WK 4: MRI Basics
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Questions and Answers

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?

    <p>Because it uses magnetic fields instead of radiation</p> Signup and view all the answers

    What is the significance of spin in NMR and MRI?

    <p>It is an intrinsic property of atomic nuclei</p> Signup and view all the answers

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

    <p>They provide information otherwise unobtainable</p> Signup and view all the answers

    Which type of contrast does MRI excel at?

    <p>Soft tissue contrast</p> Signup and view all the answers

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

    <p>Insufficient signal strength</p> Signup and view all the answers

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

    <p>The spins align with the magnetic field</p> Signup and view all the answers

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

    <p>Patient's body temperature</p> Signup and view all the answers

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

    <p>It has the highest natural abundance</p> Signup and view all the answers

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

    <p>Isotopically labelled samples</p> Signup and view all the answers

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

    <p>10 μm</p> Signup and view all the answers

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

    <p>To discriminate between different regions of tissue</p> Signup and view all the answers

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

    <p>It causes artifacts in the image</p> Signup and view all the answers

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

    <p>To measure the diffusion of nuclei</p> Signup and view all the answers

    What is the source of contrast in an MRI image?

    <p>Any NMR observable with a spatial dependence</p> Signup and view all the answers

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

    <p>It causes a small change in resonance frequency</p> Signup and view all the answers

    Why are superconducting magnets used in MRI machines?

    <p>Because they can be kept at extremely low temperatures</p> Signup and view all the answers

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

    <p>To prevent asphyxiation in case of a magnet quench</p> Signup and view all the answers

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

    <p>The signal becomes stronger</p> Signup and view all the answers

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

    <p>It increases the signal-to-noise ratio</p> Signup and view all the answers

    Why are strong magnets required in MRI machines?

    <p>To increase the signal-to-noise ratio</p> Signup and view all the answers

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

    <p>It remains on, even when the machine is turned off</p> Signup and view all the answers

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

    <p>It causes some parts of the sample to appear in the wrong place.</p> Signup and view all the answers

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

    <p>To change the relaxation properties of a specific tissue.</p> Signup and view all the answers

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

    <p>T1-weighted image.</p> Signup and view all the answers

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

    <p>Precession.</p> Signup and view all the answers

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

    <p>Incorrect setting of the imaging pulse sequence.</p> Signup and view all the answers

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

    <p>Q-space probability.</p> Signup and view all the answers

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