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Vascular transit times in calcarine cortex: Kinetic analysis of R 2* changes observed using localized 1 H spectroscopy
Author(s) -
Detre John A.,
Wang Zhiyue,
Stecker Mark M.,
Zimmerman Robert A.
Publication year - 1995
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910340308
Subject(s) - nuclear magnetic resonance , chemistry , visual cortex , spectroscopy , kinetic energy , transit time , kinetics , activation energy , analytical chemistry (journal) , neuroscience , physics , quantum mechanics , transport engineering , engineering , biology , chromatography
A kinetic analysis of water signal intensity changes measured in human visual cortex by PRESS localized 1 H 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 R 2* values for each free induction decay and the time constants for R 2* 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.