Understanding MRI Physics Principles

What is the basic principle behind MRI?

• X-ray diffraction

• Electromagnetic radiation

• The basic principle behind MRI is nuclear magnetic resonance.

• Ultrasound imaging

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NGSS.HS-PS4-3

How does the magnetic field affect hydrogen nuclei in MRI?

• The magnetic field has no effect on hydrogen nuclei during MRI scans.

• The magnetic field only affects oxygen nuclei, not hydrogen nuclei, in MRI.

• The magnetic field aligns hydrogen nuclei, allowing for signal detection in MRI.

• The magnetic field disrupts hydrogen nuclei, causing signal loss in MRI.

What role do radiofrequency pulses play in MRI?

• Radiofrequency pulses cool the hydrogen nuclei to reduce noise in MRI.

• Radiofrequency pulses excite hydrogen nuclei, allowing for signal detection to create MRI images.

• Radiofrequency pulses are used to stabilize the magnetic field during imaging.

• Radiofrequency pulses create a permanent image of the scanned area.

Explain the concept of relaxation times in MRI.

• Relaxation times are only relevant in CT scans.

• Relaxation times measure the speed of the MRI machine.

• T1 and T2 are unrelated to magnetic fields.

• Relaxation times in MRI are T1 and T2, which measure the time for protons to return to equilibrium after being disturbed by a magnetic pulse.

What is T1 relaxation and how does it differ from T2 relaxation?

• T1 relaxation is the same as T2 relaxation.

• T1 relaxation is longitudinal relaxation involving energy transfer to the lattice, while T2 relaxation is transverse relaxation due to spin-spin interactions.

• T1 relaxation occurs only in solids, while T2 occurs in liquids.

• T1 relaxation involves spin-spin interactions, while T2 involves energy transfer to the lattice.

How does the strength of the magnetic field influence image quality in MRI?

• Stronger magnetic fields improve image quality by increasing signal-to-noise ratio and resolution.

• Magnetic field strength has no effect on image quality in MRI.

• Weaker magnetic fields enhance image quality by improving contrast.

• Stronger magnetic fields decrease image quality by increasing artifacts.

What is the significance of the Larmor frequency in MRI?

• It relates to the speed of the MRI machine.

• The Larmor frequency is significant in MRI as it determines the resonance frequency of hydrogen nuclei, essential for image formation.

• It indicates the strength of the magnetic field used.

• It determines the color of the images produced.

Describe the process of image formation in MRI.

• Using X-rays to capture images of soft tissues

• The process of image formation in MRI involves aligning hydrogen nuclei in a magnetic field, applying RF pulses, detecting emitted signals, and reconstructing images.

• Injecting contrast agents to enhance image quality

• Utilizing ultrasound waves to create images of internal organs

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NGSS.HS-PS4-5

What safety considerations are important when using MRI?

• Important safety considerations when using MRI include screening for metal implants, claustrophobia, and monitoring for allergic reactions to contrast agents.

• MRI is safe for all patients regardless of conditions

• Using MRI without any prior screening

• No need to monitor for allergic reactions during MRI

How do different tissue types appear on an MRI scan?

• On an MRI scan, high water content tissues appear bright, while low water content tissues appear dark.

• MRI scans cannot differentiate between tissue types.

• High water content tissues appear dark, while low water content tissues appear bright.

• All tissues appear the same on an MRI scan.

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NGSS.HS-PS4-5