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Spleen size, platelet transit time useful in assessment of liver fibrosis

Spleen size and the mean transit time of platelets through the spleen can be used as a non-invasive method to help assess liver fibrosis, according to a recently published study.

“The assessment of liver perfusion using pharmacokinetic models requires more data and higher temporal resolution, because the liver has two sources of blood (the portal vein and the hepatic artery), whereas the spleen has only one (the splenic artery),” the researchers wrote. “Although splenic perfusion indicates liver fibrosis only indirectly, the assessment of splenic perfusion requires less data and lower temporal resolution than the assessment of liver perfusion. Thus, splenic perfusion is easier to use than liver perfusion.”

The researchers sought to compare splenic perfusion among patients with various intermediate stages of liver fibrosis, as previous studies have indicated perfusion differences between normal spleens and those associated with cirrhosis. The retrospective study comprised 133 patients who had undergone dynamic computed tomography before hepatectomy. The median age of the cohort was 68 years (range, 37-83), and 87 were men.

The stages of fibrosis analyzed included F0 or absent fibrosis (n = 43), F1 or portal fibrosis (n = 17), F2 or portal fibrosis with few septa (n = 30), F3 or septal fibrosis (n = 16), and F4 or cirrhosis (n = 27). Concomitant morbidities included hepatocellular carcinoma (either secondary to hepatitis C or other causes), non-alcoholic steatohepatitis and other carcinomas.

Using the Kruskal-Wallis test, there were significant differences, depending on the stage of liver fibrosis, in the inflow rate constant (P < .01), the mean transit time of platelets through the spleen (P < .001) and the long axis of the spleen (P < .0001).

The researchers observed significant differences (P < .05) between the inflow rate constant in stages F0 and F4 and stages F2 and F4; between the mean transit time in stages F0 and F4, F1 and F4, and F2 and F4; and between the length of the spleen axis in stages F0 and F4 and F1 and F4.

The diagnostic accuracy of combined mean transit time, length of spleen axis, and the presence or absence of hepatitis B and/or HCV in detecting liver fibrosis had an area under receiver operating characteristic of 0.886 (95% CI, 0.884-0.888) for stage F1 or greater; 0.828 (95% CI, 0.825-0.83) for stage F2 or greater; 0.818 (95% CI, 0.816-0.821) for stage F3 or greater; and 0.819 (95% CI, 0.817-0.822) for stage F4.

“Splenic blood flow increases as a progression of portal hypertension. The spleen enlarges to compensate for portal hypertension and maintain a constant splenic blood flow; [mean transit time] of the spleen does not change,” the researchers wrote. “However, the spleen cannot enlarge indefinitely because of anatomical limitations, so next, extravasation in the spleen occurs in order to compensate for the portal hypertension; [mean transit time] becomes longer in cirrhosis.” – by Talitha Bennett

Disclosure: Healio.com/Hepatology was unable to determine the researchers’ relevant financial disclosures at the time of publication.