Magnetic resonance imaging of small airways in paediatric asthma

Structural and functional alterations of the small airways in patients with
asthma are frequently observed. Small airways disease (SAD) is present in
approximately 50-60% of patients with asthma. Small airways disease is
associated with uncontrolled asthma and future loss of asthma control. It is
therefore important to detect and monitor SAD. Over the past years imaging
methods have been developed to gain knowledge on structure and function of the
(small) airways in the lung. Magnetic resonance imaging (MRI) is a radiation
free imaging modality that can provide both information on lung structure and
function in a single examination. The advantage of MRI is that it is non
ionizing and non-invasive diagnostic tool and therefore suitable to be
performed longitudinally. There are some technical challenges related to MRI in
patients with pulmonary disease: low/weak proton density of lung tissue, long
scanning times and motion artefacts. These artefacts are more prominent in
children due to their inability to lay still for a long time and their high
respiratory and cardiac rate. As a solution to the low proton density
hyperpolarising gases were introduced as contrast agent. However, the use of
polarised gases has several downsides: polarised gases are expensive,
polarisation of these gases is complicated and special training of personnel is
needed to perform MRI with hyperpolarized gases. New MRI protocols, using
proton MRI sequences, were developed to overcome the challenges in MRI imaging
of pulmonary diseases without the use of hyperpolarized gases. In adults these
MRI techniques have been shown to correlate well with computed tomography and
polarizing gases MRI. Proton MRI might therefore be a novel diagnostic tool to
assess small airways disease in asthma and evaluate effect of treatment. This
is especially important for the paediatric population as it potentially could
replace chest computed tomography that requires ionizing radiation.

To investigate whether proton MRI can be used to visualize disease and to study
lung mechanics. This new information might give us new insights into the
pathophysiology of asthma.

This is a prospective cross-sectional feasibility MRI study that will be
conducted at the Erasmus MC - Sophia Children*s Hospital.

The only perceivable risk to the children in this study is that performing an
MRI may induce claustrophobia. All available methods to familiarize the
children and reduce this risk will be applied prior to the MRI. If
claustrophophia occurs, the child will be withdrawn from the MRI machine
immediately, and withdrawn from the study. The data derived from this study has
the potential to improve our understanding of the pathophysiology of asthma in
children which can be helpful to personalize therapy. Furthermore, if it turns
out that proton MRI can be used in the paediatric population to assess small
airway disease and ventilation abnormalities in asthma than this might be used
as a tool to assess asthma control and the effect of treatment. Furthermore
this study may improve the mechanical understanding of the underlying
mechanisms that cause asthma.