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

Lecture

MRI Contrast Agents: Mechanisms and Applications

Description

This lecture covers the mechanisms of MRI contrast agents, focusing on how relaxation times are shortened by relaxivity, and discusses the applications of contrast agents in imaging blood vessels, tumours, and inflammation. Examples of intracellular contrast agents, such as Mn-enhanced MRI, are also presented.

In MOOC

Fundamentals of Biomedical Imaging: Magnetic Resonance Imaging (MRI)

Official source

Quiz

Related concepts (32)

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.

Contrast agent

A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiopharmaceuticals, which emit radiation themselves. In x-ray imaging, contrast agents enhance the radiodensity in a target tissue or structure. In magnetic resonance imaging, contrast agents shorten (or in some instances increase) the relaxation times of nuclei within body tissues in order to alter the contrast in the image.

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.

Radiocontrast agent

Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically iodine, or more rarely barium sulfate. The contrast agents absorb external X-rays, resulting in decreased exposure on the X-ray detector. This is different from radiopharmaceuticals used in nuclear medicine which emit radiation.

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.

Related lectures (32)

Contrast in MRI

Explores MRI principles, contrast agents, neural activity imaging, and functional MRI techniques.

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.

Gradient Echo Contrast T2*MOOC: Fundamentals of Biomedical Imaging: Magnetic Resonance Imaging (MRI)

Explores gradient echo contrast (T2*) in biomedical imaging, covering T2* weighting, contrast mechanisms in MRI, venography, BOLD fMRI, and spatial encoding techniques.

Overview and comparison: Imaging Modalities MOOC: Fundamentals of Biomedical Imaging: Magnetic Resonance Imaging (MRI)

Covers the comparison of bio-imaging modalities, discussing contrast mechanisms, limitations, SNR, and reconstruction techniques.

Bloch equations: MR signal basics MOOC: Fundamentals of Biomedical Imaging: Magnetic Resonance Imaging (MRI)