In vivo 1H2O T2 measurement in the human occipital lobe at 4T and 7T by Carr-Purcell MRI: Detection of microscopic susceptibility contrast

Robert Bartha, Shalom Michaeli, Hellmut Merkle, Gregor Adriany, Peter Andersen, Wei Chen, Kamil Ugurbil, Michael Garwood

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Abstract

A high-resolution spin-echo imaging method is presented (called CP-LASER) which exploits the spin refocusing capability of an adiabatic Carr-Purcell (CP) pulse sequence to measure apparent 1H2O transverse relaxation (T2) and generate contrast based on microscopic tissue susceptibility. High-resolution CP-LASER images of the human occipital lobe were acquired at four different echo times from six subjects at 4T and eight subjects at 7T to investigate the effect of magnetic field strength (B0) and the CP interpulse time (τcp) on T2. Susceptibility contrast was identified and T2 was quantified for long τcp (> 10 ms) and short τcp (7 ms at 4T and 6 ms at 7T) in gray matter, white matter, and cerebral spinal fluid. The 1H2O relaxation rate constants (1/T2) of gray and white matter each increased approximately linearly with field strength and T2 was inversely related to τcp. The average T2 value of gray matter was 19% and 9% smaller than that of white matter at 4T and 7T, respectively. These results are consistent with higher levels of compartmentalized ferritin and increased blood volume in gray matter compared to white matter in this region of the brain.

Original languageEnglish (US)
Pages (from-to)742-750
Number of pages9
JournalMagnetic resonance in medicine
Volume47
Issue number4
DOIs
StatePublished - Apr 10 2002

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Keywords

  • 4T
  • 7T
  • Adiabatic pulse
  • Apparent T
  • Carr-Purcell
  • LASER
  • Susceptibility contrast
  • T

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