Mastering Image Contrast in Medical Imaging
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Questions and Answers

Which of the following parameters controls the length of a relaxation period after the application of one RF excitation pulse to the beginning of the next?

  • Flip angle (FA)
  • Echo time (TE)
  • Turbo-factor or echo train length (ETL/TF)
  • Repetition time (TR) (correct)

    • What is the time between an RF excitation pulse and the collection of the signal called?

  • Echo time (TE) (correct)
  • Flip angle (FA)
  • Turbo-factor or echo train length (ETL/TF)
  • Repetition time (TR)

    • Which parameter reflects the strength and timing of the gradients used to generate diffusion-weighted images?

  • b-value (correct)
  • Repetition time (TR)
  • Echo time (TE)
  • Flip angle (FA)

    • Which contrast mechanism is a measure of the magnitude of diffusion within tissue?

    <p>Apparent diffusion coefficient (ADC)</p> Signup and view all the answers

    Which process is responsible for the recovery of longitudinal magnetization?

    <p>T1 recovery</p> Signup and view all the answers

    What is the process called when the amount of magnetization in the transverse plane gradually decreases?

    <p>T2 decay</p> Signup and view all the answers

    What are the three mechanisms that obtain contrast in MRI images?

    <p>T1 recovery, T2 decay, and proton density</p> Signup and view all the answers

    Contrast in an MRI image refers to

    <p>The difference in signal strength between high signal areas and low signal areas</p> Signup and view all the answers

    What is the purpose of creating contrast in an MRI image?

    <p>To distinguish between different structures/tissues/pathologies</p> Signup and view all the answers

    Which of the following is NOT a contrast mechanism in MRI?

    <p>Scanning pulse sequences</p> Signup and view all the answers

    What is the definition of contrast in an MRI image?

    <p>The difference in signal strength between high signal areas and low signal areas</p> Signup and view all the answers

    Which of the following is NOT a factor affecting image contrast in MRI?

    <p>Image resolution</p> Signup and view all the answers

    What is the mean of angiography in MRI?

    <p>The study of blood vessels using MRI</p> Signup and view all the answers

    What is the purpose of contrast agents in MRI?

    <p>To enhance the visualization of certain tissues/pathologies</p> Signup and view all the answers

    Which of the following is true about T1-weighted images?

    <p>They use a short TR and exhibit bright fat and dark fluid.</p> Signup and view all the answers

    What does the T1 time of a tissue represent?

    <p>The time it takes for 63% of the longitudinal magnetization to recover.</p> Signup and view all the answers

    How does the TR affect T1 contrast in an MRI image?

    <p>A shorter TR results in stronger T1 weighting.</p> Signup and view all the answers

    What is the main cause of dephasing in an MR signal?

    <p>Field inhomogeneity.</p> Signup and view all the answers

    Why is T2 an image contrast parameter?

    <p>Different tissues have different T2 dephasing rates.</p> Signup and view all the answers

    What is the most marked difference in T1 recovery rates?

    <p>Between fat and pure water.</p> Signup and view all the answers

    What is the role of the TR in T1 contrast?

    <p>To control the recovery of the magnetic vectors.</p> Signup and view all the answers

    Which of the following is true about T2* decay in water molecules in comparison to solid bone?

    <p>T2* decay occurs at a slower rate in water molecules</p> Signup and view all the answers

    What is the purpose of waiting for a certain time period after the application of the 90° Pulse before sampling the returning signal in MRI?

    <p>To increase the contrast between tissues</p> Signup and view all the answers

    Which of the following statements about fat in MRI is true?

    <p>Fat returns an intermediate signal</p> Signup and view all the answers

    What is the echo time (TE) in MRI?

    <p>The time between application of the excitation pulse and collection of the MR signal</p> Signup and view all the answers

    What happens to the signal differences between tissues when a short echo time (TE) is used in MRI?

    <p>The signal differences between tissues become smaller</p> Signup and view all the answers

    What happens to the signal differences between tissues when a long echo time (TE) is used in MRI?

    <p>The signal differences between tissues become larger</p> Signup and view all the answers

    What type of image is obtained with a long echo time (TE) in MRI?

    <p>T2-weighted image</p> Signup and view all the answers

    What does proton density refer to in MRI?

    <p>The number of hydrogen nuclei present within a given volume of tissue</p> Signup and view all the answers

    What is the purpose of a proton density weighted image in MRI?

    <p>To enhance proton density contrast</p> Signup and view all the answers

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