UCSF

As in conventional ¹H MRI, T₁ and T₂ relaxation times of hyperpolarized (HP) ¹³C nuclei can provide important biomedical information. Two new approaches were developed for simultaneous T₁ and T₂ mapping of HP ¹³C probes based on balanced steady state free precession (bSSFP) acquisitions: a method based on sequential T₁ and T₂ mapping modules, and a model-based joint T₁/T₂ approach analogous to MR fingerprinting. These new methods were tested in simulations, HP ¹³C phantoms, and in vivo in normal Sprague-Dawley rats. Non-localized T₁ values, low flip angle EPI T₁ maps, bSSFP T₂ maps, and Bloch-Siegert B₁ maps were also acquired for comparison. T₁ and T₂ maps acquired using both approaches were in good agreement with both literature values and data from comparative acquisitions. Multiple HP ¹³C compounds were successfully mapped, with their relaxation time parameters measured within heart, liver, kidneys, and vasculature in one acquisition for the first time.