PET Imaging In Patients With Pulmonary Tuberculosis

Tuberculosis (TB) disease affects 10 million people worldwide every year and is the leading cause of death from an infectious disease. New TB biomarkers are required for a variety of applications, including detection of sub-clinical disease for early intervention to prevent disease progression; detection of new active TB cases; and for monitoring of treatment response in clinical practice or in clinical trials of new TB therapies. A good option could be PET imaging. 

Positron emission tomography (PET) imaging in combination with structural imaging may have value as a biomarker for detecting subclinical TB disease, an active disease where the diagnosis is problematical, and an outcome measure in clinical trials. The standard PET ligand, [18F]fluoro-2-deoxy-2-D-glucose (FDG), accumulates in cells with high levels of glucose metabolism and is a non-specific marker of inflammation. There may be additional value in using alternatives to FDG if these have higher sensitivity or specificity for TB-infected cells.

Somatostatin analog PET imaging radiotracers are useful in evaluating neuro-endocrine tumors and other cancers’ cells that have upregulated cell surface somatostatin receptors (SSTRs). These receptors are also overexpressed on activated macrophages, which are a key cell population infected by TB, residing within granulomas. Over-expression of somatostatin receptors in granulomas within lymph nodes of TB patients have been visualized using in vitro autoradiography, and SSTR-positive cells have been detected using immunohistochemistry analysis in granulomas from multiple granulomatous conditions including pulmonary nodules in TB.

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