The portal venous system is associated with a wide range of congenital

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1 Dign Interv Rdiol 2011; 17: Turkish Society of Rdiology 2011 ABDOMINAL IMAGING PICTORIAL ESSAY Congenitl nd cquired normlities of the portl venous system: multidetector CT ppernces Nilgün Işıksln Özülül ABSTRACT A knowledge of norml ntomy s well s the most frequent vrints nd normlities of the portl venous system re of gret importnce for liver surgery nd interventionl procedures. An understnding of the vried MDCT ppernces of these normlities will llow more definitive dignoses nd help void flse dignoses. Key words: portl vein, normlities portl vein, thromosis portl vein, gs shunts, rterioportl tomogrphy, X-ry computed The portl venous system is ssocited with wide rnge of congenitl normlities nd cquired processes tht cn e detected incidentlly with current imging modlities. In this pictoril essy, we discuss nd illustrte the norml ntomy s well s the congenitl nd cquired normlities of the portl venous system s shown y multidetector computed tomogrphy (MDCT). Recognizing the vried fetures of these normlities of the portl venous system will help rdiologists to correctly interpret imges nd prevent misdignoses. Norml ntomy The portl vein issues from the confluence of the superior mesenteric, inferior mesenteric, nd splenic veins posterior to the neck of the pncres. In its most common rnching pttern, the portl vein divides t the port heptis into the right nd left portl veins. As it courses crnilly, the right portl vein first sends rnches to the cudte loe nd then divides into nterior nd posterior rnches. The left portl vein first follows horizontl course to the left nd then turns medilly towrd the ligmentum teres (umilicl portion), supplying the lterl nd medil segments of the left loe (Fig. 1). The Cntlie line corresponds to the medin fissure nd is defined s line pssing through the gllldder towrd the inferior ven cv (IVC) (1 3). Congenitl genesis of the portl vein rnches Congenitl genesis of the portl vein rnches is frequently reported congenitl nomly (4). An importnt distinction exists etween congenitl genesis nd trophy secondry to pthologicl process. Congenitl genesis is thought to e secondry to either the filure of the right nd left portl veins to develop or thromosis of the ffected loe or segment during emryonic growth (Fig. 2). Liver ultrsonogrphy is most often cple of identifying such vsculr normlities (5). However, the MDCT ppernces of these nomlies must e known ecuse MDCT my e the initil form of imging used. From the Deprtment of Rdiology ( nilgunisiksln@yhoo. com), Türkiye Yüksek İhtiss Hospitl, Ankr, Turkey. Received 7 Octoer 2009; revision requested 1 Decemer 2009; revision received 8 Decemer 2009; ccepted 1 Ferury Pulished online 30 July 2010 DOI / DIR Preduodenl portl vein The preduodenl portl vein (PDPV) is ssocited with nomlies tht include intestinl mlrottion nd pncretic, splenic, or crdic nomlies. The PDPV psses ventrl to the duodenum nd the hed of the pncres, so the PDPV is clerly seen on CT imges s round structure in front of the pncretic hed (2, 4, 6). An L-shped nd convex cudl mesentericoportl vein, which cn lso e seen on CT ngiogrphy, is n ngiogrphic feture typicl of PDPV (Fig. 3). MDCT imges re relile for reveling other ssocited nomlies, such s zygos or hemizygos continution of IVC, short pncres, nd viscerl heterotxi. 135

2 c Figure 1. c. The norml ntomy of the portl vein in 46-yer-old mn in n MDCT scn otined during the portl venous phse. The xil imge shows the min portl vein (MPV) formed y the union of the splenic nd superior mesenteric veins ehind the neck of the pncres (). The MPV courses to the port heptis, where it divides into the right nd left rnches (). A section more crnil thn shows tht the left portl vein psses trnsversely through the port heptis to supply the cudte nd left loes of the liver (c). Figure 2.,. A 41-yer-old womn with genesis of the horizontl segment of the left portl vein. Two sequentil xil thick-sl MIP CT imges (, ) revel lrge errnt vessels (thin rrows) running trnsversely from the right nterior portl rnch (thick rrow) to the left segmentl rnches. Note the ptency of the min portl vein (white rrowheds) nd the splenic vein (lck rrowheds). Figure 3. A 38-yer-old womn with preduodenl portl vein nd other congenitl nomlies, including polyspleni (S), midline liver (L), nd IVC sence with zygos continution (doule rrow). The xil imge revels preduodenl portl vein (rrow). Note gllldder stones. 136 June 2011 Dignostic nd Interventionl Rdiology Işıksln Özülül

3 Figure 4.,. A 54-yer-old mn with dupliction of the portl vein. Axil () nd coronl () MDCT imges show two seprte portl veins (rrows) coursing to the port heptis. Figure 5. A 48-yer-old womn with chronic liver disese nd portl hypertension. Axil MDCT imging revels extrheptic portl vein neurysm (rrow). Note collterls in the dominl wll. Dupliction of the portl vein Dupliction of the portl vein is n uncommon nomly reveled y imging s two seprte portl veins tht course upwrd to the port heptis (2, 7). Complictions of this nomly include vricel leeding, portl hypertension nd duodenl ostruction. MDCT llows multiplnr reconstructions nd is helpful in distinguishing this nomly from other disese entities (Fig. 4). Portl vein neurysm Portl vein neurysm, which cn e congenitl or cquired, is n uncommon entity. Portl venous system neurysms represent 3% of ll venous neurysms (8). Most of these neurysms re cquired, s significnt numer of portl vein neurysms re detected in ptients with underlying heptocellulr disese nd portl hyvolume 17 Issue 2 Figure 6.,. A 35-yer-old womn with no underlying liver disese. Axil () nd coronl () thick-sl MDCT imges show the intrheptic portl vein neurysm (rrow). pertension (Fig. 5). Some portl vein neurysms re found in children nd young dults who hve no evidence of liver disese or portl hypertension. Intrheptic neurysms hve tendency to occur t ifurctions (Fig. 6). MDCT of the portl venous system normlities 137

4 Figure 7. An xil MDCT imge through the upper domen showing norml reltionship etween the superior mesenteric rtery (A) nd the superior mesenteric vein (V). Figure 8.,. An xil MDCT imge otined through the upper domen () showing verticl orienttion of the superior mesenteric rtery (A) nd the superior mesenteric vein (V). Axil MDCT scn otined through the lower domen () shows contrst gent-filled smll owel (thin rrows) on the left nd colon (thick rrow) on the right. Most reported extrheptic portl vein neurysms occur t the confluence of the superior mesenteric nd splenic veins (1, 9). Most people with portl venous system neurysm re symptomtic, lthough portl venous system neurysms cn cuse symptoms. Externl compression nd rupture re rre complictions. Thromosis of portl venous system neurysm occurs frequently nd cn led to the development of portl hypertension with cliniclly severe consequences (10). Color Doppler sonogrphy nd CT hve een considered ccurte nd relile methods for oth the dignosis nd follow-up imging of portl venous system neurysms nd their complictions. Inverted reltionship etween the superior mesenteric vein nd superior mesenteric rtery On cross-sectionl imging, the superior mesenteric vein (SMV) is generlly seen lying on the right ventrl spect of the superior mesenteric rtery (SMA) (Fig. 7). Conversely, devition from the norml reltionship etween the SMV nd SMA is useful indictor of mlrottion (Fig. 8). In most quiescent mlrottion, the SMA nd SMV will ssume verticl reltionship or show left-right inversion. However, normlities of SMA-SMV orienttion re not entirely dignostic ecuse some ptients with mlrottion will hve norml reltionship, nd verticl or inverted reltionship cn lso e seen in ptients without mlrottion (Fig. 9) (2, 11, 12). Portl vein thromosis Portl vein thromosis occurs in vrious clinicl settings, with the most common eing liver cirrhosis. In numer of cses, no identifile cuse for the portl vein thromosis cn e found. Thromosis of the portl vein my prtilly or totlly occlude its flow (4). Unenhnced CT my show focl high ttenution in the portl vein nd venous enlrgement when the thromosis is cute. On contrst-enhnced CT, thromi usully mnifest s low-ttenution intrluminl lesions comined with the enlrgement of the involved portl vein (Fig. 10). Chronic thromosis cn led to the formtion of multiple collterl chnnels nd susequent cvernous trnsformtion of the portl vein (4). Clcifiction is occsionlly seen in chronic thromosis of the portl vein. 138 June 2011 Dignostic nd Interventionl Rdiology Işıksln Özülül

5 Figure 9.,. Axil MDCT scn () showing n inverted reltionship etween the superior mesenteric rtery (A) nd the superior mesenteric vein (V). A coronl MDCT reformtted imge () showing contrst gent-filled smll owel on the right nd colon on the left. Note cecl position (rrow). Figure 10.,. A 56-yer-old womn with portl vein thromosis. Axil MDCT scn demonstrtes n enlrgement of the portl vein nd lowttenution intrluminl thromus (, rrow). A more cudl section () shows thromus in the superior mesenteric vein (smll rrow). Note the nodulrity of the liver surfce due to cirrhosis. Cvernous trnsformtion of the portl vein Cvernous trnsformtion of the portl vein is defined s msslike network of intertwined veins in the heptoduodenl ligment nd port heptis tht provides n lterntive pthwy y replcing stenosed or occluded portl vein (4, 13, 14). Cvernous trnsformtion hs een demonstrted y sonogrphy s erly s 6 20 dys fter the thromotic event (Fig. 11). Pseudothromus Pseudothromus in the portl vein cused y lminr flow is often oserved during n rteril-phse CT scn. This is common flow-relted rtifct resulting from the incomplete mixing of enhnced lood in splenic veins with unenhnced lood in superior mesenteric veins (13). Delyed-phse imging will usully demonstrte homogenous portl venous enhncement (Fig. 12). Arterioportl shunts Arterioportl shunts my e congenitl (vsculr mlformtions in Osler- Weer-Rendu syndrome) or cquired (heptic tumors, trum, interventionl procedures, cirrhosis) (Fig. 13) nd consist of communiction etween the heptic rtery nd the portl venous system. Dynmic CT performed during the heptic rteril phse shows n erly nd mrked enhncement of the min portl vein, segmentl rnches or mjor triutries with n ttenution pproching tht of the ort, s well s n erly enhncement of the portl vein with nonenhncement of the splenic nd mesenteric veins (1, 13). Heptic involvement is elieved to e common mnifesttion of hereditry hemorrhgic telngiectsi (15). Contrst-enhnced CT commonly shows prominent heptic rtery. Dynmic study my lso demonstrte the presence of n rterioportl shunt nd telngiectses s diffuse heterogeneous enhncement of the heptic prenchym (Fig. 14). Volume 17 Issue 2 MDCT of the portl venous system normlities 139

6 Figure 11. c. Portomesenteric venous thromosis in 43-yerold mn with cirrhosis. Three sequentil xil MDCT imges show cvernous trnsformtion (, rrows) t the port heptis, lrge filling defect (, lrge rrow) t the level of portovenous confluence with evidence of smll-vessel collterliztion (smll rrows), nd thromus in the SMV (c, thick rrow). Periheptic fluid is present. c c 140 June 2011 Dignostic nd Interventionl Rdiology d Figure 12. d. Pseudothromosis of the min portl nd the splenic veins. Axil MDCT scns otined from the upper domen during the heptic rteril phse (, c) show low-ttenution mss (rrow) mimicking portl vein thromosis in the min portl vein nd splenic vein. Portl venous phse CT scns (, d) show norml enhncement of the portl venous confluence. Işıksln Özülül

7 Figure 13. Neoplstic rterioportl fistul in ptient with heptocellulr crcinom. The xil CT scn in the rteril phse shows n erly enhncement of the portl vein nd n incresed perfusion of the heptic loes. The MDCT scn shows tumor (str) invding the left nd the right portl veins (rrows) nd tumorl thromus within the veins. Figure 14.,. Axil rteril-phse MDCT imges in 46-yer-old womn with hereditry hemorrhgic telngiectsi of liver. CT scn showing diffuse prenchyml heterogeneity nd numerous telngiectses (). Erly filling of the left portl vein (rrow) during the rteril phse is consistent with n rterioportl shunt. Dilted common heptic rtery (, white rrow) is seen. Gs in the portl venous system On CT scns, ir in the portl vein mnifests s rmifying streks with ir Volume 17 Figure 15.,. Intestinl pneumtosis in 58-yerold mn with progressive worsening of dominl pin fter ortoifemorl ypss grfting. Portl venous phse xil MDCT scn () otined in ptient with mesenteric ischemi shows gs distriuted in rnching pttern t the periphery of the liver. Coronl MDCT reformtted imge () shows pneumtosis within the wll of the jejunum (lrge rrow) nd scending colon (smll rrow). Issue 2 ttenution tht cn rech the cpsule t the periphery of the liver (1). Air hs propensity to ccumulte in the intrheptic rdicles of the left portl vein due to its more ventrl loction (Fig. 15). MDCT of the portl venous system normlities 141

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