Progress in advanced imaging modalities has led to groundbreaking discoveries in cancer immunology, neurobiology, cardiology and many other areas. In contrast, development of functional imaging of the lung has lagged. The physical properties of the lung — essentially, a network of microscopic air sacs with very thin tissue interfaces — renders most new imaging techniques inappropriate due to poor resolution or low signal-to-noise ratios.
The gold standard for lung imaging is X-ray computed tomography (CT), which generally provides static images without the ability to obtain detailed measurements of lung function. Instead, doctors and researchers currently obtain information on lung function from pulmonary function tests, which measure the function of the lung as a whole. Thus, a substantial proportion of lung must be affected by disease before functional abnormalities can be detected. Furthermore, in the lab, measurements of pulmonary function in small animals are difficult to perform and unreliable.
For the first time, we now have a new way of imaging the lung that provides detailed three-dimensional images of the lung structure and allows detailed analysis of lung motion and function. This method, called four-dimensional (in three spatial dimensions plus time) X-ray velocimetry, or 4DXV, exploits the shift in the phase of an X-ray as it passes through an object. Phase shifts in X-rays are enhanced at air-tissue interfaces and, therefore, the exact properties of the lung that make it impossible to image by other advanced imaging techniques make it ideal for phase contrast imaging. This novel approach, invented by Andreas Fouras, PhD, provides extremely detailed and accurate information about the expansion and contraction of the lung tissue and airflow within the lungs of live animals during the respiratory cycle. The Biomedical Imaging Research Institute (BIRI) has recently been awarded a Shared Instrument Grant from the National Institutes of Health to build the first 4DXV small-animal scanner in the United States — only the second in the world — at Cedars-Sinai. We will use this scanner and other BIRI lung imaging technology in collaboration with researchers in the Women’s Guild Lung Institute and other areas to answer fundamental questions about lung development, disease and responses to treatments in animal models.