129Xe-MRI can quantify abnormal gas-exchange by defining thresholds derived from voxel-level gas-exchange distributions in healthy subjects. Previous studies assumed a constant healthy distribution independent of age. By fitting to Box-Cox Power Exponential distributions, normal distributions cannot be assumed, and the distributions vary significantly with age. The effect size of age (5-69 years) on healthy ventilation, barrier-uptake, and red-blood cell to barrier (ratio) signal distributions were 14 to 57%. Thus, age and distribution shape should be considered when defining reference distributions for gas-exchange metrics. By accounting for age-dependent variations, the reference distributions abnormal thresholds could be narrowed.
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