10.3 Magnetic resonance imaging (MRI)

• MRI is a non-invasive technique that uses ionizing radiation.

  False
• Hydrogen protons in the body are targeted by the magnetic field in MRI.

  True
• MRI exposes patients to ionizing radiation, similar to X-rays.

  False
• What three key components interact in MRI to produce images?

  Magnetic field, radio waves, hydrogen protons
• Radio waves are used to excite the aligned protons, causing them to emit a small radio signal
• The magnet in an MRI machine is a powerful superconducting magnet
• What happens to the protons when radio waves are used to excite them?

  They spin and emit radio signals
• What is the first step in the MRI process according to the step-by-step explanation?

  Alignment
• Radio waves at a specific frequency are used to excite the aligned protons
• Steps in the physics behind MRI image generation

  1️⃣ Magnetization: The magnetic field aligns protons

  2️⃣ Excitation: Radio waves excite the protons

  3️⃣ Relaxation: Protons emit radio signals as they relax

  4️⃣ Signal Detection: RF coils detect emitted signals

  5️⃣ Image Generation: Computer processes signals
• What type of radiation is avoided in MRI imaging?

  Ionizing radiation
• Diffusion-Weighted MRI (DWI) is used to detect strokes early by measuring water molecule diffusion.


  True
• MRI is contraindicated for patients with metallic implants or devices.

  True
• One advantage of MRI is that it provides high detail of soft tissues without invasive procedures.

  True
• Describe the steps in how MRI works:

  1️⃣ Magnetization: The body is placed within a strong magnetic field, aligning protons.

  2️⃣ Excitation: Radio waves are emitted, exciting the protons and changing their alignment.

  3️⃣ Signal Emission: As protons return to their aligned state, they release radio signals.

  4️⃣ Signal Detection and Image Construction: Detectors measure the emitted signals, and a computer reconstructs the data into a detailed image.
• When radio waves are used to excite the protons, they emit a small signal
• MRI produces high-quality, non-invasive images without using any radiation
• Arrange the steps of the MRI process in the correct order:

  1️⃣ Magnetization

  2️⃣ Excitation

  3️⃣ Relaxation

  4️⃣ Signal detection
• What happens to the protons as they relax back to their original alignment?

  Emit a radio signal
• What is the primary function of gradient coils in an MRI machine?

  Spatially encode proton positions
• The magnet in an MRI machine creates a strong magnetic field that aligns the hydrogen protons to produce net magnetization
• Arrange the steps of the MRI process in the correct order:

  1️⃣ Alignment

  2️⃣ Excitation

  3️⃣ Relaxation

  4️⃣ Detection
• Gradient coils in the MRI machine create additional magnetic fields to spatially encode the position of the protons.


  True
• As protons relax back to their original alignment, they emit small radio signals
• Match the MRI technique with its principle and application:

  Structural MRI ↔️ High-resolution images of anatomy; Diagnosing tumors

  Functional MRI (fMRI) ↔️ Measures blood flow changes; Studying brain activity

  Diffusion-Weighted MRI (DWI) ↔️ Measures water molecule diffusion; Detecting strokes
• What is one major advantage of MRI over X-ray and CT scans?

  No ionizing radiation
• How does MRI image quality compare to X-ray for soft tissue structures?

  Higher for soft tissue
• What does MRI use to produce detailed images of the body's internal structures?

  Magnetic fields and radio waves
• The specific frequency of the radio waves is tuned to match the precession
• List the key steps in the MRI process:

  1️⃣ Magnetic field aligns hydrogen protons.

  2️⃣ Radio waves excite the protons.

  3️⃣ Protons relax and emit a radio signal.

  4️⃣ Signals are detected by the scanner.

  5️⃣ Detected signals generate the image.
• MRI produces high-quality images without using any ionizing radiation
• During magnetization, a strong magnetic field aligns hydrogen protons in the body.


  True
• Match the components of an MRI machine with their descriptions:

  Magnet ↔️ Generates a strong, uniform magnetic field

  Gradient Coils ↔️ Creates additional magnetic fields for spatial encoding

  Radio Frequency (RF) Coils ↔️ Transmit and receive radio frequency signals

  Computer System ↔️ Processes detected signals into images
• RF coils transmit and receive radio frequency signals in MRI.


  True
• MRI is a non-invasive imaging technique that uses ionizing radiation.

  False
• What type of field does the powerful magnet in an MRI machine create?

  Strong, uniform magnetic field
• Why is MRI considered non-invasive?

  No ionizing radiation is used
• The computer system in an MRI machine processes the emitted radio signals to reconstruct a detailed image.


  True
• Functional MRI (fMRI) detects changes in blood flow to measure brain activity
• Lengthy scan times in MRI can be uncomfortable for patients