Regional pulmonary response to a methacholine challenge using hyperpolarized 3He magnetic resonance imaging
Article first published online: 25 OCT 2012
© 2012 The Authors. Respirology © 2012 Asian Pacific Society of Respirology
Volume 17, Issue 8, pages 1237–1246, November 2012
How to Cite
COSTELLA, S., KIRBY, M., MAKSYM, G. N., MCCORMACK, D. G., PATERSON, N. A. M. and PARRAGA, G. (2012), Regional pulmonary response to a methacholine challenge using hyperpolarized 3He magnetic resonance imaging. Respirology, 17: 1237–1246. doi: 10.1111/j.1440-1843.2012.02250.x
- Issue published online: 25 OCT 2012
- Article first published online: 25 OCT 2012
- Accepted manuscript online: 14 AUG 2012 04:00AM EST
- Received 28 February 2012; Invited to revise 11 April 2012, 30 May 2012; Revised 4 May 2012, 31 May 2012; accepted 1 June 2012 (Associate Editor: Robin Taylor)
- apparent diffusion coefficient;
- magnetic resonance imaging;
Background and objective: Spirometry is insensitive to small airway abnormalities in asthma. Our objective was to evaluate regional lung structure and function using hyperpolarized 3He magnetic resonance imaging (MRI) before, during and after a methacholine challenge (MCh).
Methods: Twenty-five asthmatics (mean age = 34 ± 11 years) and eight healthy volunteers (HV) (mean age = 33 ± 11 years) underwent spirometry, plethysmography and hyperpolarized 3He MRI prior to a MCh. MRI was repeated following the MCh and again 25 min after salbutamol administration. 3He MRI gas distribution was quantified using semiautomated segmentation of the ventilation defect percent (VDP). Tissue microstructure was measured using the 3He apparent diffusion coefficient (ADC). Analysis of variance with repeated measures was used to evaluate changes at each time point as well as to determine interactions between regions of interest (ROI) and subject group. Pearson's correlations were performed to evaluate associations between 3He MRI measurements and established clinical measures.
Results: In asthmatics, but not HV, whole-lung ADC was increased post-MCh (P < 0.01). In asthmatics only, ADC was increased post-MCh in posterior ROI (P < 0.01) and all ROI in the superior-inferior direction (P < 0.01). VDP was increased in posterior and inferior ROI (P < 0.001). There was a correlation between VDP and specific airway resistance (r = 0.74, P < 0.0001), dyspnoea score (r = 0.66, P < 0.01) and fractional exhaled nitric oxide (r = 0.45, P < 0.05).
Conclusions: We evaluated the regional pulmonary response to methacholine and salbutamol using 3He MRI and showed heterogeneous VDP and ADC consistent with bronchoconstriction and gas trapping, respectively, post-MCh. These regional alterations resolved post-salbutamol.