TY - JOUR T1 - Characterisation of acinar airspace involvement in patients with asthma using hyperpolarised <sup>3</sup>He magnetic resonance and quantitative computed tomography JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P540 AU - Sherif Gonem AU - Steven Hardy AU - Niels Buhl AU - Ruth Hartley AU - Marcia Soares AU - Richard Kay AU - Rino Costanza AU - Per Gustafsson AU - Christopher Brightling AU - John Owers-Bradley AU - Salman Siddiqui Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P540.abstract N2 - BackgroundThe multiple breath inert gas washout parameter Sacin is thought to be a specific marker of acinar airway involvement. We aimed to utilise 3He diffusion magnetic resonance (3He-MR) and quantitative computed tomography (CT) densitometry to determine the nature of acinar airway involvement in patients with asthma.MethodsThirty-seven patients with asthma and seventeen age-matched healthy controls underwent spirometry, body plethysmography, MBW and 3He-MR, with measurement of the apparent diffusion coefficient (ADC) at short (13ms) and long (1s) timescales. A subset of patients with asthma (n = 27) underwent quantitative CT densitometry.ResultsADC at 1s was significantly higher in patients with asthma and a high Sacin compared to healthy controls (0.024 vs 0.017, p &lt; 0.05), but ADC at 13ms did not differ significantly between the groups. ADC at both 13ms and 1s correlated strongly with the functional residual capacity percent predicted (R = 0.73, p &lt; 0.0001 for ADC at 13ms; R = 0.68, p &lt; 0.001 for ADC at 1s) and with the mean lung density expiratory / inspiratory ratio, a CT marker of expiratory air trapping (R = 0.77, p &lt; 0.0001 for ADC at 13ms; R = 0.72, p &lt; 0.001 for ADC at 1s). CT markers of emphysema did not differ significantly between control and asthma groups.ConclusionAcinar airway involvement in asthma appears to be characterised by distension of the distal airspaces due to expiratory air trapping without evidence of acinar airway remodelling or emphysema. Further work evaluating histopathology of the small airways and computational modelling is required to confirm these observations. ER -