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MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy. [1]
The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature ( STP) is defined as 0 Hounsfield units (HU), while the radiodensity of air at STP is defined as −1000 HU.
An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. [ 1 ] A multiparametric MRI is a combination of two or more sequences, and/or including other specialized MRI configurations such as spectroscopy .
The Thyrotroph Thyroid Hormone Sensitivity Index (abbreviated TTSI, also referred to as Thyrotroph T4 Resistance Index or TT4RI) is a calculated structure parameter of thyroid homeostasis. It was originally developed to deliver a method for fast screening for resistance to thyroid hormone. [ 1][ 2] Today it is also used to get an estimate for ...
Functional magnetic resonance imaging or functional MRI ( fMRI) measures brain activity by detecting changes associated with blood flow. [ 1][ 2] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.
Physics of magnetic resonance imaging#Overview of main sequences. This table does not include uncommon and experimental sequences . Measuring spin–lattice relaxation by using a short repetition time (TR) and echo time (TE). Lower signal for more water content, [1] as in edema, tumor, infarction, inflammation, infection, hyperacute or chronic ...
Spin–lattice relaxation. During nuclear magnetic resonance observations, spin–lattice relaxation is the mechanism by which the longitudinal component of the total nuclear magnetic moment vector (parallel to the constant magnetic field) exponentially relaxes from a higher energy, non-equilibrium state to thermodynamic equilibrium with its ...
007451. Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues ( physiology ). Medical imaging seeks to reveal internal structures hidden by the skin and bones, as well as to diagnose and treat disease.