FIGURE 3.

A single‐shot 3D ¹³C MRSI sequence was used to acquire [1‐¹³C]lactate (A) and [1‐¹³C]pyruvate images (B) following injection of hyperpolarized [1‐¹³C]pyruvate (images from a single slice are shown). ¹³C image intensities were normalized to the maximum intensity across the whole tumor volume, and images of the summed signal over time for each of the 16 individual slices were overlaid on the corresponding anatomical T₂‐weighted axial ¹H images (D). (E) Maps of [¹²C] and [1‐¹³C]lactate generated by MSI of a frozen section taken from the same slice from which the ¹³C MRS images shown in (A, B, and D) were acquired. A slice from a noninjected control mouse is also shown for comparison. The MS images were coregistered with those generated by ¹³C MRSI by manual registration in the z‐direction of the histological (C) and T₂‐weighted MR images (D) using anatomical landmarks and the tumor outline. ¹H, hydrogen‐1. ¹²C, carbon‐12