MR microscopy at 7.0 T: effects of brain iron.

Journal Article (Journal Article)

The T2 of brain tissue is known to be field dependent, decreasing as B0 increases. Previous studies have attributed reduced T2 in the structures of the extrapyramidal motor system (EPMS) to high iron concentrations. The present study was designed to manipulate physiologic iron concentrations and study the effects on T2 and on the field dependence of T2 at 7.0 T in whole formalin-fixed brains. A rat model was devised in which iron concentrations in the structures of interest were altered by diet manipulation. Cerebral structures with different iron content were imaged and T2 measured with MR microscopy at both 2.0 and 7.0 T. T2 of all tissues was shorter by 40%-60% at 7.0 T. Although some dependence of T2 on iron concentration was evident, it was less than expected. The strongest correlation was in the substantia nigra. The highest-resolution studies, at 30 x 30 x 50 microns, show the myelin bundles in many of the EPMS structures but not in the substantia nigra. From these data, it appears that T2 at greater field strengths depends more on susceptibility-induced spin dephasing imposed by diffusion through the tissue microstructure than on the presence of iron.

Full Text

Duke Authors

Cited Authors

  • Malisch, TW; Hedlund, LW; Suddarth, SA; Johnson, GA

Published Date

  • May 1991

Published In

Volume / Issue

  • 1 / 3

Start / End Page

  • 301 - 305

PubMed ID

  • 1802143

International Standard Serial Number (ISSN)

  • 1053-1807

Digital Object Identifier (DOI)

  • 10.1002/jmri.1880010308


  • eng

Conference Location

  • United States