Extended Validity of Hematocrit for Dual-energy CT Extracellular Volume Calculation in Cirrhosis: A 7-Day Window...

This study aimed to validate a 7-day hematocrit (Hct) window for calculating liver extracellular volume (ECV) from dual-energy CT (DECT) iodine maps could potentially replace the strict 24-hour Hct requirement in cirrhotic patients, and to evaluate its diagnostic accuracy for staging cirrhosis severity, thereby reducing the need for stringent 24-hour blood sampling in routine practice.

This retrospective study enrolled 46 clinically or pathologically confirmed patients with cirrhosis (case group) and 16 participants without hepatic disease (control group). All participants underwent DECT scanning, with Hct measurements obtained within specified time windows relative to DECT examination: Hct0 (<24 h), Hct1 (24 h to 7 d), Hct2 (8 to 30 d), and Hct3 (>30 d). ECV values corresponding to each time window (ECV0, ECV1, ECV2, and ECV3) were calculated from DECT iodine maps using the respective Hct measurements. Intergroup differences in Hct and ECV values across time windows were analyzed against baseline (Hct0/ECV0) using independent sample t tests or Mann-Whitney U tests, as appropriate. Bland-Altman analysis was used to evaluate the agreement between non-24-hour ECV measurements (ECV1, ECV2, and ECV3) and ECV0. Receiver operating characteristic (ROC) curve analysis was used to assess the discriminative capacity of ECV parameters for Child-Pugh classification in cirrhosis using DeLong test to compare areas under the curve (AUC).

The results demonstrated no significant differences in Hct and ECV measurements obtained within 24 hours to 7 days (Hct1/ECV1) compared with 24-hour baseline values (Hct0/ECV0) (all P > 0.05). Bland-Altman analysis revealed the smallest bias (-0.2%) between ECV1 and ECV0, with most data points falling within the limits of agreement. However, Hct and ECV measurements beyond 7 days (Hct2-3/ECV2-3) showed statistically significant deviations from baseline (all P <0.05), exhibiting progressively increasing bias over time. For distinguishing Child A from Child B+C cirrhosis, ECV0 and ECV1 demonstrated comparable diagnostic performance with AUCs of 0.947 and 0.909, respectively. DeLong test confirmed no significant difference in the AUCs ( P = 0.148). Similarly, when discriminating controls from Child A patients, ECV1 and ECV0 maintained comparable AUCs of 0.902 and 0.887, respectively. DeLong test confirmed no significant difference in the AUCs ( P = 0.514). Notably, ECV measurements beyond 7 days (ECV2/ECV3) showed significantly reduced diagnostic efficacy (AUC range: 0.685 to 0.842, for all, P <0.05).

Hct measurements within a 7-day window of DECT can be reliably used for ECV quantification and Child-Pugh classification assessment in patients with cirrhosis. This approach provides clinicians with a convenient workflow by reducing the necessity for restrictive same-day phlebotomy.