Short-echo spectroscopic imaging combined with lactate editing in a single scan

Area of Science:

• Magnetic Resonance Imaging
• Metabolomics
• Cancer Research

Background:

• Proton magnetic resonance spectroscopy (MRS) is crucial for non-invasive metabolite analysis.
• Distinguishing lactate from lipid signals in tumors is challenging due to spectral overlap.
• Current methods often require multiple scans or complex post-processing.

Purpose of the Study:

• To validate a novel spectroscopic imaging sequence combining short echo time and frequency-selective multiple-quantum coherence (Sel-MQC).
• To assess the method's ability to acquire water-suppressed proton spectra and filter lactate from lipids in a single scan.
• To evaluate the in vitro and in vivo performance of the combined pulse sequence for tumor metabolite characterization.

Main Methods:

• A short-echo spectroscopic imaging sequence was extended with a frequency-selective multiple-quantum-coherence (Sel-MQC) technique.
• In vitro phantom measurements were performed to confirm feasibility.
• In vivo experiments were conducted on eight tumors from two models (UT-SCC-8 and SAS) using the combined sequence.

Main Results:

• Phantom studies confirmed the method's feasibility.
• In vivo, T(1)- and T(2)-weighted metabolite and lipid ratios varied between central and outer tumor regions.
• A significant difference (p < 0.01) in the lipid methylene to choline peak ratio was observed in the central tumor area between the two models. Lactate was detected in 3/4 SAS tumors.

Conclusions:

• The combined short-echo spectroscopic imaging and Sel-MQC technique enables efficient acquisition of complete, water-suppressed proton spectra.
• This approach effectively filters lactate from co-resonant lipids, allowing for single-scan tumor metabolite characterization.
• The method successfully differentiated tumor models based on metabolite and lipid ratios, highlighting its potential for cancer research.