Abstract:
HTML
Purpose: To define Doppler ultrasound criteria for Portal Vein and Venous Outflow (Hepatic Veins or IVC) obstruction in liver transplants.
Methods and Materials: Retrospective review of all liver transplant patients over a 3 year period who had undergone post-operative angiography (61). All post-transplant patients in our institution have serial ultrasound studies in which the following parameters are measured: Peak velocities proximal to and at the portal venous anastomosis and the ratio between them, doppler spectra from the IVC, right, middle and left hepatic veins (HV) and hepatic artery. HV/IVC waveforms were classified as monophasic, biphasic or triphasic. These were correlated with angiograms and pressure measurements performed within 24 hours of the ultrasound study. Angiography was used as the gold standard.
Results: There were 12 instances of portal vein (PV) obstruction (7 stenosis, 5 complete occlusion) and 18 of venous outflow obstruction: 7 HV, 11 IVC (17 stenosis, 1 complete occlusion). All cases of complete occlusion were correctly diagnosed by absence of flow on doppler. Accuracy of Doppler parameters for stenosis was as follows: For Portal vein:- Anastomotic velocity >150cm/s = Sens. 71% Spec. 90% PPV 83% NPV 82%. Ratio of Anastomotic Velocity: Velocity proximal to anastomosis: 2:1 = Sens. 71% Spec. 80%, PPV 43% NPV 60%; 4:1 = Sens. 57% Spec. 100%, PPV 100% NPV 77%. Patients with angiographically normal portal veins, or stenosed portal veins that had been successfully stented or dilated had a mean gradient of <1.8 (p< 0.01). For HV/IVC:- Monophasic waveforms = Sens. 70% Spec. 83%, PPV 78% NPV 77%. Only one patient with HV/IVC stenosis showed normal triphasic waveforms.
Conclusion: We found several doppler sonographic parameters that are useful indicators of venous obstruction (stenosis or occlusion) in liver transplants. These include velocity of >150 cm/s or a ratio of 4:1 at the portal vein anastomosis and monophasic waveforms in the hepatic veins.
Questions about this event email: wk_chong@med.unc.edu
Chong MD, W,
Sonographic Evaluation of Venous Obstruction in Liver Transplants. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102990.html
