The fundamentals of cardiovascular magnetic resonance (CMR) rely on a knowledge of magnetic resonance imaging (MRI) physics. MRI physics describes how protons in a magnetic field behave in response to stimuli such as magnetic gradients and radiofrequency pulses, the basic building blocks of an MRI pulse sequence. MRI pulse sequences utilize the magnetic properties of tissues, specifically T1, T2, and T2* relaxation, to form images and create tissue contrast. In MRI, images are acquired in k-space and must be converted to images. A basic understanding of k-space is crucial to learning how images are formed in MRI, since the parameters of k-space acquisition are directly related to the properties of the final image, e.g., image resolution and field of view. Furthermore, fast imaging techniques, such as parallel imaging and compressed sensing, are applied in k-space. For CMR in particular, accelerated imaging techniques are used to achieve the high temporal resolution necessary to capture the dynamic heart.
In this chapter, we will cover MRI physics, image formation, accelerated imaging techniques, and basic pulse sequences for CMR.
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