FREE MRI Knowledge Questions and Answers

Question 1

Substances in the presence of an applied magnetic field that show a modest rise in magnetic field. They exhibit both positive and low susceptibility.

Accepted Answer

Paramagnetic

Answer

Paramagnetic materials exhibit a weak, positive susceptibility to an external magnetic field. Their unpaired electrons align with the field, causing a modest increase in the local magnetic field, but this effect is lost once the external field is removed. Gadolinium, a common MRI contrast agent, is a well-known paramagnetic substance.

Question 2

Positive susceptibility is present in these materials, however when exposed to an external magnetic field, they will stay magnetized even after the field is removed.

Accepted Answer

Ferromagnetic

Answer

Ferromagnetic materials are characterized by strong positive susceptibility and the ability to retain their magnetization even after the external magnetic field is removed. This property makes them suitable for creating permanent magnets. Examples include iron, nickel, and cobalt, which are strongly attracted to magnets and can become permanently magnetized.

Question 3

These materials are employed as T2 contrast agents because they show positive susceptibility, are stronger than paramagnetic materials but weaker than ferromagnetic materials.

Accepted Answer

Superpapmagnetic

Answer

Superparamagnetic materials possess magnetic properties stronger than paramagnetic substances but, unlike ferromagnetic materials, they do not retain magnetism once the external field is removed. They are often used as T2 contrast agents in MRI because their large magnetic moments create significant local field inhomogeneities, leading to rapid T2 decay and signal loss, which enhances contrast in certain tissues.

Question 4

Magnets formed of ferrous material found naturally or from blocks or slabs.

Accepted Answer

Permanent

Answer

Permanent magnets are created from naturally occurring ferromagnetic materials or specially treated blocks of ferrous material. These magnets retain their magnetism without requiring an external power source. They produce a constant magnetic field and are typically utilized in low-field MRI systems, offering a simpler and less costly design.

Question 5

To form a magnet field, wires are arranged side by side.

Accepted Answer

Selenoid magnet

Answer

A solenoid magnet is formed by coiling a wire into a cylindrical shape. When an electric current passes through this coiled wire, it generates a uniform magnetic field along the axis of the cylinder. This design is fundamental to many types of MRI magnets, particularly superconducting systems, where the solenoid configuration efficiently produces a strong, homogeneous field.

MRI - Magnetic Resonance Imaging Practice Test

MRI - Magnetic Resonance Imaging Practice Test

FREE MRI Knowledge Questions and Answers