Hepatic changes in benign obstruction of the hepatic inferior vena cava: CT findings

Cirrhosis and LI-RADS

Chronic liver disease, irrespective of cause, can eventually lead to cirrhosis, which is the primary risk factor for developing hepatocellular carcinoma (HCC). In patients with cirrhosis or appropriate risk factors, HCC can be diagnosed by imaging with high specificity using liver imaging reporting and data system v2017, obviating the need for histologic confirmation. Confident recognition of cirrhosis by conventional imaging alone can be challenging, as radiologists are not always provided with the requisite information to determine if the patient has cirrhosis or other risk factors for HCC. Moreover, cirrhosis-associated abnormalities may impair the diagnostic accuracy of imaging for HCC. This article addresses the diagnosis of cirrhosis by non-invasive imaging and the implications of cirrhosis for imaging interpretation and accuracy.

Diagnosis and treatment guidelines for aberrant portal hemodynamics: The Aberrant Portal Hemodynamics Study Group supported by the Ministry of Health, Labor and Welfare of Japan

Idiopathic portal hypertension (IPH), causing aberrant portal hemodynamics, is a disease with an as yet unidentified cause and no established treatment protocol. The Japanese research group on IPH in Japan was set up in 1975 by the Ministry of Health, Labor and Welfare. Extrahepatic portal obstruction and Budd-Chiari syndrome (BCS) have since been added to the group's research subjects. The aims of the research group are to accurately evaluate the current status of the three diseases in Japan, elucidate their etiology and pathogenesis, and develop new treatments. Due to the long-term efforts of the Japanese research group, aberrant portal hemodynamics has been investigated in a variety of aspects, from epidemiological and pathological studies to molecular biology analyses. As a result, it has been shown that there are abnormal genes in the liver, specific for IPH. In addition, pathological findings of BCS were internationally compared and the difference in findings between Japan and Europe (or North America) has been clarified. Furthermore, it was found that complication rates of hepatocellular carcinoma in BCS were higher in Japan. Based on the research, "Diagnosis and treatment of aberrant portal hemodynamics (2001)", including diagnostic criteria for aberrant portal hemodynamics, was published in 2001. In 2013, it was revised to "Diagnosis and treatment guidelines for aberrant portal hemodynamics (2013)" after the incorporation of diagnosis and treatment in accordance with its current status.

Budd-Chiari syndrome: a prospective analysis of hepatic vein obstruction on ultrasonography, multidetector-row computed tomography and MR imaging

PURPOSE

The goal of this study was to prospectively describe the imaging presentation of hepatic vein (HV) obstruction in patients with Budd-Chiari syndrome (BCS) on duplex and color Doppler ultrasonography (DCD-US), multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A total of 176 patients with primary BCS (mean age, 33 years; 101 women) were prospectively included. BCS diagnosis was made by direct visualization of HV and/or upper portion of the inferior vena cava (IVC) obstruction on DCD-US and/or MDCT and/or MRI. Location (right, middle, and left HV), type (thrombus, stenosis, or both), and age (recent vs. long-standing) of HV obstruction were described on each imaging examination.

RESULTS

HV obstruction was a constant (100%) finding and associated with IVC abnormalities in 51/176 (28.98%) patients. Obstruction of the three HVs was present in 158/176 (89.77%) patients. The prevalences of right, middle, and left HV thrombus were 151/169 (89.35%), 146/169 (86.39%), and 111/169 (65.68%), respectively. Long-standing HV thrombus was observed in more than 92% of patients on the three imaging methods. Agreement between DCD-US, MDCT, and MRI was perfect in the identification of long-standing HV thrombus (κ = 0.9); this agreement was slight to moderate in revealing the type of HV abnormality (i.e., fibrotic cord and non-visible HV).

CONCLUSION

Our results indicate that BCS is a chronic and insidious disease, more often discovered at an advanced stage. These results should warrant further evaluation of screening strategies in patients with risk factors for BCS to identify the disease at an early stage.

Budd-Chiari syndrome: an update on imaging features

Budd-Chiari syndrome (BCS) is a rare cause of portal hypertension and liver failure. This condition is characterized by an impaired hepatic venous drainage. The diagnosis of BCS is based on imaging, which helps initiate treatment. Imaging findings can be categorized into direct and indirect signs. Direct signs are the hallmarks of BCS and consist of visualization of obstructive lesions of the hepatic veins or the upper portion of the inferior vena cava. Indirect signs, which are secondary to venous obstruction, correspond to intra- and extrahepatic collateral circulation, perfusion abnormalities, dysmorphy and signs of portal hypertension.

Ectopic intracaval liver

Congenital abnormalities of the liver are rare with prior descriptions of lobar or segmental agenesis, Reidel's lobe, and ectopic hepatic lobes. Intrathoracic ectopic hepatic lobes have been reported in many instances; however, there is only one documented case of abnormally positioned liver tissue within the inferior vena cava (J Chapman-Fredricks, R Birusingh, M Ricci, M Rodriguez, Intracaval liver with cardiac extension. A new developmental anomaly? Fetal and Pediatric Pathology. 2010; 29:401-406). We report a second case of an ectopic intracaval liver defined as a mass in an adult who presented for abdominal pain and review the radiological findings.

Perfusion and parenchymal changes related to vascular alterations of the liver

Imaging plays a significant role in the diagnosis of vascular abnormalities of the liver and sometimes provides the only clue to the correct diagnosis. With advances of imaging techniques and multiphasic acquisition of liver imaging, various perfusion changes are frequently encountered. Correct imaging diagnosis of significant vascular diseases can prompt appropriate work-up and timely management. Accurate differentiation of clinically insignificant perfusion phenomena from clinically significant findings including neoplastic conditions and in the setting of post-transplantation is essential. This pictorial essay illustrates various perfusion and parenchymal changes associated with portal venous inflow, hepatic venous outflow, and non-portal venous third inflow and describes brief background pathophysiology and differential points.

Imaging of acute conditions affecting the hepatic vasculature

Liver imaging primarily consists of evaluating the parenchyma and biliary system. However, the liver has a rich, complex vascularity which can also be affected by numerous disease processes. By considering disease processes that primarily affect the hepatic veins, portal veins, and hepatic arteries, an anatomy-based approach of hepatic vascular diseases can be applied to image interpretation to allow rapid diagnosis and prompt initiation of treatment. Computed tomography, magnetic resonance imaging, and ultrasound are all effectively used to evaluate the liver and can play complimentary roles. In this article, the key imaging findings of acute conditions affecting the hepatic veins (passive congestion, acute thrombosis/Budd-Chiari, stenosis), portal veins (thrombosis, phlebitis, stenosis), hepatic arteries (laceration, pseudoaneurysm, thrombosis), and arteriovenous structures (hereditary hemorrhagic telangiectasis, arteriovenous fistula) will be reviewed.

CT of nonneoplastic hepatic vascular and perfusion disorders

The unique dual blood supply of the liver (75% portal venous, 25% hepatic arterial) makes multiphase helical computed tomography (CT) a highly suitable technique for hepatic evaluation with imaging in two (arterial and portal venous) or more phases. Multiphase helical CT has become an important tool in the detection and characterization of hepatic tumors. In some situations, hemodynamic changes might mimic neoplastic or inflammatory lesions and evoke diagnostic uncertainty. To confidently identify hepatic conditions such as venous outflow obstruction (Budd-Chiari syndrome), arterioportal shunts, hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome), peliosis hepatis, passive congestion, and hepatic infarction, radiologists must be familiar with the disease-specific CT appearances and related clinical manifestations.

Imaging of Budd-Chiari syndrome

Budd-Chiari syndrome occurs when venous outflow from the liver is obstructed. The obstruction may occur at any point from the hepatic venules to the left atrium. The syndrome most often occurs in patients with underlying thrombotic disorders such as polycythemia rubra vera, paroxysmal nocturnal hemoglobinuria and pregnancy. It may also occur secondary to a variety of tumours, chronic inflammatory diseases and infections. Imaging plays an important role both in establishing the diagnosis of Budd-Chiari syndrome as well as evaluating for underlying causes and complications such as portal hypertension. In this review article, we discuss the role of modern imaging in the evaluation of Budd-Chiari syndrome.

Budd-Chiari syndrome: a review of imaging findings

Budd-Chiari syndrome is an uncommon, often fatal disorder resulting from an obstructed hepatic venous outflow tract. The obstructive lesion is situated in the main hepatic veins, in the inferior vena cava or in both. The nature, location and extension of the obstruction can be displayed on diagnostic imaging techniques. In addition to this direct evidence, the indirect findings of venous obstruction such as the presence of intra- and extrahepatic collateral veins, when combined with the altered morphology and enhancement pattern of the liver enables one to arrive at a confident diagnosis. In patients with suspected Budd-Chiari syndrome, gray-scale sonography with complementary support of color and pulsed Doppler examinations is the first step in approaching the diagnosis. It is followed by a contrast-enhanced cross-sectional technique, preferrentially by MR angiography. The patients with a high clinical suspicion of Budd-Chiari syndrome may undergo hepatic venography or venacavography directly so that a potential of recanalization (e.g. percutaneous transluminal angioplasty with or without stent placement or TIPS) of the obstructed segment under the guidance of these techniques would not be delayed.

Triphasic helical CT in Budd-Chiari syndrome: patterns of enhancement in acute, subacute and chronic disease

AIM

To retrospectively evaluate helical computed tomography (CT) findings in a series of consecutive patients with Budd-Chiari syndrome.

METHODS

Patterns of enhancement observed at contrast-enhanced helical CT in 10 consecutive patients (six women, four men; aged 27-51 years) with either acute, subacute or chronic Budd-Chiari syndrome were retrospectively evaluated along with the status of the hepatic veins. All patients underwent triphasic helical CT (10 mm beam collimation, 7 mm rec. intervals, 120 kV, 200-250 mA, pitch = 1.0) performed at 20-25, 70-75 and 300 s after i.v. bolus (3 ml/s) injection of 150 ml iodinated non-ionic contrast media.

RESULTS

Abnormal patterns of enhancement were identified in eight patients. In all patients with acute Budd-Chiari disease (3/3) abnormal arterial enhancement of the caudate lobe, the so-called "fan-shaped pattern" was observed, whereas visible venous thrombosis was only depicted in two. Conversely, a "patchy pattern" of enhancement was observed in five out of seven patients with either sub-acute (2) or chronic Budd-Chiari disease (5) along with a strip-like appearance or lack of visualization of hepatic veins.

CONCLUSIONS

The "fan-shaped" pattern of enhancement represent a characteristic finding of acute Budd-Chiari disease, and it may help to suggest the correct diagnosis even in absence of visible venous thrombosis.

Hepatic outflow obstruction: enhancement patterns of the liver on MR angiography

Our purpose was to present the enhancement patterns of the liver on MR angiography in patients with hepatic outflow obstruction. Twenty-three patients with Budd-Chiari syndrome (4 in acute stage and 19 in chronic stage of the disease) were examined with 3D contrast-enhanced MR angiography. During early and late portal venous phase of MR angiography the pattern of parenchymal enhancement was assessed on source images. The enhancement patterns were evaluated under 4 groups as following: (a) central (b) peripheral (c) patchy and (d) homogeneous enhancement. The morphologic changes in the liver (lobar hypertrophy or atrophy, hepatic surface irregularities) were also recorded. In the acute stage global liver enlargement (75%) with caudate hypertrophy (100%) and central enhancement of the liver (75%) were suggestive findings of the hepatic outflow obstruction. The left lobe hypertrophy (53%) associated with the caudate lobe hypertrophy (72%) and irregular surface (26%) were predominant in the chronic stage of the disease. The enhancement patterns seen in chronic disease were variable and reflected the persistent stasis of the portal blood flow (patchy enhancement in 32% of the patients) or the altered hemodynamics of the liver due to the development of subcapsular collaterals (peripheral enhancement in 21% of the patients). Homogeneous enhancement of the liver in Budd-Chiari syndrome may indicate the chronicity of the outflow obstruction (37%) and shows a more stable hepatic perfusion that occurs after the formation of intra and extrahepatic collateral veins. The morphological and perfusional features on multiphase contrast-enhanced MR angiography are valuable in understanding the effects of the hepatic outflow obstruction on the liver parenchyma.

CT during hepatic arteriography and portography: an illustrative review

The combination of computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) has been used for evaluation of hepatic neoplasms before partial hepatic resection. Focal hepatic lesions that can be demonstrated with CTAP and CTHA include regenerative nodules, dysplastic nodules, dysplastic nodules with malignant foci, hepatocellular carcinoma, cholangiocarcinoma, hemangioma, and metastases. CTAP is considered the most sensitive modality for detection of small hepatic lesions, particularly small hepatic tumors such as hepatocellular carcinoma and metastatic tumors. CTHA can demonstrate not only hypervascular tumors but also hypovascular tumors and can help differentiate malignant from benign lesions. However, various types of nontumorous hemodynamic changes are frequently encountered at CTAP or CTHA and appear as focal lesions that mimic true hepatic lesions. Such hemodynamic changes include several types of arterioportal shunts, liver cirrhosis, Budd-Chiari syndrome, inflammatory changes, pseudolesions due to an aberrant blood supply, and laminar flow in the portal vein. Familiarity with the CTAP and CTHA appearances of various hepatic lesions and nontumorous hemodynamic changes allows the radiologist to improve the diagnostic accuracy.

Pericaval fat mimicking intracaval deposits on unenhanced and contrast-enhanced helical CT in patients with cirrhosis

PURPOSE

The purpose of this work was to determine whether there is a significant difference in radiographic depiction of pericaval fat mimicking intracaval deposits on CT scans in patients with cirrhosis versus those without cirrhosis.

METHOD

The incidence of radiographic pseudolesions depicted as an intracaval fat mass identified on CT scans in 62 patients with cirrhosis was compared with that in 81 patients without cirrhosis.

RESULTS

Pericaval fat depicted as an intracaval fat mass was identified more frequently in patients with cirrhosis (20/62, 32%) than in patients without cirrhosis (4/81, 5%), representing a statistically significant difference (p < 0.0001). A total of 24 lesions were seen in 20 patients with cirrhosis. Lesions were identified at the confluence of the hepatic veins (n = 19), below the confluence (n = 4), and above the confluence (n = 1). Pseudolesions appeared round (n = 5), oval (n = 15), or linear (n = 4). Locations included medial (n = 15), posteromedial (n = 4), anteromedial (n = 1), and posterior (n = 4). The average length was 1.5 cm.

CONCLUSION

The cause of pseudolesions depicted as intracaval fat masses on CT is likely secondary to morphologic changes in the liver such as cirrhosis.