Intrahepatic portosystemic venous shunts (IPSVS) are relatively rare

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1 Diagn Interv Radiol 2009; 15: Turkish Soiety of Radiology 2009 ABDOMINAL IMAGING ORIGINAL ARTICLE Intrahepati portosystemi venous shunts: radiologial evaluation Ioannis Tsitouridis, Charalaos Sotiriadis, Mihael Mihaelides, Vassilios Dimarelos, Konstantinos Tsitouridis, Sofia Stratilati PURPOSE The purpose of our study was to evaluate the imaging findings of intrahepati portosystemi venous shunts (IPSVS) in asymptomati patients. MATERIALS AND METHODS Between 2002 and 2008, we examined 8 patients with IPSVS whih were found inidentally. Diagnosis was ased on ultrasonography, omputed tomography and magneti resonane imaging findings. Three patients had a history of liver irrhosis without symptoms of enephalopathy. RESULTS Most IPSVS were loated in the right liver loe (7 ases) and in one ase in the left liver loe. Identifiation of type of shunt etween portal and systemi veins was ased on Park s lassifiation. Type III shunts were found in five patients and type I in three patients. CONCLUSION IPSVS is a rare vasular anormality that is usually asymptomati. Radiologists must e aware of these ommuniations eause IPSVS may e an inidental finding in imaging ontrol for unrelated reasons. Key words: portosystemi shunts ultrasonography omputed tomography, X-ray magneti resonane imaging From the Department of Diagnosti and Interventional Radiology (M.M. mihaelidesm@yahoo.om), Papageorgiou General Hospital, Thessaloniki, Greee. Reeived 16 June 2008; revision requested 28 Deemer 2008; revision reeived 19 January 2009; aepted 22 Marh Intrahepati portosystemi venous shunts (IPSVS) are relatively rare anomalies that are usually asymptomati. They are defined as ommuniations etween an intrahepati portal vein and a systemi vein via an anomalous intrahepati venous hannel. Shunts may e disovered inidentally during imaging for an unrelated disease. A few patients may present with hepati enephalopathy eause of a high degree of shunting. Materials and methods In our patients, 4 men and 4 women, IPSVS were found inidentally during a six-year period (from May 2002 to June 2008). The average age of the patients was years (range, years). The reasons for imaging evaluation were liver irrhosis (n = 3), anemia (n = 1), holedoholithiasis (n = 1), right upper quadrant pain (n = 1), diffuse adominal pain (n = 1), and a alified liver yst (n = 1) (Tale). Three patients were imaged with ultrasound (US), omputed tomography (CT) and magneti resonane imaging (MRI). Two patients had imaging proedures with oth US and MRI, and three underwent imaging with helial CT only (Tale). Sonographi examinations were performed with a Siemens Sonoline G60S sanner (Siemens Medial Systems, Erlangen, Germany) (proe, onvex C6-2) in oth gray-sale and olor Doppler. CT sans were performed with a Piker PQ 5000 sanner. Images were otained efore and after a olus injetion of 150 ml (3-4 ml/s) of non-ioni ontrast medium (iopromide, Ultravist 300, Shering, Germany) in arterial and portal phase with slie thikness, 5 mm; pith, 2; reonstrution interval, 5 mm; and san time, 1 seond. MRI examinations of the adomen were performed with a Siemens Expert Plus 1T devie (Siemens Medial Systems, Erlangen, Germany). T2-HASTE images (TR, 6 ms; TE, 60 ms) and T1-FLASH images (TR, 11 ms; TE, 4.2 ms) after intravenous administration of 10 ml of ontrast agent (gadopentetate dimeglumine, Magnevist, Shering, Germany) were otained in axial and oronal planes, with a slie thikness of 8 mm. In seleted ases (2 patients), T2-TRUFI images (TR, 10.2 ms; TE, 4.7 ms) in the axial plane and T1-weighted enhaned 3D gradient-eho sequene (TR, 6.4 ms; TE, 2.4 ms) in the oronal plane were also performed. Results In five patients, ommuniation etween portal and systemi veins was through a vasular lesion (aneurysm). The aneurysm was loated in the right loe of the liver in four ases and in the left loe in one ase. The size ranged from 20 mm to 40 mm in diameter (average, 32 mm). Connetion was etween the right ranh of portal vein and the inferior vena ava in two ases and etween the right ranh of portal vein and the right hepati vein in other two ases. The aneurysm, lo- 182

2 ated in the left liver loe, onneting the left ranh of portal vein with the inferior vena ava (Tale). US showed a rounded hypoehoi lesion. On olor Doppler images, flow was demonstrated within the lesions. On CT, the lesions (aneurysms) were hypodense on preontrast images, demonstrated intense enhanement on postontrast images, and showed diret ommuniation etween ranhes of the portal vein and the systemi veins. On MRI, the lesions had low signal intensity on T2-weighted (T2W) images and were strongly enhaned on T1-weighted (T1W) images after ontrast administration (Figs. 1 4). Three patients had tuular lesions onneting the right portal vein with the inferior vena ava (one ase) and peripheral ranhes of the portal vein with the inferior vena ava (two ases). These tuular onnetions were isoattenuating to the hepati veins on CT and isointense to the hepati veins on MRI (Fig. 5). Disussion Portal to systemi venous ommuniations are lassified as extrahepati and intrahepati. Extrahepati ommuniations are usually seen in patients with portal hypertension from irrhosis and are ommonly through the oronary vein, esophageal varies, or retroperitoneal ollaterals. Intrahepati ommuniations are found etween intrahepati portal veins and systemi veins and are less ommon than extrahepati ommuniations. The presene of IPSVS was first desried y Raskin et al. in 1964 (1). Although intrahepati shunts are rare vasular anormalities, advanes in diagnosti imaging tehniques have resulted in an inreased numer of ases reported. Aording to the loation of the ommuniating systemi vein and pathogeni mehanism, IPSVS are sudivided into two main types (2, 3). The first (internal type) is a shunt that onsists of an intrahepati portal venous-hepati venous pathway, whereas the other (external type) is a shunt that onsists of an intrahepati portal venous-perihepati venous pathway. In the internal type, the shunt is depited as tuular or aneurysmal ommuniation (single or multiple) etween intrahepati portal veins and hepati veins. The external type ommuniates etween the intrahepati portal vein and perihepati veins and drains into the inferior vena ava. Diret ommuniation etween the right portal vein and the inferior vena ava around the right loe is also inluded in this ategory. Park et al. (4) lassified pulished ases of IPSVS into the following types: (1) a single large tue of onstant diameter onneting the right portal vein to the inferior vena ava, (the most ommon), (2) a loalized peripheral shunt with single or multiple ommuniations etween the peripheral ranhes of the portal and hepati veins in one hepati segment, (3) a onnetion etween peripheral portal and hepati veins through an aneurysm, and (4) diffuse and multiple ommuniations etween peripheral portal and hepati veins in oth loes. Aording to Chevallier et al., IPSVS measuring more than 1 mm in diameter are alled marosopi intrahepati shunts (5). Based on anatomi, linial, and pathophysiologial riteria, Chevallier et al. divided these shunts into four different types. Type I onsists of patent paraumilial veins loated in the liver and are found in patients with portal hypertension. They ommuniate etween the portal vein and systemi venous system. Type II inludes isolated or multiple ommuniations etween a portal venous ranh and a hepati venous ranh that involve two ontiguous liver segments. Type III shunts provide multiple ommuniations etween portal and hepati venous ranhes found in liver segments that are not ontiguous. Type IV orresponds to a tuular ommuniation etween the right portal vein and the inferior vena ava (5). Small type II and III shunts may e diffiult to differentiate from small hypervasular liver lesions. In these diffiult ases, only portography should e onsidered as a pretherapeuti proedure. Aording to Park et al., in 14 ases reported in the literature, a single large tue onneting the portal vein to the inferior vena ava was the most ommon type and was found ommonly in irrhoti patients (4). Tanoue et al. and Remer et al. found that more than 50% of the shunts in their series had aneurysmal ommuniations (3, 6). The pathogenesis of IPSVS is ontroversial. Some authors elieve that IPSVS is ongenital, aused y a persistent emryoni venous anastomosis. When portosystemi ommuniation is onfirmed in a patient without history of liver disease or trauma, a ongenital origin is presumed (6 9). Others support the aquired nature of Tale. Demographi harateristis of patients and loation, size, and types of intrahepati portosystemi venous shunts Patient Age Sex Type (Park) Loation Size History Examination 1 25 y M III RLL 20 mm Biliary irrhosis US, CT, MRI 2 80 y F III LLL 36 mm Choledoholithiasis US, CT, MRI 3 67 y M III RLL 30 mm Diffuse adominal pain US, MRI 4 64 y F III RLL 40 mm Right upper quadrant pain US, MRI 5 73 y F III RLL 34 mm Cirrhosis CT 6 80 y M I RLL Anemia CT 7 18 y F I RLL Calified liver yst CT 8 67 y M I RLL Cirrhosis US, CT, MRI y, years; M, male; F, female; LLL, left liver loe; RLL, right liver loe; CT, omputed tomography; MRI, magneti resonane imaging; US, ultrasound. Volume 15 Issue 3 Intrahepati portosystemi venous shunts 183

3 a Figure 1. a e. Images of an 80-year-old woman with diffuse adominal pain. Color Doppler sonogram (a) showing flow in a vasular (aneurysmal) lesion loated in the left liver loe. Continuous CT images in portal venous phase () showing a round hypervasular lesion onneting the left portal vein with the inferior vena ava. Transverse T1W-FLASH MR image after ontrast administration () demonstrating intense enhanement of the lesion. Transverse T2W-HASTE MR image (d) showing low signal intensity in the aneurysm. Olique oronal 3D gradient eho MR image (e) demonstrating diret ommuniation of the lesion with the left portal vein (arrow). d e IPSVS, resulting from portal hypertension due to irrhosis or hroni hepatitis, iatrogeni or traumati episodes, or rupture of a portal venous aneurysm into a hepati vein (10 12). The internal type of IPSVS is thought to e ongenital in origin eause of its low prevalene of oexisting liver irrhosis. This is supported y the finding of assoiated anomalies of hepati vessels, suh as portal vein aneurysm, hepati venous anastomosis, and portal vein 184 Septemer 2009 Diagnosti and Interventional Radiology Tsitouridis et al.

4 a d e Figure 2. a e. Images of a 64-yearold woman with right upper quadrant pain. Color Doppler image (a) showing a loulated vasular lesion in the right liver loe. Transverse T1W-FLASH MR image after ontrast administration () demonstrating intense enhanement of the lesion. Transverse T2W-HASTE MR image () demonstrating flow void in the lesion. Coronal T2W-HASTE MR images (d, e) revealing diret ommuniation etween the right hepati vein (arrow, d) and a ranh of the right portal vein (arrow, e) through the vasular lesion. a Figure 3. a. Images from a 67-year-old man with holedoholithiasis. Color Doppler image (a) showing a vasular lesion in the right liver loe. Transverse T2W-HASTE MR images (, ) demonstrating ommuniation etween a ranh of the right portal vein (arrowhead) with the right hepati vein (arrow) through a vasular lesion (aneurysm). anastomosis, y Tanoue et al. (3). The aquired theory ould explain the external type of IPSVS. In these patients there is high inidene of liver irrhosis, and perihepati veins are developed as a result of portal hypertension, as intra- and extrahepati ollateral pathways (3). The theory of ongenital development of IPSVS suggests that anastomosis exists etween suardinal venous system and vitelline venous system (the preursor of portal and hepati veins) in an early stage of emryologi development. At 5 weeks gestation, hepati ords surround vitelline venous plexus; this plexus forms hepati sinusoids. Bilateral umilial veins also form sinusoids. At 8 weeks, sinusoids start to develop, and the portal and hepati venous system is formed. At the same time, the right umilial vein and the ranial portion of left umilial vein regress. The dutus venosus, a Volume 15 Issue 3 Intrahepati portosystemi venous shunts 185

5 a Figure 4. a,. Images from a 25-year-old man with iliary irrhosis. Axial olor Doppler view (a) of the right liver loe reveals flow ontaining lesion. Axial T2-TRUFI MR images () demonstrating ommuniation etween the right portal vein and the inferior vena ava through a vasular lesion. a d e Figure 5. a e. Images from a 67-year-old man with irrhosis. Color Doppler sonogram (a) shows a large tuular lesion in the right liver loe (images in gray sale). Axial CT images (, ) in portal phase demonstrating a tuular lesion with onstant diameter, onneting the right ranh of the portal vein with the inferior vena ava. Transverse T1W-FLASH MR image after ontrast administration (d) demonstrating intense enhanement of the lesion. Transverse T2W-HASTE MR image (e) demonstrating flow void in the lesion. 186 Septemer 2009 Diagnosti and Interventional Radiology Tsitouridis et al.

6 tuular struture etween the left umilial vein and the inferior vena ava, appears at this stage. At 12 weeks gestation, further differential growth of the portal and hepati venous system is noted; if omplete segregation etween these systems does not our, residual ommuniations etween them orrespond to intrahepati portosystemi venous shunt after irth (13). The linial signifiane of IPSVS is the potential for development of hepati enephalopathy (3, 9, 11, 14, 15). Uhino et al. found that in 51 ases of ongenital IPSVS, there were 12 patients with hepati enephalopathy at the time of diagnosis (9). Some authors report that the prognosis of IPSVS depends on the shunt ratio and patient age (16). The rate of hepati enephalopathy inreases with the age eause of dereasing tolerane of the rain to toxi metaolites. Also, large intrahepati shunts are more often responsile for enephalopathy than small shunts eause of the higher degree of shunting. However, aording to Remer et al., this theory does not fit the pathophysiology of hepati enephalopathy as it is understood today (6). US, CT, and MRI findings are suffiient for imaging evaluation of IPSVS. Imaging findings differ in proportion to the type of the shunt. In ase of aneurysmal ommuniation etween portal and hepati veins, olor Doppler imaging demonstrates a vasular lesion supplied y a vasular ranh with monophasi flow (portal flow shows sutle phasi variation aused y respiration-related hanges in thorai pressure) and drained y a vessel with iphasi flow (hepati vein flow has a pulsatile pattern that results from transmission of right atrial pulsations into the veins). On post-ontrast enhaned CT, a rounded mass with homogenous strong enhanement is present, aompanied y a portal vein ranh entering the lesion and a hepati vein ranh exiting it. MRI provides findings similar to CT, ut MRI offers the advantages of sagittal and oronal imaging and the potential of MR venography. In tuular ommuniation etween right portal vein and the inferior vena ava, US adequately demonstrates this tuular vessel, whereas CT and MRI provide more gloal visualization. Treatment should e onsidered only for symptomati patients. Dietary management with limitation of protein intake and supplementation with latulose are the first approah. If dietary modifiations fail to ontrol the symptoms of enephalopathy, interventional methods must e implemented. Symptomati intrahepati portosystemi venous shunts are adequately treated y transatheter emolization. Aess routes that an e followed are transileooli oliteration, perutaneous transhepati oliteration, and retrograde transaval oliteration. Symptoms related to portal-systemi enephalopathy improve or ompletely disappear after emolization (3). In our ases, the findings of IPSVS were well depited with US, CT, and MRI. Most shunts (7 of 8) were loated in the right loe of the liver; the shunt was found in the left loe in only 1 ase. Aneurysmal ommuniation etween the portal and systemi irulations (type III) was the most ommon type of IPSVS (62.5%) in our series. Type III was also the most frequent type of IPSVS in the series of Tanue et al. (70%) and of Remer et al. (54%) (3, 6). Remer et al. found that 76% of shunts were loated in the left loe of the liver, whereas only 1 (12.5%) ase had this loation in our study (6). We found type I shunts in three of eight patients (37.5%), whereas Remer et al. found only 1 ase of type I shunt in 22 patients (4.5%) (6). In onlusion, IPSVS is a rare vasular anormality that an e adequately diagnosed with US, CT, and MRI with the exeption of very small lesions. Identifiation of asymptomati shunts has inreased eause of advanes in imaging tehniques. In our series, IPSVS was loated in the right loe of the liver in almost all ases, with a vasular lesion or an aneurysm ridging a ranh of the portal vein with a ranh of the hepati vein. Radiologists should e aware of this vasular anomaly eause it an e reognized in asymptomati patients in whom treatment is not required. Referenes 1. Raskin NH, Prie JB, Fishman RA. Portal systemi enephalopathy due to ongenital intrahepati shunts. New Engl J Med 1964; 270: Itai Y, Saida Y, Irie T, Kajitani M, Tanaka YO, Tohno E. Intrahepati portosystemi venous shunts: spetrum of CT findings in external and internal sutypes. J Comput Assist Tomogr 2001; 25: Tanoue S, Kiyosue H, Komatsu E, Hori Y, Maeda T, Mori H. Symptomati intrahepati portosystemi venous shunt: angiographi findings and transatheter emolization with an alternative approah. AJR Am J Roentgenol 2003; 181: Park JH, Cha SH, Han JK, Han MC. Intrahepati portosystemi venous shunt. AJR Am J Roentgenol 1990; 155: Chevallier P, Oddo F, Soui J, Diaine B, Padovani B. Marosopi intrahepati portosystemi venous shunt: review of the literature and relassifiation. J Radiol 2000; 81: Remer E, Motta-Ramirez G, Henderson J. 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Cardiovasular system. In: Sadler TW. Langman s medial emryology, 8th ed. Philadelphia, PA: Lippinott Williams and Wilkins; 2000; Watanae A. Portal-systemi enephalopathy in nonirrhoti patients: lassifiation of linial types, diagnosis and treatment. J Gastroenterol Hepatol 2000; 15: Blei AT. Hepati enephalopathy. In: Birher J, Behnamou J-P, MIntyre N, Rizzetto M, Rodes J, eds. Oxford textook of linial hepatology, 2nd ed. New York: Oxford University Press 1999; Oguz B, Akata D, Balkani F, Akhan O. Intrahepati portosystemi venous shunt: diagnosis y olour/power Doppler imaging and three-dimensional ultrasound. Br J Radiol 2003; 76: Volume 15 Issue 3 Intrahepati portosystemi venous shunts 187