MRI Instrumentation and Safety - Lecture Notes

A collection of flashcards covering key terms and concepts related to MRI instrumentation and safety.

Permanent magnets

Consist of ferromagnetic substances, retain magnetization, common materials are iron, cobalt, nickel, and an alloy called alnico.

Electromagnets

Utilize electromagnetic induction by passing electrical current through wires to produce a magnetic field.

Resistive magnets

Magnetic field strength depends on the current through coils; operational costs are high.

Superconducting electromagnets

Use supercooled wire to minimize resistance, allowing high magnetic fields with low power requirements.

Shim coils

Extra loops of wire used to compensate for inhomogeneities in the main magnetic field, creating homogeneity.

Gradient coils

Provide linear gradation of magnetic field strength, controlling slice selection, frequency, and phase encoding.

Radiofrequency coils

Consist of wire loops that produce magnetic fields; transmit and receive RF signals for MRI imaging.

Surface coils

Used to improve signal-to-noise ratio (SNR) when imaging structures near the patient's surface.

Intracavity coils

Local coils used for signal reception deep within the patient, enhancing spatial resolution.

Exclusion zone

Defined by the 5 gauss line; area restricted to those who have passed a screening procedure to prevent projectile injuries.

Quenching

A sudden loss of superconductivity in magnet coils leading to rapid helium escape and potential damage.

Asphyxia

Condition caused by the displacement of oxygen by liquid helium, leading to suffocation.