Noninvasive Monitoring of the Response of Human Lungs to Low-Dose Lipopolysaccharide Inhalation Challenge Using MRI

Background: Development of antiinflammatory drugs for lung diseases demands novel methods for noninvasive assessment of inflammatory processes in the lung. Purpose: To investigate the feasibility of hyperpolarized 129Xe MRI, 1H T1 time mapping, and dynamic contrast-enhanced (DCE) perfusion MRI for monitoring the response of human lungs to low-dose inhaled lipopolysaccharide (LPS) challenge compared to inflammatory cell counts from induced-sputum analysis. Study Type: Prospective feasibility study. Population: Ten healthy volunteers underwent MRI before and 6 hours after inhaled LPS challenge with subsequent induced-sputum collection. Field Strength/Sequences: 1.5T/hyperpolarized 129Xe MRI: Interleaved multiecho imaging of dissolved and gas phase, ventilation imaging, dissolved-phase spectroscopy, and chemical shift saturation recovery spectroscopy. 1H MRI: Inversion recovery fast low-angle shot imaging for T1 mapping, time-resolved angiography with stochastic trajectori es for DCE MRI. Assessment: Dissolved-phase ratios of 129Xe in red blood cells (RBC), tissue/plasma (TP) and gas phase (GP), ventilation defect percentage, septal wall thickness, surface-to-volume ratio, capillary transit time, lineshape parameters in dissolved-phase spectroscopy, 1H T1 time, blood volume, flow, and mean transit time were determined and compared to cell counts. Statistical Tests: Wilcoxon signed-rank test, Pearson correlation.