Hyperpolarized Gas Magnetic Resonance Lung Imaging in Children and Young Adults

Abstract

Summary The assessment of early pulmonary disease and its severity can be difficult in children as they often cannot perform procedures such as spirometry. Computed tomography provides detailed structural images of the pulmonary parenchyma but its major drawback is that the patient is exposed to ionizing radiation. In this context, MRI is a promising technique for the evaluation of pediatric lung disease, especially when serial imaging is needed. Traditionally, MRI played a small role in evaluating the pulmonary parenchyma. Because of its low proton density, the lungs display low signal intensity on conventional proton-based MRI. Hyperpolarized (HP) gases are inhaled contrast agents with an excellent safety profile and provide high signal within the lung allowing for high temporal and spatial resolution imaging of the lung airspaces. Besides morphological information, HP MR images also offer valuable information about pulmonary physiology. HP gas MRI has already made new contributions to the understanding of pediatric lung diseases and may become a clinically useful tool. In this article, we discuss the HP gas MRI technique, special considerations that need to be considered when imaging children, and the role of MRI in two of the most common chronic pediatric lung diseases, asthma and cystic fibrosis. We also will discuss how HP gas MRI may be used to evaluate normal lung growth and development, and the alterations occurring in chronic lung disease of prematurity and in patients with a congenital diaphragmatic hernia.

A novel, noninvasive assay shows that distal airway oxygen tension is low in cystic fibrosis, but not in primary ciliary dyskinesia

“…Third, ventilation inhomogeneity was strongly suggested by the lack of association between NFO and peripheral oxygen saturation, consistent with classical ventilation/perfusion matching: if NFO reflected homogeneously low distal airway oxygen, systemic arterial saturation should be low. We hypothesize that the partial occlusion of airways, as recently demonstrated by hyperpolarized gas MRI and CT studies results in regional alveolar hypoxia (the O 2 being low because alveolar gas is not readily refreshed during tidal breathing by atmospheric air). With forced expiration, slow emptying of these heterogeneous lung units located behind mucous plugs could account for low mixed F EO2 at RV.…”

Optically polarizedHe3

“…In humans, stunning 3-D data sets of the lung with resolution of a few millimeters can now be acquired in a ten-second breath-hold (Qing et al , 2015). A variety of diseases have been studied, among them cystic fibrosis (Flors et al , 2016; Mentore et al , 2005; Paulin et al , 2015) (see Fig. 22), asthma (Kruger et al , 2014; Tustison et al , 2010), and emphysema (Kirby et al , 2013; Quirk et al , 2011; Spector et al , 2005).…”

Paediatric lung imaging: the times they are a-changin'

“…Alternative MRI techniques could be applied that allow simultaneous perfusion and ventilation imaging without using contrast [49]. Another interesting development to improve resolution is the use of inhaled hyperpolarised gases such as 129 Xe or 3 He, and other inhaled contrast agents to enhance the spatial resolution of lung airspaces [50]. The heterogeneity of ventilation can be assessed and hypoventilated areas can be easily identified.…”