Tools for cardiovascular magnetic resonance imaging

Clinical management of patients with heart disease is facilitated with accurate information regarding the underlying pathology, which may manifest as alterations in myocardial structure, function, macro and micro-vascular blood flow, viability, and metabolism. Non-invasive diagnostic imaging modalities such as echocardiography, radio-tracer based nuclear studies, X-ray computed tomography, and magnetic resonance imaging (MRI) are routinely used to help the clinician to evaluate the underlying pathologic changes. As a non-invasive imaging modality, MRI provides a number of mechanisms that can be effectively manipulated to generate different types of contrast. For example, MR images with different contrast weightings based on tissue magnetic relaxation parameters such as spin-lattice relaxation (T1), spin-spin relaxation (T2) can provide varied soft-tissue contrast between normal and pathologic states of tissue and can be used to assess tissue structure. In the last decade MR based methods have advanced sufficiently to provide cardiac gated tomographic images of the moving heart with exquisite spatial (1-2 mm in-plane resolution), temporal (50 ms or better) and contrast resolutions (1-3). Such advances have enabled routine assessment of cardiac function and blood flow. In conjunction with the administration of MR contrast agents, MR methods have been adapted to yield information about myocardial viability and myocardial perfusion (4-8). While not yet a routinely used clinical tool, MR spectroscopy (MRS) is a research tool widely used to study myocardial metabolism (9,10)