39802 - Magnetic Resonance Phisics

Learning outcomes

The student acquires the knowledge of the physics of RM, the major sequences used; the technological component of an MRI system; the operation of the antenna-coils; the S / N ratio in MRI.

Course contents

1. Magnetic Field and SPIN
1.1 Slice, voxel, pixel.
1.2 The spectrum of e.m. waves
1.3 Modulations (amplitude, frequency and phase) and the transport of information.
1.4 The magnetic field.
1.5 The spin

2. SPIN in the Magnetic Field
2.1 Larmor equation.
2.2 Boltzmann statistics.
2.3 Isotopic abundance and biological abundance.

3. Relaxation Times
3.1 Relaxation times T1 and T2.
3.2 Wave e.m. polarized.
3.3 Free Induction Decay (pure and inhomogeneous).

4. Formation of the Contrast
4.1 Image contrast.
4.2 Reference systems for times T1 and T2 (TE and TR).
4.3 The signal (as a response from the spin system).
4.4 Saturation and flip angle.

5. Frequency and Phase Encodes
5.1 Rotating reference system.
5.2 Frequency encoding.
5.3 Bandwidth in transmission and SYNC pulse.
5.4 Crosstalk and its minimization.
5.5 Structure of the gradient coils.
5.6 Phase encoding.
5.7 Phase equation.

6. The k-Space
6.1 Series and Fourier Transform.
6.2 Structure of the k-space.
6.3 The chemical shift. Structure of some artifacts in k-space. Wrap-around.
6.4 Factors that determine image quality.
6.5 FOV, NEX, reception bandwidth and Signal-to-Noise Ratio.
6.6 Protection from e.m. fields and SAR.

7. Fourier Transform Imaging
7.1 Sequences and Sequence Components.
7.2 Excitation (slice selection).
7.3 Phase coding.
7.4 Generation of the Echo.
7.5 Signal measurement.
7.5 Filling the k-space. K-space filling methods.

8. The Fundamental Sequences
8.1 Spin-echo.
8.2 Inversion-recovery.
8.3 Gradient-echo.
8.4 Deepening on the formation of the echo in the three cases.

9. Structure of the MRI
9.1 Photographic analysis of the structure of the MRI.
9.2 Functional block diagrams.
9.3 Structure and operation of the most important coils and their applications.
9.4 Notes on superconductivity.

10. Insights
10.1 Electrical structure of the most used coils.
10.2 Slew-rate, and its importance.
10.3 Sequences that require high slew-rates.
10.4 Tissue suppression techniques.
10.5 Techniques for visualizing blood flows.
10.6 Notes on some advanced sequences.

Readings/Bibliography

- Lecture notes by the teacher carefully prepared

- An easily understandable but, in many ways, insufficient text is the following:
Weishaupt, Kochli, Marincek - How does MRI work? - Springer

- The student interested in a high-level discussion can read the text:
Liang, Lauterbur - Principles of Magnetic Resonance Imaging - IEEE Press

- A more general text (with a not too extensive mathematical treatment) dedicated to the medical imaging specialist is:
Princes, Links - Medical Imaging Signals and Systems - Pearson Prentice Hall

Teaching methods

- Frontal lessons

- We will try to stimulate the student's interaction with the teacher, not for evaluation purposes but rather to optimize the understanding of the subject (which is difficult from various points of view).

- Didactic programs, java applets, MRI simulation programs will be used.

In consideration of the types of activities and teaching methods adopted, the attendance of this training activity requires the carrying out for all students of modules 1 and 2 in e-learning mode [https://www.unibo.it/it/servizi-e-opportunita/salute-e-assistenza/salute-e-sicurezza/sicurezza-e-salute-nei-luoghi-di-studio-e-tirocinio] and the participation in module 3 of specific training on safety and health in the places of study. Information on dates and methods of attendance of module 3 can be consulted in the specific section of the degree program website.

Assessment methods

Oral interview during which the student is invited to discuss the topics covered during the lessons which are also found in the texts recommended for study and in the teaching material presented and discussed during the lessons.

The interview will be assessed on the basis of the following parameters:
- knowledge, mastery and in-depth analysis of the contents
- critical and expository skills
- technical and scientific terminological correctness

Teaching tools

- We will use simulation programs of physical and mathematical phenomena (modulations, harmonic decomposition of signals and images) to make them easier to understand.

 

- An image processing program will be used to visualize the phenomena in the frequency space.

 

- An MRI simulation program will be used to aid learning the operating parameters and their influence on the diagnostic image.

Office hours

See the website of Giuseppe Baldazzi