68Ga-citrate PET/CT in tuberculosis: a pilot study

Tuberculosis remains an important cause of morbidity and mortality worldwide, the diagnosis, staging and treatment response evaluation of which remains sub-optimal. We evaluated PET/CT imaging with a novel tracer, 68Ga-citrate, in this setting.Thirteen patients with tuberculosis underwent PET/CT imaging with 68Ga-citrate. Tuberculosis was diagnosed with bacteriological or histopathology studies (N.=8) or based on a combination of clinical data, biochemistry and imaging (N.=5). PET images were analyzed qualitatively and semi-quantitatively and compared to CT findings.All 13 patients demonstrated abnormal tracer accumulation in the lungs or extra-pulmonary or both. 68Ga-citrate accumulated in every lung lesion noted on CT in six cases (46%). In seven cases (54%) some of the lung lesions noted on CT were not 68Ga-citrate avid, which is suggestive of non-active tuberculous lesions. Ten patients (77%) demonstrated extrapulmonary involvement, which included various lymph node groups, skeletal lesions, pleural-, splenic- and gastrointestinal tract involvement. Detection of extra-pulmonary involvement was higher on PET compared to CT (more lesions detected) in eight cases (80%).68Ga-citrate PET accumulates in both pulmonary and extra-pulmonary tuberculous lesions and may provide a way of distinguishing active from inactive lesions for treatment response evaluation. 68Ga-citrate PET may be superior to CT in the detection of extrapulmonary involvement.