Functional MRI at 3T using intermolecular double-quantum coherence (iDQC) with spin-echo (SE) acquisitions.
OBJECTIVE
To reinvestigate the dependence of the signal and contrast on sequence parameters and tissue relaxation times for intermolecular double-quantum coherence (iDQC) signals, and to explore the possibility to use a spin-echo (SE)-iDQC sequence for detecting activation signals at 3T.


METHODS
Brain activations were detected in five human volunteers in a visual simulation study using a SE-iDQC sequence, in addition to a GE-iDQC and a conventional single-quantum coherence (SQC) blood-oxygenation-level-dependent (BOLD) sequence. A brain phantom was also used for some quantitative measurements.


RESULTS
By choosing an optimal echo time TE (approximately T2) and iDQC evolution time tau(approximately 20 ms), robust brain activations were detected using the SE-iDQC sequence, in addition to the GE-iDQC and a conventional single-quantum coherence (SQC) BOLD sequence. A higher percentage signal change due to activation was observed for both the iDQC-based measurements in comparison to the conventional SQC acquisition.


CONCLUSIONS
Even though a phenomenological analysis consistent with the experimental results was provided, a detailed model is still needed for the contrast mechanism at microscopic level to guide potential applications of brain functional imaging based on the SE-iDQC.
Gu
T
T
Department of Imaging Sciences, University of Rochester, Rochester, NY 14642, USA.
Kennedy
S D
SD
Chen
Z
Z
Schneider
K A
KA
Zhong
J
J
D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D010775:Photic Stimulation