MRS Resources

Magnetic Resonance Spectroscopy material gathering point.
Focus: Multi-nuclear (X-nuclei) applications at 3T (Clinical).

Technical Configuration

Scanner: 3T Siemens Prisma (Multinuclear)

Coils & Ancillary:

Polarean: Xenon Hyperpolarizer + Xe Vest Coil
PulseTeq: Dual-tuned surface coils
- ¹³C / ¹H Surface Coil (cf. PulseTeq Liver Coil)
- ³¹P / ¹H Surface Coil

Hardware & Instrumentation Requirements for non-proton imaging on clinical scanners.
- Broadband amplifiers (Multi-transmit capable?)
- Double-tuned coils (e.g., 1H/31P, 1H/13C) for anatomical localization + shimming
- B0 Shimming challenges (2nd order shims essential)
Pulse Sequences & Physics Adapting standard sequences for X-nuclei.
- FID vs. Spin Echo (T2* considerations)
- NOE (Nuclear Overhauser Effect) enhancement - proton decoupling
- SAR (Specific Absorption Rate) limits with decoupling
- Chemical Shift Imaging (CSI) / MRSI vs. SVS (Single Voxel)

Bioenergetics The primary clinical application of 31P MRS.
- PCr (Phosphocreatine) / ATP ratios - Energy reserve status
- Pi (Inorganic Phosphate) - Metabolic byproducts
- Intracellular pH measurement (chemical shift of Pi)
- Mg2+ concentration (chemical shift difference between ATP resonances)
Membrane Metabolism Markers of synthesis and degradation.
- PME (Phosphomonoesters) - Membrane building blocks (e.g., PC, PE)
- PDE (Phosphodiesters) - Membrane breakdown products (e.g., GPC, GPE)
- Relevance in oncology (turnover rates)

Metabolic Flux Analysis Tracking dynamic metabolic pathways.
- Natural Abundance (1.1%) challenges - requires long scan times. See: Liver Glycogen
- 13C-Glucose infusion studies (TCA cycle rate, Glutamate/Glutamine cycling)
- Glycogen metabolism (Muscle/Liver)
Hyperpolarized 13C (Pyruvate) Emerging clinical applications (requires polarizer).
- Real-time metabolic imaging (Pyruvate -> Lactate conversion)
- Warburg effect visualization in tumors

Hyperpolarized Imaging Using laser-polarized gas for enhanced signal.
- Lung ventilation imaging (Gas phase)
- Dissolved Phase Spectroscopy (The "MRS" component)
Dissolved Phase Peaks Chemical shift separation of compartments.
- Gas peak (0 ppm reference)
- Barrier peak (Tissue/Plasma ~197 ppm)
- RBC peak (Red Blood Cells ~217 ppm)
- Gas exchange metrics (RBC/Barrier ratios) - Pulmonary fibrosis, COPD assessment