Feasibility and reproducibility of BOLD and TOLD measurements in the liver with oxygen and carbogen gas challenge in healthy volunteers and patients with hepatocellular carcinoma

Purpose To quantify baseline relaxation ratesR 2 *and R 1 in the abdomen, their changes after respiratory challenges, and their reproducibility in healthy volunteers and patients with hepatocellular carcinoma (HCC) at 1.5T and 3.0T. Materials and MethodsR 2 *measurements were acquired in the liver in 8 volunteers and 27 patients with 34 HCCs using multiechoT 2 *at baseline and after respiratory challenges with 100% oxygen (O 2 ) and carbogen (CB = 95%O 2 /5%CO 2 ). R 1 was measured at 1.5T in one volunteer and 21 patients with 23 HCCs. Test–retest coefficient of variation (CV) was assessed in 10 subjects. Intra‐ and interobserver variability ofR 2 *and R 1 measurements was assessed in 12 and 10 patients, respectively. Parameters for HCC, liver, and muscle were compared between baseline and after gas challenges. Results We observed thatR 2 *and R 1 imaging of HCCs with O 2 and CB is feasible and reproducible (test–retest CVR 2 * <15%/R 1 <5%; intra‐ and interobserver intraclass correlation coefficientR 2 * >0.88/R 1 >0.7 and CVR 2 * <7%/R 1 <3% at 1.5T).R 2 *measurements were observed to be less reproducible at 3.0T (CV<35%). There was a statistically significant decrease inR 2 *values in HCC before and after O 2 ( P  = 0.02) and increase in R 1 after O 2 ( P  = 0.004). CB had no significant effect ( PR 2 *  = 0.47/R 1  = 0.278). ConclusionR 2 *measurements in HCC and liver parenchyma are more reproducible at 1.5T than at 3.0T, and with O 2 than with CB challenge. We observed a decrease inR 2 *and an increase in R 1 of HCCs from baseline in response to O 2 challenge, as expected with increased tissue and blood oxygenation. J. Magn. Reson. Imaging 2016;43:866–876