Presenter: W. Quinn Meadus
Abstract: Pulmonary edema or elevated lung water is defined as the accumulation of extravascular fluid in the lungs and leads to shortness of breath and hypoxia. The presentation of pulmonary edema is generally a sign of underlying health issues related to heart disease or lung injury. The severity of pulmonary edema is an indicator of patient outcomes but the most common measurement methods are insensitive, only qualitative or pose health risks. The purpose of this study is to develop an optimized MRI approach to quantify pulmonary edema. A proton-density weighted MRI scan measures the amount of hydrogen protons present, meaning water in the lungs can be directly correlated to MRI signal. However, the lungs are naturally difficult to image having quickly decaying signal due to complex air-tissue interfaces affecting magnetic susceptibility (short T2*). This is compensated for with an ultra-short echo time (UTE) approach. Full 3D, 2.5 mm isotropic resolution scans of the chest are achieved in a time efficient manner with Yarn-Ball k-space acquisition. Full scans are complete in 16-26 seconds with a volunteer breath hold, or in approximately 2 minutes while free breathing with motion correction. The MRI sequence is paired with custom automated image processing code, which corrects for background fields and applies a mask to the lung region. Phantom experiments and healthy volunteer scans are ongoing for method validation. A slope coefficient of 1.0075 (p < 0.001) was found between physical water content and MRI predicted values in phantom experiments. Preliminary healthy control data shows lung water content ranging from 25% to 35% relative to surrounding tissues. Yarn Ball UTE MRI could prove to be an accurate, quantitative and safe new tool in quantifying pulmonary edema.