Vascular transit times in calcarine cortex: kinetic analysis of R2* changes observed using localized 1H spectroscopy

Magn Reson Med. 1995 Sep;34(3):326-30. doi: 10.1002/mrm.1910340308.

Abstract

A kinetic analysis of water signal intensity changes measured in human visual cortex by PRESS localized 1H spectroscopy at 500 ms resolution with light-emitting diode (LED) goggle stimulation was used to determine vascular transit times for transitions between rest and activation. Monoexponential curve fitting was used to determine both R2* values for each free induction decay and the time constants for R2* changes with activation and deactivation. Measured transit time values were in general agreement with the literature, and were significantly shorter for "Off-->On" than for "On-->Off" transitions, consistent with known alterations in blood flow with activation and deactivation. The differences in transit times between "Off-->On" and "On-->Off" also varied with stimulus frequency in accordance with known physiology. This type of analysis may provide a useful means of analyzing functional activation data and for quantitatively comparing functional activation results from differing subjects and imaging sessions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Cerebrovascular Circulation*
  • Female
  • Humans
  • Magnetic Resonance Spectroscopy*
  • Male
  • Photic Stimulation
  • Time Factors
  • Visual Cortex / blood supply*