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Objective: Fractional extracellular space has been validated as a marker of hepatic fibrotic in cirrhotic patients at CT-scan as well as on dual-energy CT, which takes advantage from iodine uptake. Since no consensus still exists between equilibrium phases performed at 3 or 10 min, the first aim of this work is to evaluate performances at the two different time points. Moreover, correlation between fractional extracellular space and oesophageal varices, directly related to liver fibrosis, has been assessed., Materials and Methods: Dual-Energy equilibrium phases at 3 and 10 min were performed within a follow-up CT-protocol scan in cirrhotic patients. Oesophageal varices were endoscopically assessed according to their size. At the two different time points, correlation between iodine density of the right and left liver lobes and correlation between the fractional extracellular space values were assessed. Correlation between fractional extracellular space and endoscopic grade of oesophageal varices was calculated., Results: No statistical differences were found between the iodine density values from the two liver lobes at the two time points (p = 0.8 at 3'; p = 0.5 at 10'). No statistical difference about fractional extracellular space estimation was found between the two time points (p = 0.17). Correlation between fractional extracellular space values and oesophageal varices was moderate (ρ = 0.45, IC 0.08-0.71, p < 0.05)., Conclusion: Fractional extracellular space assessed on dual-energy CT at equilibrium phases with different timing was substantially similar. The moderate correlation found between fractional extracellular space and endoscopic grade of oesophageal varices confirms that CT-scan is not currently reliable as endoscopy.

Magnetic resonance imaging (MRI) is particularly attractive for clinical application in perfusion imaging thanks to the absence of ionizing radiation and limited volumes of contrast agent (CA) necessary. Dynamic contrast-enhanced MRI (DCE-MRI) involves sequentially acquiring T 1 -weighted images through an organ of interest during the passage of a bolus administration of CA. It is a particularly flexible approach to perfusion imaging as the signal intensity time course allows not only rapid qualitative assessment, but also quantitative measures of intrinsic perfusion and permeability parameters. We examine aspects of the T 1 -weighted image series acquisition, CA administration, post-processing that constitute a DCE-MRI study in clinical practice, before considering some heuristics that may aid in interpreting the resulting contrast enhancement time series. While qualitative DCE-MRI has a well-established role in the diagnostic assessment of a range of tumours, and a central role in MR mammography, clinical use of quantitative DCE-MRI remains limited outside of clinical trials. The recent publication of proposals for standardized acquisition and analysis protocols for DCE-MRI by the Quantitative Imaging Biomarker Alliance may be an opportunity to consolidate and advance clinical practice.

Background: One of the main features of liver fibrosis is the expansion of the interstitial space. All water-soluble CT contrast agents remain confined in the vascular and interstitial space constituting the fractional extracellular space (fECS). Indirect measure of its expansion can be quantified during equilibrium phase with CT. The goal of this prospective study was to assess the feasibility of dual-energy CT (DECT) with iodine quantification at equilibrium phase in the evaluation of significant fibrosis or cirrhosis., Methods: Thirty-eight cirrhotic patients (according to Child-Pugh and MELD scores), scheduled for liver CT, were enrolled in the study group. Twenty-four patients undergoing CT urography with a 10-min excretory phase were included in the control group. fECS was calculated as the ratio of the iodine concentration of liver parenchyma to that of the aorta, multiplied by 1 minus hematocrit., Results: Final study and control group were, respectively, composed of 22 and 20 patients. Mean hepatic fECS value was statistically greater in study group (P < 0.05). Positive correlation was observed between hepatic fECS value and MELD score (r = 0.64, P < 0.05). Analysis of variance showed statistical differences between control group and the Child-Pugh grades and between Child-Pugh A and B patients and Child-Pugh C patients (P < 0.05). ROC curves analysis yielded an optimum fECS cutoff value of 26.3% for differentiation of control group and cirrhotic patients (AUC 0.88; 86% sensitivity, 85% specificity)., Conclusions: Dual-source DECT is a feasible, noninvasive method for the assessment of significant liver fibrosis or cirrhosis.