Abdominal Imaging

ª Springer Science+Business Media, LLC 2007 Published online: 12 August 2007

Abdom Imaging (2008) 33:72–79 DOI: 10.1007/s00261-007-9200-x

Portal vein thrombosis: CT features Hae-Kyung Lee,1 Seong Jin Park,1 Bum-Ha Yi,1 Eun-Kyeong Yeon,1 Jung Hoon Kim,2 Hyun-Sook Hong1 1

Department of Radiology, Soonchunhyang University, Bucheon Hospital, 1174 Jung-Dong Wonmi-Gu, Bucheon-Shi Kyungki-Do, South Korea 2 Department of Radiology, Soonchunhyang University, Seoul Hospital, Seoul, South Korea

Abstract There are many causative diseases to produced portal vein thrombosis (PVT) with the most common being liver cirrhosis with hepatocellular carcinoma. Visualization of abnormalities associated with PVT is crucial to diagnosis and appropriate intervention. Dynamic contrast enhanced CT is the best means of diagnosis of PVT and evaluation of various causative diseases. The findings of PVT of the dynamic CT are filling defect partially or totally occluding the vessel lumen and rim enhancement of the vessel wall. Signs and symptoms of PVT may be subtle or nonspecific and overshadowed by the underlying illness. Radiologists should be aware of the clinical situations that predispose a patient to portal or mesenteric vein thrombosis. Key words: Portal vein thrombosis—CT—Liver disease—Neoplasm—Infection

thrombus within the portal vein lumen (Fig. 1). Thrombus is usually seen as a hypodense-filling defect in the portal vein lumen, with partial or complete occlusion on contrast-enhanced scans, sometimes with extension into splenic or superior mesenteric veins [4]. Unenhanced scans have been shown to be of minimal benefit in the identification of thrombus. Indirect signs of PVT are the presence of cavernous transformation of the portal vein (Fig. 2), portosystemic collateral vessels and arterioportal shunts. Differentiation between a bland thrombus and a tumoral thrombus is not always possible with dynamic CT. Increased, streaky enhancement of the thrombus during the hepatic arterial phase suggests the presence of portal vein invasion and tumoral thrombosis (Fig. 3) [5]. In this article, we present CT features of portal vein thrombosis with various causative disease.

Diffuse liver disease Portal vein thrombosis (PVT) occurs in various clinical settings, with the most common being liver cirrhosis and hepatocelluar carcinoma (HCC). Other processes that may cause portal vein thrombosis are neoplasms, infectious diseases, myeloproliferative disorder, hypercoagulable states, surgery, and embolism from a thrombus located in the superior mesenteric or splenic vein [1, 2]. Signs and symptoms of PVT may be subtle or nonspecific and overshadowed by the underlying illness [3]. And PVT may be recognized only after imaging studies of the abdomen are performed for other reasons. Radiologists should be aware of the clinical situations that predispose a patient to portal vein thrombosis and should also be able to recognize the sequelae of chronic thrombosis. The primary abnormality in PVT is direct visualization of Correspondence to: Hae-Kyung Lee; email: [email protected]

Portal vein thrombosis is considered a rare event in the course of diffuse liver disease including liver cirrhosis (Fig. 4). Clinical presentation of non-neoplastic PVT in cirrhotic patients has not been specifically studied and risk factors of PVT in cirrhosis are still poorly understood [6], but it is known that the most common cause of PVT is decreased or reversed portal venous blood flow due to portal hypertension. And prothrombotic condition is another factor of PVT in patients without cancer and in good condition [3]. The incidence of non-neoplastic PVT in cirrhotic patients is unknown, while its prevalence ranges from 0.6 to 15.8% [7]. In contrast, studies performed at necropsy or in transplant candidates confirm the higher prevalence of PVT with more severe liver disease [2, 3]. It is a common experience to observe partial, spontaneously resolving, thrombi in the portal vein (Figs. 5, 6). Al-

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Fig. 1. Low-density thrombus within the portal vein. A. CT shows low density thrombus in contrast filled splenoportal junction. B. Coronal reconstruction CT image shows irregular tubular shaped low-density thrombus in main portal vein.

and there is no significant difference in relative risk of surgical resection or liver transplantation regardless of where PVTT existed [9, 10].

Other Gastrointestinal tumor

Fig. 2. Cavernous transformation of the portal vein. Normal main portal vein is obliterated and multiple collateral vessles are developed at porta hepatis.

though PVT may be completely asymptomatic in patients with liver cirrhosis, however in more than half of cases it presents with life-threatening complications such as gastrointestinal hemorrhage and intestinal infarction [6].

Primary hepatic tumor Hepatocellular carcinoma (HCC) is the most common cause of PVT (Fig. 7) but other primary tumors including cholangiocarcinoma (Fig. 8) is not uncommon. PVT by primary hepatic tumors are caused by intraluminal tumor thrombus directly from the tumor mass and signals an advanced tumoral stage. In a small percentage of patients, PVT may be the initial sign of an undetected HCC. In a series of 47 patients with malignant PVT, Tublin et al. [8] reported a rather low overall sensitivity (43%) of thrombus neovascularity on CT scans, even when specificity was 100%, because no patients with benign thrombosis showed thrombus vascularity. In case of large thrombi (PVT caliber >23 mm), sensitivity for diagnosis of malignant thrombi increased to 86%. The clinical value of recognizing malignant PVT in a patient with HCC relies on the effect that malignant PVT has on therapeutic strategy. Currently, if the portal trunk is not occluded, tumor and thrombus can be removed together

Portal vein involvement by neoplasms is possible by (1) extrinsic portal vein occlusion, and (2) intraluminal tumor thrombus originating directly from the primary lesion or originating indirectly from the liver metastasis. The former is usually caused by pancreatic cancer, gallbladder cancer (Fig. 9), and enlarged metastatic lymph nodes (Figs. 10, 11), while the latter is usually caused by hepatocellular carcinoma (HCC). Apart from being associated with HCC, intraluminal PVTT has also been reported to be associated with various other cancers [7]. Pancreatic cancer is the most common primary site followed by gastric cancer (Fig. 12) and colorectal cancer [2].

Liver abscess Liver abscesses may result from direct extension of bacteria from the biliary system in patients with suppurative cholangitis (Fig. 13). Other sources of infection include the gastrointestinal tract (appendicitis, diverticulitis) via the portal vein, subacute bacterial endocarditis and osteomyelitis via the hepatic artery, and direct contiguous spread. No source can be found in up to 50% of cases. In the liver abscess, complete or partial obstruction of the regional portal vein (45%) is frequently observed around a hepatic abscess [11].

Thrombophlebitis Septic thrombophlebitis of the portal vein and superior mesenteric veins (SMV) is very uncommon and usually develops secondary to infection in the region drained by the portal system or in the structures contiguous to the portal vein, such as the common bile duct. Despite major advances in antibiotic therapy, the mortality rate is still higher than 30% [12]. Moreover, although modern imaging techniques provide supportive diagnostic evidence, which helps early surgical treatment, establishing

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Fig. 3. HCC with portal vein tumor thrombosis. A, B, C. Early arterial images show thread like contrast enhancement within thrombosis.

Fig. 4. Developed portal vein thrombosis in liver cirrhosis. A. CT shows that the liver margin is serrated with heterogenous parenchymal density. Main and right portal vein are well opacified with contrast. B. Follow up 5 months later, thrombus

has developed at the splenoportal junction. C. Follow up 1 year later, thrombus has extended to the proximal right portal vein.

Fig. 5. Spontaneously resolved portal vein thrombosis. A. Parenchymal density of liver is heterogenous with serrated margin and collateral veins are noted in the gastrohepatic ligament, representing liver cirrhosis with portal hypertension.

Ascites is present. Low-density thrombus is noted in the right portal vein. B. Follow up after 4 months later, thrombus in right portal vein is resolved and ascites has also subsided.

the clinical diagnosis is sometimes difficult and delayed because of its nonspecific symptoms. The most common symptoms are fever, upper abdominal pain, nausea, diarrhea, and jaundice. Septic thrombophlebitis was a well-known and serious complication of appendicitis

(Fig. 14) of the past. However, this entity is now very rare due to advances in antibiotic treatment and improved surgical techniques [1, 4]. Subsequently, diverticulitis (Fig. 15) has replaced appendicitis as the most common cause of this entity, followed by cholecystitis,

H.-K. Lee et al.: Portal vein thrombosis: CT features

Fig. 6. Resolving portal vein thrombosis in toxic hepatitis. A. Initial CT shows irregular heterogenous parenchymal density in the right lobe of the liver and diffuse low density is noted within the right portal vein without contrast enhancement. Thrombus is also noted in the splenoportal junction. B. Follow

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up 1 year later, parenchymal density of right lobe is relatively homogenous. Contrast enhancement is noted in the right portal vein but caliber is very small. The thrombus at the splenoportal junction has resolved.

Fig. 7. Infiltrative HCC with portal vein thrombosis and dilatation. A, B. Ill defined tumor is noted in the right lobe and medial segment. The right portal vein is dilated and replaced by thrombus, which shows contrast enhancment.

Fig. 8. Intrahepatic cholangiocarcinoma with portal vein thrombosis. A, B, C. Irregular marginal enhancing low-density tumor is noted in the left lobe with capsular retraction. Sep-

arate intrahepatic metastasis is noted in the right lobe. Main and both intrahepatic portal veins are dilated and contain slightly enhancing tumor thrombosis.

Fig. 9. Gallbladder cancer with developed portal vein thrombosis. A. Initial CT shows irregular enahncing wall thickening at fundus of GB (arrow). B. Postopertive follow up CT shows conglomerated lymph nodes in the hepatoduode-

nal ligament with bile duct dilatation. Low-density thrombus with enhancement is developed in the main and both intrahepatic portal veins.

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Fig. 10. Metastasis from unknown primary site with portal vein thrombosis. A, B. CT shows large conglomerated lymph nodes at portocaval region and dilatation of both intrahepatic bile ducts. Several metastatic lesions are noted in both lobes of liver. Low-density thrombus is present in the main, right and proximal left portal vein.

Fig. 11. Metastasis from unknown primary site and portal vein thrombosis. A. CT shows irregular marginal enhancing low-density lesion in lateral segment of liver with infiltration at the perihepatic space. There is low-density thrombus in the

left portal vein without dilatation. There is a low-density metastatic lesion in spleen. B. A linear low-density thrombus is present in the splenic vein without dilatation and it is difficult to differentiate tumor thrombosis from bland thrombosis.

Fig. 12. Advanced gastric cancer with portal vein thrombosis. A. Preoperative CT shows diffuse circumferential wall thickening of stomach body. Low-density thrombus is present in splenoportal junction. B. Postoperative follow up image shows cavernous transformation.

Fig. 13. Liver abscess due to cholangitis with intrahepatic stones. A, B. Multifocal clustered abscesses are noted in the lateral segment of the liver and the neighboring left intrahepatic bile duct is dilated and contains highdensity stones. Low-density thrombus is present in the left and proximal right portal vein without dilatation.

pancreatitis, and abdominal and pelvic infections. Further more, idiopathic pylephlebitis due to a deficiency of clotting factors is not unusual [4]. The consequences of portal vein thrombosis are related to the extension of the thrombus. Upstream from the thrombus, there is little effect on the intestine as long as the mesenteric venous arches remain patent. Ischemia results from extension of

the thrombus into the mesenteric veins and the mesenteric venous arches (1) and emergency surgery is indicated (Fig. 16). If there is no evidence of intestinal infarction on imaging diagnosis, anticoagulation therapy with addition of thrombolytic therapy may enhance the clearance of thrombus and hasten the clinical improvements [13].

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Fig. 14. Perforated appendicitis with liver abscess and portal vein thrombosis. A. CT shows multiple clustered abscesses in the right lobe of the liver and thrombosis of right and main portal vein, and SMV. B. CT shows dilated appendix with neighboring abscess formation.

Fig. 15. Diverticulitis with thrombosis of portal and superior mesenteric veins. A. CT shows abscess abutting terminal ileum (arrow) and low-density thrombus in SMV and right portal vein. B. US shows abscess is directly connected to terminal ileum.

Aneurysm of portal vein Portal vein aneurysm (PVA) is a rare vascular anomaly, the reporting of which has increased with the frequent

use of radiological investigations for the diagnosis and screening of abdominal disorders. Two major etiologies, acquired and congenital, have been proposed. Known acquired etiologies of portal vein aneurysm include

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Fig. 16. Portal vein thrombosis with small bowel infarction. A. CT shows diffuse thrombosis of right and main portal vein with extension to SMV. B. Coronal reconstructed CT image shows diffuse small bowel wall thickening without contrast enhancement.

Fig. 17. Portal vein aneurysm with calcification. A. Precontrast CT shows dilated portal vein containing calcification. B. Contrast enhanced CT shows non-enhanced dilated portal vein (arrow) with cavernous transformation.

Fig. 18. Portal vein aneurysm with intraluminal hematoma. CT shows fusiform dilatation of the right and main portal vein with extension to the gastroduodenal vein (arrow) containing high-density hematoma. Left portal vein is intact. Hepatic cysts are noted in both lobes of liver.

portal hypertension, pancreatitis, and trauma [14]. A significant number of patients have underlying diseases such as hepatocellular cancer and portal hypertension. The release of pancreatic juice in patients with pancreatitis could cause a weakening of the vessel wall with concomitant development of portal vein aneurysm. Congenital portal vein aneurysm results from an inherent weakness of the vessel, which is supported by the fact that most patients with an aneurysm have no relevant

history such as portal hypertension [15]. In addition, in uterus diagnosis of a portal vein aneurysm has suggested a congenital origin. The most common location are the splenomesenteric confluence, main portal veins and intrahepatic portal vein branches at bifurcation site (Fig. 17). Since there are variations in the diameters of both normal and cirrhotic portal veins, an aneurysm of the portal venous system is considered to be present if the vessel diameter is significantly larger at that point than in

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the remainder of the vessel, especially if the morphology is saccular or fusiform (Fig. 18) [14]. Most portal vein aneurysm is asymmptomatic and do not demonstrate a significant increased in size once discovered, although some manifest with nonspecific abdominal pain as a major symptom. Complications of portal vein aneurysm are abdominal pain, thrombosis portal hypertension, rupture, thrombosis and distal embolism, compression of CBD causing jaundice, cholestasis and cholelithiasis. Surgical intervention is suitable for patients when a symptomatic aneurysm is unstable, with the occurrence of jaundice or progressive abdominal pain, or with portal hypertension or cirrhosis.

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References 1. Abbasakoor F, Singhvi R, Robert A, Carr ND (1999) Portal vein embolism. J R Soc Med 92:197–198 2. Ogren M, Bergqvist D, Bjorck M, Acosta S, Eriksson H, Sternby NH (2006) Portal vein thrombosis: prevalence, patient characteristics and lifetime risk: a population study based on 23,796 consecutive autopsies. World J Gastroenterol 12:2115–2119 3. Valla DC, Condat B (2000) Portal vein thrombosis in adults: pathophysiology, pathogenesis and management. J Hepatol 32:865–871 4. Marn CS, Francis IR (1992) CT of portal venous occlusion. AJR 159:717–726 5. Gallego C, Velasco M, Marcuello P, Tejedor D, Campo LD, Friera A (2002) Congenictal and acquired anomalies of the portal venous system. RadioGraphics 22:141–159 6. Amitrano L, Guardascione MA, Brancaccio V, Margaglione M, Manguso F, Iannaccone L, Grandone E, Balzano A (2004) Risk

12. 13.

14. 15.

factors and clinical presentation of portal vein thrombosis in patients with liver cirrhosis. Hepatology 40:736–741 Okuda K, Ohnishi K, Kimura K, Matsutani S, Sumida M, Goto N, et al. (1985) Incidence of portal vein thrombosis in liver cirrhosis. An angiographic study in 708 patients. Gastroenterology 89:279– 286 Tublin ME, III Dodd GD, Baron RL (1997) Benign and malignant portal vein thrombosis: differentiation by CT characteristics. AJR 168:719–723 Minagawa M, Makuuchi M, Takayama T, Ohtomo K (2001) Selection criteria for hepatectomy in patients with hepatocellular carcinoma and portal vein tumor thrombus. Ann Surg 233:379–384 Manzanet G, Sanjuan F, Orbis P, Lopez R, Moya A, Juan M, Vila J, Asensi J, Sendra P, Ruiz J, Prieto M, Mir J (2001) Liver transplantation in patients with portal vein thrombosis. Liver Transpl 7:125–131 Lee KH, Han JK, Jeong JY, Kim YJ, Lee HJ, Park SH, Choi BI (2005) Hepatic attenuation differences associated with obstruction of the portal or hepatic veins in patients with hepatic abscess. AJR 185:1015–1023 Lim HE, Cheong HJ, Woo HJ, Kim WJ, Kim MJ, Lee HC, Park SC (1999) Pylephlebitis associated with appendicitis. Korean J Intern Med 14:73–76 Lee H, Kim TH, Oh HJ, Kim JI, Park SH, Han JY, Kim JK, Choi KY, Chung IS, Lee SH, Hahn ST (2006) Portal and superior mesenteric venous thrombosis treated with urokinase infusion via superior mesenteric artery. Korean J gastroenterol 48:46–50 Ozbeck SS, Killi MR, Porbagher MA, Parildar M, Katranci N, Solak A (1999) Portal vein aneurysm. J Ultrasound Med 21:147– 151 Fulcher A, Turner M (1997) Aneurysm of the portal vein and superior mesenteric vein. Abdom Imaging 22:289–292