WK 4: MRI Basics

What is the primary reason why MRI does not require labelled probe molecules?

The sensitivity of each isotope is the same
Only biologically important elements have NMR sensitive isotopes
All elements have at least one NMR sensitive isotope
Most elements have at least one NMR sensitive isotope (correct)

What is the property of atomic nuclei that NMR and MRI take advantage of?

Electrical properties
Magnetic properties (correct)
Optical properties
Thermal properties

What is the fundamental reason behind the unique sources of contrast in an MRI?

Different spin alignment of atomic nuclei (correct)
Different magnetic moments of atomic nuclei
Different sensitivity of each isotope
Different quantum mechanical angular momentum

Why does MRI not require high energy radiation?

Because it uses magnetic fields instead of radiation (C) Signup and view all the answers

What is the significance of spin in NMR and MRI?

It is an intrinsic property of atomic nuclei (B) Signup and view all the answers

What is the main advantage of NMR and MRI over other imaging techniques?

They provide information otherwise unobtainable (C) Signup and view all the answers

Which type of contrast does MRI excel at?

Soft tissue contrast (A) Signup and view all the answers

What is the primary limitation of performing MRI with isotopes other than 1H?

Insufficient signal strength (C) Signup and view all the answers

What happens to the spin alignment when a magnetic field is applied?

The spins align with the magnetic field (A) Signup and view all the answers

Which of the following is NOT a factor affecting the overall sensitivity of a nucleus in MRI?

Patient's body temperature (D) Signup and view all the answers

Why is 1H the isotope of choice for clinical MRI?

It has the highest natural abundance (B) Signup and view all the answers

What is necessary to perform MRI with isotopes of low abundance, such as 13C?

Isotopically labelled samples (A) Signup and view all the answers

What is the typical resolution of high-resolution MRI, also known as 'NMR Microscopy'?

10 μm (B) Signup and view all the answers

What is the main reason to combine MRI with NMR sources of contrast?

To discriminate between different regions of tissue (A) Signup and view all the answers

What is the effect of motion during an MRI imaging sequence?

It causes artifacts in the image (A) Signup and view all the answers

What is the purpose of a Diffusion-MRI pulse sequence?

To measure the diffusion of nuclei (D) Signup and view all the answers

What is the source of contrast in an MRI image?

Any NMR observable with a spatial dependence (D) Signup and view all the answers

What is the effect of chemical shift on the NMR signal?

It causes a small change in resonance frequency (C) Signup and view all the answers

Why are superconducting magnets used in MRI machines?

Because they can be kept at extremely low temperatures (A) Signup and view all the answers

What is the purpose of an oxygen sensor in an MRI facility?

To prevent asphyxiation in case of a magnet quench (B) Signup and view all the answers

What is the effect of increasing B0 on the acquired signal?

The signal becomes stronger (D) Signup and view all the answers

What is the advantage of using an RF coil that is just big enough?

It increases the signal-to-noise ratio (A) Signup and view all the answers

Why are strong magnets required in MRI machines?

To increase the signal-to-noise ratio (D) Signup and view all the answers

What happens to an MRI magnet when it is not in use?

It remains on, even when the machine is turned off (A) Signup and view all the answers

What is the effect of a local distortion of the magnetic field on the MRI image?

It causes some parts of the sample to appear in the wrong place. (D) Signup and view all the answers

What is the purpose of introducing a contrast agent in MRI?

To change the relaxation properties of a specific tissue. (B) Signup and view all the answers

What type of image is obtained when the relaxation properties of the tissue are weighted?

T1-weighted image. (A) Signup and view all the answers

What is the term for the movement of nuclei in a magnetic field?

Precession. (C) Signup and view all the answers

What is the cause of the artifact in the MRI image if the acquisition parameters are improperly set?

Incorrect setting of the imaging pulse sequence. (B) Signup and view all the answers

What is the term for the probability of finding a nucleus in a particular position?

Q-space probability. (D) Signup and view all the answers