Using Hyperpolarized129Xe MRI to Quantify the Pulmonary Ventilation Distribution.
Ventilation heterogeneity is impossible to detect with spirometry. Alternatively, pulmonary ventilation can be imaged three-dimensionally using inhaled129Xe magnetic resonance imaging (MRI). To date, such images have been quantified primarily based on ventilation defects. Here, we introduce a robust means to transform129Xe MRI scans such that the underlying ventilation distribution and its heterogeneity can be quantified.



Quantitative129Xe ventilation MRI was conducted in 12 younger (24.7 ± 5.2 years) and 10 older (62.2 ± 7.2 years) healthy individuals, as well as in 9 younger (25.9 ± 6.4 yrs) and 10 older (63.2 ± 6.1 years) asthmatics. The younger healthy population was used to establish a reference ventilation distribution and thresholds for six intensity bins. These bins were used to display and quantify the ventilation defect region (VDR), the low ventilation region (LVR), and the high ventilation region (HVR).



The ventilation distribution in young subjects was roughly Gaussian with a mean and standard deviation of 0.52 ± 0.18, resulting in VDR = 2.1 ± 1.3%, LVR = 15.6 ± 5.4%, and HVR = 17.4 ± 3.1%. Older healthy volunteers exhibited a significantly right-skewed distribution (0.46 ± 0.20, P = 0.034), resulting in significantly increased VDR (7.0 ± 4.8%, P = 0.008) and LVR (24.5 ± 11.5%, P = 0.025). In the asthmatics, VDR and LVR increased in the older population, and HVR was significantly reduced (13.5 ± 4.6% vs 18.9 ± 4.5%, P = 0.009). Quantitative129Xe MRI also revealed altered ventilation heterogeneity in response to albuterol in two asthmatics with normal spirometry.



Quantitative129Xe MRI provides a robust and objective means to display and quantify the pulmonary ventilation distribution, even in subjects who have airway function impairment not appreciated by spirometry.
Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina; Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina.
Mu
M
He
Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina; Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina; Department of Biomedical Engineering, Duke University, Durham, North Carolina; Department of Radiology, Duke University Medical Center, Durham, North Carolina.
Bastiaan
B
Driehuys
Department of Medicine, Duke University Medical Center, 1821 Hillandale Road, Suite 25A, Durham, NC 27710.
Loretta G
LG
Que
Department of Medicine, Duke University Medical Center, 1821 Hillandale Road, Suite 25A, Durham, NC 27710. Electronic address: huang002@mc.duke.edu.
Yuh-Chin T
YT
Huang
D000328:Adult; D000420:Albuterol / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration / Q000187:drug effects; D013147:Spirometry; D014979:Xenon Isotopes; D055815:Young Adult
D001993:Bronchodilator Agents; D014979:Xenon Isotopes; D000420:Albuterol
Asthma; aging; albuterol