Functional Assessment of Cystic Fibrosis Lung Disease

Abstract

Cystic fibrosis is the most common early lethal genetic disorder in white populations. Defective epithelial ion transport results in highly viscous airway secretions, which provide the basis for chronic inflammation from birth. Newborn screening is implemented in most Western countries, allowing for early treatment in subclinical stage. Imaging plays an increasing role in disease monitoring, when lung function using spirometry is normal. Initially, scoring systems have been used to quantify the heterogeneous structural lung changes in CF, now being supplemented by functional techniques, based on lung pathophysiology. Functional techniques using computed tomography (CT) and magnetic resonance imaging (MRI) can be subdivided into non-contrast and contrast-dependent techniques. The earlier use physiological changes in lung signal to compute images of lung ventilation and perfusion. The latter exploit exogenous injectable and volatile contrast materials in order to induce signal changes related to lung function. Several functional techniques such as paired inspiratory-expiratory CT and 4D perfusion MRI have proven clinically meaningful and robust, and are being developed into imaging endpoint for noninvasive monitoring of disease activity. Initial data available documents their sensitivity to disease progression despite stable lung function and to detect therapy response in small prospective cohorts.