Efficient 31P band inversion transfer approach for measuring creatine kinase activity, ATP synthesis, and molecular dynamics in the human brain at 7 T

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Abstract

Purpose: To develop an efficient 31P magnetic resonance spectroscopy (MRS) method for measuring creatine kinase (CK) activity, adenosine triphosphate (ATP) synthesis, and motion dynamics in the human brain at 7 Tesla (T). Methods: Three band inversion modules differing in center frequency were used to induce magnetization transfer (MT) effect in three exchange pathways: (i) CK-mediated reaction PCr → γ-ATP; (ii) de novo ATP synthesis Pi → γ-ATP; and (iii) ATP intramolecular 31P-31P cross-relaxation γ-(α-) ↔ β-ATP. The resultant MT data were analyzed using a 5-pool model in the format of magnetization matrix according to Bloch-McConnell-Solomon formalism. Results: With a repetition time (TR) of 4 s, the scan time for each module was approximately 8min. The rate constants were kPCr → γATP 0.38±0.02 s-1, kPi → γATP 0.19±0.02 s-1, and σγ(α) ↔ βATP 0.19±0.04 s-1, corresponding to ATP rotation correlation time τc (0.8±0.2) ·10-7 s. The T1 relaxation times were Pi 7.26±1.76 s, PCr 5.99±0.58 s, γ-ATP 0.98±0.07 s, α-ATP 0.95±0.04 s, and β-ATP 0.68±0.03 s. Conclusion: Short-TR band inversion modules provide a time-efficient way of measuring brain ATP metabolism and could be useful in studying metabolic disorders in brain diseases. Magn Reson Med, 2016.

Original languageEnglish (US)
JournalMagnetic Resonance in Medicine
DOIs
Publication statusAccepted/In press - 2016

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Keywords

  • 31P MRS
  • ATP
  • Human brain
  • Inversion transfer
  • Magnetization transfer
  • Relaxation time

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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