Hyperpolarized 129Xenon Magnetic Resonance Imaging to Quantify Regional Ventilation Differences in Mild to Moderate Asthma: A Prospective Comparison Between Semiautomated Ventilation Defect Percentage Calculation and Pulmonary Function Tests.
The aim of this study was to investigate ventilation in mild to moderate asthmatic patients and age-matched controls using hyperpolarized (HP) Xenon magnetic resonance imaging (MRI) and correlate findings with pulmonary function tests (PFTs).



This single-center, Health Insurance Portability and Accountability Act-compliant prospective study was approved by our institutional review board. Thirty subjects (10 young asthmatic patients, 26 ± 6 years; 3 males, 7 females; 10 older asthmatic patients, 64 ± 6 years; 3 males, 7 females; 10 healthy controls) were enrolled. After repeated PFTs 1 week apart, the subjects underwent 2 MRI scans within 10 minutes, inhaling 1-L volumes containing 0.5 to 1 L of Xe. Xe ventilation signal was quantified by linear binning, from which the ventilation defect percentage (VDP) was derived. Differences in VDP among subgroups and variability with age were evaluated using 1-tailed t tests. Correlation of VDP with PFTs was tested using Pearson correlation coefficient. Reproducibility of VDP was assessed using Bland-Altman plots, linear regression (R), intraclass correlation coefficient, and concordance correlation coefficient.



Ventilation defect percentage was significantly higher in young asthmatic patients versus young healthy subjects (8.4% ± 3.2% vs 5.6% ± 1.7%, P = 0.031), but not in older asthmatic patients versus age-matched controls (16.8% ± 10.3% vs 11.6% ± 6.6%, P = 0.13). Ventilation defect percentage was found to increase significantly with age (healthy, P = 0.05; asthmatic patients, P = 0.033). Ventilation defect percentage was highly reproducible (R = 0.976; intraclass correlation coefficient, 0.977; concordance correlation coefficient, 0.976) and significantly correlated with FEV1% (r = -0.42, P = 0.025), FEF25%-75% (r = -0.45, P = 0.019), FEV1/FVC (r = -0.71, P < 0.0001), FeNO (r = 0.69, P < 0.0001), and RV/TLC (r = 0.51, P = 0.0067). Bland-Altman analysis showed a bias for VDP of -0.88 ± 1.52 (FEV1%, -0.33 ± 7.18).



Xenon MRI is able to depict airway obstructions in mild to moderate asthma and significantly correlates with PFTs.
From the *Department of Radiology, and †Center for In Vivo Microscopy, Duke University Medical Center; ‡Department of Electrical and Computer Engineering, Duke University; §Department of Pulmonary and Critical Care Medicine, Duke University Medical Center; ∥Department of Biomedical Engineering, and ¶Medical Physics Graduate Program, Duke University, Durham, NC.
Lukas
L
Ebner
Mu
M
He
Rohan S
RS
Virgincar
Timothy
T
Heacock
Suryanarayanan S
SS
Kaushik
Matthew S
MS
Freemann
H Page
HP
McAdams
Monica
M
Kraft
Bastiaan
B
Driehuys
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012123:Pulmonary Ventilation / Q000502:physiology*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D014979:Xenon Isotopes; D055815:Young Adult
D014979:Xenon Isotopes
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