Recent

  • Show all results for ""

🎧 New: AI-Generated Podcasts Turn your study notes into engaging audio conversations. Learn more

MRI Questions
50 Questions
0 Views

MRI Questions

Created by
@GladEnlightenment

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the difference in resonant frequency between fat and water protons at 1.5 T?

  • 430 Hz
  • 215 Hz (correct)
  • 3.4 ppm
  • 3.4 x 10-6

    • What is the most common cause of chemical shift artifacts?

  • Respiration
  • Swallowing
  • Fat surrounding water-containing structures (correct)
  • Cardiac pulsation

    • What is the purpose of gradients coils in MRI?

  • To distort the main magnetic field
  • To encode the MR signal in space (correct)
  • To measure SAR
  • To measure tissue temperature

    • What is the most common way for T2 relaxation to occur?

    <p>Local static field disturbance</p> Signup and view all the answers

    What type of energy loss occurs when the spin system is in a pure state of rotation?

    <p>Spin-up relaxation</p> Signup and view all the answers

    What is the most effective way to reduce truncation errors in the Fourier representation of images?

    <p>Reducing the field of view</p> Signup and view all the answers

    What type of energy loss occurs when the spin system is in a spin-up state and energy is transferred into nearby nuclei, atoms, and molecules?

    <p>T1-relaxation</p> Signup and view all the answers

    How is the FID signal generated?

    <p>Precession of the magnetization vector around the z-axis</p> Signup and view all the answers

    How is the z-gradient produced?

    <p>By using two Maxwell coils carrying current in opposite directions</p> Signup and view all the answers

    How does Philips define receiver bandwidth?

    <p>The fat/water shift in pixels</p> Signup and view all the answers

    What type of noise levels can cause permanent threshold shifts (PTS)?

    <p>130-140 dB</p> Signup and view all the answers

    What is the partial volume effect?

    <p>A concept well recognized in cross-sectional imaging</p> Signup and view all the answers

    What is the relationship between SAR and RF frequency?

    <p>SAR is proportional to the square of the RF frequency</p> Signup and view all the answers

    What is the peak of the echo caused by?

    <p>The area under the readout gradient</p> Signup and view all the answers

    What is the effect of making TE short compared to T2?

    <p>T2 effects largely disappear</p> Signup and view all the answers

    What is the purpose of reducing the height of the readout gradient but increasing its width?

    <p>To increase the sampling time of the MR signal</p> Signup and view all the answers

    How does SAR affect tissue temperature?

    <p>It is one of many factors that determine tissue temperature</p> Signup and view all the answers

    What is the most common artifact seen around water-containing structures?

    <p>Chemical shift artifacts</p> Signup and view all the answers

    What type of protection is mandatory for all patients undergoing MRI?

    <p>Ear protection</p> Signup and view all the answers

    What is the time between the 180° inverting pulse and the 90°-pulse in an inversion recovery (IR) sequence?

    <p>Inversion time (TI</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    What is the most effective way to reduce artifacts caused by physiologic motions?

    <p>Increasing the number of phase-encode steps</p> Signup and view all the answers

    What is the unit of measurement for receiver bandwidth?

    <p>Hz</p> Signup and view all the answers

    What is the effect of certain medications on thermoregulatory responses?

    <p>They impair thermoregulatory responses</p> Signup and view all the answers

    What is the main purpose of an inversion recovery (IR) sequence?

    <p>To decrease signal intensity</p> Signup and view all the answers

    What is the relationship between the signal intensity (S) of a SE sequence and [H]?

    <p>S is directly proportional to [H]</p> Signup and view all the answers

    What does Ampère's Law describe?

    <p>The direction and magnitude of gradient fields</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body, depending on the level of stimulus that is being used?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    What type of images are produced by different methods and have different properties?

    <p>SE and GRE images</p> Signup and view all the answers

    What technique may be used to reduce truncation artifacts while still maintaining image quality?

    <p>Post-processing optimization techniques</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body, depending on the type of stimulus that is being used and the time that the stimulus is being applied?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    What does FOV stand for?

    <p>Field of View</p> Signup and view all the answers

    What direction are artifacts most prominent in?

    <p>Phase-encode</p> Signup and view all the answers

    What is the relationship between SAR and RF-flip angle?

    <p>SAR is proportional to the square of the RF-flip angle</p> Signup and view all the answers

    What is the purpose of a RF-pulse?

    <p>To induce a current in the receiver coils</p> Signup and view all the answers

    What is the effect of making TE long compared to T2?

    <p>T2 effects become more pronounced</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body, depending on the type of stimulus that is being used and the time that the stimulus is being applied, and the type of relaxation that is taking place?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    How are MR images produced?

    <p>With RF pulses</p> Signup and view all the answers

    What is the effect of body size on SAR?

    <p>It increases significantly with body size</p> Signup and view all the answers

    What is the most common artifact seen around fat?

    <p>Chemical shift artifacts</p> Signup and view all the answers

    What is the right-hand rule used for?

    <p>To describe the direction and magnitude of gradient fields</p> Signup and view all the answers

    What is the purpose of T1 relaxation?

    <p>To cause T2 relaxation</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body, depending on the type of stimulus that is being used and the time that the stimulus is being applied, and the type of relaxation that is taking place, and the type of magnetic field that is being used?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    What is the relationship between FOV and the spacing between samples in k-space?

    <p>FOV is inversely proportional to the spacing between samples</p> Signup and view all the answers

    What is the most effective way to reduce artifacts propagated in the phase?

    <p>Increasing the number of phase-encode steps</p> Signup and view all the answers

    What is the purpose of the dephase lobe?

    <p>To nullify the phase dispersal</p> Signup and view all the answers

    What is the effect of regional perfusion on tissue temperature?

    <p>It has no effect on tissue temperature</p> Signup and view all the answers

    What is the most effective way to minimize truncation errors?

    <p>Decreasing the number of phase-encode steps</p> Signup and view all the answers

    What type of MRI is used to image the body in different parts of the body, depending on the type of stimulus that is being used and the time that the stimulus is being applied, and the type of relaxation that is taking place, and the type of magnetic field that is being used, and the type of person that is being scanned?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    When was the use of fast spin echo (FSE) signal generation introduced?

    <p>Late 1990's</p> Signup and view all the answers

    Study Notes

    • Gradients coils are used to encode the MR signal in space.
    • Gradients are created by sending current in opposite directions through coils, and they produce a gradient field that slightly distorts the main magnetic field.
    • The direction and magnitude of gradient fields can be appreciated by using Ampère's Law and the right-hand rule.
    • The z-gradient is produced using two coils carrying current in opposite directions, and this is known as a Maxwell coil configuration.
    • When added to the constant (Bo) field, the result is a gradually increasing field along the z-axis.
    • SAR is a measure of the amount of power deposited by a radiofrequency field in a certain mass of tissue.
    • SAR increases significantly with body size.
    • SAR is proportional to the square of the RF frequency.
    • SAR is proportional to the square of the RF-flip angle.
    • SAR is a measure of the intensity of RF radiation.
    • SAR is only one factor that determines tissue temperature.
    • Certain factors, like regional perfusion, baseline patient body temperature, and the patient's thermoregulatory capacity, can also affect tissue temperature.
    • Overheating is a risk for patients with reduced thermoregulatory capacities, like infants, pregnant women, the elderly, obese, diabetics, febrile patients, and those with cardiac decompensation.
    • Certain medications, like beta-blockers, diuretics, calcium-channel blockers, amphetamines, and sedatives, can also impair thermoregulatory responses.
    • These factors should always be considered when scanning a susceptible patient, even if predicted SAR values seem to be within safe limits.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    More Quizzes Like This

    MRI Imaging Quiz
    9 questions

    MRI Quiz: Test Your Knowledge with MRI Imaging Questions

    HandsomeEuler avatar
    HandsomeEuler
    MRI Brain Imaging Basics Quiz
    18 questions

    MRI Brain Anatomy Quiz: Test Your Knowledge of Brain Imaging Basics

    FruitfulLandArt avatar
    FruitfulLandArt
    MRI Exam #1 Flashcards
    38 questions

    MRI Exam #1 Flashcards

    AudibleFresno2256 avatar
    AudibleFresno2256
    MRI Anatomy Quiz - Abdomen Images
    16 questions

    MRI Anatomy Quiz - Abdomen Images

    InvulnerableGold2463 avatar
    InvulnerableGold2463
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser