Preoperative risk stratification of early recurrence in resected pancreatic ductal adenocarcinoma: Novel equilibrium-phase-computed tomography biomarker of extracellular volume

Figure 2 Computed tomography-derived extracellular volume calculation workflow. The diagram illustrates the extracellular volume (ECV) calculation process in a 61-year-old male with pancreatic ductal adenocarcinoma who underwent radical (R0) resection, with a known hematocrit value of 40.8%. Region of interests were placed on the tumor, portal vein, and abdominal aorta. A and B: In preoperative baseline unenhanced; C and D: Equilibrium phase computed tomography (CT) images. The absolute difference between the ΔHounsfield unit (HU)_aorta and ΔHU_portal measured < 10 HU, confirming measurement validity. Two independent readers calculated CT-ECV values using the formula shown in the figure, with the final patient ECV (15.53%) derived as the mean of both measurements. ECV: Extracellular volume; Hct: Hematocrit; HU: Hounsfield unit.