Relaxation & the Bloch Equations

Matthias Weigel¹
¹University Hospital Basel and University of Basel, Basel, Switzerland

Synopsis

Keywords: Physics & Engineering: Nuclear Magnetic Resonance, Physics & Engineering: Physics

The Bloch equations depict the evolution of macroscopic magnetization in Nuclear Magnetic Resonance (NMR). They are phenomenological equations based on classical physics and include relaxation effects. Extensions of the Bloch equations allow adding further physical effects such as diffusion or exchange.

This lecture will introduce the Bloch equations and discuss their basis and limitations. The implications of excitation and a rotating coordinate system are analyzed. Relaxation will be explained as a 'necessity of nature' and its importance for Magnetic Resonance Imaging (MRI) emphasized.

Target Audience

The full breadth of physicists, engineers, general scientists and clinicians who are interested in this basic topic and who have a minimum of mathematical background.

Learning Objectives

- Understand the basis of the Bloch equations and how extensions can be added
- Learn how different frames of reference can simplify understanding and application
- Analyze different special cases
- Gain an insight into the importance and source of relaxation effects
- Relate the basic physics effects to imaging

Acknowledgements

No acknowledgement found.

References

- Bernstein MA, King KF and Zhou XJ. Handbook of MRI Pulse Sequences. Elsevier (2004)

- Bloch F. Nuclear Induction. Phys. Rev. 70, 460 (1946)

- Haacke EM, Brown RW, Thompson MR, Venkatesan R. Magnetic Resonance Imaging: Physical Principles and Sequence Design. Wiley-Liss (1999)

- Liang Z and Lauterner PC. Principles of Magnetic Resonance Imaging: A signal processing perspective. IEEE Press (2000)

Proc. Intl. Soc. Mag. Reson. Med. 31 (2023)