The relation between brain iron and NMR relaxation times: An in vitro study

Josef Vymazal, Rodney A. Brooks, Charles Baumgarner, Vu Tran, David Katz, Jeff W.M. Bulte, E. Rivka Bauminger, Giovanni Di Chiro

Research output: Contribution to journalArticlepeer-review

Abstract

T1 and T2 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 T1-shortening that falls off somewhat at high fields, a T2-shortening that is field-independent and thus important at low fields, and a contribution to 1/T2 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 T2-shortening, but with a 2.7 times larger magnitude, attributed to larger clusters of hemosiderin in macrophages. The dependence on interecho time 2τ was measured in three brains; 1/T2 increased significantly for τ 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.

Original languageEnglish (US)
Pages (from-to)56-61
Number of pages6
JournalMagnetic resonance in medicine
Volume35
Issue number1
DOIs
StatePublished - Jan 1996
Externally publishedYes

Keywords

  • T
  • T shortening
  • brain iron
  • ferritin

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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