Morphology of the small-animal lung using magnetic resonance microscopy.

Small-animal imaging with magnetic resonance microscopy (MRM) has become an important tool in biomedical research. When MRM is used to image perfusion-fixed and "stained" whole mouse specimens, cardiopulmonary morphology can be visualized, nondestructively, in exquisite detail in all three dimensions. This capability can be a valuable tool for morphologic phenotyping of different mouse strains commonly used in genomics research. When these imaging techniques are combined with specialized methods for biological motion control and animal support, the lungs of the live, small animal can be imaged. Although in vivo imaging may not achieve the high resolution possible with a fixed specimen, dynamic functional studies and survival studies that follow the progression of pulmonary change related to disease or environmental exposure are possible. By combining conventional proton imaging with gas imaging, using hyperpolarized 3He, it is possible to image the tissue and gas compartments of the lung. This capability is illustrated in studies on an emphysema model in rats and on radiation damage of the lung. With further improvements in imaging and animal handling technology, we will be able to image faster and at higher resolutions, making MRM an even more valuable research tool.