Using imaging as a biomarker for asthma

Abstract

There have been significant advancements in the various imaging techniques that are being used in the evaluation of patients with asthma, both from a clinical and research perspective. Imaging characteristics can be used to identify specific asthmatic phenotypes and provide a more detailed understanding of endotypes contributing to the pathophysiology of the disease. Computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) can be used to assess pulmonary structure and function. It has been shown that specific airway and lung density measurements by CT correlate with clinical parameters including severity of disease and pathology but also provide unique phenotypes. Hyperpolarized 129Xe and 3He are gases used as contrast media for MRI that provide measurement of distal lung ventilation reflecting small airway disease. PET scanning can be useful to identify and target lung inflammation in asthma. Furthermore, imaging techniques can serve as a potential biomarker and be used to assess response to therapies, including newer biological treatments and bronchial thermoplasty.

Clinical and lung function outcomes in a cohort of children with severe asthma

“…Previously abnormal spirometry has not been observed as highly discriminatory for different severities of asthma in children [25,29] and our results support this by showing that an abnormal LCI appears more discriminatory (e.g., Table 3: 79% abnormal LCI versus 48% abnormal FEV1% in SAC children). The novel finding of highly abnormal LCI values in children with SA is consistent with recent specialised imaging studies that have described the presence of significant ventilation inhomogeneities with hyperpolarized gas MRI imaging, with the degree of abnormality associated with asthma severity and due to subsegmental narrowing or complete obstruction of small airways [30,31]. Improvements were observed in ACT and lung function parameters before and after BD inhalation, and a reduction in "trapped air" was apparent.…”

Dismantling the pathophysiology of asthma using imaging

“…The topographical distributions of airway narrowing have not been comprehensively quantified from CT images. However, the three-dimensional distributions of airway narrowing and closure, which might represent patterns of inflammation and remodelling might be clinically relevant [24]. Hence, methods to measure the distribution of airway narrowing and closure need to be developed and then correlated with clinical parameters, e.g.…”

“…The physiological information derived from imaging will complement what is contained in spirometry, rather than demonstrating strong correlations to it. Hence, imaging data will potentially characterise patients, to show differences in responses to new and current treatments, prognosis, loss of lung function and other clinically important outcomes beyond what we currently know and how we use type II high biomarkers in clinical practice [24]. For example, ventilation patterns may provide mechanistic insights into treatment responsiveness regardless of inflammatory phenotype; this may be particularly relevant in TABLE 1 Characteristics of computed tomography (CT) and three-dimensional ventilation imaging type II low disease where strategies such as macrolides [5], high fine particle fraction aerosols [25] and bronchial thermoplasty [26][27][28] are used.…”

Advances in asthma in 2017: Mechanisms, biologics, and genetics

“…These are described in several reviews and perspectives. [73][74][75] In addition, there are research reports of newer imaging techniques using quantitative computed tomography (QCT). QCT estimates airway wall remodeling by measuring airway wall thickness percentage and wall area percentage.…”