Simultaneous T 1 and T 2 mapping of hyperpolarized 13 C compounds using the bSSFP sequence.

As in conventional ¹ H MRI, T ₁ and T ₂ relaxation times of hyperpolarized (HP) ¹³ C nuclei can provide important biomedical information. Two new approaches were developed for simultaneous T ₁ and T ₂ mapping of HP ¹³ C probes based on balanced steady state free precession (bSSFP) acquisitions: a method based on sequential T ₁ and T ₂ mapping modules, and a model-based joint T ₁ /T ₂ approach analogous to MR fingerprinting. These new methods were tested in simulations, HP ¹³ C phantoms, and in vivo in normal Sprague-Dawley rats. Non-localized T ₁ values, low flip angle EPI T ₁ maps, bSSFP T ₂ maps, and Bloch-Siegert B ₁ maps were also acquired for comparison. T ₁ and T ₂ maps acquired using both approaches were in good agreement with both literature values and data from comparative acquisitions. Multiple HP ¹³ C compounds were successfully mapped, with their relaxation time parameters measured within heart, liver, kidneys, and vasculature in one acquisition for the first time.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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