Title

The difference in ventilation heterogeneity between asthmatic and healthy subjects quantified using hyperpolarized 3He MRI

UMMS Affiliation

Department of Radiology

Date

11-22-2008

Document Type

Article

Subjects

Adult; Anti-Asthmatic Agents; Asthma; Bronchoconstrictor Agents; Female; Helium; Humans; Magnetic Resonance Imaging; Male; Methacholine Chloride; Middle Aged; Pilot Projects; Pulmonary Ventilation; Respiratory Function Tests; Young Adult

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

In this pilot study, algorithms for quantitatively evaluating the distribution and heterogeneity of human ventilation imaged with hyperpolarized (HP) (3)He MRI were developed for the goal of examining structure-function relationships within the asthmatic lung. Ten asthmatic and six healthy human subjects were imaged with HP (3)He MRI before bronchial challenge (pre-MCh), after bronchial challenge (post-MCh), and after a series of deep inspirations (post-DI) following challenge. The acquired images were rigidly coregistered. Local voxel fractional ventilation was computed by setting the sum of the pixel intensity within the lung region in each image to 1 liter of inhaled (3)He mixture. Local ventilation heterogeneity was quantified by computing regional signal coefficient of variation. Voxel fractional ventilation histograms and overall heterogeneity scores were then calculated. Asthmatic subjects had a higher ventilation heterogeneity to begin with (P = 0.025). A methacholine challenge elevated ventilation heterogeneity for all subjects (difference: P = 0.08). After a DI postchallenge, this heterogeneity reversed substantially toward the baseline state for healthy subjects but only minimally in asthmatic subjects. This difference was significant in absolute quantity (difference: P = 0.007) as well as relative to the initial increase (difference: P = 0.03). These findings suggest that constriction heterogeneity is not a characteristic unique to asthmatic airway trees but rather a behavior intrinsic to all airway trees when provoked. Once ventilation heterogeneity is established, it is the lack of reversal following DIs that distinguishes asthmatics from non-asthmatics.

Rights and Permissions

Citation: J Appl Physiol. 2009 Mar;106(3):813-22. Epub 2008 Nov 20. Link to article on publisher's site

DOI of Published Version

10.1152/japplphysiol.01133.2007

Related Resources

Link to Article in PubMed

Journal Title

Journal of applied physiology (Bethesda, Md. : 1985)

PubMed ID

19023025