3D localized 2D NMR spectroscopy on an MRI scanner

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Magnetic Resonance Spectroscopy (MRS)
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Two-dimensional (2D) NMR sequences are powerful tools for spectral analysis.
• Localization is crucial for in vivo studies to isolate specific tissues or regions.
• Integrating 3D localization with 2D NMR techniques enhances spatial resolution and analytical capabilities.

Purpose of the Study:

• To implement and evaluate three-dimensionally localized versions of various 2D NMR sequences on a 1.5 T MRI/MRS scanner.
• To demonstrate the feasibility of these localized 2D NMR techniques for in vivo human studies.
• To showcase the potential for precise metabolic profiling in specific anatomical regions.

Main Methods:

• Implementation of localized 2D NMR sequences including 2D J-resolved, 2D zero-quantum, 2D double-quantum, zero-quantum-filtered COSY/SECSY, and double-quantum-filtered COSY/SECSY.
• Utilized slice-selective radiofrequency (RF) pulses for both voxel localization and coherence manipulation.
• Performed phantom studies with alanine and metabolite mixtures, alongside in vivo studies on healthy volunteers.

Main Results:

• Successfully localized several 2D NMR sequences in three dimensions.
• Presented 2D plots from phantom studies, illustrating spectral information from localized regions.
• Demonstrated the feasibility of localized double-quantum-filtered COSY within clinically acceptable timeframes.
• Acquired the first reported 3D localized 2D J-resolved 1H MR spectrum in vivo from human cerebral white matter.

Conclusions:

• Three-dimensionally localized 2D NMR sequences are feasible on standard MRI/MRS scanners.
• These techniques allow for precise spatial localization and spectral analysis of metabolites in vivo.
• The presented methods hold significant promise for advanced diagnostic applications in neuroimaging and beyond.