Hyperpolarized ³He magnetic resonance imaging: preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease.
OBJECTIVE
Emphysema and small airway obstruction are the pathological hallmarks of chronic obstructive pulmonary disease (COPD). The aim of this pilot study in a small group of chronic obstructive pulmonary disease (COPD) patients was to quantify hyperpolarized helium-3 ((3)He) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for (3)He MRI in detecting the lung structural and functional COPD phenotypes.


METHODS
We evaluated 20 ex-smokers with stage I (n=1), stage II (n=9) and stage III COPD (n=10). All subjects underwent same-day plethysmography, spirometry, (1)H MRI and hyperpolarized (3)He MRI at 3.0T. (3)He ventilation defect percent (VDP) was generated from (3)He static ventilation images and (1)H thoracic images and the (3)He apparent diffusion coefficient (ADC) was derived from diffusion-weighted MRI.


RESULTS
Based on the relative contribution of normalized ADC and VDP, there was evidence of a predominant (3)He MRI measurement in seven patients (n=3 mainly ventilation defects or VDP dominant (VD), n=4 mainly increased ADC or ADC dominant (AD)). Analysis of variance (ANOVA) showed significantly lower ADC for subjects with predominantly elevated VDP (p=0.02 compared to subjects with predominantly elevated ADC; p=0.008 compared to mixed group) and significantly decreased VDP for subjects with predominantly elevated ADC (p=0.003, compared to mixed group).


CONCLUSIONS
In this small pilot study, a preliminary analysis shows the potential for (3)He MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies.
Mathew
Lindsay
L
Imaging Research Laboratories, Robarts Research Institute, London, Canada. lmathew@imaging.robarts.ca
Kirby
Miranda
M
Etemad-Rezai
Roya
R
Wheatley
Andrew
A
McCormack
David G
DG
Parraga
Grace
G
D000368:Aged; D000704:Analysis of Variance; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006371:Helium; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D010641:Phenotype; D010865:Pilot Projects; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology*; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects
D006371:Helium