Tissue Magnetization And Relaxation

Outline

Mind Map

Learning Objectives

Teaching Visuals

Online Module
(Requires Enrollment)

Text Reference

 

Outline and Learning Guide


INTRODUCTION AND OVERVIEW

TISSUE MAGNETIZATION

Magnetic Direction

Magnetic Flipping

Flip Angle

The 90 Pulse, Saturation, and Excitation

LONGITUDINAL MAGNETIZATION AND RELAXATION

T1 Contrast

Molecular Size

Magnetic Field Strength Effect

TRANSVERSE MAGNETIZATION AND RELAXATION

T2 Contrast

Proton De-phasing

T2 Tissue Characteristics

T2* Magnetic Field Effects

MAGNETIC SUSCEPTIBILITY

Contrast Agents

Diamagnetic Materials

Paramagnetic Materials

Superparamagnetic Materials

Ferromagnetic Materials

MIND MAP and SUMMARY

 

 

 

Learning Objectives

 
  • Explain the difference between longitudinal and transverse magnetization of tissue.
     
  • Explain how, and under what conditions, longitudinal tissue magnetization is produced.
     
  • Explain how transverse magnetization is produced.
     
  • Describe the concept and significance of RF pulse flip angle.
     
  • Describe the two possible states or conditions (with respect to time) that longitudinal magnetization will always be in.
     
  • Describe the general state or condition (with respect to time) that transverse magnetization will always be in.
     
  • Sketch a graph and describe the general relationship between longitudinal magnetization and time.
     
  • Explain and illustrate how T1 values apply to longitudinal magnetization growth (relaxation).
     
  • Sketch a graph showing longitudinal magnetization versus time for two tissues with different T1 values. Mark the area that represents T1 contrast.
     
  • Identify the primary tissue chemical characteristic that determines its T1 value.
     
  • Describe the general relationship between T1 values and magnetic field strength.
     
  • Know the approximate T1 and T2 values for common tissues and fluid.
     
  • Draw graphs showing the relationship between transverse magnetization and time for two tissues with different T2 values.
     
  • Describe the relationship of T2 values to the rate of transverse magnetization decay.
     
  • Describe the basic process involving protons within tissue that produces transverse magnetization relaxation.
     
  • Distinguish between T2 and T2* (called T2 star).
     
  • Sketch graphs of transverse magnetization versus time for two tissues with different T2 values. Mark the area that represents T2 contrast.
     
  • Describe the phase relationship of protons and the de-phasing that occurs during transverse magnetization relaxation.
     
  • Explain the concept of magnetic susceptibility of a material.
     
  • Explain in general terms how contrast agents work in MRI.
     
  • Briefly describe the process of "spin-spin" relaxation.
     
  • Describe the effect of magnetic field inhomogeneity on transverse magnetization relaxation.
 

 

Text Reference

Chapter 4

Magnetic Resonance Imaging: Principles, Methods, and Techniques
Medical Physics Publishing,  http://www.medicalphysics.org

 

 

Mind Map