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COMPUTED TOMOGRAPHY EVALUATION OF HEPATIC PERFUSION DISORDERS . I MARZOUK MOUSSA, F KSONTINI, L BEN FARHAT, A MANAMANI, N DALI, L HENDAOUI MEDICAL IMAGING AND INTERVENTIONNAL DEPARTEMENT, MONGI SLIM HOSPITAL, LA MARSA TUNISIA. GI12. Introduction.
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COMPUTED TOMOGRAPHY EVALUATION OF HEPATIC PERFUSION DISORDERS I MARZOUK MOUSSA, F KSONTINI, L BEN FARHAT, A MANAMANI, N DALI, L HENDAOUI MEDICAL IMAGING AND INTERVENTIONNAL DEPARTEMENT, MONGI SLIM HOSPITAL, LA MARSA TUNISIA GI12
Introduction • The liver has a dual blood supply , which comes from the hepatic artery ( 25% of vascularization) and the portal vein ( 75% of vascularization). • There are several communications between both systems including hepatic sinusoids and peribiliary plexus . • when vascular compromise of hepatic blood supply or venous drainage occurs ,control systems intervene inducing in imaging abnormalities of parenchymal enhancement time varying.
Thesehepatic perfusion disorders (HPD) canbedetectedwithmultiphasescomputedtomographyimagingthrough the study of the parenchymalenhacementkinetic. • HPD are commonlyassociatedwith changes in arterial , portal or venous flow and sometimes have mixed origin .
Material and Methods A retrospectivestudyincludingseven patients withhepatic perfusion disorders : • hepatic abscess • Rendu-Osler disease • Pancreatic head cancer with an hepatic hilar lymph node compressing the hepatic artery • Budd Chiari syndrome • Superior vena cava thrombosis • Hepatic cirrhosis • Thrombosis of the left portal branch.
Results Arterialorigin • Arterial occlusion : It rarelyinduceshepatic perfusion disorders in imagingexcept in case of: *Thrombosis of hepaticartery in transplantation *An associetedvenous occlusion (figure 3 ) .
Arterial origin CT findings: • a triangularsegmentary or lobarhypodensitypersisting in different phases of Iodincontrast injection withhilarsomet and peripheral base . • Intrahepatic bile ducts are sensitive to arterialischemia and maynecrosegivingbiliar false cyst.
Arterial origin Figure 3 : Lymphadenopathy of hepatichilum () secondary to cancer of pancreasowntail (), compressing the hepaticartery and the portal veincausing HPD of the leftliver ()
Arterial origin • Arterial flow increase: • Hypervasculartumor . • Intense inflammatoryreaction ( figure 1) . • HereditaryHemorrhagicTelangiectasia (HHT) calledDisease of Rendu_Osler (figure 2) .
Arterial origin Figure 1 : Hepaticabcess of segment II and III ( ) , surrounded by an abnormalenhacement of the hepaticparenchyma ()
Arterialorigin HHT is a vascular disease with autosomal dominant transmission characterized by multiple telangiectases. It affects mucocutaneous tissue most frequently, but any part of the body can be affected including the liver traduced by numerous arteriovenous shunts between hepatic artery branches and branches of the hepatic or portal veins.
Arterialorigin Figure 2: Disease of Rendu _Osler : significantincrease of the caliberof the hepaticartery()and its branches withmanyarteriovenousfistulas and abnormalparenchymalenhacement of leftliver ().
Portal origin • HPD are often caused by venous inflow obstruction due to portal vein thrombosis , tumor invasion ,compression or surgical ligation . • The causes of portal vein thrombosis include neoplasm that invades or compresses the portal system , infection process , embolisation , hypercoagulative states and myeloproliferative disorders.
Potal origin CT findings : intense enhacement of the hypoperfusedparenchyma in hepatiarterial phase images ( explicated by arterial flow increase ) thatreturns to normal in portal phase . Figure 4: Abnormalcontrastinhacement of the leftlivercaused by thrombosis of the ipsilateral portal branch.
Venousorigin • Cardiacliver . • Budd Chiari syndrome ( figure 5). CTfindings: hypoperfusion of peripheralparenchymacontrastingwith a normal perfusion of the central parenchyma .
Budd-Chiari syndrome is defined as lobar or segmental hepatic venous outflow obstruction at the level of the hepatic veins or inferior vena cava (IVC) and may be primary or secondary . This Hepatic venous outflow obstruction leads to elevation of sinusoidal pressure and diminished portal venous flow, which culminates in centrilobular congestion followed by necrosis and atrophy. Venous origin
Venous origin Figure 5 Budd Chiari syndrome : significanthapertrophy of segment I (←) thatnormallyinhacecontrastingwith the peripheral parenchyme whichremainshypodense ().
Mixed origin • Arterio portal fistula (APF) : • An APF is an organic or a functionnal communication between an arterialhepaticbranch and the portal venous system , resulting in redistribution of arterial flow into a focal region of portal venous flow . • The causes of APF include : livercirrhosis (figure 6) , hepato cellular carcinoma , iatrogenicfistulaeafterliverbiopsy ,traumatic or spontaneousfistulae .
Mixed origin Figure 6 : Hepaticcirrhosis : Earlyenhacement of segment III ()thatisirregularlyshaped , non systematized , with opacification of the left portal branch in arterial phases through an arterio portal fistula.
Mixed origin • Superior vena cava obstruction : A reflux througharterio portal collateralinheritancerarelyused ( figure 7) . Figure 7: Intense opacification of segment III ()on portal phase througharterio portal collateralinheritancessecondary to superiorvena cava thrombosis.
Discussion Hepatic diffuse diseases ,benign conditions and malignanttumors are commonlyassocietedwith changes in arterial , portal or hepaticvenous flow, detected in imaging by abnormalparenchymalenhacementafteriodincontrast injection ; whichcanbeinerpreted as false positives and negatives in tumordetect and staging.
The mechanismcanbe obstruction , fistulae or compression . Such images are verycommon: thrombosis of the portal branch induces an early parenchymal enhancement disappearing in portal phase. Arterial obstruction induces segmentary or lobar hypodensity persisting in different phases of iodin contrast injection .
Arterio_portal fistulae can be mistaken with hypervascular tumors or intense inflammatory reaction. Cardiac liver and Budd Chiari syndrome induces a normal enhancement of the central parenchyma contrasting with a low enhancement in the peripheral tissue.
Conclusion The study of different aspects of hepatic perfusion disorders which are sometimes misleading allows to not confuse them with organic hepatic lesion.