Detection of early sub-clinical lung disease in children with cystic fibrosis by lung ventilation imaging with hyperpolarized gas MRI

Hyperpolarised 3He ventilation-MRI, anatomical lung MRI, lung clearance index (LCI), low-dose CT and spirometry were performed on 19 children (6–16 years) with clinically stable mild cystic fibrosis (CF) (FEV1>−1.96), and 10 controls. All controls had normal spirometry, MRI and LCI. Ventilation-MRI was the most sensitive method of detecting abnormalities, present in 89% of patients with CF, compared with CT abnormalities in 68%, LCI 47% and conventional MRI 22%. Ventilation defects were present in the absence of CT abnormalities and in patients with normal physiology, including LCI. Ventilation-MRI is thus feasible in young children, highly sensitive and provides additional information about lung structure–function relationships

Supine posture changes lung volumes and increases ventilation heterogeneity in cystic fibrosis

INTRODUCTION: Lung Clearance Index (LCI) is recognised as an early marker of cystic fibrosis (CF) lung disease. The effect of posture on LCI however is important when considering longitudinal measurements from infancy and when comparing LCI to imaging studies. METHODS: 35 children with CF and 28 healthy controls (HC) were assessed. Multiple breath washout (MBW) was performed both sitting and supine in triplicate and analysed for LCI, Scond, Sacin, and lung volumes. These values were also corrected for the Fowler dead-space to create 'alveolar' indices. RESULTS: From sitting to supine there was a significant increase in LCI and a significant decrease in FRC for both CF and HC (p<0.01). LCI, when adjusted to estimate 'alveolar' LCI (LCIalv), increased the magnitude of change with posture for both LCIalv and FRCalv in both groups, with a greater effect of change in lung volume in HC compared with children with CF. The % change in LCIalv for all subjects correlated significantly with lung volume % changes, most notably tidal volume/functional residual capacity (Vtalv/FRCalv (r = 0.54,p<0.001)). CONCLUSION: There is a significant increase in LCI from sitting to supine, which we believe to be in part due to changes in lung volume and also increasing ventilation heterogeneity related to posture. This may have implications in longitudinal measurements from infancy to older childhood and for studies comparing supine imaging methods to LCI

Demographics and baseline lung function data for healthy control and cystic fibrosis subjects.

<p>Demographics and baseline lung function data for healthy control and cystic fibrosis subjects.</p

A comparison of the % change in ‘alveolar’ multiple breath washout outcomes between healthy controls and cystic fibrosis subjects.

<p>A comparison of the % change in ‘alveolar’ multiple breath washout outcomes between healthy controls and cystic fibrosis subjects.</p

Sitting to supine comparison of multiple breath washout (MBW) outcomes for both cystic fibrosis (CF) and healthy control (HC) subjects.

<p>Sitting to supine comparison of multiple breath washout (MBW) outcomes for both cystic fibrosis (CF) and healthy control (HC) subjects.</p

LCI and FRC change from sitting to supine in both cystic fibrosis (CF) and healthy controls (HC).

<p>There is a significant increase in LCI from sitting to supine in both CF and HC and a significant decrease in FRC.</p

Scatter plot with Spearman correlation of the % change in the ‘alveolar’ Vt_alv/FRC_alv with the % change in ‘alveolar’ LCI_alv for both cystic fibrosis (CF) and healthy control (HC) subjects combined.

<p>The Spearman correlation suggests a positive relationship between increasing % change Vt_alv/FRC_alv and increasing % change LCI_alv.</p