Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Bloch equations: MR signal basics

Description

This lecture covers the Bloch equations, which describe the change in magnetization in MRI, by adding relaxation terms (T₁, T₂) to the fundamental equation of motion. It explains the basic MR signal, including free induction decay, precession, and relaxation. The lecture also discusses how T₁ changes can be measured through repetitive pulsing and multipulse experiments, emphasizing the impact of T₁ and T₂ relaxation on signal intensity. The summary highlights the equilibrium magnetization, the effect of T₁ and T₂ on image contrast, and the factors influencing the precession of transverse magnetization in MRI.

In MOOC

Fundamentals of Biomedical Imaging: Magnetic Resonance Imaging (MRI)

Official source

Quiz

Related concepts (15)

Spin–spin relaxation

In physics, the spin–spin relaxation is the mechanism by which Mxy, the transverse component of the magnetization vector, exponentially decays towards its equilibrium value in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). It is characterized by the spin–spin relaxation time, known as T2, a time constant characterizing the signal decay. It is named in contrast to T1, the spin–lattice relaxation time.

Nuclear magnetic resonance

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca.

Spin–lattice relaxation

During nuclear magnetic resonance observations, spin–lattice relaxation is the mechanism by which the longitudinal component of the total nuclear magnetic moment vector (parallel to the constant magnetic field) exponentially relaxes from a higher energy, non-equilibrium state to thermodynamic equilibrium with its surroundings (the "lattice"). It is characterized by the spin–lattice relaxation time, a time constant known as T1.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans.

École polytechnique

École polytechnique, also known as Polytechnique or l'X liks, is a grande école located in Palaiseau, France. It specializes in science and engineering and is a founding member of the Polytechnic Institute of Paris. The school was founded in 1794 by mathematician Gaspard Monge during the French Revolution and was militarized under Napoleon I in 1804. It is still supervised by the French Ministry of Armed Forces. Originally located in the Latin Quarter in central Paris, the institution moved to Palaiseau in 1976, in the Paris-Saclay technology cluster.

Related lectures (29)

Spin Relaxation in Magnetic Resonance

Introduces the fundamentals of spin relaxation in magnetic resonance, covering spin-lattice and spin-spin relaxation, and rotational motion in liquids.

NMR Experiments: Basics and Applications

Explores the basic steps in magnetic resonance, including INEPT pulse sequences and two-dimensional NMR experiments like COSY and NOESY.

Basic Steps in Magnetic Resonance

Covers the basic steps in magnetic resonance, including NMR experiments and signal averaging.

Spin echoes & coherence transfer

Explores spin echoes, coherence transfer, product operator formalism, and the INEPT experiment in NMR spectroscopy.

Neural Signals and Signal Processing