Eleanor F Cox1,2, Naaventhan Palaniyappan2,3, Guruprasad P Aithal2,3, I Neil Guha2,3, Susan T Francis1,2. 1. Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham, UK. 2. NIHR Nottingham BRC, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK. 3. Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK.
Abstract
BACKGROUND: Noninvasive assessment of dynamic changes in liver blood flow, perfusion, and oxygenation using MRI may allow detection of subtle hemodynamic alterations in cirrhosis. PURPOSE: To assess the feasibility of measuring dynamic liver blood flow, perfusion, and T2 * alterations in response to meal, hypercapnia, and hyperoxia challenges. STUDY TYPE: Prospective. SUBJECTS: Ten healthy volunteers (HV) and 10 patients with compensated cirrhosis (CC). FIELD STRENGTH/SEQUENCE: 3T; phase contrast, arterial spin labeling, and T 2 * mapping. ASSESSMENT: Dynamic changes in portal vein and hepatic artery blood flow (using phase contrast MRI), liver perfusion (using arterial spin labeling), and blood oxygenation ( T 2 * mapping) following a meal challenge (660 kcal), hyperoxia (target PET O2 of 500 mmHg), and hypercapnia (target increase PET CO2 of ∼6 mmHg). STATISTICAL TESTS: Tests between baseline and each challenge were performed using a paired two-tailed t-test (parametric) or Wilcoxon-signed-ranks test (nonparametric). Repeatability and reproducibility were determined by the coefficient of variation (CoV). RESULTS: Portal vein velocity increased following the meal (70 ± 9%, P < 0.001) and hypercapnic (7 (5-11)%, P = 0.029) challenge, while hepatic artery flow decreased (-30 ± 18%, P = 0.005) following the meal challenge in HV. In CC patients, portal vein velocity increased (37 ± 13%, P = 0.012) without the decrease in hepatic artery flow following the meal. In both groups, the meal increased liver perfusion (HV: 82 ± 50%, P < 0.0001; CC: 27 (16-42)%, P = 0.011) with faster arrival time of blood (HV: -54 (-56-30)%, P = 0.074; CC: -42 ± 32%, P = 0.005). In HVs, T 2 * increased after the meal and in response to hyperoxia, with a decrease in hypercapnia (6 ± 8% P = 0.052; 3 ± 5%, P = 0.075; -5 ± 6%, P = 0.073, respectively), but no change in CC patients. Baseline between-session CoV <15% for blood flow and <10% for T 2 * measures. DATA CONCLUSION: Dynamic changes in liver perfusion, blood flow, and oxygenation following a meal, hyperoxic, and hypercapnic challenges can be measured using noninvasive MRI and potentially be used to stratify patients with cirrhosis. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1577-1586.
BACKGROUND: Noninvasive assessment of dynamic changes in liver blood flow, perfusion, and oxygenation using MRI may allow detection of subtle hemodynamic alterations in cirrhosis. PURPOSE: To assess the feasibility of measuring dynamic liver blood flow, perfusion, and T2 * alterations in response to meal, hypercapnia, and hyperoxia challenges. STUDY TYPE: Prospective. SUBJECTS: Ten healthy volunteers (HV) and 10 patients with compensated cirrhosis (CC). FIELD STRENGTH/SEQUENCE: 3T; phase contrast, arterial spin labeling, and T 2 * mapping. ASSESSMENT: Dynamic changes in portal vein and hepatic artery blood flow (using phase contrast MRI), liver perfusion (using arterial spin labeling), and blood oxygenation ( T 2 * mapping) following a meal challenge (660 kcal), hyperoxia (target PET O2 of 500 mmHg), and hypercapnia (target increase PET CO2 of ∼6 mmHg). STATISTICAL TESTS: Tests between baseline and each challenge were performed using a paired two-tailed t-test (parametric) or Wilcoxon-signed-ranks test (nonparametric). Repeatability and reproducibility were determined by the coefficient of variation (CoV). RESULTS: Portal vein velocity increased following the meal (70 ± 9%, P < 0.001) and hypercapnic (7 (5-11)%, P = 0.029) challenge, while hepatic artery flow decreased (-30 ± 18%, P = 0.005) following the meal challenge in HV. In CC patients, portal vein velocity increased (37 ± 13%, P = 0.012) without the decrease in hepatic artery flow following the meal. In both groups, the meal increased liver perfusion (HV: 82 ± 50%, P < 0.0001; CC: 27 (16-42)%, P = 0.011) with faster arrival time of blood (HV: -54 (-56-30)%, P = 0.074; CC: -42 ± 32%, P = 0.005). In HVs, T 2 * increased after the meal and in response to hyperoxia, with a decrease in hypercapnia (6 ± 8% P = 0.052; 3 ± 5%, P = 0.075; -5 ± 6%, P = 0.073, respectively), but no change in CC patients. Baseline between-session CoV <15% for blood flow and <10% for T 2 * measures. DATA CONCLUSION: Dynamic changes in liver perfusion, blood flow, and oxygenation following a meal, hyperoxic, and hypercapnic challenges can be measured using noninvasive MRI and potentially be used to stratify patients with cirrhosis. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1577-1586.