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An MRI's Skeleton

Short answer: The machine in the footage is almost certainly a CT (computed tomography) scanner with its covers off, not an MRI.

In a CT scanner, an X-ray tube and detector array are mounted on a ring-shaped gantry that spins rapidly around the patient, and a computer turns the measurements into cross-sectional images. An MRI works differently and has no spinning parts. A strong static magnet lines up hydrogen nuclei in the body, radio-frequency pulses tip them, and stationary gradient coils briefly vary the magnetic field so the signals can be located in space. The nuclei give off radio signals as they relax, and a computer builds images in which tissues differ by how fast they relax. The Reel's description of magnets, radio waves and gradient fields fits MRI; only the 'spinning' parts and the footage belong to CT.

VideoWrite-up4 sources

In collections:Inside the Body

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What should you know about An MRI's Skeleton?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. MRI uses magnets and radio waves and has no spinning parts.

    DD-290-F01 · Write-up · Exhibit A (Magnets and radio)

  2. A CT scanner's X-ray tube spins on a ring gantry.

    DD-290-F02 · Write-up · Exhibit D (CT spins)

Video transcript: An MRI's Skeleton: Strip the Covers off a Scanner and the Ring Starts Spinning

DID YOU KNOW? An MRI or magnetic resonance imaging machine works by using powerful magnets and radio waves to generate detailed images of the body's internal structures. The machine's spinning gradient coil assembly creates varying magnetic fields allowing for precise spatial encoding. This process manipulates the resonance frequency of hydrogen protons in the body, which emits signals that are converted into detailed images by a computer. The spinning component aids in differentiating tissues. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 23.6s Reel ·

Video coming soonAn MRI's Skeleton · Instagram Reel
An MRI's Skeleton: Strip the Covers off a Scanner and the Ring Starts Spinning Instagram Reel · · 23.6s

The write-up

Strip the covers off a scanner and the ring starts spinning. An MRI has no spinning parts; the whirling ring belongs to a CT scanner.

  1. Exhibit A

    Magnets and radio

    MRI uses a strong magnet and radio-frequency pulses to get signals from hydrogen nuclei.

  2. Exhibit B

    Gradient coils

    Stationary gradient coils vary the field so signals can be located.

  3. Exhibit C

    Tissue contrast

    Tissues differ by how fast their nuclei relax after each pulse.

  4. Exhibit D

    CT spins

    A CT scanner's X-ray tube and detectors spin on a ring around the patient.

  5. Exhibit E

    The footage

    The spinning ring in the footage matches an uncovered CT gantry.

Questions people ask about An MRI's Skeleton

What does MRI use to image the body?

The signals come from hydrogen nuclei.

Source: Write-up · Exhibit A (Magnets and radio) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

Do MRI gradient coils spin?

They vary the field electrically.

Source: Write-up · Exhibit B (Gradient coils) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

What creates contrast between tissues in MRI?

Different tissues relax at different rates.

Source: Write-up · Exhibit C (Tissue contrast) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

Which scanner has a spinning ring?

The X-ray tube and detectors rotate.

Source: Write-up · Exhibit D (CT spins) · NIBIB (NIH): Computed Tomography (CT); US FDA: Computed Tomography (CT); Wikipedia: CT scan

What does the footage most likely show?

That's why the ring spins.

Source: Write-up · Exhibit E (The footage) · NIBIB (NIH): Computed Tomography (CT); Wikipedia: CT scan

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What does MRI use to image the body?

    1. A strong magnet and radio waves
    2. X-rays
    3. Ultrasound
    4. Visible light
    Show the answer

    Answer: A. A strong magnet and radio waves The signals come from hydrogen nuclei. Source: Write-up · Exhibit A (Magnets and radio) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

  2. Do MRI gradient coils spin?

    1. No, they're stationary
    2. Yes, rapidly
    3. Only during startup
    4. Only in old models
    Show the answer

    Answer: A. No, they're stationary They vary the field electrically. Source: Write-up · Exhibit B (Gradient coils) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

  3. What creates contrast between tissues in MRI?

    1. How fast nuclei relax
    2. Their color
    3. Their temperature
    4. Their weight
    Show the answer

    Answer: A. How fast nuclei relax Different tissues relax at different rates. Source: Write-up · Exhibit C (Tissue contrast) · NIBIB (NIH): Magnetic Resonance Imaging (MRI)

  4. Which scanner has a spinning ring?

    1. CT
    2. MRI
    3. Ultrasound
    4. PET only
    Show the answer

    Answer: A. CT The X-ray tube and detectors rotate. Source: Write-up · Exhibit D (CT spins) · NIBIB (NIH): Computed Tomography (CT); US FDA: Computed Tomography (CT); Wikipedia: CT scan

  5. What does the footage most likely show?

    1. A CT gantry with covers off
    2. An MRI magnet
    3. A jet engine
    4. A washing machine
    Show the answer

    Answer: A. A CT gantry with covers off That's why the ring spins. Source: Write-up · Exhibit E (The footage) · NIBIB (NIH): Computed Tomography (CT); Wikipedia: CT scan

Cite this case file

Easterling, Marcus. "An MRI's Skeleton." The Detail Department (DetailEnjoyer), case file DD-290, last updated Aug 5, 2024. https://detailenjoyer.com/case/an-mris-skeleton/

Permalink: https://detailenjoyer.com/case/an-mris-skeleton/ · Last updated

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