‘To CT or not to CT? That is the question’: outcome surrogates for surveillance in childhood cystic fibrosis
- Cardio-thoracic Imaging Unit, Great Ormond Street Hospital for Children NHS Trust, London, UK
- Correspondence to Dr Catherine Owens, Cardio-thoracic Imaging Unit, Great Ormond Street Hospital, London WC1N 3JH, UK;
The benefit of the increasing utility of CT has been promoted as a potential long-term outcome surrogate for monitoring patients with cystic fibrosis (CF), and is recognised as a crucial part of CF research.1 The study by the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) on the use of thin-section CT highlights the sensitivity of this imaging modality in providing insight into the early development of CF lung disease. The factors associated with the development and progression of structural lung disease in infants and preschool children diagnosed by the newborn CF screening programme2 are described.
The argument for the increasing use of annual CT of the thorax as an outcome surrogate for measuring and monitoring the progression of lung disease in patients with CF is the ability of CT to detect subtle, salient lung parenchymal changes, as opposed to using conventional plain chest radiography or spirometry. However, lung clearance index (LCI), being more effective than spirometry, has been found to be as sensitive as high-resolution CT (HRCT) in detecting early lung abnormalities in infants, and together they compliment each other in providing markers for early CF lung disease in children.3 Application of LCI is suitable in all age groups, which suggests its potential as an outcome measure to monitor progression of disease throughout the life of patients with CF, and thus help reduce the cumulative radiation dose.4 5 It is suggested that, in clinical practice, LCI should be the first line of investigation to assess the presence of CF lung disease, and that HRCT should only be performed when LCI is normal. This is because a normal result on either measure is not predictive of a normal result in the other.3 This approach would reduce unnecessary CT imaging and the ensuing associated …