Pediatric Functional Lung Imaging: A Scoping Review

Functional lung imaging enables pulmonary parameters, including ventilation, perfusion, gas exchange, and biomechanics, to be mapped and quantified noninvasively throughout the lungs. Pulmonary function testing is generally more difficult to perform in a child in comparison to an adult, and so pulmonary functional imaging has the potential to significantly benefit pediatric cohorts, giving clinicians an additional tool in assessing and managing pediatric lung disease. This scoping review aims to (1) identify current and emerging functional lung imaging techniques that have been investigated in pediatric cohorts and (2) describe how they have been compared to pulmonary function tests. PubMed, EMBASE, and CINAHL were searched for studies comparing pulmonary functional imaging techniques with pulmonary function testing in pediatric cohorts ≤ 18 years old. A total of 54 studies were included. Techniques were grouped into magnetic resonance imaging (MRI), computed tomography (CT), electrical impedance tomography (EIT), X-ray, and nuclear medicine methods. Most studies compared spirometry, multiple breath nitrogen washout, or both. At present, hyperpolarized gas MRI studies are the most widely investigated modality in children. However, despite the multiple different modalities investigated, there are no methods that have entered standard clinical pediatric use. Further research into functional lung imaging in pediatrics is required to provide validation, standardization, and establishment of normal values prior to implementation of these modalities into routine clinical care.