MRI Equipment

The link between the technologist and the computerized electronic environment of the MR system hardware

• Equipment room

• Equipment cabinet

• Operator's console

• Gradient amplifiers

Which of the following is the defintion of shimming

• Adjusting homogeneity of the magnetic field

• Creating a linear change in the magnetic field

• Confining the magnetic field to a smaller arfea

• Rapidly shutting off the magnetic field

Which of the following is a disadvantage of resistive magnets?1.  high energy consumption2.  high cooling requirements3.  not easy to shut off magnetic field

• 1 and 2

• 1 only

• 1 and 3

• 2 only

Which of the following is not a function of a PACS system

• Image display for the radiologists

• Digital distribution of images

• Long term data storage

• Reconstruction of the image from the raw data

The __ is located within an equipment cabinet

• Magnetic shielding

• RF power amplifier

• Gradient coils

• Rf coils

The _ provides the electrical power to the gradient coils

• Pulse sequence controller

• Rf power amplifier

• Gradient power amplifier

• Host computer

Which of the following describes an electromagnet

• Magnetic bricks are stacked together to form the magnet

• Electrical current flows through a coil of wire and generates a magnetic field

• A changing magnetic field around a coil of wire generates an electic field

• A moving magnetic field induces an electrical current in a neighboring conductive material

The magnetic shielding

• Reconstructs the images using the Fourier transform

• Makes the magnetic field more uniform

• Liearly varies the magnetic field along the axis of the magnet

• Constrains the fringe magnetic field to a smaller space

The host computer

• Is the interface between the technologist and the MR system

• Constrains the fringe magnetic field to a smaller space

• Digitizes the MR echoes

• Reconstructs the MR images

The array processor

• Constrain sthe magnetic field within a smaller space

• Lineraly varies the magnetic field along an axis of the magnet

• makes the magnetic field more uniform

• Reconstructs the images using the Fourier transform

The fourier transform is performed by which MRI system component

• Receiver amplifier

• DAC

• Array processor

• Host computer

The _ provides the elctrical power to the gradient coils

• Pulse sequence controller

• Rf power amplifier

• Gradient power amplifier

• Host computer

A component used to increasze the strength of a signal

• Gradient coil

• Equipment cabinet

• Digital to analog converter

• Amplifier

_ magnets can be shut off most quickly in the case of an emergency

• Permanent

• Superconducting

• Resistive

• Bar

__ magnets must remain connected to a power source to maintain their magnetc field.

• Resistive

• Permanent

• Superconducting

• Bar

The operators may be used for:1.  converting digital to analog 2.  viewing images3.  archiving images

• 1 and 2

• 1 and 3

• 2 and 3

• 1, 2, and 3

The RF shielding:  1.  prevents the RF energy generated by the MR system from disturbing external radio signals2.  restricts external radio signals from being detected 3.  prevents RF related artifacts from resulting

• 1and 3

• 1 and 2

• 1, 2, and 3

• 2 and 3

An RF coil geometry which links together several small surface coils in order to image a larger field of view is called _ coil

• An array coil

• A volumetric coil

• A circularly polarized

• A quadrature

The _ is responsible for telling the gradients when and at what strength to turn on

• Magnetic shielding

• Pulse sequence controller

• Rf power amplifier

• Host computer

__ magnets must be taken apart in order to shut off the magnetic field

• Permanent

• Superconducting

• Electro

• Resistive

Which of the following is true regarding function of RF coils1. The same coil may be used to transmit and receive the MR echoes2.  seperate coils may be used to transmit the RF pulses and to receive the MR echoes3.  a surface coil would be optimal for imaging structures deep within the brain

• 1 only

• 2 only

• 1 and 2

• 1 and 3

• 1, 2, and 3

Which of the following is the function of the RF coils?1.  transmission of the RF pulses2.  digitizing the received MR echoes3.  reception of the MR echoes

• 1 and 2

• 1 and 3

• 2 and 3

• 1, 2, and 3

MR guided _ is an application of interventional MRI1.  biopsy2.  surgery3.  ablation therapy

• 2 and 3

• 1, 2, and 3

• 1 and 2

• 1 and 3

On a sagittal image which of the following would be affected if the gradient power amplifier for the x gradient coil malfuctioned and produced a gradient in the magnetic field of twice the prescribed strength

• Thickness of the slice

• Field of view of the slice

• Image orientation

• Image matrix

The fringe magnetic field:

• Is eliminated by using magnetic shielding

• Is eliminated by shimming

• Poses no safety risk if magnetic shielding is used

• Can cause other nearby medical devices to malfuntion

Which of the following is a disadvantage of resistive magnets?1.  high energy consumption2.  high cooling requirements3.  not easy to shut off magnetic field

• 1 and 2

• 1 only

• 1 and 3

• 2 only

Upon installing a new MRI system, the service engineer mistakenly connects the x-gradient power amplifier to the y-gradient coil, the y-gradient power amplifier to the z-gradient coil, and the z-gradient power amplifier to the x-gradient coil.  A __ image would result when the technologist runs the first transverse sequence.

• Tranverse

• Oblique

• Coronal

• Sagittal

The pulse sequence controller is located

• Inside the magnet

• In the operator's console

• On an rf coil

• In the equipment cabinet

The echoes received from the patientgo through an amplifier to:

• Close the RF recevier coil

• In the operator's console

• Close to the gradient power cabinet

• In the pulse sequence controller

The __ gradient coils are wrapped on the top and bottom of the gradient cylinder

• Z

• X

• X and z

• Y

The __ encodes frequencies and phases into the MR echoes

• Gradient coils

• Host computer

• RF coils

• Analog to digital convertor

A quadrature coil is also known as a

• An array coil

• A circular polarized coil

• A surface coil

• A cardiac array coil

Which of the following statements is true regarding the magnets used in MR systems1.  some superconducting magnets can produce magnetic fields up to 10 T2.  resistive magnets may only have horizontal magnetic fields3.  permanent magnets are ideal for use in mobile MR systems

• 1 only

• 1 and 2

• 3 only

• 1 and 3

_is the definition of Faraday's law

• A moving electron that will induce an electric field in a neighboring conductor

• A moving electron that will induce a magnetic field in a neighboring conductor

• A changing magnetic field that will induce an electrical current in a neighboring conductive material

• A changing electric field that will induce a magnetic field in a neighboring conductor

A _ coil is preferable when a very uniform signal intensity level must be achieved throughout a cross section of anatomy

• Volumetric

• Linear

• Flat array

• Surface

A quadrature RF coil:1.  uses two sets of coils oriented perpendicular to each other2.  requires more power than an otherwise identical linear coil when transmitting3.  has a higher signal to noise ratio than an otherwise identical linear coil

• 1 and 2

• 1 and 3

• 2 and 3

• 1, 2, and 3

Which of the following is an example of Faradays law of induction?1.  precessing net magnetization of protons inducing an electrical current in a surface coil2.  precessing net magnetization of protons emitting an echo in response to RF pulses3.  net magnetization of protons precessing at a rate governed by the strength of the magnetic field they are exposed to

• 1 only

• 2 only

• 3 only

• 1 AND 2

The equipment cabinet houses...

The magnet room houses...