Downfield proton MRSI with whole-brain coverage at 3T

İpek Özdemir, Sandeep Ganji, Joseph Gillen, Semra Etyemez, Michal Považan, Peter B. Barker

Research output: Contribution to journalArticlepeer-review


Purpose: To develop a 3D downfield (DF) MRSI protocol with whole brain coverage and post-processing pipeline for creation of metabolite maps. Methods: A 3D, circularly phase-encoded version of the previously developed 2D DF MRSI sequence with (Figure presented.) spectral-spatial excitation and frequency selective refocusing was implemented and tested in five healthy volunteers at 3T. The DF metabolite maps with a nominal spatial resolution of 0.7 cm3 were recorded in eight slices at 3T in a scan time of 22 m 40 s. An MRSI post-processing pipeline was developed to create DF metabolite maps. Metabolite concentrations and uncertainty estimates were compared between region differences for nine DF peaks. Results: LCModel analysis showed Cramer Rao lower bounds average values of 3%–4% for protein amide resonances in the three selected regions (anterior cingulate, dorsolateral prefrontal cortex, and centrum semiovale); Cramer Rao lower bounds were somewhat higher for individual peaks but for the most part were less than 20%. While DF concentration maps were visually quite homogeneous throughout the brain, general linear regression analysis corrected for multiple comparisons found significant differences between centrum semiovale and dorsolateral prefrontal cortex for peaks at 7.09 ppm (p = 0.014), 7.90 ppm (p = 0.009), 8.18 ppm (p = 0.009), combined amides (p = 0.009), and between anterior cingulate and dorsolateral prefrontal cortex for the 7.30 ppm peak (p = 0.020). Cramer Rao lower bounds values were not significantly different between brain regions for any of the DF peaks. Conclusion: The 3D DF MRSI of the human brain at 3T with wide spatial coverage for the mapping of exchangeable amide and other resonances is feasible at a nominal spatial resolution of 0.7 cm3.

Original languageEnglish (US)
Pages (from-to)814-822
Number of pages9
JournalMagnetic resonance in medicine
Issue number3
StatePublished - Sep 2023


  • Downfield
  • MR spectroscopic imaging
  • human brain

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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