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Physics In Magnetic Resonance Imaging - Essay Example


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Physics In Magnetic Resonance Imaging

Two Fourier transformations are required to convert k-space data to an image because the first Fourier transformation is in the read direction while the second one is n the phase direction of the K space data. Explanation After the first Fourier transformation, it is imperative to note that the intensity profiles that occur I the read direction is only a graphical representation of the of the real signal intensity in the Fourier’s read direction, as shown in figure 2 bellow: Figure 2: k space after the first Fourier transformation If the information is to be viewed in reference to the phase direction, the intensity of the signal variation is likely to remain in an echo form as shown below: Figure 3: Data as echo However in this direction, the spins are usually spatially encoded by just incrementing the actual phase of the spins. In the phase direction, the spins are spatially encoded by incrementing the phase of the spins. As the magnetic field is passing through zero, which is at the centre of the imaging magnet used, it is necessary to add the magnetic field strength to the spins occurring at the axis of the applied gradient. This may result in no change in phase for the nuclei positioned at the midpoint of the applied phase gradient. In the second Fourier transformation, the actual position of the nuclei in the frequency, as well as direction is easily determined. It is also healthy to state that the image of the actual nuclear spin density is generated inside the slice with respect

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to its position inside the same slice (Vinitski, et al, 2003pp, 501-511). Q3: Draw a pulse program diagram for a spin echo pulse sequence. Discuss how each component of the MRI experiment affects transverse spin coherence and how this...
However, Low, et al, in argues that the RF which is a slice selective 90-degree pulse is usually followed by either two or multiple 180-degree refocusing pulses. It is essential to note that the GS, GP, and GF are mainly sliced selective, phase encoding, and the frequency encoding gradients, correspondingly. However, the echo in the diagram represents all the signals that are received from the actual slice succinct in the body. It is also advisable to note that if the TR and the TE are short, they will give a T1-weighted image.On the other hand, long TR and short TE are likely to give a proton density image. However, a long TR and TE give a T2-weighted image. These changes in the net magnetization are shown below as they occur for s spin echo sequence.Typical T1’s, T2’s and ρ’s for Brain Tissues at 1.5 T. Selective irradiation is critical in reducing a three-dimensional sample must be reduced into a one-dimensional component. This is also referred to as slice selection. The effects are also felt as there is the need to saturate all the spins that are outside the actual area of interest. Then the unsaturated spins must also be tipped into another transverse plan by applying a gradient along an x-axis, then again along the y axis: The Fourier method is efficient for this as it helps in eliminating the limitation of fast imaging sequences like the EPI, especially when implementing and switching the gradients at a faster rate. This is achieved by use of spiral imaging as it covers the k-space.


The paper "Physics In Magnetic Resonance Imaging" describes MRI is an image created by a complex interaction that occurs between radio frequency pulses and other fields with interruptions. To obtain an MP-image must be a combination of both spatial and intense information…
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Physics In Magnetic Resonance Imaging essay example
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