Intrahepatic portal venous system: variations demonstrated with duplex and color Doppler US

Seventeen cases of variations of the intrahepatic portal venous system were investigated with use of duplex and color Doppler ultrasound (US). Seven cases involved absence of the horizontal segment of the left portal vein, with portal supply to the left lobe arising from the right lobe. The 10 remaining cases involved variations of intrahepatic portal branching resulting from absence of the right portal vein, taking four patterns. It is thought that these findings represent variants of normal. These variants are important in two settings: in planning hepatic surgery and in the differential diagnosis of chronic portal vein thrombosis.     

Hepatofugal flow in the portal venous system: pathophysiology, imaging findings, and diagnostic pitfalls.

Hepatofugal flow (ie, flow directed away from the liver) is abnormal in any segment of the portal venous system and is more common than previously believed. Hepatofugal flow can be demonstrated at angiography, Doppler ultrasonography (US), magnetic resonance imaging, and computed tomography (CT). The current understanding of hepatofugal flow recognizes the role of the hepatic artery and the complementary phenomena of arterioportal and portosystemic venovenous shunting. Detection of hepatofugal flow is clinically important for diagnosis of portal hypertension, for determination of portosystemic shunt patency and overall prognosis in patients with cirrhosis, as a potential pitfall at invasive arteriography performed to evaluate the patency of the portal vein, and as a contraindication to specialized imaging procedures (ie, transarterial hepatic chemoembolization and CT during arterial portography). Hepatofugal flow is generally diagnosed at Doppler US without much difficulty, but radiologists should beware of pitfalls that can impede correct determination of flow direction in the portal venous system.     

Intrahepatic portal venous variations: prevalence with US.

A prospective ultrasound study was undertaken to determine the prevalence of variants of the intrahepatic branching of the portal venous system. Of the 507 patients examined, 55 (10.8%) had trifurcation, 24 (4.7%) had a right posterior segmental branch arising from the main portal vein, 22 (4.3%) had a right anterior segmental branch originating from the left portal vein, and one (0.2%) had absence of the horizontal segment of the left portal vein. Not one patient had complete absence of the right portal vein in this series. The remaining 405 (79.9%) patients had normal distribution of the portal venous system; some patients of the normal group had minor variations in distribution.     

Hepatodiaphragmatic portosystemic shunt in cirrhosis

A case of an unusual form of hepatodiaphragmatic portosystemic shunt arising from the periphery of left posterosuperior portal vein branch, running beneath the inferior aspect of left hemidiaphragm and draining into the left lateral abdominal wall is demonstrated and assessed with digital subtraction portography, maximum-intensity-projection images reconstructed from helical CT during arterial portography and pulsed Doppler sonography with flow velocity measurement. This is a reported case of this unusual intrahepatic portosystemic shunt and discussion on the utility of current radiological techniques.     

Portal venous variations. Prevalence with contrast-enhanced helical CT

PURPOSE: To review the distribution of intrahepatic portal venous branching in order to determine the prevalence of variations. MATERIAL AND METHODS: We made a retrospective review of 655 contrast-enhanced helical CT (CECT) images of patients referred to our department for upper abdominal CT examination during an 8-month period. Of the 655 patients, 70 were eliminated from the study because of improper opacification of the portal venous system. Variations of portal venous branching in the remaining 585 patients were classified. RESULTS: Of 585 patients, 504 (86.2%) had classical bifurcation of the main portal vein (MPV); 72 (12.3%) had a trifurcation of the MPV, 5 (0.9%) had a right anterior segmental branch originating from the left portal vein (LPV), 2 (0.3%) had an LPV originating from the right anterior segmental branch and 2 (0.3%) had a right posterior segmental branch arising from the MPV. CONCLUSION: Variations of portal venous branching are common and helical CT is efficacious in identifying these variations.     

Abernethy malformation with portal vein aneurysm

We present the case of a 24-year-old man who was incidentally diagnosed with congenital extrahepatic portosystemic shunt with portal vein aneurysm during an investigation for non-specific abdominal pain. These are rare anomalies, and to the best of our knowledge, this is the first case reported with both anomalies associated together. Ultrasound, including color Doppler, computed tomography, and magnetic resonance imaging were performed which revealed a side-to-side shunt between the extrahepatic portal vein and the inferior vena cava, with aneurysmal fusiform dilatation of the proximal intrahepatic portal vein which ended abruptly. Etiology, clinical significance, and management strategies with regard to these abnormalities are discussed.     

Altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein: evaluation with Doppler US in 14 patients

PURPOSE: To evaluate with Doppler ultrasonography (US) the altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein. MATERIALS AND METHODS: The study group consisted of 14 patients being considered for hepatic arterial infusion or transarterial embolization. In all patients, maximum peak velocity of the blood flow in the right portal vein was measured with Doppler US before and during the occlusion of the right hepatic vein. In 13 patients, color Doppler US was performed to evaluate Doppler signal in the portal venous branch in the occluded area before and during occlusion. Average peak velocity in the right hepatic artery in eight patients was measured by using a transducer-tipped guide wire before and during occlusion. RESULTS: Maximum peak velocity of the right portal vein significantly decreased with occlusion (P <.01). Hepatic venous occlusion changed the Doppler signal in the portal venous branch in the occluded area from hepatopetal to no signal in 10 patients; to weakened hepatopetal in two; and to hepatofugal in one. Average peak velocity of the right hepatic artery showed a decrease or plateau for 15-30 seconds after the start of occlusion and then a rapid increase to reach a plateau at around 75-90 seconds, with 1.5-2 times as much velocity as that before occlusion. CONCLUSION: Increase in hepatic arterial velocity is accompanied by a decrease in the portal velocity with temporary occlusion of the right hepatic vein; the expected increased drainage through the portal vein was almost undetectable.     

Aneurysms of the portal venous system: Gray-scale and color doppler ultrasonographic findings with CT and mri correlation

Two cases of incidentally detected aneurysms involving the portal venous system are described with emphasis on gray-scale and color Doppler ultrasonographic (US) findings. Appearing on US as anechoic masses showing direct luminal continuity with the right portal vein and superior mesenteric vein, the lesions displayed spectral findings characteristic of portal venous system on color Doppler US. Dynamic helical computed tomography (CT) demonstrated simultaneous enhancement with the portal system, while the aneurysms were hypointense owing to flow void on T1-weighted spin-echo magnetic resonance (MR) images.     

Comparison of Ultrasound,CT, and MR Imaging in the Evaluation of Candidates for TIPS

To compare ultrasound (US), CT, and MRI in the evaluation of hepatic vascular anatomy, portal and splenic venous flow, and collateral pathways (varices and spontaneous shunts) in candidates for transjugular intrahepatic portosystemic shunting (TIPS), 17 patients with history of refractory variceal bleeding or intractable ascites underwent duplex US, contrast-enhanced CT, and MRI before TIPS. The appearance of portal and hepatic anatomy was graded from 1 (not visible) to 4 (excellent visualization) independently by four radiologists. Presence and direction of portal and splenic venous flow, and presence and location of varices and spontaneous portosystemic shunts were also assessed. Results and effects of interobserver variation were assessed for significance using Friedman's ANOVA and Wilcoxon's signed-rank test. MRI yielded higher scores than CT or US for hepatic veins (P <.0001) and inferior vena cava (P <.0001). MRI and CT scored better than US for portal vein branches (P =.012) and splenic vein (P =.0038). All tests demonstrated the main portal vein well, with no statistically significant difference. US and MRI were more sensitive than CT for detecting portal vein flow and direction (US 76%, CT 0%, MRI 82%). MRI was most sensitive for splenic vein flow and direction (US 41%, CT 0%. MRI 76%). CT and MRI were more sensitive than US in detecting varices (US 5%, CT 50%, MRI 58%) and spontaneous shunts (US 13%, CT 75%, MRI 75%). Interobserver variation did not influence results significantly P =.3691). MRI provides the most useful information and may be the preferred single imaging test prior to TIPS.     

Doppler ultrasonography evaluation of paraumbilical vein and portal hypertension

Portal hypertension is associated to the development of portosystemic collateral veins, particularly the paraumbilical vein. PURPOSE: To evaluate the biometric and hemodynamic characteristics of the portal vessels related to the presence of a patent paraumbilical vein, in the setting of portal hypertension secondary to hepatosplenic schistosomiasis. METHODS: 75 patients with portal hypertension secondary to hepatosplenic schistosomiasis were evaluated by Doppler US. The patients were studied based on the presence (group B) or not (Group A) of a patent paraumbilical vein. The diameter and blood flow velocity of the portal vessels and of the paraumbilical vein were recorded. RESULTS: The paraumbilical vein was detected in 17.33% of patients. The results showed an increase of the diameter of the main and left portal vessels whenever a patent paraumbilical vein was present (portal vein: A = 1.14 +/- 0.29 cm/B = 1.33 +/- 0.16 cm; left branch: A = 0.95 +/- 0.25 cm/B = 1.30 +/- 0.24 cm). The mean blood flow velocity was also increased in the portal trunk (A = 15.96 +/- 6.17 cm/sec/B = 19.82 +/- 6.26 cm/sec) and in the left portal branch (A = 14.77 +/- 4.29 cm/sec/B = 19.92 +/- 6.88 cm/sec). CONCLUSION: The presence of a patent paraumbilical vein is related to significant biometric and hemodynamic variations in the portal venous system, in the setting of portal hypertension secondary to hepatosplenic schistosomiasis.     

下腔静脉畸形的64层螺旋CT表现

目的 探讨64层螺旋CT下腔静脉畸形的影像表现.方法 回顾性分析6986例受检者的腹部64层螺旋CT增强扫描资料,共发现25例下腔静脉先天畸形.分析下腔静脉畸形的影像表现.结果 25例下腔静脉畸形中包括左下腔静脉6例,CT表现为肾下段腹主动脉左侧上行的下腔静脉.双下腔静脉10例,CT表现为肾下段腹主动脉两侧上行的下腔静脉.左肾静脉畸形5例,CT增强扫描横断面显示腹主动脉后和环主动脉走行的左肾静脉.肝下段下腔静脉中断伴奇静脉延续2例,胸腹部CT增强扫描显示肝段至肾上段下腔静脉缺如,肾段下腔静脉由奇静脉延续回流人上腔静脉,而肝静脉直接回流右心房.腔静脉血管造影见对比剂经增粗的奇静脉和半奇静脉通过上腔静脉回流右心房.肝下段下腔静脉中断伴门静脉延续1例,增强CT显示下腔静脉直接与门静脉在肝门部连接,肝门部门静脉呈瘤样扩张.左下腔静脉伴半奇静脉延续1例,增强CT可见左下腔静脉与半奇静脉连接,上行汇入奇静脉.结论 64层螺旋CT可清晰显示下腔静脉及其属支的畸形,可成为下腔静脉畸形的重要诊断方法.     

Intrahepatic portal venous variations: demonstration by helical CT during arterial portography

PURPOSE: We assessed the prevalence and types of intrahepatic portal venous variations by helical computed tomography performed with arterial portography (CTAP). METHODS: In 192 patients without evidence of vascular invasion or distortion, CTAP images were reviewed retrospectively to identify portal venous variations. RESULTS: Of the 192 patients examined, 10 (5.2%) had trifurcation, 5 (2.6%) had a right posterior segmental branch arising from the main portal vein, 5 (2.6%) had an absence of the horizontal segment of the left portal vein, and 1 (0.5%) had an absence of the left lateral segmental portal branch. Of the patients without a horizontal segment, two had a right-sided ligamentum teres associated with malposition of the gallbladder, while another had complete ramification of intrahepatic portal branches from an umbilical vein-like segment. In the patient missing the left lateral segmental branches, the right portal vein segments were subcapsularly located. CONCLUSION: Variations of the intrahepatic portal veins can be recognized on CTAP imaging. tomography-Portal vein, computed tomography.     

Multidetector CT findings of right intrahepatic portosystemic venous shunt

PurposeTo evaluate multidetector CT features of right intrahepatic portosystemic venous shunt (IPSVS).Materials and MethodsPathways of right IPSVS were evaluated from 20 patients. Diameters of right portal veins were measured in IPSVS patients, 30 cirrhotic and 30 healthy patients.ResultAmong 22 IPSVSs, shunt between posterior branch and inferior phrenic vein was most common. Diameters of the posterior branch were larger in IPSVS patients than in other groups.ConclusionMost right IPSVSs drain to inferior phrenic vein through dilated posterior branch.     

经颈静脉肝内门脉左支-体静脉分流术的临床意义

目的 评价选择性门静脉左支作为TIPS分流道的临床意义，分析门静脉左、右支的血液动力学变化及重要液道物质浓度差异对术后预防肝性脑病及远期疗效的影响。方法 341例有目的的选择肝内门静脉左支作为穿刺靶点，行经颈静脉矸内静脉左支门腔分流术建立门腔分流道，避开富含营养、毒素的门静脉右支血液。肝实质通道用8mm直径球囊扩张，限制分流口径。结果 所有患者术后3个月内无一例发生肝性脑病。随访期间TIPS术后341例患者仅5例（1.47%）出现肝性脑病和19例（5.57%)一年随访造影出现支架内狭窄。结论 选择性门静脉左支作为门腔静脉分流道，可心显著降低肝性脑病发生率，对保护肝功能，提高分流道远期开通率具有重要的临床意义。     

肝内门静脉和肝静脉的解剖与变异(三维动态增强磁共振血管成像分析)

目的用三维动态增强磁共振血管成像（３ｄｉｍｅｎｔｉｏｎａｌｄｙｎａｍｉｃｃｏｎｔｒａｓｔｅｎｈａｎｃｅｄＭＲＡ,３ＤＤＣＥＭＲＡ）前瞻性地观测肝内门静脉（简称门脉）和肝静脉的解剖和变异。方法共进行１４２例门脉和肝静脉３ＤＤＣＥＭＲＡ检查。对肝内门脉和肝静脉的解剖和变异做分型,计算每一型所占总调查人数的比例,并计算右后下肝静脉的显示率。结果１４２次成像中,８例（５．６％）显示门脉呈三分叉状,７例（４．９％）门脉先分出右后支,然后上行分为左支和右前支,４例（２．８％）门脉右前支源于左支,未发现有门脉左支水平段或右支缺如,余下１２３例（８６．６％）显示正常门脉分支。绝大多数情况下（９５．１％）肝中、肝左静脉合并,而三大支肝静脉单独汇入下腔静脉仅占４．９％。右后下肝静脉的显示率为７．７％。结论肝内门脉变异并不少见。肝中和肝左静脉多合并后汇入下腔静脉。部分病人有较为粗大的右后下肝静脉。３ＤＤＣＥＭＲＡ能方便而清楚地显示上述血管的解剖和变异     

A rare Abernethy Ib malformation was initially misdiagnosed as chronic portal vein thrombosis in a 27-year-old female

Abernethy malformation or congenital portosystemic shunt is a rare congenital vascular malformation and anomaly of the splanchnic venous system defined by diverting portal blood away from the liver. It is commonly associated with multiple congenital anomalies. Imaging modalities such as computed tomography or magnetic resonance have a crucial role in prompting diagnosis and determining the prognosis based on the type of malformation and associated anomalies. Misdiagnosis could be harmful and may lead to inappropriate treatment. We present a case of Abernethy malformation with a complete end-to-side shunt of portal venous flow into the systemic venous flow and complete bypass of the liver, which was initially misdiagnosed with portal venous thrombosis.     

Portal venous calcifications 20 years after portosystemic shunting: demonstration by spiral CT with CT angiography and 3D reconstructions

BACKGROUND: Evaluation of the value of spiral computed tomography (SCT), and postprocessing procedures in patients with extensive portal venous calcifications 20 years after portosystemic shunting was performed. METHODS: In two patients spiral CT (SCT) examinations of the abdomen (slice thickness 3 mm, table feed 6 mm/s) were performed prior and after application of 150 ml of contrast material administered at a flow rate of 4 ml/s. Axial images were reconstructed at 2 mm increments for postprocessing procedures and 6 mm increments for axial source images. Postprocessing was performed with a maximum intensity projection (MIP) and shaded surface display (SSD) imaging program. RESULTS: In both cases preoperative plain film radiography of the chest and abdomen showed large curvilinear calcifications located at the upper quadrant of the abdomen. The calcifications were directed along the expected axis and position of the portal vein and the portosystemic venous anastomosis. Axial CT slices and CTA showed that the calcifications were located in the vessel wall and that the portal vein lumen as well as the portosystemic venous anastomosis were patent. CONCLUSION: Long-standing portal hypertension is capable of causing portal venous calcifications due to mechanical stress to the vessel wall even years after performing portosystemic shunting. Typically, the calcifications are directed along the expected axis and position of the portal vein. SCT of the portal venous system is a reliable method to differentiate between calcifications in a thrombus or in the vessel wall, which may have therapeutic significance.     

Traesjugular intrahepatic portosystemic shunt in portai vein thrombosis: Role of the right gastric vein with anomalous insertion

Transjugular intrahepatic portosystemic shunt (TIPS) was performed in two patients with portal vein thrombosis. In both patients, hepatopetal flow had been maintained by an anomalous insertion of the right gastric vein (RGV) into the portal vein bifurcation and into the left portal branch respectively. In one patient, the main portal trunk could not be recanalized and the RGV was used as an accessory portal vein to place one stent for TIPS. In the other case, access through the partial portal-vein occlusion was gained and three stents were placed from the hepatic vein to the main portal vein distal to the thrombus. In portal vein thrombosis, the aberrant insertion of the RGV into the left or right portal branches may maintain patency of the intrahepatic portal system and, in case of unsuccessful recanalization of the porta, may represent the sole pathway for placing a TIPS     

Adrenal pseudomasses due to varices: angiographic-CT-MRI-pathologic correlations

Periadrenal and adrenal portosystemic collaterals are a recently reported cause of adrenal pseudotumor on computed tomography (CT). Nine patients with this left adrenal pseudotumor illustrate its typical position and appearance on CT, angiography, CT-angiography, and magnetic resonance imaging (MRI). The anatomic basis for variceal adrenal pseudotumors is the left inferior phrenic vein, which passes immediately anterior to the left adrenal gland and which serves as a collateral pathway from splenic to left renal vein in portal hypertension. Thus, unlike previously described adrenal pseudotumors, these venous collaterals are not anatomically distinguishable from the adrenal gland on CT. Bolus dynamic CT is usually diagnostic, but in equivocal cases, MRI may prove useful.     

Intrahepatic portosystemic venous shunt: occurrence in patients with and without liver cirrhosis

Portosystemic venous shunt within the hepatic parenchyma is rare, and its cause is disputed. Only 12 cases have been reported in the literature. Four new patients are presented here, all of whom had cerebral manifestations due to elevated blood-ammonia levels. One patient, initially misdiagnosed as having a psychiatric disorder, had multiple small portohepatic venous shunts in the peripheral hepatic parenchyma that were believed to be congenital in origin. The other three patients with clinical evidence of cirrhosis and portal hypertension had large tubular shunts between the posterior branch of the portal vein and the inferior vena cava. Shunts of this type were considered to be the collateral pathways developed in the hepatic parenchyma as a result of portal hypertension. The diagnosis of intrahepatic portosystemic venous shunts was established by angiography in all four patients. Sonography and CT failed to show the multiple small shunts, but did provide diagnostic information concerning the large tubular shunts. Intrahepatic portosystemic venous shunt can be the cause of hepatic encephalopathy. One should be familiar with the typical radiographic manifestations of this condition to prevent misdiagnosis as a psychiatric or neurologic disorder.