WorksheetsMRI Chapter 9 Review Questions
Total questions: 10
Worksheet time: 4mins
Why does an MRI scan make such a loud noise?
The noise is caused by the gradient coils
The noise is a safety feature that the magnetic field is on
The noise is the RF energy being transmitted into the patient
The noise correlates to the patient's heartbeat
Why are superconducting magnets preferred in MRI systems?
They can carry high current with no resistivity losses, allowing for a powerful magnetic field.
They are less expensive than other types of magnets.
They are easier to install than permanent magnets.
They do not require any cooling systems.
Why is the body area to be scanned positioned at the center of the magnet bore (isocenter)?
Isocenter is where the magnetic field is most homogeneous.
Isocenter is where the magnetic field is the weakest.
Positioning depends on patient tolerance. Claustrophobic patients don't need to be positioned at isocenter.
Isocenter is where the gradient noise is the lowest.
What is meant by shimming?
Shimming refers to the process required to optimize the homogeneity of an MRI magnet once installed
Shimming eliminates the need for tuning for each patient
Shimming transmits RF into the patient during scanning
Shimming keeps the magnet wire windings cool during scanning
What are the advantages of an open-magnet design vs closed bore?
Claustrophobic patients and children are less enclosed
Patients with metal implants can be scanned without screening
Patients who require high-resolution imaging can be images more quickly
Can scan patients who need rapid scans due to pain
What are the primary functions of spatially varying gradients in an MRI acquisition?
To create slopes along the main magnetic field
To cool the MRI machine
To generate the main magnetic field
To shield the scanner from RF interference
Why is a magnet room typically lined with copper or aluminum sheeting?
To provide radiofrequency shielding
To improve image resolution
To reduce patient discomfort
To enhance magnetic field strength
What is meant by the “filling factor” of an RF receive coil?
This term describes how much of the sensitive volume of a coil is filled with the patient’s body tissue
This term describes how much of the bore a patient fills during the scan
The term describes how full the patient's stomach is during scanning
The term describes how much contrast has been loaded into the power injector
Which of the following is an advantage of a phased-array coil over a standard surface coil?
Higher SNR with a large field of view
Lower SNR with a small field of view
Slower acquisition time
Reduced image quality
What differentiates ferromagnetism from paramagnetism or diamagnetism?
Ferromagnetic objects retain their magnetism when removed from an external magnetic field
Ferromagnetic objects are heavier than paramagnetic or diamagnetic objects
Nothing, they're all magnetic
Ferromagnetic objects do not react to the external magnetic field
