MR Images acquired using ultra-short echo time (UTE) sequence of control and LPS-induced COPD lungs, with or without injection of M2 macrophages (a).

<p>From top to bottom: Control, Control/M2, COPD, COPD/M2 groups imaged at (from left to right) −10 min, 2 h, 24 h and 168 h post M2 macrophages injection. Black arrows highlight the inflammatory regions in COPD groups and red arrows highlight the presence of void signal dots related to higher macrophage infiltrations in the inflammatory lungs. Signal-to-noise (SNR) attenuation of lung parenchyma, during the 7 days follow-up study, measured before and after intravenous injection of either free SPIO, SPIO labeled M1 or M2 macrophages in control and COPD mice (b). Error bars are standard deviation of triplicates. Representative regions of interest (ROI) which were drawn around apparent vascular structures (filled in red) and subtracted from the map to retain lung parenchyma (c).