Last updated on January 2020

Validation of the Analysis Methodology Behind the Use of Quantitative 18F-FDG PET/CT to Assess Lung Inflammation

Brief description of study

The purpose of this study is to validate the method of analysing Positron Emission Tomography (PET) images to assess lung inflammation. Development of novel therapeutic drugs requires a biomarker which is sensitive to the underlying disease and can respond to therapeutic interventions. PET is a potential imaging biomarker which can target molecular and cellular processes. There is currently no standardised method of analysing PET lung data and a lack of validation for the existing techniques.

This study is divided in to two parts. Part A aims to determine the best method to perform 18F-FDG PET/CT lung analysis and how it correlates with cell counts from bronchoalveolar lavage (BAL) samples taken from participants with active pulmonary sarcoidosis.

Part B will compare imaging data from healthy volunteers who have either undergone a Lipopolysaccharide (LPS) challenge (whereby the lung is temporarily inflamed) or saline equivalent to determine whether lung inflammation can be detected by 18F-FDG PET/CT. No medications will be given and patients will not be asked to stop or change existing medication.

Detailed Study Description

Inflammation plays an important role in a myriad of human diseases. Interstitial Lung Diseases (ILDs) are characterised by widespread inflammation and represent a major burden to the health sector. Imaging offers a method of assessing lung inflammation which is non-invasive and may help facilitate the development of new therapeutic drugs. Positron Emission Tomography (PET) is a sensitive imaging modality that uses radioactive material to highlight areas of disease. 18F-FDG is the most common radioactive tracer it accumulates in cells with an increased metabolic rate. Previous studies have shown that inflammatory cells have an increased metabolic rate, thus PET imaging could highlight inflammation. 18F-FDG PET has been used in many studies exploring lung diseases the concentration of tracer is thought to relate to the severity of inflammation.

There is currently no standardised method to analyse FDG-PET scans to assess the concentration of tracer in the lung (and therefore inflammation). A major challenge is providing corrections to ensure that the image only represents tracer in the lung tissue. Such corrections are non-trivial and affect how images are interpreted. A robust validation is needed to ensure that the analysis methods used in FDG-PET images truly represent the degree of lung inflammation.

Part A of this study aims to validate and compare the different analysis methods. Pulmonary sarcoidosis is a disease characterised by widespread lung inflammation. In Part A of the study the investigators will recruit patients with this condition, as well as age and gender matched (wherever possible) healthy volunteers. All Part A participants will receive one dynamic 18F-FDG PET/CT scan. The investigators will assess the uptake of 18FDG from PET images from patients with sarcoidosis versus those taken from healthy volunteers to validate and assess the reliability of the analysis method.

For Part B of the study the investigators will recruit healthy volunteers aged 50 or more. If sarcoidosis patients in Part A are 50 years old or more, the age-matched HV will be recruited in to Part B instead, thus potentially minimising the number of HVs that might need to be recruited in to Part A of the study.

The aims of this research study are:

i) To compare FDG-PET derived tissue inflammation measures against measures of inflammation from BAL samples.

ii) To compare different models of 18F-FDG lung analysis in patients with pulmonary sarcoidosis.

iii) To identify whether FDG PET is sensitive enough to detect a change in inflammation induced in healthy volunteers.

Clinical Study Identifier: NCT03312712

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