Evaluation of 18F-FDG PET/CT in extra-pulmonary tuberculosis: Preliminary results of an observational pilot study

Objectives Extra-pulmonary tuberculosis treatment is difficult to assess and there is a need for new tools. The aim of this observational pilot study is to evaluate the potential role of 18F-FDG PET/CT in the initial staging and treatment evaluation of extra-pulmonary tuberculosis.

Methods 28 patients were included between January 2009 and 2010. 23 had a 18F-FDG PET/CT before treatment and/or during and/or after treatment. All patients will be followed for 18 months after the end of treatment. A control group of 5 patients with previous history of tuberculosis was also included and PET/CT was performed.

Results Three cases of differential diagnosis were excluded of the study. The initial PET for staging showed additional lesions in 8/10 patients compared to conventional imaging. At the end of treatment, 6/11 patients had a negative PET, and 5/11 patients had a positive PET. PET had a significant clinical impact for 3/10 patients at initial staging (guiding biopsy or increase of planned treatment duration), and for 3/16 during follow up (extend or early interruption of the treatment). All PET scans in the control group were negative.

Conclusions 18F-FDG PET has an excellent sensibility for the detection of extra-pulmonary tuberculosis lesion and an excellent negative predictive value. The impact of initial PET staging seems significant. The interest of 18F-FDG PET for the evaluation of response to treatment remains to be assessed and will be correlated with patients’ follow up, in a second phase of this study