Related Experiment Video
Updated: Jan 9, 2026
09:55
Author Spotlight: Using Hyperpolarized Xenon-129 MRI to Study Lung Diseases
Published on: January 5, 2024
1.8K
Hypercapnia-induced effects on image contrast based on intermolecular double-quantum coherences.
Andreas Schäfer1, Stefan Zysset, Wolfgang Heinke
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Magnetic Resonance in Medicine
|November 26, 2008
Summary
Intermolecular double-quantum coherences (iDQCs) in MRI reveal physiological changes during neuronal activation. Carbogen inhalation experiments show iDQC signal changes correlate with hemodynamic responses, aiding understanding of brain activity.
Area of Science:
- Biophysics
- Neuroimaging
- Magnetic Resonance Imaging
Background:
- Intermolecular double-quantum coherences (iDQCs) are sensitive to magnetic field variations in tissues.
- The precise link between iDQC contrast in MRI and physiological processes remains unclear.
Purpose of the Study:
- To explore factors influencing iDQC signal alterations during neuronal activation.
- To investigate iDQCs as a potential MRI contrast mechanism for hemodynamic responses.
Main Methods:
- Carbogen-inhalation experiments were conducted on eight volunteers at 2.9 T.
- Gradient-recalled echo (GRE) and spin-echo (SE) sequences were used to select iDQCs.
- Results were compared with conventional blood oxygen level-dependent (BOLD) MRI.
Main Results:
- iDQC and conventional MRI showed similar voxel activation patterns following carbogen challenge, after sensitivity adjustments.
- Diffusion weighting and transverse relaxation in iDQC sequences reduced intravascular signal.
- Significant iDQC signal changes (up to 21.7% +/- 2.5%) were observed, correlating with hemodynamic changes.
Conclusions:
- iDQC MRI can detect hemodynamic responses during neuronal activation.
- The observed iDQC signal changes quantitatively align with the balloon model of BOLD MRI.
- iDQC MRI offers a promising method for studying brain physiology with potential for improved contrast mechanisms.
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.4K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.4K
01:04¹³C NMR: ¹H–¹³C Decoupling
1.7K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
1.7K
01:12Double Resonance Techniques: Overview
665
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
665
01:182D NMR: Overview of Heteronuclear Correlation Techniques
722
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other...
722
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.6K
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
1.6K
01:13¹H NMR: Complex Splitting
1.8K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.8K