angular momentum - spin, amount of rotation considering speed, volume,mass, shape., precession - change of rotational axis when external magnetic field produces a secondary spin or wobble of the nucleus around the main/static field, magnetic moment - otherwise called torque. measures the tendency of an object to interact with external magnetic field. Determines the toque that a magnetic field will exert on a proton and the force proton can exert on electric current, nuclear magnetic resonance - this property is only present if a nucleus has both magnetic moment and angular momentum= spin, Larmor frequency - also called precessional frequency or resonance frequency which is proportional to the strength of the magnetic field.Frequency at which H absorbs energy and resonates- RF coil needs to be fine-tuned to this frequency for MRI to work. , gyromagnetic ratio - ratio of a particle's magnetic moment to angular momentum. different for each nucleus , high energy state - when the nucleus aligns itself in the opposite direction from B0 with reversed spin axis taking energy from applied RF field. , frequency of precession depends on - magnetic field, nature of the nucleus, Excitation/Radiation - process of sending electromagnetic energy to a sample at its resonant frequency. some spins go from low to high energy state. , Reception/Detection - process of receiving EM energy emitted by a sample at its resonant frequency- as spins return to low energy state/relax they emit energy (free induction decay at T2) measured by receiving RF coil, Net magnetization - sum of magnetic moments of all spins within a spin system. In the absence of strong MF, spins of H+ are oriented randomly, cancel out (small net m.) B0= increases m.f, Echo time (TE) - the amount of time necessary for energy coming back from the sample to be received (usually within 30ms). It can be selected to receive a specific type of signal, TR - repitition time when the signal returns to equilibrium along B0 and RF is reapplied to once again excite the nucleus,

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