Purpose To explore whether Chemical Exchange Saturation Transfer (CEST) MRI can detect liver composition changes between after-meal and over-night-fast statuses. Procedures 15 healthy volunteers were scanned on a 3.0 T human MRI scanner in the evening 1.5–2 hour after dinner and in the morning after over-night (12-hour) fasting. Among them seven volunteers were scanned twice to assess the scan-rescan reproducibility. Images were acquired at offsets (n=41, increment=0.25ppm) from −5 to 5ppm using a turbo spin echo (TSE) sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified with the asymmetric magnetization transfer ratio (MTRasym) at 3.5ppm and the total MTRasym integrated from 0.5 to 1.5ppm from the corrected Z-spectrum, respectively. To explore scan time reduction, CEST images were reconstructed using 31 offsets (with 20% time reduction) and 21 offsets (with 40% time reduction), respectively. Results For reproducibility, GlycoCEST measurements in 41 offsets showed the smallest scan-rescan mean measurements variability, indicated by lowest mean difference of −0.049% (95% limits of agreement: −0.209% to 0.111%); for APTw, the smallest mean difference was found to be 0.112% (95% limits of agreement: −0.698% to 0.921%) in 41 offsets. Compared with after-meal, both GlycoCEST measurement and APTw measurement under different offset number decreased after 12-hour fasting. However, as the offsets number decreased (41 offsets vs. 31 offsets vs. 21 offsets), GlycoCEST map and APTw map became more heterogeneous and noisier. Conclusion Our results show that CEST liver imaging at 3.0 T has high sensitivity for fasting.

Purpose To evaluate Chemical Exchange Saturation Transfer (CEST) MRI for liver imaging at 3.0-T. Materials and Methods Images were acquired at offsets (n=41, increment=0.25ppm) from −5 to 5ppm using a TSE sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified as the asymmetric magnetization transfer ratio (MTRasym) at 3.5ppm and the total MTRasym integrated from 0.5 to 1.5ppm, respectively, from the corrected Z-spectrum. Reproducibility was assessed for rats and humans. Eight rats were devoid of chow for 24-hours and scanned before and after fasting. Eleven rats were scanned before and after one-time CCl4 intoxication. Results For reproducibility, rat liver APTw and GlycoCEST measurements had 95% limits of agreement of −1.49% to 1.28% and −0.317% to 0.345%. Human liver APTw and GlycoCEST measurements had 95% limits of agreement of −0.842% to 0.899% and − 0.344% to 0.164%. After 24-hours fasting rat liver APTw and GlycoCEST signals decreased from 2.38±0.86% to 0.67±1.12% and from 0.34±0.26% to −0.18±0.37% respectively (p<0.05). After CCl4 intoxication rat liver APTw and GlycoCEST signals decreased from 2.46±0.48% to 1.10±0.77%, and from 0.34±0.23% to −0.16±0.51% respectively (p<0.05). Conclusion CEST liver imaging at 3.0-T showed high sensitivity for fasting as well as CCl4 intoxication.