18F-FDG PET/CT in tuberculosis: a single hospital experience

1742 Objectives To evaluate the role of FDG PET/CT in tuberculosis (TB) in different clinical settings: in patients with probable or confirmed TB, in the evaluation of therapeutic response (during and after treatment) and in patients with a previous history of TB infection. Methods We retrospectively analyzed our nuclear medicine data from the beginning of 2014 to the end of 2015 with the keywords TB and FDG PET/CT. We found 73 consecutive patients who performed 89 PET/CT (Gemini, Big Bore TOF, Philips). 51 male (70%), 22 female (30%), median age 45 years (range 19-82). Inpatients were 62 and 58 came from Infectious Disease Department, thirty of them were placed on respiratory isolation by clinicians. In the cohort of patients there were 7 transplantations, 5 dialysis patients and 5 HIV cases; 43 patients were born in endemic countries. FDG PET/TC scans were performed in 40 patients with suspect of probable TB, in 22 patients with a past history of TB, in 11 patients to taste the response to therapy. The maximum standardised uptake value (SUVmax) of the most FDG avid lesions and the pattern of abnormal findings in both modalities (PET and CT) were recorded. Results Using a cut-off value of SUVmax of 1.3, PET/CT correctly identified 10 (14%) true negative patients (TN). Among the remaining 63 patients with abnormal FDG findings and SUVmax >1.3, there were 44 (60%) cases of true TB (TP) while in 19 (26%) patients TB were ruled out after biopsies and microbiological cultures (four cases of tumors and 15 cases of infections and inflammations). In patients with confirmed TB, PET/TC identified active pulmonary TB in 12 cases (27%), extra-pulmonary TB in 10 (23%) patients (mainly lymph nodes, visceral and spinal TB) and both sites in 22 (50%) patients. In patients with previous TB (n. 22), metabolic imaging depicted 17 patients with active TB (SUVmax range 3.7 to 13.5), the remaining 5 patients had negative scans and were true negative (TN). In the group of patients with probable TB (n.40), there were 21 cases of active TB (SUVmax range 1.6 to 20.1) : pulmonary TB (n.5), extra-pulmonary (n.5) , both (n.12). In 19 patients with abnormal FDG findings, PET/CT was useful to guide biopsy. After therapy (n.8), four patients were TN with SUVmax Conclusions FDG PET/CT was useful to distinguish active from inactive TB in patients with a positive history of this infection. It was a valid tool in the evaluation of therapeutic response, especially in patients at high risk of complication (transplant or dialysis patients, HIV). FDG PET/CT could not distinguish between tuberculosis and malignancies but it guided biopsy and could assist early diagnosis. PET/CT provided a more detailed information to clinicians in the overall evaluation of these patients.