Evaluation of Somatostatin Receptor Imaging Using PET/MRI as a Novel Approach to Detecting Pathology in Pulmonary TB

Evaluation of Somatostatin Receptor Imaging Using PET/MRI as a Novel Approach to Detecting Pathology in Pulmonary TB

Evaluation of Somatostatin Receptor Imaging Using PET/MRI as a Novel Approach to Detecting Pathology in Pulmonary TB

Imaging using 68Ga-DOTANOC PET (positron emission tomography) has the potential to detect granulomas in pulmonary tuberculosis, leading to previously unexplored indications for this PET tracer, including identification of subclinical disease in latently infected individuals. This study aims to assess the ability of 68Ga-DOTANOC PET/MRI to detect pulmonary lesions in individuals with active pulmonary tuberculosis.

Granulomas, the hallmark of tuberculosis (TB) infection, have an increased density of somatostatin receptors. Somatostatin analog PET tracers, such as 68Ga-DOTANOC, may be able to identify these pulmonary granulomas. Although currently used for other medical indications, 68Ga-DOTANOC PET scanning has not previously been used to detect TB lesions. This is a pilot study which aims to assess the ability of 68Ga-DOTANOC PET/MRI to detect pulmonary lesions in individuals with active pulmonary tuberculosis. The 68Ga-DOTANOC PET scan and 'standard' 18F-fludeoxyglucose (FDG) PET scan will be compared to enable analysis of differences in uptake between these tracers in terms of number, size and distribution of lesions. Demonstrating the clinical utility of 68Ga-DOTANOC in active pulmonary TB is necessary prior to using this PET tracer to further explore other potential uses in TB such as identifying individuals with latent TB who are at risk of progressing to active TB, measuring therapeutic response to TB treatment and identifying extrapulmonary lesions.

Different uptake values between and within the pulmonary lesions will be measured and compared between the 2 tracers.

The net tracer uptake rate for 68Ga-DOTANOC (Ki) will be derived from kinetic analysis in combination with dynamic imaging and the relationship between SUV and Ki.

Inclusion Criteria: Age 21 years and above Willing to comply with the study visits and procedures Willing and able to provide written informed consent Clinical diagnosis of pulmonary TB with characteristic symptoms and compatible X-ray findings plus microbiological confirmation with one or more of (i) Acid fast bacilli (AFB) smear-positive or (ii) molecular test positive or (iii) TB culture positive Not on TB treatment or have completed less than 28 days of TB treatment Exclusion Criteria: Diabetes that is, in the judgment of the investigator, so poorly controlled that it would prevent adequate PET scanning Cardiac pacemaker, aneurysm clip or other metallic implant considered unsafe for MRI Known chronic kidney disease Occupation involving substantial exposure to radiation Malignancy requiring chemotherapy or radiation Women who are currently pregnant or breastfeeding