Spleen Stiffness Measurement Using 2-Dimensional Shear Wave Elastography: The Predictors of Measurability and the Normal Spleen Stiffness Value.

Objectives To investigate the success rate of spleen stiffness measurement and factors that affect measurement success and to determine the spleen stiffness value of normal individuals by 2-dimensional shear wave elastography. Methods The spleen and liver stiffnesses of 313 consecutive patients were measured with SWE. The body mass index, abdominal wall thickness, spleen size, and liver stiffness of the patients were evaluated to identify factors associated with successful measurement of spleen stiffness. Patients were grouped by body mass index, spleen size, and liver stiffness, and the success rates and mean spleen stiffness values of the groups were compared. Independent predictors for successful spleen stiffness measurement and their cutoff values were evaluated. The mean spleen stiffness values of patients considered to have normal spleen stiffness were investigated. Results The overall success rate of spleen stiffness measurement was 52.9%. It was significantly higher in nonobese than in obese patients and in patients with splenomegaly and liver cirrhosis. The spleen stiffness value was higher in the splenomegaly group than the nonsplenomegaly group (P < .001) and increased as liver stiffness increased (P < .001). There was no significant difference in spleen stiffness values between the obese and nonobese groups. Abdominal wall thickness and splenic longitudinal diameter were identified as independent predictors of successful spleen stiffness measurement, and their cutoff values were 17.2 mm or less and greater than 9.4 cm, respectively. The mean spleen stiffness value +/- SD of the normal patient group was 20.5 +/- 5.4 kPa. Conclusions The success rate of spleen stiffness measurement is lower than that of liver stiffness measurement. Spleen stiffness measurement is affected by abdominal wall thickness and spleen size.