Premium
The relation between brain iron and NMR relaxation times: An in vitro study
Author(s) -
Vymazal Josef,
Brooks Rodney A.,
Baumgarner Charles,
Tran Vu,
Katz David,
Bulte Jeff W. M.,
Bauminger E. Rivka,
Chiro Giovanni Di
Publication year - 1996
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910350108
Subject(s) - nuclear magnetic resonance , relaxation (psychology) , in vitro , chemistry , neuroscience , physics , biology , biochemistry
T 1 and T 2 relaxation times and iron concentrations were measured in 24 specimens of gray matter from fresh human and monkey brains at magnetic fields from 0.05 to 1.5 Tesla. Three different effects were found that correlate with iron content: a T 1 ‐shortening that falls off somewhat at high fields, a T 2 ‐shortening that is field‐independent and thus important at low fields, and a contribution to 1/ T 2 that increases linearly with field strength. This linear field dependence has been seen only in ferritin and other ferric oxyhydroxide particles. Our results are in agreement with in vivo MRI studies and are generally consistent with values for ferritin solution, except for differences such as clustering of ferritin in tissue. A cerebral cavernous hemangioma specimen showed similar T 2 ‐shortening, but with a 2.7 times larger magnitude, attributed to larger clusters of hemosiderin in macrophages. The dependence on interecho time 2 T was measured in three brains; 1/ T 2 increased significantly for T up to 32 ms, as expected from the size of the ferritin clusters. These findings support the theory that ferritin iron is the primary determinant of MRI contrast in normal gray matter.