Noninvasive Hepatic Extracellular Volume Quantification by Photon-Counting CT for Portal Hypertension Risk

Overview

This prospective cohort study demonstrates that hepatic extracellular volume (ECV) quantification via photon-counting CT (PCCT) correlates with liver stiffness measurement (LSM) and histologic fibrosis severity, enabling noninvasive risk stratification of clinically significant portal hypertension (CSPH). PCCT-derived ECV offers a reproducible imaging biomarker that complements existing noninvasive liver disease assessments.

Background

Chronic liver disease (CLD) and cirrhosis are major global mortality causes, with progression from compensated to decompensated stages marked by clinically significant portal hypertension (CSPH). The hepatic venous pressure gradient (HVPG) is the gold standard for CSPH diagnosis but is invasive and not widely available. Noninvasive surrogates like liver stiffness measurement (LSM) are used but have limitations including operator dependence and reduced reliability in obesity or ascites. Photon-counting CT (PCCT) enables precise hepatic extracellular volume (ECV) quantification, potentially serving as an objective, widely accessible imaging biomarker for CSPH risk stratification.

Data Highlights

Key Findings

• PCCT-derived hepatic ECV correlates strongly with LSM values, supporting its validity as a fibrosis and CSPH surrogate.
• ECV quantification is reproducible and less operator-dependent compared to elastography.
• ECV measurement utilizes equilibrium phase iodine density normalized to aortic iodine and hematocrit, obviating the need for non-contrast scans.
• ECV values increase with histologically confirmed fibrosis severity, demonstrating concordance with liver biopsy findings.
• PCCT imaging can be integrated into routine multiphasic liver CT protocols, enabling opportunistic CSPH risk assessment during HCC surveillance.

Clinical Implications

PCCT-derived hepatic ECV offers a noninvasive, objective imaging biomarker for CSPH risk stratification that complements existing elastography-based assessments. Its integration into routine liver CT protocols may enhance early detection of portal hypertension, particularly in patients where elastography is limited by obesity or ascites. This approach could facilitate timely clinical decision-making and improve management of patients with compensated advanced chronic liver disease.

Conclusion

Hepatic extracellular volume quantification by photon-counting CT is a promising noninvasive tool for assessing fibrosis severity and stratifying CSPH risk, potentially augmenting current noninvasive liver disease assessment strategies. Further validation may establish PCCT-derived ECV as a routine imaging biomarker in chronic liver disease management.

References

1. Baveno VII Consensus Workshop -- Portal Hypertension Guidelines
2. AASLD Practice Guidance -- Noninvasive Assessment of Liver Disease
3. Siemens Healthineers -- Photon-Counting CT Technology