Abstract:
Patients who complete a standard course of anti-tuberculous treatment (ATT) for
pulmonary tuberculosis and are declared cured according to the current standard
of care commonly have residual metabolic activity (RMA) in their lungs on
fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography
(FDG PER/CT) imaging. RMA seen in this setting has been shown to be associated with
relapse of tuberculosis. The routine clinical use of FDG PET/CT imaging for treatment
response assessment in tuberculosis is hindered by cost and availability. CT is a more
readily available imaging modality. We sought to determine the association between CT
features suggestive of active tuberculosis and RMA on FDG PET/CT obtained in patients
who completed a standard course of ATT for pulmonary tuberculosis. We prospectively
recruited patients who completed a standard course of ATT and declared cured based
on negative sputum culture. All patients had FDG PET/CT within 2 weeks of completing
ATT. We determined the presence of RMA on FDG PET images. Among the various
lung changes seen on CT, we considered the presence of lung nodule, consolidation,
micronodules in tree-in-bud pattern, FDG-avid chest nodes, and pleural effusion as
suggestive of active tuberculosis. We determine the association between the presence
of RMA on FDG PET and the CT features of active tuberculosis. We include 75 patients
with a mean age of 36.09 ± 10.49 years. Forty-one patients (54.67%) had RMA on
their FDG PET/CT while 34 patients (45.33%) achieved complete metabolic response to
ATT. There was a significant association between four of the five CT features of active
disease, p < 0.05 in all cases. Pleural effusion (seen in two patients) was the only CT feature of active disease without a significant association with the presence of RMA. This
suggests that CT may be used in lieu of FDG PET/CT for treatment response assessment
of pulmonary tuberculosis.
