Can functional parameters from hepatobiliary phase of gadoxetate MRI predict clinical outcomes in patients with cirrhosis?

OBJECTIVES: To determine the value of quantitative parameters of gadoxetate-enhanced magnetic resonance imaging (MRI) in predicting prognosis in patients with cirrhosis. METHODS: A cohort of 63 cirrhotic patients who had gadoxetate MRI and 2-year clinical follow-up was enrolled. Enhancement ratio (ER), contrast enhancement index (CEI) and contrast enhancement spleen index (CES) were calculated. The usefulness of these parameters and clinical scores, such as Child-Pugh score (CPS) and model for end stage liver disease (MELD), in predicting adverse outcomes, such as variceal bleeding (VB), hepatic encephalopathy (HE) and mortality at 2 years were evaluated. RESULTS: Fifteen, 31 and 27 patients, respectively, had VB, HE and mortality within 2 years. The ER at 15 min (ER 15) and CES at 20 min (CES 20) were found to be the best MRI predictors. Areas under the receiver operating characteristic curve (AUC) for predicting VB were 0.785, 0.729, 0.673, 0.714, respectively, for ER 15, CES 20, CPS and MELD scores. ER 15 of less than 48 had sensitivity of 96% and specificity of 84% for predicting onset of HE within 2 years. CONCLUSIONS: In patients with cirrhosis, ER 15 or CES 20 were equivalent or better predictors of major morbidity and mortality compared with commonly used clinical scores. KEY POINTS: • Gadoxetate parameters may identify cirrhotic patients at risk of adverse events. • Gadoxetate parameters usually show superior predictive values compared to clinical scores. • CES 20 score is associated with risk of mortality within 2 years.

Does intravoxel incoherent motion reliably stage hepatic fibrosis, steatosis, and inflammation?

OBJECTIVE: To investigate the usefulness of intravoxel incoherent motion (IVIM) in determining the severity of hepatic fibrosis, steatosis, and inflammation in patients with chronic liver disease. METHODS: Forty-nine patients who had liver MRI with IVIM sequence and liver biopsy within three months of MRI were enrolled. A reviewer, blinded to histology, placed regions of interest of 1-2 cm2 in the right liver lobe. In addition, the first twenty patients were assessed with a second reviewer. Perfusion fraction (f), pseudodiffusion coefficient (D fast), true diffusion coefficient (D slow), and apparent diffusion coefficient (ADC) were calculated from normalized signal intensities that were fitted into a biexponential model. Errors in the model were minimized with global stochastic optimization using Simulated Annealing. ANOVA with post hoc Tukey-Kramer test and multivariate generalized linear model analysis were performed, using histological findings as the gold standard. RESULTS: The most common etiologies for liver disease were hepatitis C and alcohol, accounting together for 76% (37/49) of patients. Low-grade fibrosis (F0, F1), hepatic steatosis, and inflammation were seen in 24% (12/49), 31% (15/49), and 29% (14/49) of patients, respectively. The interobserver correlation was poor for D fast and D slow (0.105, 0.173) and moderate for f and ADC (0.461, 0.418). ANOVA showed a strong inverse association between D fast and liver fibrosis grade (p = 0.001). A weak inverse association was seen between ADC and hepatic steatosis (p = 0.059). Multivariate general linear model revealed that the only significant association between IVIM parameters and pathological features was between D fast and fibrosis. On ROC curve analysis, D fast < 23.4 × 10-3 mm2/s had a sensitivity of 82.8% and a specificity of 64.3% in predicting high-grade fibrosis. CONCLUSION: D fast has the strongest association with hepatic fibrosis but has weak interobserver correlation. IVIM parameters were not significantly associated with hepatic inflammation or steatosis.