MRI Physics Chapter 1 Questions and
Answers Latest Update Graded A+
What effect does a longer T2 relaxation time have on tissue appearance in MRI?
✔✔ The tissue appears brighter on T2-weighted images
Why do tissues with short T1 relaxation times appear bright on T1-weighted images?
✔✔ Because they recover quickly and emit a strong signal
What happens when the magnetic field is turned off in MRI?
✔✔ The protons gradually return to their natural alignment
What is the relationship between proton density and signal strength in MRI?
✔✔ Higher proton density leads to stronger MRI signals
How does MRI detect differences between normal and abnormal tissues?
✔✔ By analyzing variations in T1, T2, and proton density
1
,What is the effect of temperature on MRI signal strength?
✔✔ Increased temperature can slightly alter relaxation times
Why does MRI not use ionizing radiation like X-rays?
✔✔ It relies on magnetic fields and radiofrequency waves instead
What role does the phase-encoding gradient play in MRI?
✔✔ It provides spatial information for image reconstruction
What is the purpose of a 180-degree RF pulse in a spin-echo sequence?
✔✔ To refocus dephased spins and generate an echo
Why do different MRI sequences exist?
✔✔ To emphasize different tissue properties and enhance contrast
How does increasing voxel size affect image resolution in MRI?
✔✔ It reduces spatial resolution but increases signal strength
2
, What is the significance of echo formation in MRI?
✔✔ It allows signal detection after an RF pulse is applied
What property of hydrogen makes it ideal for MRI?
✔✔ Its single proton creates a strong magnetic moment
Why do metallic implants cause artifacts in MRI?
✔✔ They disrupt the local magnetic field and distort the image
What happens to proton spins when they absorb RF energy?
✔✔ They flip to a higher energy state
Why is an external magnetic field required in MRI?
✔✔ To align hydrogen protons and generate a measurable signal
What is the primary component required to generate an MRI signal?
✔✔ A strong magnetic field
3
Answers Latest Update Graded A+
What effect does a longer T2 relaxation time have on tissue appearance in MRI?
✔✔ The tissue appears brighter on T2-weighted images
Why do tissues with short T1 relaxation times appear bright on T1-weighted images?
✔✔ Because they recover quickly and emit a strong signal
What happens when the magnetic field is turned off in MRI?
✔✔ The protons gradually return to their natural alignment
What is the relationship between proton density and signal strength in MRI?
✔✔ Higher proton density leads to stronger MRI signals
How does MRI detect differences between normal and abnormal tissues?
✔✔ By analyzing variations in T1, T2, and proton density
1
,What is the effect of temperature on MRI signal strength?
✔✔ Increased temperature can slightly alter relaxation times
Why does MRI not use ionizing radiation like X-rays?
✔✔ It relies on magnetic fields and radiofrequency waves instead
What role does the phase-encoding gradient play in MRI?
✔✔ It provides spatial information for image reconstruction
What is the purpose of a 180-degree RF pulse in a spin-echo sequence?
✔✔ To refocus dephased spins and generate an echo
Why do different MRI sequences exist?
✔✔ To emphasize different tissue properties and enhance contrast
How does increasing voxel size affect image resolution in MRI?
✔✔ It reduces spatial resolution but increases signal strength
2
, What is the significance of echo formation in MRI?
✔✔ It allows signal detection after an RF pulse is applied
What property of hydrogen makes it ideal for MRI?
✔✔ Its single proton creates a strong magnetic moment
Why do metallic implants cause artifacts in MRI?
✔✔ They disrupt the local magnetic field and distort the image
What happens to proton spins when they absorb RF energy?
✔✔ They flip to a higher energy state
Why is an external magnetic field required in MRI?
✔✔ To align hydrogen protons and generate a measurable signal
What is the primary component required to generate an MRI signal?
✔✔ A strong magnetic field
3
