Short echo time MR Imaging of the lungs : methods and applications for experimental models of lung diseases in rodents

In this work, ultra-short echo time (UTE) MR imaging of the lungs is presented as a way of detecting pulmonaryMRI signal, thus providing an opportunity to develop new imaging tools for the investigation of experimentalmodels of lung diseases in rodents. The UTE imaging technique (TE=450 μs) was implemented on a 4.7 Tscanner and applied to detect indicators of Chronic Obstructive Pulmonary Disease (COPD) inducedexperimentally in rodents. The improved signal detection from the lung parenchyma provided valuable markersof disease associated with airspace enlargement and inflammation. When used to investigate of inflammationspecificity, this technique had advantages when delineating regions of early cellular infiltration into the site ofinflammation. In the case of edematous signal quantification, the UTE technique was explored to improve thereliability of the volumetric measurements. This technique was demonstrated to be of use when easy protocolimplementation (relatively high throughput and low-cost experiments) and longitudinal studies (limitedinterference with physiopathology) are of concern. The repetitive probing of the k-space center with a temporalresolution of the sequence's repetition time achieved with this technique was used to develop a self-gatingmethod which relies on the tracking of cardio-respiratory motions, yielding images free from motion artifacts.