Magnetism in MRI Questions and Answers with Certified Solutions

Magnetism in MRI Questions and Answers with Certified Solutions What is the primary function of the magnetic field in MRI? To align hydrogen nuclei in the body for image formation Why is a strong magnetic field necessary in MRI? A stronger field improves signal strength and image quality What happens to hydrogen protons when placed in a magnetic field? They align with or against the field and begin to precess Why is the unit Tesla (T) used in MRI? It measures the strength of the magnetic field What is the typical range of magnetic field strength used in clinical MRI scanners? Between 0.5T and 3T 2 What is the term for the motion of hydrogen protons in a magnetic field? Precession How does increasing the magnetic field strength affect signal-to-noise ratio (SNR)? A higher field strength increases SNR, improving image quality Why are superconducting magnets commonly used in MRI? They provide a strong, stable magnetic field with minimal power consumption What role do gradient coils play in magnetism for MRI? They create small variations in the magnetic field for spatial encoding How does the main magnetic field in MRI remain stable over time? It is maintained by superconducting currents and shim systems What is magnetic field homogeneity, and why is it important? It refers to uniformity in the magnetic field, ensuring accurate image formation 3 What effect does a non-uniform magnetic field have on MRI images? It can cause distortions and artifacts Why do some metallic implants pose a risk in an MRI environment? Ferromagnetic materials can move or heat up due to the strong magnetic field What is the purpose of active shielding in an MRI magnet? To confine the magnetic field and prevent interference outside the scanner Why is a stray magnetic field around an MRI scanner a safety concern? It can attract ferromagnetic objects, creating projectile hazards How does the fringe field of an MRI magnet impact nearby electronic devices? It can interfere with their operation or cause