Dynamic contrast-enhanced magnetic resonance imaging of the lung reveals important pathobiology in idiopathic pulmonary fibrosis.

Introduction: Evidence suggests that abnormalities occur in the lung microvasculature in idiopathic pulmonary fibrosis (IPF). We hypothesised that dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) could detect alterations in permeability, perfusion and extracellular extravascular volume in IPF, thus providing in vivo regional functional information not otherwise available.

Methods: Healthy controls and IPF subjects underwent DCE-MRI of the thorax using a dynamic volumetric radial sampling sequence and administration of gadoterate meglumine at a dose of 0.1 mmol·kg-1 at 2 mL·s-1 . Model-free analysis of signal intensity versus time curves in regions of interest from a lower, middle and upper axial plane, a posterior coronal plane and the whole lung yielded parameters reflective of perfusion and permeability (peak enhancement and rate of contrast arrival (kwashin )) and the extracellular extravascular space (rate of contrast clearance (kwashout )). These imaging parameters were compared between IPF and healthy control subjects, and between fast/slow IPF progressors.

Results: IPF subjects (n=16, 56% male, age (range) 67.5 (60-79) years) had significantly reduced peak enhancement and slower kwashin in all measured lung regions compared to the healthy volunteers (n=17, 65% male, age (range) 58 (51-63) years) on unadjusted analyses consistent with microvascular alterations. kwashout , as a measure of the extravascular extracellular space, was significantly slower in the lower lung and posterior coronal regions in the IPF subjects consistent with an increased extravascular extracellular space. All estimates were attenuated after adjusting for age. Similar trends were observed, but only the associations with kwashin in certain lung regions remained statistically significant. Among IPF subjects, kwashout rates nearly perfectly discriminated between those with rapidly progressive disease versus those with stable/slowly progressive disease.

Conclusions: DCE-MRI detects changes in the microvasculature and extravascular extracellular space in IPF, thus providing in vivo regional functional information.