Transverse relaxation of solvent protons induced by magnetized spheres: application to ferritin, erythrocytes, and magnetite

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Magnet. Reson. Med.; (United States)

DOI:https://doi.org/10.1002/mrm.1910050404· OSTI ID:5606359

Gillis, P; Koenig, S H

Since 1/T2 of protons of tissue water is generally much greater than 1/T1 at typical imaging fields, small single-ion contrast agents--such as Gd(DTPA), which make comparable incremental contributions and therefore smaller fractional contributions to 1/T2 compared to 1/T1--are not as desirable for contrast-enhancement as agents that could enhance 1/T2 preferentially. In principle, such specialized agents will only be effective at higher fields because the field dependence (dispersion) of 1/T1 is such that it approaches zero at high fields whereas 1/T2 approaches a constant value. The residual 1/T2 is called the secular contribution and arises from fluctuations in time--as sensed by the protons of diffusing solvent or tissue water molecules--of the component of the magnetic field parallel to the static applied field. For solutions or suspensions of sufficiently large paramagnetic or ferromagnetic particles (greater than or equal to 250 A diameter), the paramagnetic contributions to the relaxation rates satisfy 1/T2 much greater than 1/T1 at typical imaging fields. We examine the theory of secular relaxation in some detail, particularly as it applies to systems relevant to magnetic resonance imaging, and then analyze the data for solutions, suspensions, or tissue containing ferritin, erythrocytes, agar-bound magnetite particles, and liver with low-density composite polymer-coated magnetite. In most cases we can explain the relaxation data, often quantitatively, in terms of the theory of relaxation of protons (water molecules) diffusing in the outer sphere environments of magnetized particles.

• Research Organization: Universite de Mons-Hainaut, Belgium
• OSTI ID: 5606359
• Journal Information: Magnet. Reson. Med.; (United States), Journal Name: Magnet. Reson. Med.; (United States) Vol. 5:4; ISSN MRMEE
• Country of Publication: United States
• Language: English

Related Subjects

550600* -- Medicine
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
BARYONS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
COMPLEXES
CONTRAST MEDIA
DIAGNOSTIC TECHNIQUES
ELEMENTARY PARTICLES
ELEMENTS
ERYTHROCYTES
FERMIONS
FERRITIN
HADRONS
IRON
IRON COMPLEXES
MAGNETIC FIELDS
MAGNETIC MATERIALS
MAGNETIC RESONANCE
MAMMALS
MATERIALS
METALLOPROTEINS
METALS
NMR IMAGING
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
PROTEINS
PROTONS
RATS
RESONANCE
RODENTS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
VERTEBRATES