on computed tomography.

New non-invasive methods have been developed to detect lung malignancies. One of them is positron emission tomography (PET) using 18F 2-deoxy-D-glucose (FDG) as a radiotracer. Objective: Evaluate the FDG-PET results performed through a hybrid coincidence-gamma camera in patients with pleuropulmonary infectious diseases or lung tumors. Material and methods: Fifteen patients were evaluated, and divided into: group I - five patients with active lung tuberculosis, and group II - ten patients with possible pleuropulmonary neoplasia. Doses of 185 MBq of FDG were given intravenously, and scans were performed with a two-headed ADAC Vertex Plus camera. Results: In group I all scans were positive. In group II after thoracotomy in nine patients and mediastinoscopy in one, the following diagnoses were observed: two adenocarcinomas, two granulomas, one small cell carcinoma, one large cell carcinoma, one hamartoma, one rounded atelectasis, one mesothelioma, and one antracosis. The scans were positive in six patients (five malignant neoplasias and one granuloma) and negative in the other four cases. Conclusion: The FDG-PET performed through a hybrid camera produces images of quality that permit identification of active infectious process. FDG-PET in association with clinical and radiological exams can differentiate malignant from benign lung neoplasias.

Keywords: emission-computed tomography, lung neoplasms, lung diseases

Tuberculosis is a disease of high incidence and prevalence in Brazil. Imaging methods can reveal signs suggestive of tuberculosis activity or sequelae. Chest radiographs can reveal active lung tuberculosis through consolidations, cavitations, interstitial patterns (nodular and reticulo-nodular), mediastinal or hilar lymphadenopathy and pleural effusions. Images compatible with the active disease, such as centrilobular nodules segmentarily distributed, thick-walled cavities, thickened bronchial or bronchiolar walls, bronchiectasis and lymphadenopathy can be observed by computerized tomography. Thin-walled cavities, traction bronchiectasis, parenchymal bands, emphysema and mosaic pattern are signs suggestive of inactive disease. Gallium-67 citrate scyntigraphy is a complementary method useful in the detection of infectious diseases, including tuberculosis, especially in immunocompromised patients. Inhalation / perfusion analyses are used in the pre-operative assessment of patients carrying tuberculosis sequelaes and multiresistant tuberculosis. Positron emission tomography with fluorine-18 labeled deoxyglucose allows the detection of the inflammatory process that takes place during the active stage of tuberculosis and may persist, not so intense, after specific treatment is over. Imaging methods are valuable tools to be used in the diagnosis and follow up of pulmonary tuberculosis.

Keywords: Tuberculosis. Radiography. Computed tomography. Scintigraphy. Emission-computed tomography.

Pulmonary artery sarcomas are rare, difficult-to-diagnose tumors that frequently mimic chronic pulmonary thromboembolism. We report the cases of two female patients with clinical signs of dyspnea and lung masses associated with pulmonary artery filling defects on chest CT angiography. We performed 18F-fluorodeoxyglucose positron emission tomography, which revealed increased radiotracer uptake in those lesions. Pulmonary artery sarcoma was subsequently confirmed by anatomopathological examination. We emphasize the importance of this type of tomography as a noninvasive method for the diagnosis of these tumors.

Keywords: Positron-emission tomography; Pulmonary artery; Pulmonary embolism; Leiomyosarcoma; Histiocytoma, malignant fibrous.