Lung Imaging with UTE MRI

Abstract

Cross-sectional imaging of the lungs, or pulmonary imaging, has proven to be an incredibly valuable tool in a wide range of pulmonary diseases. The vast majority of lung imaging is done with CT, as it is fast enough to freeze respiratory motion and provides high spatial resolution to visualize fine structure of the lungs. MRI of the lungs is inherently challenging due to the presence of large local magnetic field gradients, relatively low proton density, and motion. The benefits of performing MRI for lung imaging include no ionizing radiation, opportunities for multiple contrasts, and integration with other MRI also offers the opportunity to obtain multiple tissue contrasts. The most common lung MRI techniques are structural T1-weighted scans, but also emerging are functional contrasts such as ventilation and perfusion, as well as other MRI contrast mechanisms including T2-weighting and diffusion-weighting. Finally, lung MRI can be combined with other MRI scanning techniques, including cardiac MRI, abdominal MRI, whole-body MRI, and PET/MRI, for increasing examination efficiency by only requiring a single scan session and providing more comprehensive assessment that includes evaluation of the pulmonary system. This article covers pulse sequences, motion management methods, image reconstruction, and contrast mechanisms of UTE MRI (e.g. T1-weighting, ventilation mapping) for imaging of the lung.