Chest
Volume 130, Issue 4, October 2006, Pages 1055-1062
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Original Research
Evaluation of Asthma With Hyperpolarized Helium-3 MRI: Correlation With Clinical Severity and Spirometry

https://doi.org/10.1378/chest.130.4.1055Get rights and content

Background

Accurate characterization of asthma severity is difficult due to the variability of symptoms. Hyperpolarized helium-3 MRI (H3HeMR) is a new technique in which the airspaces are visualized, depicting regions with airflow obstruction as “ventilation defects.” The objective of this study was to compare the extent of H3HeMR ventilation defects with measures of asthma severity and spirometry.

Methods

Patients with a physician diagnosis of asthma and normal control subjects underwent H3HeMR. For each person, the number and size of ventilation defects were scored and the average number of ventilation defects per slice (VDS) was calculated. The correlations of the imaging findings with measures of asthma severity and spirometry were determined.

Results

There were 58 patients with asthma (mild-intermittent, n = 13; mild-persistent, n = 13; moderate-persistent, n = 20; and severe-persistent, n = 12) and 18 control subjects. Mean ± SE VDS for asthmatics was significantly greater than for control subjects (0.99 ± 0.15 vs 0.26 ± 0.22, p = 0.004). Among asthmatics, VDS was significantly higher for the group with moderate-persistent and severe-persistent disease than for the group with mild-intermittent and mild-persistent disease (1.37 ± 0.24 vs 0.53 ± 0.12, p < 0.001). VDS correlated significantly with FEV1/FVC (r = − 0.51, p = 0.002), forced expiratory flow between 25% and 75% from the beginning of FVC (FEF25–75%) percentage of predicted for height, sex, and race (%predicted) [r = − 0.50, p = 0.001], and FEV1 %predicted (r = − 0.40, p = 0.002), but not with FVC %predicted (r = − 0.26, p = 0.057) and peak expiratory flow %predicted (r = − 0.16, p = 0.231). Many asthmatics had an elevated VDS, but their spirometric indexes, except FEF25%-75%, were normal. Most ventilation defects were < 3 cm in size for all asthmatics. In the group of patients with moderate-to-severe persistant asthma, there were more defects ≥3 cm than in the group with mild-intermittent and mild-persistent disease (p = 0.021).

Conclusions

Regional changes of airflow obstruction in asthmatics depicted by H3HeMR correlate with measures of asthma severity and spirometry.

Section snippets

Methods and Materials

Patients with asthma and age-matched normal control subjects from 16 to 35 years old were enrolled. A maximum age of 35 years was selected to maximize confidence in the diagnosis of asthma since older adults may have COPD, a disease that can mimic asthma. Asthmatics had to carry the diagnosis of having asthma as determined by their primary physician. Further characterization of the disease with bronchodilator, methacholine challenge, or sputum induction was not performed. Patients using inhaled

Results

Seventy-six subjects (58 asthmatics [mild-intermittent, n = 13; mild-persistent, n = 13; moderate-persistent, n = 20; and severe-persistent, n = 12; female/male gender, n = 45/n = 13; age range, 14 to 37 years; mean, 23.4 years]) and 18 healthy volunteers (female/male gender, n = 14/n = 4; age range, 14 to 36 years; mean, 23.6 years) underwent H3HeMR and were able to inhale the gas and hold their breath without difficulty. There were no significant differences in age, height, weight, and

Discussion

In this study, it was found that the number of the ventilation defects in asthmatics correlated with the severity of disease as determined by clinical symptoms and spirometry. However, there were asthmatics, including severe asthmatics, who had large numbers of ventilation defects but normal spirometry results. Others had severe symptoms but few ventilation defects, and had normal or near-normal spirometry results. Clearly in these patients there was discordance between clinical symptoms and

Acknowledgment

We thank Doris Harding, RN, BSN, Joanne C. Gersbach, RN, BSN, Jaime Mata, PhD, John Christopher, RT(R)(MR), and Adam P. Juersivich, BS, for their valuable contributions.

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  • Cited by (0)

    This work was performed at the University of Virginia.

    This work was funded by National Institutes of Health/National Heart, Lung, and Blood Institute (grant RO1 HL66479) and by contributions from the Commonwealth of Virginia Technology Research Fund (grant IN2002–01) and Siemens Medical Solutions.

    Dr. Mugler receives research funding from and has been a consultant for Siemens Medical Solutions. None of the other authors had involvement in any organization with a direct financial, intellectual, or other interest in the subject of this article.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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