MR imaging of low signal intensity pulmonary lesions using flow-sensitive techniques

Various spin echo techniques can be used to define the nature of low signal intensity lesions of the lung. A pulmonary arteriovenous malformation and a chronic pulmonary hematoma had a similar appearance on standard spin echo magnetic resonance (MR) images. Both lesions demonstrated central absence of signal surrounded by a thin rim of tissue, suggesting a vascular lesion. For further characterization of these lesions, a rotating gated MR technique was used in which images are obtained at different points in the cardiac cycle, such that pulsatile flow alters signal intensity with velocity changes during the cardiac cycle. Phase images also discriminated flowing blood in the arteriovenous malformation from stationary lung tissues, whereas the hematoma was not distinguished from lung parenchyma. Rotating gated sequences and reconstructed phase images may be useful in determining the etiology of low signal intensity pulmonary lesions.