Blood supply model and theoretical simulation results. (a) Blood supply model for the hepatic tissue. Ca(t), Cp(t), Cv(t), C I (t) and C(t) represent time-dependent xenon (Xe) concentrations in the arterial blood, portal-organ tissue, portal venous blood, inflow blood, and hepatic tissue, respectively. Fa and Fv indicate arterial blood flow (ml/min) and portal venous blood flow (ml/min), respectively. (b) Graphs for Eq. (6) are shown. The fitted curve (arrow) using Eq. (4) is drawn through eight data points (t = 1, 2, …, 8 min) on the graph of Fa/Fv = 1/3 and Kp = 0.5 min−1 [mean squared error (MSE) is 0.024 HU2]. (c) Relationships between Kp and MSE.
K I , λ, and blood flow (f) maps of the liver and the spleen of a 39-year-old male patient with nonalcoholic steatohepatitis (NASH). Two regions were formed with red lines on the liver and the spleen in the baseline CT image, and were used as the areas for creating K I , λ, and f maps. In the K I maps, pixels that have no solution for K I are removed (Ref. 15). The average values of the λ and f maps of the liver were 1.06 and 53.5 ml/100 ml tissue/min, respectively, and those of the spleen were 0.69 and 71.3 ml/100 ml tissue/min, respectively.
Baseline CT images, λ maps of the liver and the spleen, and histological findings of the liver for three NASH patients. Using the histological findings, steatosis of the liver was evaluated and its severity was divided into ten grades according to the fat deposition percentage [(severity 1) ⩽ 10%, 10% < (severity 2) ⩽ 20%, …, 90% < (severity 10) ⩽ 100%]. The average λ values of the liver were 0.89, 1.76, and 7.81 for the patients with steatosis severity 1, 3, and 9, respectively. Fat droplets are observed in the histological findings.
Relationships (a) between the average λ value () and liver/spleen ratio, and (b) between and steatosis severity for 26 NASH patients.
Article metrics loading...
Full text loading...