Asthma diagnosis and treatment
The variability of regional airflow obstruction within the lungs of patients with asthma: Assessment with hyperpolarized helium-3 magnetic resonance imaging

https://doi.org/10.1016/j.jaci.2006.12.659Get rights and content

Background

It is unknown whether focal changes of airflow obstruction within the lungs of patients with asthma vary or are fixed in location with time or repeated bronchoconstriction. With hyperpolarized helium-3 magnetic resonance (H3HeMR) imaging, the airspaces are depicted and focal areas of airflow obstruction are shown as “ventilation defects.”

Objective

To investigate the regional changes of airflow obstruction with time and repeated bronchoconstriction.

Methods

H3HeMR and spirometry were performed before (pre) and immediately after (post) methacholine challenge in 10 young patients with asthma on 2 days that were 7-476 days (mean, 185.3 ± 37.2 days) apart. Pair-wise image comparisons were performed to determine the change in location of ventilation defects within the lung and their change in size.

Results

When comparing premethacholine versus premethacholine and postmethacholine versus post-methacholine images of the 2 days, 41% ± 10% and 69% ± 5% (P = .017) of defects, respectively, were in the same location, and of those, 69% ± 12% and 43% ± 5% (P = .022), respectively, did not change size. Comparing premethacholine versus postmethacholine images, 58% ± 9% of defects were in the same location on day 1 and 73% ± 7% (P = .088) on day 2. On both days, the percent increase in defect number from premethacholine to postmethacholine was much greater than the percent decrease in spirometric values (P < .001).

Conclusion

Many of the ventilation defects persisted or recurred in the same location with time or repeated bronchoconstriction, suggesting that the regional changes of airflow obstruction are relatively fixed within the lung.

Clinical implications

The findings give new insight into the regional airflow variability within the lungs of patients with asthma.

Section snippets

Methods

Our study involving patients with asthma was designed to enroll only young subjects between 18 and 35 years of age to maximize confidence in the diagnosis of the asthma because older adults may have chronic obstructive pulmonary disease, a condition that can mimic asthma. Patients had to carry the diagnosis of asthma as determined by their primary physician, and they had to have no history of other lung disease or smoking and no contraindications for MRI. Each subject was asked to complete a

Results

The study group consisted of 10 patients, all female, with a mean age of 20.9 years (Table I). That all patients were female was determined by chance because no selection bias occurred in the design of the study with respect to gender. Based on the answers from the NAEPP symptom questionnaire and the spirometry obtained on each study day, 1 subject had mild intermittent, 6 had mild persistent, and 3 had moderate persistent asthma on study day 1, and 3 had mild intermittent, 3 had mild

Discussion

Several important observations were made in this study. First, as would be expected when stimulating bronchoconstriction, most ventilation defects on the postmethacholine images were new as compared with the baseline (premethacholine) images. Most likely, these defects were the result of decreased filling of the airways with the H3He gas from the increased bronchoconstriction induced by the methacholine. What is most interesting, however, is that most defects that were present on the first

References (27)

  • G.G. King et al.

    Airway closure measured by a technegas bolus and SPECT

    Am J Respir Crit Care Med

    (1997)
  • H. Arakawa et al.

    Air trapping on expiratory high-resolution CT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis

    AJR Am J Roentgenol

    (1998)
  • N.T. Tgavalekos et al.

    Indentifying airways responsible for heterogeneous ventilation and mechanical dysfunction in asthma: an image functional modeling approach

    J Appl Physiol

    (2005)
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    Supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health (grant RO1 HL 66479), the Commonwealth of Virginia Technology Research Fund (grant IN2002-01), and Siemens Medical Solutions.

    Disclosure of potential conflict of interest: J. R. Brookeman and J. P Mugler have received grant support from Siemens Medical Solutions. The rest of the authors have declared that they have no conflict of interest.

    Dr Altes is currently affiliated with the Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pa.

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