Cogent Medicine (Jan 2017)
Pulmonary magnetic resonance imaging biomarkers of lung structure and function in adult survivors of bronchopulmonary dysplasia with COPD
Abstract
Bronchopulmonary dysplasia (BPD) is an emerging risk factor for chronic obstructive pulmonary disease. For BPD survivors, there are no guidelines for the management of lung disease that is often misdiagnosed as asthma. Pulmonary magnetic resonsance imaging (MRI) provides clinically-relevant lung biomarkers of ventilation abnormalities and emphysema. Here our objective was to quantify lung MRI biomarkers in adults with BPD to understand the underlying pathophysiologies responsible for their symptoms and abnormal pulmonary-function. We hypothesized that MRI measurements would be abnormal and reflect emphysema, not airways disease. Patients aged 20–29 year and born ≤32 weeks gestational age were included and those with MRI contraindications were excluded. A 25-year-old female never-smoker born <28 weeks gestation (S1) and a 27-year-old male ex-smoker born ~30 weeks gestation (S2) provided written-informed-consent and underwent pulmonary-function-tests and MRI. Lung abnormalities were quantified using ventilation defect percent (VDP), apparent diffusion coefficients (ADC) and mean linear intercept (Lm). Forced expiratory volume-in 1 sec (S1 = 46%pred/S2 = 33%pred), residual-volume (S1 = 192%pred/S2 = 267%pred) and diffusing-capacity-of-the-lung-for-carbon-monoxide (S1 = 73%pred/S2 = 72%pred) were abnormal. Chest–X-ray and computed tomography (CT) revealed mild structural abnormalities, while MRI VDP (S1 = 6%/S2 = 10%), ADC (S1 = 0.36 cm2/s/S2 = 0.37 cm2/s) and Lm (S1 = 400 μm/S2 = 430 μm) were markedly abnormal with ventilation defects spatially concordant with regions of low MRI signal-intensity and greater Lm, reflecting emphysema and/or gas-trapping. In BPD survivors, MRI biomarkers have the potential to serve as intermediate endpoints and help evaluate therapy.
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