49 The use of positron emission tomography (PET) in adult patients with cystic fibrosis (CF)

Abstract

PET using 18F-FDG is widely used in the diagnosis, monitoring and staging of malignancy. Tissue FDG uptake is determined by metabolic activity and can identify neutrophilic inflammation and in stable patients, enhanced uptake is often absent. We report our experience of PET in three patients with CF and how results helped support clinical decision making. A 38 year old post lung transplant patient presented with recurrent right sided chest pain, fever and elevated CRP. Despite extensive investigation by the transplant unit, no focal abnormality was identified and symptoms failed to resolve with iv antibiotics. PET revealed FDG avidity in the right middle lobe and she required a right middle and upper lobectomy. A 30 year old patient chronically colonised with P. aeruginosa and M. abscessus, developed aggressive lung disease and despite regular intravenous, nebulised and oral antibiotics, continued to decline with a fall in lung function, pyrexia and malaise. PET revealed marked FDP avidity within multiple lung nodules. Treatment was continued with the addition of interferon gamma. Despite a worsening CXR, PET showed significant improvement. These results have helped guide therapy. A 36 year old presented with persistent respiratory symptoms. Sputum was repeatedly culture positive for M. abscessus. There were no clinical or radiological evidence of deterioration. PET was undertaken to exclude active focal inflammation. The scan was unremarkable and a less intense regimen was instituted. Sputum has since been persistently negative for M. abscessus. PET is a useful adjunct to conventional investigations and in selected individuals can be helpful in guiding clinical management.