Diagnostic Ultrasound - Abdomen and Pelvis

Transjugular Intrahepatic Portosystemic Shunt (TIPS)
TERMINOLOGY
Abbreviations
• Transjugular intrahepatic portasystemic shunt (TIPS)
Definitions
• Shunt between portal vein (PV) and hepatic vein (HV)
created typically with balloon-expandable
polytetrafluoroethylene (PTFE)-covered stent graft
• Shunt dysfunction
○ Reduction > 50% of shunt lumen
○ Portosystemic gradient > 12-15 mmHg
○ Complete occlusion of shunt
IMAGING
General Features
• Location
○ Most common route: Right PV → right HV
• Size
○ 10-12 mm in diameter
• Morphology
○ Typically follows curved course through hepatic
parenchyma
○ Portal end in right portal vein near main PV bifurcation
○ Hepatic end located near junction of HV/inferior vena
cava (IVC)
Ultrasonographic Findings
• Grayscale ultrasound
○ Echogenic stent easily seen
○ Stent typically curved but should not be kinked
○ Hepatic and portal ends "squarely" within veins (best
seen on grayscale US)
• Pulsed Doppler
○ PV, shunt malfunction
– Peak velocity < 35 cm/sec
– Change in direction of flow in left portal branch (i.e.,
change from hepatofugal to hepatopetal)
○ Within shunt, malfunction
– Shunt velocity < 90 cm/sec or > 200 cm/sec at any
point
– Temporal change in velocity ≥ 50 cm/sec compared to
prior studies
– Focal severe turbulence or elevated velocity can
suggest stenosis
– Absence of flow: Occlusion
□ Always confirm angiographically
– Loss of pulsatility or respiratory variation (less specific
finding)
• Color Doppler
○ Within shunt, malfunction
– Visible stenosis, focal or diffuse
– Focal aliasing indicates high velocity and suggests
stenosis
– Absence of flow: Occlusion
□ Check with spectral Doppler (more sensitive);
confirm angiographically
• Goal of US: Detection of stenosis before shunt occludes or
symptoms recur
Angiographic Findings
• Shunt venography (gold standard)
○ Direct catheterization of shunt via peripheral vein
approach
○ Detection and quantification of shunt patency or degree
of stenosis
○ Simultaneous measurement of portosystemic gradient
○ Intervention if necessary
○ Limitation: Invasive nature
Other Modality Findings
• CTA, MRA
○ Anatomic depiction of stenosis, occlusion, and
collateralization
○ Contrast enhancement essential for CTA, generally
required for MRA
○ Obtain a global view
Imaging Recommendations
• Best imaging tool
○ US is primary TIPS surveillance tool
○ CTA/MRA indicated if US technically compromised or
equivocal
• Protocol advice
○ Post-TIPS assessment (grayscale, color Doppler, spectral
Doppler)
– Stent configuration/position
– Patency and flow direction in PV and its branches
□ Measure velocity mid-PV (not adjacent to shunt)
– Assess shunt with color Doppler
□ Measure Doppler waveforms/peak velocities:
Proximal, mid, distal shunt
□ Compare findings with prior results (velocities
ideally within 50 cm/sec of prior measurement)
– Presence of stenosis
□ If present, document peak stenosis velocity, usually
at point of maximum turbulence
– Patency, flow direction, Doppler waveforms in HV
– Always check for coexisting hepatic masses, especially
in cirrhotic patients
– Evaluate presence/volume of ascites and pleural fluid
DIFFERENTIAL DIAGNOSIS
PV Occlusion
• Predisposing factors
○ Hypercoagulable states, pancreatitis, tumor invasion,
dehydration, trauma, cirrhosis
• Acute
○ CECT may demonstrate transient hepatic attenuation
difference (THAD) with affected lobe or segment on
arterial phase
○ If main PV acutely thrombotic, central perihepatic low
attenuation on arterial phase
• Chronic
○ Cavernous transformation
○ Innumerable periportal collaterals along
hepatoduodenal ligament
○ "Cavernoma," i.e., mass-like tangle of collateral veins in
porta hepatis
Diagnoses: Liver
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