The stiffness of the liver and spleen on ARFI Imaging pre and post TIPS placement: a preliminary observation

Abstract

Purpose: To prospectively assess the stiffness of the liver and spleen with acoustic radiation force impulse (ARFI) imaging pre and post transjugular intrahepatic portosystemic shunt (TIPS) placement.

Material and methods: Between February, 2011 and September, 2011, we prospectively measured stiffness of the liver and spleen with mean shear wave velocity (MSV, m/s) on ARFI imaging in 10 healthy volunteers (mean age 32.2 ± 10.3 years, age range 23-53 years) and 10 patients (mean age, 38.6 ± 6.4 years, age range 30-48 years) who underwent TIPS placement for treatment of portal hypertension (PHTN). The portal vein pressure was measured while placing the TIPS. To assess the changes in the stiffness of the liver and spleen following TIPS placement, we measured MSV of the liver and spleen one day before TIPS insertion and 4-9 days after TIPS placement (mean interval 5.9 ± 2.0 days, interval range 5 to 10 days).

Results: There was significant difference in portal vein pressure pre (27.67 ± 5.86 mmHg) and post (18.00 ± 6.93 mmHg) TIPS insertion (P<.01). The MSV of the liver in healthy subjects, patients with PHTN pre TIPS and patients with PHTN post TIPS measured 1.16 ± 0.06 m/s, 2.48 ± 0.39 m/s, and 2.37 ± 0.28 m/s, respectively. The MSV of the spleen in healthy subjects, patients with PHTN pre TIPS and patients with PHTN post TIPS measured 2.22 ± 0.22 m/s, 3.65 ± 0.32 m/s, and 3.27 ± 0.30 m/s, respectively. There were significant differences in MSV of the liver and spleen between healthy subjects and patients with PHTN (all P<.001). There was no significant difference in MSV of the liver pre and post TIPS placement (P>.05). However, a statistically significant difference in MSV of the spleen pre and Post TIPS placement (P<.001) was demonstrated. In addition, we observed a significant difference in spleen index between healthy subjects and patients with PHTN (P<.001), as well as between pre and post TIPS placement (P<.01).

Conclusion: The MSV of the spleen measured with ARFI correlates well with portal vein pressure. Hence, the spleen stiffness by means of MSV on ARFI imaging can be used as a quantitative marker in monitoring the portal vein pressure as the function of the TIPS.