Functional Pulmonary Magnetic Resonance Imaging for Detection of Ischemic Injury in a Porcine Ex-Vivo Lung Perfusion System Prior to Transplantation

Abstract

To evaluate the feasibility of multiparametric magnetic resonance imaging (MRI) of the lungs to detect impaired organ function in a porcine model of ischemic injury within an ex-vivo lung perfusion system (EVLP) prior to transplantation. Twelve pigs were anesthetized, and left lungs were clamped to induce warm ischemia for 3 hours. Right lungs remained perfused as controls. Lungs were removed and installed in an EVLP for 12 hours. Lungs in the EVLP were imaged repeatedly using computed tomography, proton MRI (1H-MRI) and fluorine MRI (19F-MRI). Dynamic contrast-enhanced derived parenchymal blood volume, oxygen washout times, and 19F washout times were calculated. PaO2 was measured for ischemic and normal lungs, wet/dry ratio was determined, histologic samples were assessed, and cytokines in the lung tissue were analyzed. Statistical analysis was performed using nonparametric testing. Eleven pigs were included in the final analysis. Ischemic lungs showed significantly higher wet/dry ratios (p = 0.024), as well as IL-8 tissue levels (p = 0.0098). Histologic assessment as well as morphologic scoring of computed tomography and 1H-MRI did not reveal significant differences between ischemic and control lungs. 19F washout (p = 0.966) and parenchymal blood flow (p = 0.32) were not significantly different. Oxygen washout was significantly prolonged in ischemic lungs compared to normal control lungs at the beginning (p = 0.018) and further prolonged at the end of the EVLP run (p = 0.005). Multiparametric pulmonary MRI is feasible in lung allografts within an EVLP system. Oxygen-enhanced imaging seems to be a promising marker for ischemic injury, enabling detection of affected lung segments prior to transplantation.