Figure 1.

Ketone body metabolism in the perfused rat heart at 11.7 T. (A) Spectrum acquired following the administration of hyperpolarized acetoacetate. The observed resonances are: 1, [1‐¹³C]acetoacetate (175 ppm); 2, [5‐¹³C]glutamate + unknown (believed to be acetate impurity, 182 ppm); 3, [1‐¹³C]β‐hydroxybutyrate (181 ppm); 4, unknown (believed to be acetoacetate hydrate impurity, 180 ppm); 5, unknown (178.8 ppm); 6, [1‐¹³C]citrate (178.7 ppm); 7, unknown (177 ppm); 8, [1‐¹³C]acetyl‐carnitine (172.5 ppm); 9, [1‐¹³C]ethylacetoacetate (batch reagent impurity, 169 ppm); 10, ¹³C‐bicarbonate (161 ppm); 11, [3‐¹³C]acetoacetate (210 ppm). (B) Spectrum acquired following the administration of hyperpolarized [1‐¹³C]β‐hydroxybutyrate. The observed resonances are: 1, [1‐¹³C]acetoacetate; 3, [1‐¹³C]β‐hydroxybutyrate; 8, [1‐¹³C]acetyl‐carnitine. The y‐axis is shown relative to maximum peak intensity