Distinguishing metabolic signals of liver tumors from surrounding liver cells using hyperpolarized 13C MRI and gadoxetate

Abstract Purpose To use the hepatocyte‐specific gadolinium‐based contrast agent gadoxetate combined with hyperpolarized (HP) [1‐ 13 C]pyruvate MRI to selectively suppress metabolic signals from normal hepatocytes while preserving the signals arising from tumors. Methods Simulations were performed to determine the expected changes in HP 13 C MR signal in liver and tumor under the influence of gadoxetate. CC531 colon cancer cells were implanted into the livers of five Wag/Rij rats. Liver and tumor metabolism were imaged at 3 T using HP [1‐ 13 C] pyruvate chemical shift imaging before and 15 min after injection of gadoxetate. Area under the curve for pyruvate and lactate were measured from voxels containing at least 75% of normal‐appearing liver or tumor. Results Numerical simulations predicted a 36% decrease in lactate‐to‐pyruvate (L/P) ratio in liver and 16% decrease in tumor. In vivo, baseline L/P ratio was 0.44 ± 0.25 in tumors versus 0.21 ± 0.08 in liver ( p = 0.09). Following administration of gadoxetate, mean L/P ratio decreased by an average of 0.11 ± 0.06 ( p < 0.01) in normal‐appearing liver. In tumors, mean L/P ratio post‐gadoxetate did not show a statistically significant change from baseline. Compared to baseline levels, the relative decrease in L/P ratio was significantly greater in liver than in tumors (−0.52 ± 0.16 vs. −0.19 ± 0.25, p < 0.05). Conclusions The intracellular hepatobiliary contrast agent showed a greater effect suppressing HP 13 C MRI metabolic signals (through T 1 shortening) in normal‐appearing liver when compared to tumors. The combined use of HP MRI with selective gadolinium contrast agents may allow more selective imaging in HP 13 C MRI.