[68Ga]Ga-FAPI-04 Positron Emission Tomography/Computed Tomography: A Promising Imaging Tool for the Diagnosis of Disseminated Tuberculosis, with a Caveat in Treatment Response Evaluation

A 56-year-old woman presented with 1-month history of dyspnea, unintentional weight loss, and right upper quadrant abdominal pain. High-resolution computed tomography of the thorax demonstrated multiple centrilobular nodules and a large consolidation in the left lung. Abdominal ultrasonography showed altered hepatic parenchymal texture and mild splenomegaly. Disseminated tuberculosis (TB) was subsequently confirmed by sputum Xpert and liver biopsy. Whole-body fibroblast activation protein (FAP) targeted imaging using Gallium-68–labelled FAP inhibitor, [68Ga]Ga-FAPI-04 positron emission tomography/computed tomography (PET/CT), demonstrated intense tracer uptake in the left lung consolidation, heterogeneous uptake throughout the hepatic parenchyma, and diffuse splenic uptake. After completion of 4 months of first-line antitubercular therapy with weight-based combined fixed dose regimen of rifampicin, isoniazid, pyrazinamide, and ethambutol, she reported symptomatic relief of dyspnea and abdominal pain, with improving appetite and weight gain. A repeat imaging showed resolution of the lung consolidation but persistent tracer uptake in the liver and spleen. This case highlights the ability of [68Ga]Ga-FAPI-04 PET/CT to depict extensive hepatosplenic involvement in disseminated TB and illustrates the potential challenge in interpreting persistent tracer uptake during treatment, which may represent ongoing inflammation or postinfectious fibrosis.