# FREE MRI Registry Questions and Answers

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#### The gradient subsystem's primary goal is to

Correct! Wrong!

In an MRI, the gradient subsystem is in charge of several functions. It is employed in the process of choosing the slice plane, which establishes the precise region of the body to be scanned. It also aids in choosing the imaging plane, which establishes the image's orientation. Furthermore, the MR signal is spatially encoded by the gradient subsystem, enabling the production of precise and detailed pictures. Thus, "all of the above" is the right response.

#### A method of expressing the gradient performance in terms of T/m/s, which is the gradient magnetic field's acceleration to its maximum amplitude.

Correct! Wrong!

Measured in T/m/s, the "slew rate" is the rate at which the gradient magnetic field reaches its greatest amplitude. It specifies the rate of change of the field strength with respect to acceleration. The arrangement of the coils used to generate the magnetic field is referred to as coil configuration, while the rise time is the amount of time it takes for the gradient magnetic field to reach its maximum amplitude. The best explanation for the provided response is hence "slew rate."

#### A small bandwidth makes _slices possible.

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Since bandwidth is the range of frequencies that may be processed or transmitted, narrower bandwidths enable thinner slices. A narrow bandwidth in the context of slicing refers to the utilization of a limited range of frequencies. Thicker slices are produced by more accurate and detailed slicing made possible by this restricted range.

#### The magnetic field's intensity is changed by this gradient coil from right to left.

Correct! Wrong!

Since the gradient coil is what produces a changing magnetic field in different directions, the correct response is x. In this instance, the magnetic field's intensity is explicitly changed from right to left. Since the x-axis is frequently connected to the direction from right to left in many coordinate systems, the above response is accurate.

#### Provide more coverage area without sacrificing signal-to-noise ratio by using numerous coils and receivers.

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With many coils and receivers, a phase array increases coverage area without lowering signal-to-noise ratio (SNR). This increases the phase array system's overall coverage area by enabling it to simultaneously receive signals from several directions. In order to steer and focus the beam in the desired direction, it uses both constructive and destructive interference of the signals received by the individual coils. Phase arrays are therefore especially helpful in applications like wireless communication networks and radar systems.

#### The magnetic field's intensity is varied from head to foot by this gradient coil.

Correct! Wrong!

The magnetic field's intensity in the head-to-foot direction is adjusted by the z gradient coil. The z-axis, which extends from the subject's head to its foot, is where this coil is located. This coil's current can be adjusted to change the magnetic field strength along this path in a controlled manner. This is crucial for magnetic resonance imaging (MRI) because it makes it possible to adjust the magnetic field strength in various bodily parts to create intricate images.

#### The quantity of determines the receiver bandwidth.

Correct! Wrong!

The number of frequency samples in the matrix determines the receiver bandwidth. This implies that the receiver bandwidth will increase with the number of frequency samples in the matrix. This is so that the receiver can identify the precise frequency range that each frequency sample represents. Consequently, a bigger bandwidth is produced by the receiver's ability to detect a wider range of frequencies due to the presence of more frequency samples. A smaller bandwidth, on the other hand, would arise from having fewer frequency samples.

#### The range of frequencies sampled during the process is represented by the receiver bandwidth.

Correct! Wrong!

The signal's spatial placement inside the image is determined by the frequency encoding gradient. It is used to encode the frequency information of the MR signal during the data acquisition procedure. The frequency range that is sampled in this operation is known as the receiver bandwidth. Different frequency components can be recorded by varying the receiver bandwidth, which enables the recording of particular frequency information and enhances image quality.

#### The difference between the hydrogen's periodic frequency in fat and water is known as

Correct! Wrong!

The term "chemical shift" refers to the variation in hydrogen's precessional frequency between fat and water. In nuclear magnetic resonance (NMR) spectroscopy, a phenomenon known as "chemical shift" occurs when a nucleus's resonance frequency is modified as a result of its chemical surroundings. When it comes to hydrogen, the surrounding electron density and molecular structure are what produce the chemical change. Since it offers details on the molecular structure and composition, the chemical shift is a crucial NMR spectroscopy parameter.

#### Require the employment of solenoid coils because of the B0's orientation; these coils are more effective than linear coils and can be electrically combined with other coils to enhance signal homogeneity across an area of interest.

Correct! Wrong!

According to the explanation provided, "vertical" is the right response since it is more effective than a linear coil and can be electrically integrated with other coils to increase signal uniformity. Additionally, it states that solenoid coils are necessary because of the B0's position, suggesting that the vertical coil is the best choice in this particular situation.

#### The placement of the slice is established by the

Correct! Wrong!

The transmit frequency of the radiofrequency (RF) pulse determines the slice location in magnetic resonance imaging (MRI). The body's protons are excited by an RF pulse, and the energy level at which the protons resonate is determined by the transmit frequency. It is possible to select different body slices for imaging by varying the transmit frequency. Finding the slice location is unrelated to the other options mentioned, such as the phase gradient and receiver frequency.