In vivo abdominal magnetic resonance elastography for the assessment of portal hypertension before and after transjugular intrahepatic portosystemic shunt implantation.

OBJECTIVE: The objective of this study was to investigate the correlation between hepatic venous pressure gradient (HVPG) and in vivo viscoelasticity of the liver and spleen before and after transjugular intrahepatic portosystemic shunt (TIPS) implantation.

MATERIALS AND METHODS: Ten patients with portal hypertension were examined twice by 3-dimensional multifrequency magnetic resonance elastography as well as prior and subsequent TIPS intervention; HVPG was also measured during TIPS placement. Five harmonic vibrations (25-60 Hz) were transferred to the abdominal region and recorded for the reconstruction of 2 viscoelastic constants, |G*| and φ, corresponding to the magnitude and the phase angle of the complex shear modulus G* of the liver and spleen.

RESULTS: All patients had cirrhosis, yielding high |G*| values in the liver (8.34 ± 2.18 kPa) and spleen (8.44 ± 1.36 kPa). In both organs, a decrease of |G*| after TIPS placement was observed (liver: 8.34 ± 2.18 kPa vs 7.02 ± 1.46 kPa, P = 0.01; spleen: 8.44 ± 1.36 kPa vs 7.06 ± 1.32 kPa, P = 0.01), whereas φ was insensitive to TIPS. Relative changes in |G*| of the spleen were correlated with the relative change of HVPG (R² = 0.659, P = 0.013).

CONCLUSIONS: The observed linear correlation between spleen viscoelasticity HVPG raises the prospect of an image-based noninvasive assessment of portal pressure by magnetic resonance elastography in the follow-up of TIPS placements.