MR Physics: Precessional Phase and Resonance
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Questions and Answers

Which of the following does not fall under the operator's control in MRI?

  • Proton density
  • Echo train length
  • Flow
  • T1 recovery (correct)

    • What does the Apparent Diffusion Coefficient (ADC) measure?

  • The magnitude of diffusion of water molecules within tissue (correct)
  • The balance between opposing magnetic forces
  • The rapid movement of electrons
  • The strength of a magnetic field

    • What is meant by dephasing in MRI?

  • The acquisition of high-resolution images
  • The alignment of magnetic fields
  • The introduction of external magnetic fields
  • The loss of phase coherence of signals within the transverse plane (correct)

    • What is the purpose of excitation in MRI?

    <p>To induce energy into the spinning nuclei using radiofrequency pulses</p> Signup and view all the answers

    What is an electromagnet?

    <p>A magnet formed by electric current flowing through wire coils</p> Signup and view all the answers

    What does precessional phase refer to when magnetic moments of hydrogen are involved?

    <p>Magnetic moments are at different places on the precessional path.</p> Signup and view all the answers

    Which statement best describes resonance in the context of MRI?

    <p>It happens when an oscillating force matches the Larmor frequency.</p> Signup and view all the answers

    What happens to the NMV when the RF excitation pulse is switched off?

    <p>It attempts to realign with B0.</p> Signup and view all the answers

    What is the process called when hydrogen nuclei lose energy after the RF pulse is turned off?

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

    What does dephasing in MRI indicate?

    <p>Magnetic moments become incoherent due to field inhomogeneities.</p> Signup and view all the answers

    What is the role of Faraday's law in MRI?

    <p>It explains how motion and electricity can produce magnetic fields.</p> Signup and view all the answers

    What occurs simultaneously with the relaxation of hydrogen nuclei?

    <p>Dephasing of magnetic moments occurs.</p> Signup and view all the answers

    What is the result of hydrogen nuclei being exposed to an RF pulse?

    <p>They absorb energy and become excited.</p> Signup and view all the answers

    What is the term for the signal that decays due to the transverse coherent magnetization decreasing?

    <p>Free induction decay (FID)</p> Signup and view all the answers

    What does the TR parameter determine in the context of RF excitation pulses?

    <p>The amount of longitudinal relaxation occurring</p> Signup and view all the answers

    How is the TE parameter defined?

    <p>Time from RF excitation pulse to signal collection peak</p> Signup and view all the answers

    Which of the following is NOT considered an extrinsic contrast parameter?

    <p>Spin density</p> Signup and view all the answers

    What does increasing the flip angle do in an imaging scenario?

    <p>Changes the NMV orientation during RF pulses</p> Signup and view all the answers

    Which parameter reflects the timing of gradients used to create diffusion-weighted images?

    <p>'b' value</p> Signup and view all the answers

    What effect does the TE parameter have on T2 relaxation when reading the signal?

    <p>It determines how much T2 relaxation has occurred.</p> Signup and view all the answers

    In what unit is the TR measurement expressed?

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

    What occurs when the magnetic moments of hydrogen gain energy from an external source?

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

    What phenomenon results from the magnetic moments of hydrogen aligning with each other after being affected by resonance?

    <p>Coherence restoration</p> Signup and view all the answers

    During the free induction decay (FID) signal, what primarily influences the net magnetization vector (NMV) after the RF excitation pulse is turned off?

    <p>B0 field</p> Signup and view all the answers

    What process describes the return of high-energy hydrogen nuclei to a low-energy population after the RF pulse is shut off?

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

    What leads to the dephasing of magnetic moments in hydrogen after RF excitation?

    <p>Inhomogeneities in the B0 field</p> Signup and view all the answers

    What is the condition of magnetic moments being in different places on the precessional path at a specific moment called?

    <p>Precessional phase</p> Signup and view all the answers

    What is the phenomenon when an object is exposed to a frequency similar to its natural oscillation frequency?

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

    What process is primarily responsible for the signal captured in MRI during relaxation?

    <p>Magnetic energy decay</p> Signup and view all the answers

    Which of the following terms describes the loss of phase coherence in MRI?

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

    What is the term for the spacing between each echo in a Fast Spin Echo (FSE) sequence?

    <p>Echo spacing</p> Signup and view all the answers

    Which of the following best describes an electromagnet?

    <p>A magnet that uses wire coils to generate a magnetic field</p> Signup and view all the answers

    What does the term 'Apparent Diffusion Coefficient (ADC)' indicate?

    <p>The measurement of water molecule diffusion in tissue</p> Signup and view all the answers

    In MRI, what is the effective TE referred to?

    <p>The time between the echo and the RF pulse that initiated it</p> Signup and view all the answers

    What signal is produced as the transverse coherent magnetization decreases?

    <p>Free induction decay (FID) signal</p> Signup and view all the answers

    How does TR affect the imaging process in MRI?

    <p>It influences the amount of T1 relaxation before the next RF pulse</p> Signup and view all the answers

    What does TE specifically control in MRI imaging?

    <p>The amount of T2 relaxation occurring in the signal</p> Signup and view all the answers

    Which of the following is NOT considered an extrinsic contrast parameter in MRI?

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

    What primarily influences the decay of the voltage induced in the receiver coil?

    <p>Magnitude of transverse coherent magnetization</p> Signup and view all the answers

    Which statement best describes flip angle in the context of MRI?

    <p>It refers to the angle through which the NMV is moved by the RF pulse.</p> Signup and view all the answers

    Which parameter specifically affects the decay period following the removal of an RF excitation pulse?

    <p>Echo time (TE)</p> Signup and view all the answers

    What role does the 'b' value play in MRI imaging?

    <p>It reflects the strength and timing of the gradients for diffusion-weighted images.</p> Signup and view all the answers

    Which factor is considered an intrinsic contrast mechanism in MRI?

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

    What characterizes the term 'dephasing' in MRI?

    <p>The loss of phase coherence of signals</p> Signup and view all the answers

    Which of the following is primarily involved in achieving resonance in MRI?

    <p>The delivery of RF energy</p> Signup and view all the answers

    Which parameter is affected by the timing of RF pulses in an MRI sequence?

    <p>Effective TE</p> Signup and view all the answers

    In the context of MRI, what does the term 'electromagnet' refer to?

    <p>A magnet that utilizes coils of wire</p> Signup and view all the answers

    How does the net magnetization vector (NMV) behave during the free induction decay (FID) signal after the RF pulse is turned off?

    <p>It tries to realign with B0 while undergoing relaxation.</p> Signup and view all the answers

    What does the free induction decay (FID) signal primarily result from?

    <p>The decrease in transverse coherent magnetization</p> Signup and view all the answers

    What effect does dephasing have on the magnetic moments of hydrogen nuclei over time?

    <p>It leads to a loss of phase coherence in the magnetic moments.</p> Signup and view all the answers

    What is the relationship between resonance and the energy acquired by a nucleus?

    <p>Resonance allows the nucleus to gain energy from an external force.</p> Signup and view all the answers

    Which factor directly influences the amount of T1 relaxation before the signal is read?

    <p>Repetition time (TR)</p> Signup and view all the answers

    What is the significance of echo time (TE) in MRI signal acquisition?

    <p>It controls the amount of T2 relaxation that has occurred</p> Signup and view all the answers

    Which factor primarily contributes to the recovery process during FID in MRI?

    <p>The magnetic moments aligning with each other.</p> Signup and view all the answers

    What does the flip angle impact in MRI imaging?

    <p>The orientation of the net magnetization vector (NMV)</p> Signup and view all the answers

    Which of the following is a consequence of an RF pulse affecting the magnetic moments of hydrogen nuclei?

    <p>The magnetic moments move out of alignment with B0.</p> Signup and view all the answers

    In the context of MRI, what does increasing the turbo-factor (ETL/TF) affect?

    <p>The efficiency of signal acquisition</p> Signup and view all the answers

    What does the term Larmor frequency refer to in the context of a nucleus in MRI?

    <p>The natural frequency of a nucleus's magnetic moment.</p> Signup and view all the answers

    What primarily drives the process of relaxation in hydrogen nuclei following RF excitation?

    <p>Loss of energy to the surrounding environment.</p> Signup and view all the answers

    Which parameter influences the timing of gradients for generating diffusion-weighted images?

    <p>The 'b' value</p> Signup and view all the answers

    What is the effect of a shorter repetition time (TR) on imaging?

    <p>It decreases the amount of T1 relaxation</p> Signup and view all the answers

    Which situation best describes precessional phase in MRI?

    <p>Magnetic moments are out of phase with each other.</p> Signup and view all the answers

    Which of the following best defines the role of echo time (TE) in MRI?

    <p>It measures the decay period of transverse magnetization</p> Signup and view all the answers

    Which parameter is NOT typically considered an intrinsic contrast mechanism in MRI?

    <p>Signal-to-noise ratio</p> Signup and view all the answers

    What is primarily affected by the equilibrium state in MRI?

    <p>Magnetization of tissue</p> Signup and view all the answers

    In the context of MRI, which of the following reflects the characteristics of an electromagnet in use?

    <p>It is influenced by the presence of a coil and current.</p> Signup and view all the answers

    Which factor contributes the least to the loss of phase coherence in the transverse plane during MRI?

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

    What is the overall purpose of echo train length (ETL) in MRI sequences?

    <p>To optimize the balance between time and signal acquisition</p> Signup and view all the answers

    What primarily determines the amount of T1 relaxation by the time the signal is read?

    <p>The repetition time (TR)</p> Signup and view all the answers

    Which of the following best describes how echo time (TE) impacts the MRI signal?

    <p>It influences how much T2 relaxation has occurred by the time the signal is read.</p> Signup and view all the answers

    Which parameter is affected by the timing of gradients in diffusion-weighted imaging?

    <p>b value</p> Signup and view all the answers

    What is the relationship between TR and the signal decay in MRI?

    <p>TR affects how much longitudinal relaxation occurs before signal acquisition.</p> Signup and view all the answers

    What occurs to the net magnetization vector (NMV) after it is influenced only by B0 post RF excitation pulse?

    <p>The NMV seeks to realign with B0</p> Signup and view all the answers

    Which factor directly contributes to the phenomenon of resonance in MRI?

    <p>The oscillation frequency of the RF pulse</p> Signup and view all the answers

    In MRI, which parameter describes the angle through which the net magnetization vector is rotated?

    <p>Flip angle (FA)</p> Signup and view all the answers

    What role does dephasing play in MRI signal integrity?

    <p>It leads to loss of coherence among magnetic moments</p> Signup and view all the answers

    How does a greater flip angle typically affect MRI imaging?

    <p>It can improve the contrast of the images.</p> Signup and view all the answers

    What is the expected behavior of hydrogen nuclei's magnetic moments during the process of relaxation?

    <p>They return to align with B0 while losing energy</p> Signup and view all the answers

    What is the primary effect of the time from inversion (TI) on MR imaging?

    <p>It affects the timing of signal acquisition after inversion pulses.</p> Signup and view all the answers

    In MRI, what consequence arises from the inhomogeneities present in the B0 field?

    <p>Contributing to dephasing of magnetic moments</p> Signup and view all the answers

    Which of the following best describes the effect of echo train length (ETL) on MRI?

    <p>It affects the number of echoes obtained per sequence.</p> Signup and view all the answers

    How does the Faraday law relate to the generation of MRI signals?

    <p>It relates motion of charges to changes in magnetic fields</p> Signup and view all the answers

    Which statement best characterizes the frequency at which a nucleus resonates?

    <p>It corresponds to the natural frequency of its magnetic moment</p> Signup and view all the answers

    What is the impact of external RF perturbation on hydrogen nuclei in MRI?

    <p>It energizes the nucleus, allowing greater signal generation</p> Signup and view all the answers

    Study Notes

    Precessional Phase

    • Hydrogen magnetic moments line up at the same place on the precessional path at a given time.
    • If hydrogen magnetic moments are at different positions on the precessional path, they are not in phase.

    Resonance

    • Occurs when an object is exposed to an oscillating perturbation close to its natural frequency of oscillation.
    • When a nucleus is exposed to an external force that oscillates similarly to its magnetic moment's natural frequency (Larmor frequency), it gains energy.

    ### MR Signal

    • Motion + electricity = magnet (Faraday's law).
    • MR signal generated when hydrogen nuclei precess in a non-uniform magnetic field.
    • NMV (Net Magnetization Vector) moves away from B0 (Main Magnetic Field) during resonance.
    • Hydrogen magnetic moments move into phase with each other during resonance.
    • The FID (Free Induction Decay) signal is the decaying voltage induced in the receiver coil as transverse magnetization decreases, resulting from spin dephasing and relaxation.
    • The FID signal is caused by spins freely precessing influenced by B0 alone, decaying with time and inducing a current in the receiver coil.

    ### Pulse Timing Parameters

    • TR (Repetition Time): The time between two RF excitation pulses (milliseconds).
    • Affects the amount of longitudinal relaxation between pulses.
    • Determines the amount of T1 relaxation before reading the signal.
    • TE (Echo Time): The time between an RF excitation pulse and the peak of the signal in the receiver coil (milliseconds).
    • Affects the amount of transverse magnetization decay.
    • Determines the amount of T2 relaxation before reading the signal.

    ### Extrinsic Contrast Parameters

    • Controlled by the MRI system operator.
    • Examples include:
      • TR (Repetition Time)
      • TE (Echo Time)
      • Flip Angle
      • Turbo factor/Echo Train length (ETL/TF)
      • Time from Inversion (TI)
      • 'b' value: reflects the strength and timing of diffusion-weighted gradients

    Intrinsic Contrast Mechanism

    • Not controlled by the operator.
    • Examples include:
      • T1 recovery
      • T2 decay
      • Proton density
      • Flow
      • ADC (Apparent Diffusion Coefficient)

    ### MRI Terms

    • Dephasing: Loss of phase coherence of signals in the transverse plane.
    • Diffusion: Movement of molecules due to random thermal motion.
    • Dipole: Magnetic field with north and south poles separated by a distance.
    • Display Matrix: Number of pixels in an image, determined by the product of phase and frequency axis.
    • Electromagnet: Magnet using coils of wire, typically wound on an iron core, that becomes magnetized when current flows through the coil.
    • Equilibrium: A state of balance between opposing forces.
    • Excitation: Delivering energy to spinning nuclei with radiofrequency pulses, putting them in a higher energy state.
    • Echo spacing: Spacing between each echo in FSE (Fast Spin Echo) sequences.
    • Echo train: Series of 180° rephasing pulses and echoes in FSE sequences.
    • Echo train length (ETL): Number of 180° RF pulses and echoes in FSE sequences.
    • Effective TE: Time between an echo and the RF pulse that initiated it in SSFP (Steady State Free Precession) and FSE sequences.
    • Electron Orbit: Electrons orbiting the nucleus in distinct shells, carrying negative charges.
    • External Magnetic Field (EMF): A changing magnetic field inducing an electric field, driving a current in a circuit.

    MRI Basics

    • Precessional Phase: Hydrogen nuclei have magnetic moments that spin in a similar phase, aligned in a specific direction along the precession path.
    • Resonance: A phenomenon where an object absorbs energy from an external source when the source's oscillation frequency is close to the object's natural frequency.
    • MR Signal: The signal produced by MRI comes from the magnetic moments of hydrogen nuclei, which are aligned in a specific direction by an external magnetic field.
    • Free Induction Decay (FID) Signal: The FID signal is the decaying voltage induced in the receiver coil as the net magnetization (NMV) returns to its equilibrium state. This occurs because hydrogen nuclei lose energy and their magnetic moments dephase.
    • Pulse Timing Parameters:
      • TR (Repetition Time): Time between two consecutive RF pulses for a single slice. Determines the amount of longitudinal relaxation that occurs before the next pulse.
      • TE (Echo Time): Time between the RF pulse and the peak of the signal. Determines the amount of transverse magnetization decay that occurs.
      • Flip Angle: Angle to which the NMV is rotated by the RF pulse.
      • Turbo-Factor/Echo Train Length (ETL/TF): The number of echoes acquired per excitation pulse.
      • Time from Inversion (TI): In inversion recovery sequences, it's the time between an inversion pulse and the 90° pulse.
      • ‘b’ value: Indicates the strength and duration of diffusion gradients used in diffusion-weighted imaging.
    • Extrinsic Contrast Parameters: Controlled by the system operator and influence contrast in MRI images. Examples include Repetition Time (TR), Echo Time (TE), Flip Angle, Turbo-Factor/Echo Train Length (ETL/TF), TI, and ‘b’ value.
    • Intrinsic Contrast Mechanisms: Not controlled by the operator but contribute to contrast:
      • T1 Recovery: The rate at which longitudinal magnetization recovers after RF excitation.
      • T2 Decay: The rate at which transverse magnetization decays.
      • Proton Density (PD): Concentration of hydrogen nuclei in a tissue.
      • Flow: The movement of fluids or blood in the body.
      • Apparent Diffusion Coefficient (ADC): Measures the rate of water diffusion in tissue.
    • Dephasing: Loss of phase coherence among signals in the transverse plane, leading to signal loss.
    • Diffusion: Random movement of molecules due to thermal energy.
    • Dipole: A magnetic field with a north and south pole, resulting from a separation of charges.
    • Display Matrix: Grid of pixels used to display MRI images.
    • Electromagnet: A magnet generated by passing electrical current through coils of wire, often wound around an iron core. Examples include Resistive Magnets and Superconducting Magnets.
    • Equilibrium: A state of balance where opposing forces are equal.
    • Excitation: Transfer of energy to nuclei via radiofrequency pulses, putting them into a higher energy state and producing a measurable signal.
    • Echo Spacing: Time between two consecutive echoes in a fast spin echo (FSE) sequence.
    • Echo Train: A series of 180° rephasing pulses and echoes in an FSE sequence.
    • Echo Train Length (ETL): The number of 180° RF pulses or the turbo factor, which determines the number of echoes acquired per excitation pulse in an FSE sequence.
    • Effective TE: Time between a particular echo and the RF pulse that initiated it in steady-state free precession (SSFP) and FSE sequences.
    • Electrons Orbit: Negatively charged particles that orbit the nucleus of an atom in discrete shells.
    • External Magnetic Field (EMF): A magnetic field produced externally, which influences the magnetic moments of hydrogen nuclei in MRI.

    Precessional Phase

    • When hydrogen's magnetic moments are at the same place on the precessional path at a given time, the nuclear magnetic moments (NMV) are in phase.
    • When they are at different places on the precessional path at a given time, the NMV are out of phase.

    Resonance

    • Objects exposed to an oscillating perturbation close to their natural frequency of oscillation undergo resonance.
    • Nuclei exposed to an external force with oscillation similar to their Larmor frequency gain energy from the external source.

    Result of Resonance

    • NMV moves out of alignment with B0.
    • Magnetic moments of H nuclei phase together.

    MRI Signal

    • Faraday's Law states that motion interacting with electricity generates a magnetic field.
    • Recovery re-aligns the NMV with B0 after RF pulse excitation.
    • Dephasing is the process where the NMV spins lose phase coherence.

    Free Induction Decay (FID) Signal

    • The FID signal is the voltage induced in the receiver coil as the NMV relaxes, moves back into alignment with B0, and loses phase coherence.
    • The relaxation process causes high-energy nuclei to return to the low-energy state, aligning with B0.
    • Dephasing is caused by inhomogeneities in the B0 field and interactions between spins.
    • The FID signal decays as the transverse coherent magnetization decreases.

    Pulse Timing Parameters

    • Repetition Time (TR) is the time between RF excitation pulses, measured in milliseconds.
    • TR controls the amount of longitudinal relaxation (T1) that occurs before the next RF excitation pulse.
    • Echo Time (TE) is the time between the RF excitation pulse and the peak of the signal received in the receiver coil, also measured in milliseconds.
    • TE controls the amount of transverse relaxation (T2) that happens before the signal is read.

    Extrinsic Contrast Parameters

    • These parameters are controlled by the operator, including:
      • TR: Repetition Time
      • TE: Echo Time
      • Flip Angle: The angle the NMV moves due to the RF pulse
      • Turbo Factor/Echo Train Length (ETL/TF): The number of echoes used in fast spin echo sequences.
      • Time from Inversion (TI): In inversion recovery sequences, the time between the inversion pulse and the excitation pulse.
      • b-value: Measure of the strength and timing of diffusion gradients used in diffusion-weighted imaging.

    Intrinsic Contrast Mechanism

    • These parameters are not controlled by the operator and are influenced by the tissue itself:
      • T1 Relaxation: The rate of recovery of longitudinal magnetization.
      • T2 Relaxation: The rate of decay of transverse magnetization.
      • Proton Density: The concentration of hydrogen atoms in a tissue.
      • Flow: The movement of fluids within a tissue.
      • Apparent Diffusion Coefficient (ADC): Measure of how fast water molecules diffuse within a tissue.

    MRI Terms

    • Dephasing: Loss of phase coherence of signals in the transverse plane.
    • Diffusion: Random thermal motion of molecules.
    • Dipole: A magnetic field with its own north and south poles.
    • Display Matrix: The number of pixels in the image, defined by the phase and frequency axes.
    • Electromagnet: A magnet created by current flowing through coils of wire.
    • Equilibrium: A state of balance between opposing forces.
    • Excitation: The process of energizing nuclei with RF pulses to create transverse magnetization.
    • Echo Spacing: The time between echoes in fast spine echo sequences.
    • Echo Train: A series of echoes generated by rephasing pulses in fast spin echo sequences.
    • Echo Train Length (ETL): The number of echoes or turbo factor in fast spin echo sequences.
    • Effective TE: The time between an echo and the RF pulse initiating it in SSFP and FSE.
    • Electron Orbit: Electrons orbiting the nucleus in shells.
    • External Magnetic Field (EMF): A magnetic field generated by moving charges.

    Precessional Phase

    • In-phase: Magnetic moments of hydrogen are at the same place on the precessional path at a moment in time.
    • Out-of-phase: Magnetic moments of hydrogen are at different places on the precessional path at a moment in time.

    Resonance

    • Phenomenon where an object is exposed to an oscillating perturbation that has a frequency close to its own natural frequency of oscillation.
    • When a nucleus is exposed to an external force with an oscillation similar to its magnetic moment’s natural frequency (Larmor frequency) it gains energy from the external source.
    • The result of resonance:
      • The Net Magnetic Vector (NMV) moves out of alignment away from B0
      • The magnetic moments of H nuclei move into phase with each other.

    MRI Signal

    • Based on Faraday's law: Motion + electricity = magnet.
    • MRI signal is generated during the transition from precessional phase to the relaxation phase.
    • Relaxation is the process by which hydrogen loses the energy given to it by the RF excitation pulse.
    • Dephasing occurs independently of relaxation, losing coherency due to inhomogeneities in B0 field and interactions between spins in tissue.

    Free Induction Decay (FID) Signal

    • Occurs when the RF excitation pulse is switched off and the NMV is influenced only by B0.
    • The NMV realigns with B0 as the hydrogen nuclei lose energy.
    • Dephasing creates a decay in transverse coherent magnetization which reduces the magnitude of the voltage induced in the receiver coil.
    • This decaying voltage is called the FID signal because it shows the magnetic moments of spins freely precessing under the influence of B0 and the signal decays with time, inducing a current in the receiver coil.

    Pulse Timing Parameters

    • Repetition Time (TR): Time from one RF excitation pulse to the next for each slice. Measured in milliseconds.
    • Echo Time (TE): Time between the RF excitation pulse and the peak of the signal induced in the receiver coil. Measured in milliseconds.
    • Flip Angle: The angle through which the NMV is moved by an RF excitation pulse.
    • Turbo-factor or Echo Train Length (ETL/TF):
    • Time from Inversion (TI):
    • ‘b’ value: strength and timing of gradients used to generate diffusion-weighted images.

    Extrinsic Contrast Parameters

    • Controlled by the system operator
    • These include:
      • Repetition Time (TR): controls the length of relaxation period
      • Echo Time (TE): controls the length of the relaxation period after RF excitation pulse
      • Flip Angle:
      • Turbo-factor or Echo Train Length (ETL/TF)
      • Time from Inversion (TI)
      • ‘b’ value:

    Intrinsic Contrast Mechanism

    • Not controlled by the operator.
    • These include:
      • T1 Recovery:
      • T2 Decay:
      • Proton Density:
      • Flow:
      • Apparent Diffusion Coefficient (ADC): measures the magnitude of diffusion of water molecules within tissue.

    MRI Terms

    • Dephasing: Loss of phase coherence of signals in the transverse plane.
    • Diffusion: Moving molecules due to random thermal motion.
    • Dipole: A magnetic field with north and south magnetic poles separated by a finite distance.
    • Display Matrix: Total number of pixels, described by the product of phase and frequency axis.
    • Electromagnet: Magnet using coils of wire, typically wound on an iron core, producing magnetization when current flows.
    • Equilibrium: Balance between opposing forces.
    • Excitation: Inducing energy into nuclei via radiofrequency pulses.
    • Echo Spacing: Spacing between echoes in FSE.
    • Echo Train: Series of 180° rephasing pulses and echoes in a fast spin echo pulse sequence.
    • Echo Train Length (ETL): Number of 180° RF pulses, or turbo factor, resulting in echoes in FSE.
    • Effective TE: Time between the echo and the RF pulse that initiated it in SSFP and FSE sequences.
    • Electron Orbit: Electrons orbit the nucleus in distinct shells with negative charge.
    • External Magnetic Field (EMF): Drives current in a circuit induced by a changing magnetic field.

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    Description

    Test your understanding of magnetic resonance and precessional phase in hydrogen nuclei. This quiz covers key concepts like resonance, MR signals, and the dynamics of magnetic moments in a magnetic field. Enhance your knowledge of the principles that govern magnetic resonance.

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