Improving whole-brain deuterium metabolic imaging

Deuterium Metabolic Imaging (DMI) is an emerging technique to probe metabolic pathways. Due to its almost negligible natural abundance, we investigate the spatial and temporal evolution of orally ingested deuterated glucose in the brain. The concentration and conversion rates of metabolic intermediates can be used as highly specific biomarkers to detect and characterize abnormalities in energy metabolism, such as cancer.
Higher SNR and better spectral resolution at ultra-high field (9.4 T) make it an ideal choice for imaging deuterium-labelled metabolic intermediates with low gyromagnetic ratio and low concentration. Typically, the preferred approach for conducting DMI is the use of a 3D localized spectroscopy method, because of its widespread availability and ease of use. The short and relatively similar longitudinal and transverse relaxation times of glucose, and its metabolic intermediates make SSFP-based imaging techniques an attractive alternative to conventional spectroscopy methods due to their higher SNR efficiency. Recently, multi-echo bSSFP has been shown to  improve the SNR of metabolite detection by 3-5 times compared to the conventional spectroscopic technique  in preclinical settings. However, the large off-resonance in the human brain and SAR limitations at ultra-high field makes the direct translation challenging.
We propose a flexible method to perform DMI in the brain using bSSFP technique with both multiple echoes, and phase cycling. Metabolite amplitudes were estimated by fitting a theoretical bSSFP signal model to the measured data. The initial results suggest that the proposed bSSFP technique can significantly improve the spatial resolution of human dynamic DMI at ultra-high fields.


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