Chapter 2

Principles of Magnetic Resonance Imaging

2.1 Introduction

2.2 Nuclear Magnetic Resonance

2.2.1 The Quantum Mechanical description of NMR
2.2.2 The Classical Description of NMR
2.2.3 Relaxation and Signal Detection
2.2.4 Chemical Shift and Magnetic Resonance Spectroscopy

2.3 Magnetic Resonance Imaging

2.3.1 Magnetic Field Gradients
2.3.2 Reciprocal (k) Space
2.3.3 Slice Selection
2.3.4 Early MR Imaging Techniques
2.3.5 Fourier and Echo Planar Imaging
2.3.6 Other Imaging Sequences

2.4 Image Contrast in Biological Imaging

2.4.1 T₁ Contrast
2.4.2 T₂^* Contrast
2.4.3 T₂ Contrast
2.4.4 Flow and Diffusion Contrast

2.5 Image Artefacts

2.5.1 Field Artefacts
2.5.2 Sampling Artefacts
2.5.3 Fourier Artefacts and External R.F. Interference

2.6 Imaging Hardware

2.6.1 The Magnet
2.6.2 The Gradient Coils
2.6.3 R.F. Transmission and Reception
2.6.4 Control and Processing

2.7 Safety Considerations in MRI

2.7.1 Static Magnetic Fields
2.7.2 Time Varying Magnetic Fields
2.7.3 Other Safety Considerations

2.8 References