MRI Exam 3 Quiz

What causes the loud thumping noise during an MRI scan?

Lorentz Force

What is the process of gradually decreasing the current in a superconducting magnet to return it to a non-superconducting state called?

Ramping down

Which of the following components of an MRI magnet functions to deliberately spoil magnetic field homogeneity?

Gradient coil

The objects pictured here are _______

RF coils

Which of the following components of an MRI magnet functions to receive the MRI signal?

RF receive coil

What is the only moving part of an MRI machine?

The table

In which zone is the MRI Operating Console Room typically located?

Zone 3

What is the maximum magnetic field strength typically achieved by permanent magnets in whole-body MRI systems?

0.3T

What is the container that houses the superconducting wires and cryogens called?

Cryostat

What is the purpose of shimming a magnet?

Creating a more homogenous magnetic field

What is the most common type of magnet used in MRI systems?

Superconducting electromagnet

Which type of MRI system produces a vertical B0 field and looks like a large C-arm?

Resistive electromagnet

What is the cryogen used primarily to cool MRI magnet coils?

Liquid helium

What material is commonly used in superconducting electromagnets for MRI?

Niobium-titanium alloy

Which of the following components of an MRI magnet functions to help keep the main magnetic field more homogeneous?

Shim coil

Which type of RF receive coil can detect signals from multiple directions?

Quadrature coil

In a permanent magnet MRI system, which axis is vertical?

Z-axis

Which type of MRI system is most often used in clinical settings today?

Superconducting electromagnet

What is the typical weight limit for a patient on an MRI couch?

350 lbs

What is the critical temperature for superconductivity in niobium-titanium alloys used in MRI magnets?

9 Kelvin

What is the term for the loss of superconductivity in the B0 coil that may occur unexpectedly?

Quench

What does the term slew rate refer to?

The maximum rise of a gradient coil

What is a bore diameter of a typical clinical MRI magnet?

60 cm

What units do we use to specify magnetic field homogeneity?

Parts per million (ppm)

What is the primary advantage of a permanent magnet MRI system?

Low fringe magnetic field

Which of the following is NOT an advantage of permanent magnet MRI systems?

High magnetic field homogeneity

An MRI head coil is typically what type of coil?

Birdcage coil

Which of the following is NOT one of the four electrical states of matter mentioned in the document?

Plasma

What are the three major components of a magnetic resonance imaging (MRI) system?

Magnet (Gantry), Operating console, System electronics

Which of the following components of an MRI magnet functions to create a large magnetic field?

B0

Which component is often referred to as the “traffic cop” of the MRI scanner?

Sequencing system (Pulse programmer)

Which of the following components of an MRI magnet functions to change the direction of the net magnetization vector?

RF transmit coil

Which of the following is NOT a subassembly of a superconducting MRI system?

Resistive coils

How many sets of gradient coils are inside an MRI machine?

3

What is the purpose of shim coils in an MRI system?

To make the B0 field homogenous

What is the purpose of the frequency synthesizer in an MRI system?

To generate the fundamental resonance frequency

What is a major disadvantage of a resistive electromagnet MRI system?

High electric power consumption

What is the geometric center of an MR magnet called?

Isocenter