Role of iron and ferritin in MR imaging of the brain: A study in primates at different field strengths

Alberto Bizzi, Rodney A. Brooks, Arturo Brunetti, Joanna M. Hill, Jeffrey R. Alger, Robert S. Miletich, Thomas L. Francavilla, Giovanni Di Chiro

Research output: Contribution to journalArticlepeer-review

Abstract

The authors measured in vivo signal intensity on magnetic resonance (MR) images and postmortem iron concentrations in the brains of three young and two old rhesus monkeys. T2-weighted MR imaging was done at 0.5, 1.5, 2.0, and 4.7 T. Relative assessment of iron concentration was made from the optical density of brain sections stained with the Peris' method intensified with diaminobenzidine. MR imaging and optical density measurements were made in the centrum semiovale (white matter) and in four gray matter areas: the insular cortex, caudate nucleus, putamen, and globus pallidus, the latter three of which accumulate significant iron deposits with age. High optical density and decreased signal intensity were found in these areas, and the inverse correlation between gray matter/ white matter signal ratio and optical density was in good agreement with the theory of T2 shortening caused by diffusion of water through magnetic inhomogeneities. However, the dependence of T2 shortening on field strength was not quadratic, as expected for paramagnetic iron, but instead showed a marked leveling off at higher field strengths. This magnetic "saturation" is explainable by antiferromagnetism and superparamagnetism of the ferritin core and has been observed in ferritin solutions at low temperatures. Similar observations at body temperature are needed before the iron-ferritin explanation for T2 shortening can be considered proved.

Original languageEnglish
Pages (from-to)59-65
Number of pages7
JournalRadiology
Volume177
Issue number1
Publication statusPublished - Oct 1990

Keywords

  • Brain, anatomy, 10.92
  • Brain, MR studies, 10.1214
  • Iron
  • Magnetic resonance (MR), experimental, 10.1214
  • Magnetic resonance (MR), physics

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology

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