Segmental fECV measurement using PCD-CT as an early predictor of liver function decline in chronic liver disease

The aim of this study was to investigate the utility of segmental hepatic extracellular volume fractions (fECV) calculated using a photon-counting detector CT (PCD-CT) for predicting liver function decline, as reflected by the modified albumin-bilirubin (mALBI) grade in chronic liver disease (CLD).

A total of 146 patients with CLD underwent PCD-CT of the liver, including 3-minute equilibrium phase imaging. Iodine densities of the aorta and liver segments (S2-S8), based on Couinaud's classification, were measured to calculate fECV. The diagnostic accuracy of segmental fECV for predicting early liver function decline was assessed using mALBI grade as the functional reference standard, with receiver operating characteristic (ROC) analysis.

For mALBI grades 1, 2b, and 3, no significant differences in fECV were found among segments. For mALBI grade 2a, fECV values were significantly larger in S4 and S5 compared to S2, S3, S6, and S7 (p < 0.05), and the fECV in S8 was significantly larger than in S7 (p < 0.05). The fECV values in S6 and S7 significantly increased with higher mALBI grade, while other segments showed less pronounced increases. ROC analysis revealed that fECV in S4, S5, and S8 demonstrated sensitivities, specificities, and accuracies of approximately 90% for predicting early liver function decline (distinguishing mALBI grade 1 from grades 2a or above).

Segmental fECV measurement using PCD-CT offers preliminary insights into liver function. Increased fECV in the medial (S4) and anterior (S5, S8) segments showed potential as an early indicator of functional decline, while fECV in the posterior segments (S6, S7) suggested utility in disease staging. As a proof-of-concept study, these findings require further validation before this approach can be adopted in clinical practice.