Hyperpolarized (3)He ventilation defects used to predict pulmonary exacerbations in mild to moderate chronic obstructive pulmonary disease.

PURPOSE

To evaluate the predictive value of imaging and clinical and physiological measurements of chronic obstructive pulmonary disease ( COPD chronic obstructive pulmonary disease ) in patients monitored for more than 5 years for pulmonary exacerbations that required hospitalization.

MATERIALS AND METHODS

Exacerbations requiring hospitalization were monitored over 5 years in 91 subjects who provided written informed consent. Study was local research ethics board and Health Canada approved and HIPAA compliant. Subjects with COPD chronic obstructive pulmonary disease underwent spirometry, plethysmography, diffusing capacity of carbon monoxide, St George's Respiratory Questionnaire, 6-minute walk test, and imaging. Computed tomographic (CT) wall area and relative area with attenuation values less than -950 HU ( RA950 relative area with attenuation values less than -950 HU ), helium 3 ((3)He) magnetic resonance (MR) imaging ventilation defect percentage ( VDP ventilation defect percentage ), and apparent diffusion coefficient were generated. Zero-inflated Poisson model was used to compare number of hospitalizations with lung function and imaging measurements.

RESULTS

Twenty-four subjects were hospitalized 58 times and had significantly worse forced expiratory volume in 1 second ( FEV1 forced expiratory volume in 1 second ) (P < .0001), CT RA950 relative area with attenuation values less than -950 HU (P = .02), and (3)He VDP ventilation defect percentage (P < .0001) than values in 67 subjects who were not hospitalized. In mild to moderate COPD chronic obstructive pulmonary disease , nine hospitalized subjects had significantly worse FEV1 forced expiratory volume in 1 second (P = .02) and (3)He VDP ventilation defect percentage (P = .02) than values in 52 subjects who were not hospitalized. (3)He VDP ventilation defect percentage was quantitatively related to CT airway morphology (r = 0.26, P = .01) and quantitatively (r = 0.61, P < .0001) and spatially related to emphysema; this spatial relationship was significantly greater for hospitalized patients with COPD chronic obstructive pulmonary disease than unhospitalized patients (P = .0006). For all subjects, number of prior hospitalizations (P < .0001), 6-minute walk test distance (P < .0001), CT RA950 relative area with attenuation values less than -950 HU (P = .03), and (3)He VDP ventilation defect percentage (P = .002) were significantly related to number of hospitalizations. For 61 subjects with mild to moderate COPD chronic obstructive pulmonary disease , only (3)He VDP ventilation defect percentage was significantly associated with COPD chronic obstructive pulmonary disease exacerbations (P = .01).

CONCLUSION

(3)He MR imaging VDP ventilation defect percentage represents a mixed airways-emphysema phenotype and helps identify subjects with mild to moderate COPD chronic obstructive pulmonary disease who are at risk for exacerbation that requires hospitalization.