Figure 1

Characterization of the hyperpolarized probe, [1,3-¹³C₂]acetoacetate ([1,3-¹³C₂]AcAc). (A) [1,3-¹³C₂]AcAc was prepared by mixing 250 μL of [1,3-¹³C₂]ethyl-AcAc with 4 mL of 1 M NaOH at 37 °C for 24 hours. (B) [1,3-¹³C₂]AcAc thermal equilibrium spectrum (1, NT = 16, x80) and first hyperpolarized spectrum (2, NT = 1) were acquired at 11.7T and showed a ~20% increase in liquid-state polarization level by the dissolution dynamic nuclear polarization technique (NT = number of transient). Resonances of [1-¹³C]AcAc (δ[1-¹³C]AcAc = 175.5 ppm), [3-¹³C]AcAc (δ[3-¹³C]AcAc = 210.9 ppm) and ¹³C-contaminants (δ[1-¹³C]Acetate = 182.1 ppm, δ[¹³C]Unknown = 180.5 ppm and δ[¹³C]Bicarbonate = 161 ppm) were detectable. (C) Stack plot of ¹³C MR spectra of hyperpolarized [1,3-¹³C₂]AcAc in solution acquired at 11.7T showing decay of the hyperpolarized signals as a function of time (temporal resolution 3 sec). Resonances of [1-¹³C]AcAc (δ[1-¹³C]AcAc = 175.5 ppm), [3-¹³C]AcAc (δ[3-¹³C]AcAc = 210.9 ppm) and ¹³C-contaminants (δ[1-¹³C]Acetate = 182.1 ppm, δ[¹³C]Unknown = 180.5, 179.7, 179.2 ppm and δ[1-¹³C]Acetone = 216.1 ppm) were detectable.