10.3 Magnetic resonance imaging (MRI)

• Steps in the production of MRI images

  1️⃣ Proton Alignment

  2️⃣ Radio Wave Excitation

  3️⃣ Magnetic Field Gradients

  4️⃣ Signal Detection

  5️⃣ Image Reconstruction
• T1-weighted MRI images highlight fat, while T2-weighted images highlight water.


  True
• MRI images can be T1-weighted or T2-weighted depending on the time parameters
• T2-weighted MRI is valuable for detecting edema
• Match the MRI technique with its key feature and application:

  T1-weighted ↔️ Highlights fat and water, shows anatomical structures

  T2-weighted ↔️ Enhances water content, detects inflammation

  DWI ↔️ Measures water diffusion, diagnoses stroke

  fMRI ↔️ Detects blood flow changes, studies brain function
• DWI is used to identify restricted water movement in tissues.

  True
• DWI highlights areas of restricted water movement
• In which area of medical diagnosis is MRI particularly valuable for stroke detection?

  Neuroimaging
• What type of force can the strong magnetic field in MRI exert on ferromagnetic objects?

  Powerful
• MRI uses strong magnetic fields and radio waves to generate detailed images.
• What type of signal do protons emit as they return to their original alignment in MRI?

  Radio signal
• What is the relative cost of an MRI compared to an X-ray or CT scan?

  High
• Which imaging technique provides excellent soft tissue contrast without ionizing radiation?

  MRI
• In MRI, protons emit a signal as they return to their original alignment.
• What happens to protons when radio waves are applied in MRI?

  They precess
• What two types of energy are used in MRI to create images?

  Magnetic fields and radio waves
• Steps in MRI image creation

  1️⃣ Strong magnetic field aligns protons

  2️⃣ Radio waves cause protons to precess

  3️⃣ Protons emit a signal as they realign

  4️⃣ Signals are detected and processed into an image
• MRI uses ionizing radiation to generate images.

  False
• MRI is a non-invasive medical imaging technique.


  True
• What is the spatial encoding of MRI signals achieved by?

  Magnetic field gradients
• What is the purpose of Gradient Coils in an MRI system?

  Produce magnetic field gradients
• The Main Magnet generates a strong magnetic field typically between 1.5 and 3 Tesla
• What is magnetic resonance imaging (MRI)?

  Non-invasive medical imaging
• Radio waves in MRI cause protons to precess at a specific frequency.
• MRI is more expensive and requires the patient to remain still for longer periods.
• Match the imaging technique with its characteristics:

  X-ray ↔️ Ionizing radiation, poor soft tissue contrast

  CT Scan ↔️ Ionizing radiation, good soft tissue contrast

  MRI ↔️ Non-ionizing radiation, excellent soft tissue contrast
• MRI requires the use of strong magnetic fields and radio waves.


  True
• Sequence of events in MRI

  1️⃣ Strong magnetic field aligns protons

  2️⃣ Radio waves cause protons to precess

  3️⃣ Protons emit a detectable signal

  4️⃣ Signal is processed to create an image
• MRI provides excellent soft tissue contrast without ionizing radiation.


  True
• MRI is more expensive than X-ray or CT scan and requires longer imaging times.


  True
• Gradient coils produce magnetic field gradients in three dimensions
• Radio frequency pulses cause protons to precess and emit a signal
• Match the MRI component with its purpose:

  Main Magnet ↔️ Generates a strong magnetic field

  Gradient Coils ↔️ Produce magnetic field gradients

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

  Computer System ↔️ Processes signals to reconstruct the image
• The Main Magnet generates a strong magnetic field to align protons
• What does the Computer System do in an MRI system?

  Processes signals to reconstruct images
• MRI uses ionizing radiation to generate images of soft tissues.

  False
• Radio waves cause protons to precess at a specific frequency
• What type of tissue contrast is highlighted in T1-weighted MRI images?

  Fat and water
• What is the purpose of T1-weighted MRI?

  Visualize anatomical structures
• What does Functional MRI (fMRI) measure?

  Brain activity