In MRI Physics for Physicians the author presents the physical principles of magnetic resonance imaging without detailing the more sophisticated mathematics and physics typically used by physicists when explaining such phenomena. This book is mainly intended for radiologists and clinical physicians who are interested in learning the basic principles of how and why magnetic resonance imaging works but do not want to become excessively involved with the mathematics. It is divided into two parts: the first covers the general aspects of magnetic resonance and the resulting signals while the second explains how the magnetic resonance signals form the three-dimensional images. Explanations of all relevant physical and mathematical terms and concepts, including basic vector and field theory and the more complicated principles of wave theory and Fourier transform mathematics, are given in an easily understood, straightforward, yet thorough, manner.
Inhalt
1 Overview.- 2 Magnetic Field.- Fields.- Basic Types of Magnets.- Permanent Magnet.- Superconducting Magnet.- Vectors.- Paramagentic, Diamagentic, Ferromagnetic.- Angular Momentum-Nuclear Spin.- Magnetic Dipole Moment.- Resultant BO Vector.- Precession and the Larmor Equation.- 3 Radiofrequency Pulse.- Electromagnetic Waves.- Periodic Functions.- Axis Conventions.- Perturbance of the B0 Vector.- Rotating Frame of Reference.- Resonance.- B0 vs. the Component MDM Vectors.- The Signal and the B1 Vector.- Controlling the Flip of B0.- Motion of B0 in the X-Y Plane.- 4 Relaxation.- T1 and T2 Components of Relaxation.- T1 Curves.- 5 Pulse Cycles, Pulse Sequences, and Tissue Contrast.- TR and TE.- T1 and T2 Weighting.- Balanced (Spin Density) Scans.- 6 T2 and the Spin-Echo Pulse Cycle.- Graph of MR Signal-Free Induction Decay (FID).- Envelopes of the Signal.- T2*.- Concept of Phase.- Phase and the MR Signal.- De-Phasing and the MR Signal.- Re-Phasing the MR Signal-180° Refocusing Pulse.- The Spin Echo Pulse Cycle.- The True T2 Curve.- T2 Curves for Different Tissues for Long TR'S.- T1 and T2 Constants.- T2 Curves for Different Tissues for Short TR's.- 7 Some Other Pulse Cycles.- Saturation Recovery and Partial Saturation.- Inversion Recovery.- Fast Scans.- Pulse Cycle Summary.- 8 Gradients.- 9 The Slice Select Gradient.- Changing Slice Thickness.- 10 Frequency Gradient.- The Pixel Grid.- Sine Functions for Each Pixel.- Application of Frequency Gradient.- 11 The Fourier Transform.- The Spectrum.- The Fourier Series.- Fourier Transform of Pixel Grid.- Rotating Gradients-One Alternative.- 12 The Phase Encoding Gradient.- Degrees of Phase Shift per Row.- Phase Shift in Sine Functions.- Multiple Repetitions to Form the Image.- Phase Encoding Repetitions and the Pixel Grid.- Phase Encoding Repetitions and the MDM Vectors.- The 2-D Fourier Transform.- 13 Miscellaneous Topics.- The Gradients in Perspective.- Imaging in Other Planes.- The Multislice Technique.- Averages, Excitations.- Exam Time.- 14 Coils.- Receiver, Transmitter Coils.- Gradient Coils.- Shim Coils.- Conclusion.- Appendix: The Mathematics of MRI.