Longitudinal proton relaxation rates in rabbit tissues after intravenous injection of free and chelated Mn2+

Journal Article · Tue Nov 01 04:00:00 EST 1988 · Magnet. Reson. Med.; (United States)

DOI:https://doi.org/10.1002/mrm.1910080307· OSTI ID:6536207

Spiller, M; Brown, III, R D; Koenig, S H; Wolf, G L

The factors that determine the field-dependent increase in 1/T1 of tissue water protons were investigated for MnCl2 and Mn2+ (PDTA) (1,3-propylenediamine-N,N',N'',N'''-tetraacetic acid) introduced intravenously into rabbits. Mn2+ was used in preference to other paramagnetic ions in part because of the distinct NMRD profiles (magnetic field dependence of 1/T1) of free Mn2+ ions, their small chelate complexes, and their macromolecular conjugates, and in part because the relatively low toxicity of Mn2+ is favorable for animal studies. Tissue content of Mn2+ was determined in all samples by inductively coupled plasma analyses the state of Mn2+ in excised tissues was determined from the form of the 1/T1 NMRD profile of water protons; and distribution of contrast agent within tissue and access of water on a T1 time scale were determined by double-exponential analyses of proton relaxation behavior in intact doped tissue, as well as by the change of single-exponential relaxation rates and proton signal intensity upon gentle disruption of the tissue. MnCl2 is found in all tissues, except fat and skeletal muscle, but liver is most avid at low dose, and Mn2+ accumulates in spleen after high doses. Chelation targets Mn2+ to liver and kidney, saturating the liver chemically at relatively low dose. We suggest that pronounced increase in tissue relaxivity results from irrotationally bound Mn2+, ostensibly associated with the polar head groups of cell membranes. Compartmentalization of contrast agent and restricted diffusion of tissue water influences the maximum relaxation rates attainable, so that there is an optimal dose of these contrast agents which is rather low.

• Research Organization: T. J. Watson Research Center, New York, NY (USA)
• OSTI ID: 6536207
• Journal Information: Magnet. Reson. Med.; (United States), Journal Name: Magnet. Reson. Med.; (United States) Vol. 8:3; ISSN MRMEE
• Country of Publication: United States
• Language: English

Related Subjects

550600 -- Medicine
560300* -- Chemicals Metabolism & Toxicology
62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINO ACIDS
ANIMALS
BARYONS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHELATING AGENTS
CONTRAST MEDIA
DISTRIBUTION
EDTA
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HADRONS
INJECTION
INTAKE
INTRAVENOUS INJECTION
MAMMALS
MANGANESE
MEMBRANES
METALS
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROTONS
RABBITS
TISSUE DISTRIBUTION
TOXICITY
TRANSITION ELEMENTS
VERTEBRATES