· In proper clinical settings and based on imaging findings (CDUS, MDCT and MRI), after the exclusion of other causes of graft dysfunction (such as immunologic, toxic or infectious reasons), only suspicion of steal syndrome could be made.
 
Color Doppler ultrasound (CDUS)
· CDUS can demonstrate increased hepatic artery resistive index (RI, peak systolic velocity - end-diastolic velocity/peak systolic velocity) (see Fig.1), which is not a specific criteria. Elevated RI (>0.80) is relatively common during first post-transplantation days without any pathologic relevance.
 
Multidetector Computed Tomography (MDCT) and Magnetic Resonance Imaging (MRI)
· MDCT and MRI can demonstrate enlarged spleen, increased splenic artery diameter (see Fig.2) with decreased hepatic artery diameter (see Fig.3), early postcontrast opacification of splenic and portal vein already in arterial phase and dilatation of splenic and portal vein (see Fig.4).
· Imaging findings could also include biliary tract dilatation (cholestasis) and less postcontrast opacification of the liver parenchyma (parenchyma hypoperfusion) (see Fig.5) due to hypoperfusion of the graft.
· However, splenomegaly, enlarged splenic artery and associated hypersplenism are also well-known conditions in patients with liver cirrhosis without steal syndrome, so these findings are not sufficient for the diagnosis. Additional dynamic angiographic findings reflecting a relative hypoperfusion of the liver is required for the diagnosis of SASS.
 
Digital subtraction angiography (DSA)
· DSA is necessary to distinguish between SASS and other arterial complications. DSA better defines vascular anatomy and haemodynamics of blood flow through HA and SA prior to embolization.
· Arteriographic diagnostic criteria of SASS are (see Fig.6):
- SA to HA diameter ratio >1.5 (or increased SA diameter > 4 mm),
- early filling of the SA with deleyed HA filling,
- late or lack of filling of the intrahepatic branches of the HA,
- contrast enhancement of PV and HA at the same time.
· Although these findings are highly suspicious of SASS, diagnosis is definitely confirmed only after successful treatment and normalization of angiogram and liver enzyme levels (see Fig.7 and Fig.8).
 
Treatment options
· Surgery has been the initial treatment option for SASS, however, due to its high invasive nature and risk of complications, interventional radiological procedure is currently the preferred treatment of choice.
· Radiological interventions are minimally invasive procedures associated with high success rates and low rates of complications, offering at the same setting diagnostic information and therapeutic option.
· Exclusion of splenic artery from systemic circulation is the main aim of radiological intervention. This can be achieved by slowing the flow within SA (with coils and/or stent grafts), inducing thrombosis (with coils and liquid embolics) and stimulating inflammation (with coils and liquid agents).
· Coils or micro-coils are the preferred and most widely used agents for proximal embolization of SA. Coils are slowing the flow by causing mechanical obstruction, inducing thrombosis via their thrombogenic fibres and initiating inflammatory reaction.
· Surgical options include SA banding, SA ligation and splenectomy but are employed only when radiological interventional treatments are not effective or prophylactically in selected cases.
 
Controversies
· The diagnosis and treatment of SASS are still not well established. The pathogenesis is still not well understood, pre-transplant risk factors are uncertain, there are no specific clinical or diagnostic criteria, symptoms could be the same as with other post-OLT vascular complications and patients with characteristic radiological findings may be asymptomatic. Because of all these controversies, further studies are needed.