Improved neuronal tract tracing using manganese enhanced magnetic resonance imaging with fast T(1) mapping

Magn Reson Med. 2006 Mar;55(3):604-11. doi: 10.1002/mrm.20797.

Abstract

There has been growing interest in using manganese-enhanced MRI (MEMRI) to detect neuronal activation, neural architecture, and neuronal connections. Usually Mn(2+) produces a very wide range of T(1) change. In particular, in neuronal tract tracing experiments the site of Mn(2+) injection can have very short T(1) while distant regions have small T(1) reductions, primarily due to dilution of Mn(2+). Most MEMRI studies use T(1)-weighted sequences, which can only give optimal contrast for a narrow range of T(1) changes. To improve sensitivity to the full extent of Mn(2+) concentrations and to optimize detection of low concentrations of Mn(2+), a fast T(1) mapping sequence based on the Look and Locker technique was implemented. Phantom studies demonstrated less than 6.5% error in T(1) compared to more conventional T(1) measurements. Using center-out segmented EPI, whole-brain 3D T(1) maps with 200-microm isotropic resolution were obtained in 2 h from rat brain. Mn(2+) transport from the rat olfactory bulb through appropriate brain structures could be detected to the amygdala in individual animals. The method reliably detected less than 7% reductions in T(1). With this quantitative imaging it should be possible to study more extensive pathways using MEMRI and decrease the dose of Mn(2+) used.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Brain / anatomy & histology
  • Chlorides
  • Contrast Media*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Manganese Compounds
  • Manganese*
  • Nervous System / anatomy & histology*
  • Phantoms, Imaging
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Chlorides
  • Contrast Media
  • Manganese Compounds
  • Manganese
  • manganese chloride