Budd Chiari Syndrome Acute Chronic

Budd-Chiari syndrome is defined as an obstruction of the venous outflow from the sinusoidal bed of the liver. It leads to portal hypertension, ascites and progressive hepatic failure [57].

The treatment of Budd-Chiari syndrome depends on the cause of the obstruction and, hence, careful examination of the hepatic veins, the inferior caval vein (ICV) and the right atrium is necessary [37, 73]. For example, a membranous occlusion of the ICV is a common cause of obstruction in the Asian population. In such cases, mem-branectomy should be performed. On the other hand, if a solitary occlusion of the ICV is present without the hepatic veins being affected, a shunting from the ICV to the right atrium should be the primary treatment of choice.

If only the hepatic veins are obstructed, a shunt between the superior mesenteric vein and the ICV, a so-called "mesocaval shunt", may be inserted to lower the pressure in the portal-venous system. On the other hand, when both the ICV and the hepatic veins are occluded, the appropriate therapy would be a bypass from the superior mesenteric vein to the right atrium, a so-called "mesoatrial shunt". For patients in whom a neoplasm is the primary cause of Budd-Chiari syndrome, extensive surgery is often contraindicated.

Given the different therapeutic approaches available, accurate imaging in Budd-Chiari syndrome not only serves for diagnosis but should also indicate the most appropriate therapy for the patient. Ultrasonography may be used to detect hepatic vein occlusion (Fig. 15), however, the ICV is not reliably visualized on ultrasonography and ascites in Budd-Chiari syndrome may interfere with the appropriate depiction of the hepatic confluence [41].

In contrast, MRI, which is not affected by the individual constitution of the patient, represents a non-invasive imaging modality for the evaluation of both the intra- and extrahepatic vascular anatomy in Budd-Chiari syndrome and the possible intra- or extrahepatic causal pathologies [38].

However, if portocaval shunting is planned, the examination frequently has to be completed by means of venography in order to determine the presence or absence of a significant pressure gradient across the ICV. Even if a patent ICV is demonstrated by non-invasive imaging modalities, a pressure gradient may be present, in most cases due to hypertrophy of the caudate lobe. In such cases, portocaval shunting is contraindicated and shunting should be performed from the portal-venous system to either the right atrium or the left inferior pulmonary vein [5,60,61].

Vascular findings. MR imaging is an accurate modality for the demonstration of the diverse pattern of vascular changes indicative of Budd-Chiari syndrome. Frequently, a significant reduction in caliber or a complete absence of hepatic veins may be found or, alternatively, newly arising intrahep-atic collateral veins with a comma-like shape may be seen. Other findings include a constriction of the intrahepatic ICV or, less commonly, the hepatic veins appear patent but do not show any connection to the iCv. Since thrombus formation in the hepatic veins may be located some centimeters from the ICV, patent central hepatic veins and a normal hepatic confluence may be seen.

MRI not only permits the diagnosis of Budd-Chiari syndrome but may also reveal the etiologi-cal cause. For example, it is possible to visualize an obstruction of the ICV or the right atrium caused by neoplasms, such as primary sarcomas of the vein, or tumors of the liver, kidney or adrenal gland, and the resulting tumor thrombus formation.

Increased coagulability of the blood causing thrombosis of the hepatic veins (such as in poly-cytemia vera or paroxysmal nocturnal hemoglo-binuria), may be identified by MRI. In patients with polycytemia vera, a diffusely decreased intensity of the bone marrow together with splenomegaly can point to the diagnosis. In patients suffering from paroxysmal nocturnal hemoglobinuria, an SI decreased in the liver and renal cortex but normal in the spleen is observed [57,69].

Morphologic features. In most cases of Budd-Chiari syndrome, the hepatic venous outflow is not eliminated completely since a variety of accessory hepatic veins may drain above or below the principal site of obstruction. The most frequent accessory site of venous drainage occurs at the inferior right hepatic vein and the veins of the caudate lobe that drain directly into the inferior portion of the ICV. Additional collaterals draining to other systemic veins may be present, such as the azygos and the vertebral and/or intercostal veins which show characteristic enlargement if present. Reversed flow in some portal vein branches may occur, since connections between the portal and the hepatic veins are relatively common [62, 70]. However, the main portal flow usually remains antegrade [30]. Since some hepatic venous drainage is usually preserved for the caudate lobe and for central portions of the right and left liver lobes, a compensatory hypertrophy of the caudate lobe may develop. However, this may lead to a secondary obstruction of the ICV. Although subcap-sular hepatic veins may also contribute to collateral blood flow, the resulting venous drainage is usually insufficient to prevent peripheral atrophy of the liver.

In patients with a completely obstructed venous outflow, shunting is performed from the hepatic veins and arteries to the portal veins, which thereafter demonstrate reversed flow [11].

As a result of collateral venous drainage, Budd-Chiari syndrome is typically associated with peripheral hepatic atrophy and, conversely, caudate and central hypertrophy which, together, may lead to a displacement of the porta hepatis towards the anterior portion of the liver [20]. These morphological changes can be visualized on MRI, together with a clear depiction of the occluded liver veins. Other findings include regional differences in liver SI due to central lobular necrosis and hepatocellu-lar fat or iron content. Dynamic MR imaging of acute Budd-Chiari syndrome after bolus injection of extracellular contrast agents (Fig. 16) frequently reveals atypical parenchymal enhancement, which indirectly indicates the presence of increased vascular resistance. Unlike patients with liver cirrhosis, patients with acute Budd-Chiari syndrome demonstrate acute clinical symptoms and a large tender liver without signs of nodular changes. However, in chronic disease, nodular regenerative hyperplasia may develop which may lead to the misdiagnosis of liver cirrhosis [33] (Fig. 17).

Another disease leading to hepatic venous obstruction is the so-called "hepatic veno-occlusive disease". This is often caused by chemotherapy, especially after bone marrow transplantation [8]. In this disease, the post-sinusoidal venules are usually obstructed while the major hepatic veins and ICV do not show pathological changes and remain patent (Fig. 18). Since diagnosis by means of MRI is difficult in most cases, confirmation needs to be established either by histopathological examination of a biopsy or by wedge hepatic venography. Dynamic CT and MR imaging of the liver in the arterial and portal-venous phases may indicate an increased arterial perfusion of the affected regions and a prolonged liver transit time of the contrast agent [60] (Figs. 19,20).

Fig. 14a-r. Subacute portal vein thrombosis. T2-weighted images (a, b) reveal intermediate to high SI in the area of the portal vein without any flow void (arrows). Additionally, perihepatic and perisplenic ascites can be noted. On Tl-weighted images (c-e), again no flow void in the portal vein can be noted although a mass with hypointense and hyperintense areas (arrows) does seem to be present in the portal vein. Flow sensitive gradient echo images (f-k) clearly depict a thrombus within the portal vein (arrows) with some residual peripheral flow indicated by a peripheral high SI rim. The thrombosis can be followed to the confluence of the mesenteric and splenic veins. Irregular enhancement of the liver parenchyma can be noted on arterial phase images after contrast agent injection (l-n). On portal-venous phase images (o-r), again the thrombus in the portal vein is clearly depicted and can be followed into the periphery (arrow). Note that the mesenteric vein is also occluded (r, arrow)

Fig. 14a-r. Subacute portal vein thrombosis. T2-weighted images (a, b) reveal intermediate to high SI in the area of the portal vein without any flow void (arrows). Additionally, perihepatic and perisplenic ascites can be noted. On Tl-weighted images (c-e), again no flow void in the portal vein can be noted although a mass with hypointense and hyperintense areas (arrows) does seem to be present in the portal vein. Flow sensitive gradient echo images (f-k) clearly depict a thrombus within the portal vein (arrows) with some residual peripheral flow indicated by a peripheral high SI rim. The thrombosis can be followed to the confluence of the mesenteric and splenic veins. Irregular enhancement of the liver parenchyma can be noted on arterial phase images after contrast agent injection (l-n). On portal-venous phase images (o-r), again the thrombus in the portal vein is clearly depicted and can be followed into the periphery (arrow). Note that the mesenteric vein is also occluded (r, arrow)

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Fig. 15a-c. Acute Budd-Chiari syndrome. On US (a), the middle hepatic vein is displayed with an enlarged diameter and in the more peripheral parts some internal echo is visible due to thrombus formation within the vessels. On the corresponding Color Doppler study (b, c) no flow signal can be detected within the liver veins and the spectrum shows no flow signs (c)

Fig. 16a-j. Acute Budd-Chiari syndrome. T2-weighted images (a, b) reveal diffuse swelling of the liver and perihepatic and perisplenic ascites. The large intrahepatic liver veins show no signs of flow void and the periphery of the liver parenchyma, especially in the right liver lobe, shows increased SI. On the corresponding Tl-weighted images (c, d), again the liver veins are depicted only as small hypointense bands and low SI areas (arrows) can be noted in the more caudal parts of the liver. On contrast-enhanced images during the arterial phase (e, f), only enhancement of the periphery of the liver can be seen (arrows). The more central parts do not show obvious enhancement due to increased vascular resistance. Still no enhancement of portal-venous branches is visible on the portal-venous phase images (g, h), although enhancement of the central parts of the liver can now be noted. Homogenous enhancement of the left liver lobe and central parts of the right liver lobe is more apparent on equilibrium phase images (i, j). Peripheral hypointense areas (arrows) can still be depicted in the right liver lobe in this phase. These areas correspond to liver necrosis due to acute Budd-Chiari syndrome

Fig. 17a-n. Longstanding Budd-Chiari syndrome. Unenhanced T2-weighted images (a, b) reveal a comma-like shape of the intrahepatic collateral veins (arrows) that is typical of Budd-Chiari syndrome. These veins (arrows) appear with low SI on unenhanced Tl-weighted images (c, d) due to flow void, and show a flow signal on flow sensitive gradient echo sequences (e, f). As in the case of acute Budd-Chiari syndrome (see Fig. 16), delayed enhancement of the liver can be noted on dynamic imaging. Although diffuse enhancement of the liver parenchyma can already be observed on arterial phase images (g, h), full homogeneous enhancement is not yet seen even on portal-venous phase images (i, j). On the other hand, nodular enhancement due to regenerative processes is visible. Some hypointense areas in the liver parenchyma are still apparent on images acquired 5 min after contrast agent injection (k, l) indicating decreased blood flow. Isoin-tensity with the surrounding liver tissue is finally observed on images acquired 15 min after contrast agent administration (m, n)

Fig. 17a-n. Longstanding Budd-Chiari syndrome. Unenhanced T2-weighted images (a, b) reveal a comma-like shape of the intrahepatic collateral veins (arrows) that is typical of Budd-Chiari syndrome. These veins (arrows) appear with low SI on unenhanced Tl-weighted images (c, d) due to flow void, and show a flow signal on flow sensitive gradient echo sequences (e, f). As in the case of acute Budd-Chiari syndrome (see Fig. 16), delayed enhancement of the liver can be noted on dynamic imaging. Although diffuse enhancement of the liver parenchyma can already be observed on arterial phase images (g, h), full homogeneous enhancement is not yet seen even on portal-venous phase images (i, j). On the other hand, nodular enhancement due to regenerative processes is visible. Some hypointense areas in the liver parenchyma are still apparent on images acquired 5 min after contrast agent injection (k, l) indicating decreased blood flow. Isoin-tensity with the surrounding liver tissue is finally observed on images acquired 15 min after contrast agent administration (m, n)

Fig. 18. Hepatic veno-occlusive disease in a 21-year old patient during chemotherapy for acute lymphoblastic leukemia. On Color Doppler US, the right hepatic vein is narrowed, however the ICV and hepatic veins are patent

Fig. 19a-d. Hepatic veno-occlusive disease. Same case as demonstrated in Fig. 18. On the unenhanced CT scan (a), the liver parenchyma shows heterogeneous density and streaky hypodense areas. In the arterial phase after contrast medium administration (b), the liver shows heterogeneous enhancement with some peripheral areas (arrows) of increased arterial perfusion. On the portal-venous phase scan (c), again the streaky signal of the liver parenchyma is visible and the liver veins are poorly delineated (arrows). The diameter of the hepatic veins seems to be reduced and splenic infarction is apparent. Perfusion-related differences in density of the liver parenchyma cannot be visualized in the equilibrium phase (d)

Budd Chiarisyndrome

Fig. 20a-f. Hepatic veno-occlusive disease. Same case as demonstrated in Fig. 18 and 19. On the pre-contrast T1-weighted image (a), the liver shows heterogeneous SI with some areas of increased signal and other areas of decreased signal. The Tl-weighted out-of-phase image (b) reveals that these differences of SI are not related to fatty liver, since no signal drop is observed. The hepatic veins near the confluence are patent. On the arterial phase image (c) after the bolus injection of Gd-BOPTA (0.1 mmol/kg BW), the liver shows heterogeneous, predominantly peripheral arterial perfusion (arrows), most likely related to increased intrahepatic resistance. In the portal-venous phase (d), the liver veins are contrasted but a very heterogeneous enhancement of the liver parenchyma is seen, with large, streaky areas of decreased perfusion. Note the missing enhancement of large areas of the spleen due to splenic infarction. The Tl-weighted (e) and Tl-weighted fat suppressed (f) images acquired in the hepatobiliary phase reveal streaky enhancement of the liver with preferential uptake of Gd-BOPTA in the peri-venous liver tissue. Uptake of Gd-BOPTA in more distant areas of the liver is considerably more limited due to veno-occlusive disease

Fig. 20a-f. Hepatic veno-occlusive disease. Same case as demonstrated in Fig. 18 and 19. On the pre-contrast T1-weighted image (a), the liver shows heterogeneous SI with some areas of increased signal and other areas of decreased signal. The Tl-weighted out-of-phase image (b) reveals that these differences of SI are not related to fatty liver, since no signal drop is observed. The hepatic veins near the confluence are patent. On the arterial phase image (c) after the bolus injection of Gd-BOPTA (0.1 mmol/kg BW), the liver shows heterogeneous, predominantly peripheral arterial perfusion (arrows), most likely related to increased intrahepatic resistance. In the portal-venous phase (d), the liver veins are contrasted but a very heterogeneous enhancement of the liver parenchyma is seen, with large, streaky areas of decreased perfusion. Note the missing enhancement of large areas of the spleen due to splenic infarction. The Tl-weighted (e) and Tl-weighted fat suppressed (f) images acquired in the hepatobiliary phase reveal streaky enhancement of the liver with preferential uptake of Gd-BOPTA in the peri-venous liver tissue. Uptake of Gd-BOPTA in more distant areas of the liver is considerably more limited due to veno-occlusive disease

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Responses

  • Christy
    How is MRI superior to ultrasound in budd chiari diagnosis?
    4 months ago

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