Titlebook: Clinical MR Imaging and Physics; A Tutorial Haris S. Chrysikopoulos Book 2009 Springer-Verlag Berlin Heidelberg 2009 MR Angiography.MR Phys

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https://doi.org/10.1007/978-3-658-43717-6gth of the static field B. So, if we force B to grow in a smooth and continuous manner along a line, then we spread the resonance frequencies, and each voxel along that line is tied to a unique frequency. Thus, the frequency of the received signal betrays the position of the voxel in question.

Accommodation

,Image Formation – Fourier Transform – Gradients,gth of the static field B. So, if we force B to grow in a smooth and continuous manner along a line, then we spread the resonance frequencies, and each voxel along that line is tied to a unique frequency. Thus, the frequency of the received signal betrays the position of the voxel in question.

Pillory

y, that has not been seen before.Includes supplementary mateKeywords Spin ? Electromagnetic radiation ? Resonance ? Nucleus ? Hydrogen ? Proton ? Certain atomic nuclei possess inherent magnetic Let us summarize the MRI procedure. Te patient properties called spin, and can interact with electro- is p

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impaction

Heather Jones,Kiron Chatterjee,Selena Grayplished with an RF pulse of 180°, called the refocusing pulse. After the activation of such a pulse all spins are instantaneously shifted into mirror-image positions with respect to the z-axis (Fig. 20).

Bravura

https://doi.org/10.1007/978-3-658-43717-6of the standard SE sequence. The new variable, called inversion time (TI), is the delay between the inversion and the excitation pulses. Thus, the familiar T1 curve is modified two-fold: it is “stretched” to twice the (vertical) distance as before, and it has to cross the zero (null) point (Fig. 26).

POWER

https://doi.org/10.1007/978-3-662-28279-3verall signal and poor tissue contrast, since we slide leftward on the T1 curve (Fig. 38). The ingenious solution is to disengage tissue saturation and tissue contrast from the influence of TR, using excitation pulses (θ) less than 90° (partial flip angle).

背景

,T2 Relaxation (Transverse or Spin–Spin Relaxation), positive or negative deviations from the nominal strength of the main field B. Since the Larmor frequency follows the apparent value of B, there is a spread of the precession rates of the spins, around the nominal value. After a short time the microscopic spins (μ) move apart like a fan, and occupy random orientations (Fig. 11).

LEER

Spin Echo,plished with an RF pulse of 180°, called the refocusing pulse. After the activation of such a pulse all spins are instantaneously shifted into mirror-image positions with respect to the z-axis (Fig. 20).

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