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Paramagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Magnetic relaxation in tissues can be enhanced using contrast agents. The most commonly used for MRI are the paramagnetic contrast agents, which have their strongest effect on the T1, by increasing T1 signal intensity in tissues where they have accumulated.
MRI collects signal from the water protons, but the presence of these contrast agents enhances the relaxation of water protons in their vicinity. Paramagnetic contrast agents contain magnetic centers that create magnetic fields approximately one thousand times stronger than those corresponding to water protons. These magnetic centers interact with water protons in exactly the same way as the neighboring protons, but with much stronger magnetic fields, and therefore, have a much greater impact on relaxation rates, particularly on T1. In MRI, contrast agents are routinely injected intravenously to help identify areas of hypervascularity, as in malignant tumors.

See also Contrast Agents, Gadovist®, MultiHance®, Omniscan®, OptiMARK®.

See also the related poll result: 'The development of contrast agents in MRI is'
 
Images, Movies, Sliders:
 MRI Upper Abdomen T1 with Contrast  Open this link in a new window
    
 MRI Orbita T1  Open this link in a new window
 MRI Orbita T1 with Contrast  Open this link in a new window
    
 
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• Related Searches:
    • T1 Relaxation
    • Superparamagnetic Contrast Agents
    • Positive Oral Contrast Agents
    • Oral Contrast Agents
    • Contrast Agents
 
Further Reading:
  Basics:
LEARNING CENTER FOR PARAMAGNETISM
2003   by www.naturesalternatives.com    
Contrast Agents: Safety Profile
   by www.clinical-mri.com    
Contrast Agents in Magnetic Resonance Imaging
1997
  News & More:
Gadolinium-containing contrast agents: removal of Omniscan and iv Magnevist, restrictions to the use of other linear agents
Friday, 5 January 2018   by www.gov.uk    
EMA's final opinion confirms restrictions on use of linear gadolinium agents in body scans
Friday, 21 July 2017   by www.ema.europa.eu    
FDA Drug Safety Communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings
Tuesday, 19 December 2017   by www.fda.gov    
RSNA Statement on Gadolinium-Based MR Contrast Agents
Thursday, 1 February 2018   by www.rsna.org    
Contrast MRIs cause claims, concern, over residual metal in brain
Tuesday, 8 December 2015   by www.afr.com    
MRI Resources 
Image Quality - Breast MRI - Supplies - Cardiovascular Imaging - Distributors - Societies
 
Paramagnetism
 
Paramagnetic materials attract and repel like normal magnets when subject to a magnetic field. This alignment of the atomic dipoles with the magnetic field tends to strengthen it, and is described by a relative magnetic permeability greater than unity. Paramagnetism requires that the atoms individually have permanent dipole moments even without an applied field, which typically implies a partially filled electron shell. In pure Paramagnetism (without an external magnetic field), these atomic dipoles do not interact with one another and are randomly oriented in the absence of an external field, resulting in zero net moment.
Paramagnetic materials in magnetic fields will act like magnets but when the field is removed, thermal motion will quickly disrupt the magnetic alignment. In general, paramagnetic effects are small (magnetic susceptibility of the order of 10-3 to 10-5).
In MRI, gadolinium (Gd) one of these paramagnetic materials is used as a contrast agent. Through interactions between the electron spins of the paramagnetic gadolinium and the water nuclei nearby, the relaxation rates (T1 and T2) of the water protons are increased (T1 and T2 times are decreased), causing an increase in signal on T1 weighted images.

See also contrast agents, magnetism, ferromagnetism, superparamagnetism, and diamagnetism.
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Further Reading:
  Basics:
Magnet basics
   by my.execpc.com    
Paramagnetism
Wednesday, 23 November 2005   by en.wikipedia.org    
  News & More:
LEARNING CENTER FOR PARAMAGNETISM
2003   by www.naturesalternatives.com    
MRI Resources 
Patient Information - MRI Technician and Technologist Jobs - MRI Training Courses - MRI Accidents - Software - Sequences
 
Primovist™InfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Primovist™ (U.S brand name Eovist®) is a highly specific MRI contrast agent for the imaging, detection and characterization of liver conditions, including liver tumors, cysts, as well as other malignant and benign lesions. It is a water-soluble ethoxybenzyl derivative of Gd-DTPA. This compound is taken up by the hepatocytes (approximately 30% of the dose goes to the hepatocytes) and is equally excreted renal and biliary in humans.
Primovist™ brightens the signal of T1 weighted MR images immediately after contrast administration. Dynamic scanning and imaging of the accumulation phase (best after 20 min.) can also be performed after bolus injection of Primovistâ„¢. The hepatocytes uptake will increase the signal intensity of normal liver parenchyma. This results in improved lesion-to-liver contrast because malignant tumors (metastases, the majority of hepatocellular carcinomas) do not contain either hepatocytes or their functioning is hampered.

WARNING: Gadolinium-based contrast agents increase the risk for nephrogenic systemic fibrosis (NSF) in patients with acute or chronic severe renal insufficiency (glomerular filtration rate less than 30 mL/min/1.73m2), or acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period.
Drug Information and Specification
NAME OF COMPOUND
Gadoxetic acid disodium, Gd-EOB-DTPA
CENTRAL MOIETY
Gd2+
CONTRAST EFFECT
T1, Predominantly positive enhancement
Short T1-relaxation time
PHARMACOKINETIC
50% hepatobiliary, 50% renal excretion
884 mosm/kgH2O
CONCENTRATION
0.25 mol/L
DOSAGE
12,5 - 25 µmol/kg
PREPARATION
Finished product
INDICATION
Liver lesions
DEVELOPMENT STAGE
for sale
DISTRIBUTOR
See below
PRESENTATION
DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE
NOT A SUBSTITUTE FOR THE ACCOMPANYING PACKAGE INSERT!
Distribution Information
TERRITORY
TRADE NAME
DEVELOPMENT
STAGE
DISTRIBUTOR
EU
Primovist™
for sale
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Further Reading:
  Basics:
New MRI liver contrast agent Primovist® approved in EU
Thursday, 30 September 2004   by www.secinfo.com    
New MRI Liver Contrast Medium
Wednesday, 13 October 2004   by www.hospimedica.com    
Important Drug Warning for Gadolinium-Based Contrast Agents
Wednesday, 12 September 2007   by www.ismrm.org    
MAGNETIC RESONANCE IMAGING OF FOCAL LIVER LESIONS(.pdf)
2002
  News & More:
Comparison of liver scintigraphy and the liver-spleen contrast in Gd-EOB-DTPA-enhanced MRI on liver function tests
Thursday, 18 November 2021   by www.nature.com    
EMA's final opinion confirms restrictions on use of linear gadolinium agents in body scans
Friday, 21 July 2017   by www.ema.europa.eu    
FDA Drug Safety Communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings
Tuesday, 19 December 2017   by www.fda.gov    
Gadolinium-containing contrast agents: removal of Omniscan and iv Magnevist, restrictions to the use of other linear agents
Friday, 5 January 2018   by www.gov.uk    
Searchterm 't1' was also found in the following services: 
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News  (18)  Resources  (5)  Forum  (54)  
 
Rapid Excitation Magnetic Resonance ImagingInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
(RE MRI) There are several approaches to speeding up the MRI data acquisition process by repeating the excitation by RF pulses in times short compared to T1, typically using small flip angles and gradient echo refocusing. When TR is also on the order of or shorter than T2, the repeated RF pulses will tend to refocus transverse magnetization remaining from prior excitations, setting up a condition of steady state free precession, and a dependence of signal strength (and image contrast) on both T1 and T2.
This can be modified in various ways, particularly:
1) to spoil the tendency to build up a steady state by reducing coherence between excitations, e.g. by variation of the phase or timing of consecutive RF pulses or of the strength of spoiler gradient pulses, thus increasing the relative dependence of signal strength on T1 or
2) acquire the signal when it is refocusing immediately prior to the next RF pulse, thus increasing the relative dependence of signal strength on T2.

See also Ultrafast Gradient Echo Sequence.
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MRI Resources 
MRI Technician and Technologist Schools - Image Quality - Liver Imaging - Quality Advice - Lung Imaging - General
 
Signal Intensity
 
Signal intensity interpretation in MR imaging has a major problem.
Often there is no intuitive approach to signal behavior as signal intensity is a very complicated function of the contrast-determining tissue parameter, proton density, T1 and T2, and the machine parameters TR and TE. For this reason, the terms T1 weighted image, T2 weighted image and proton density weighted image were introduced into clinical MR imaging.
Air and bone produce low-intensity, weaker signals with darker images. Fat and marrow produce high-intensity signals with brighter images.
The signal intensity measured is related to the square of the xy-magnetization, which in a SE pulse sequence is given by
Mxy = Mxy0(1-exp(-TR/T1)) exp(-TE/T2) (1)
where Mxy0 = Mz0 is proportional to the proton or spin density, and corresponds to the z-magnetization present at zero time of the experiment when it is tilted into the xy-plane.

See also T2 Weighted Image and Ernst Angle.
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• View the NEWS results for 'Signal Intensity' (1).Open this link in a new window.
 
Further Reading:
  Basics:
Contrast mechanisms in magnetic resonance imaging
2004   by www.iop.org    
Image Characteristics and Quality
   by www.sprawls.org    
  News & More:
Specialized MRI sensor can detect light deep within tissues
Thursday, 22 December 2022
Study compares effect of food intake on manganese-based MRI contrast agent absorption
Saturday, 3 December 2022   by www.itnonline.com    
Kidney stone imaging with 3D ultra-short echo time (UTE) magnetic resonance imaging. A phantom study - Abstract
Wednesday, 11 March 2015   by www.urotoday.com    
MRI Resources 
Manufacturers - Lung Imaging - Intraoperative MRI - Breast MRI - Shoulder MRI - Examinations
 
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