Abstract:
PURPOSE:Imaging of [2-13 C]lactate, a metabolic product of [2-13 C]pyruvate, is over considerable interest in hyperpolarized 13 C studies. However, artifact-free imaging of a J-coupled nuclear spin species can be challenging due to the peak-splitting induced by the spin-spin interactions. In this work, two new techniques resolving these J-modulated artifacts are presented. THEORY AND METHODS:The Product Operator Formalism (POF) of density matrix theory is used to both numerically and analytically derive the coherences arising during radiofrequency excitation and readout of a J-coupled spin system. A combination of computer simulations and experiments with [2-13 C]lactate and 13 C-formate phantoms are then used to verify the performance of two imaging methods. In the first approach, a quadrature imaging technique is used to eliminate scalar coupling artifacts via the combination of in-phase and quadrature images acquired at echo times differing by 1/2J with an echoplanar readout. The second approach employs a highly narrowband RF excitation pulse to image a single peak from the J-coupled doublet. RESULTS:Simulations using a numerical Shepp-Logan phantom, in vitro experiments using thermally polarized [2-13 C]lactate, thermally and hyperpolarized 13 C-formate phantoms, and in vivo imaging of [2-13 C]lactate produced in rat brain following injection of hyperpolarized [2-13 C]pyruvate show artifact-free images and demonstrate potential utility of these methods. CONCLUSION:The quadrature imaging and the narrowband excitation techniques resolve the J-coupling induced ghosting and blurring artifacts present with conventional MRI of J-coupled signals such as [2-13 C]lactate.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Datta K,Spielman Ddoi
10.1002/mrm.28532subject
Has Abstractpub_date
2021-03-01 00:00:00pages
1522-1539issue
3eissn
0740-3194issn
1522-2594journal_volume
85pub_type
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