Imaging Pearls ❯ Liver ❯ Vascular
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- “Hepatic artery aneurysms are the second most common type of visceral arterial aneurysms(following splenic artery aneurysms) and are more common in men.The common hepatic artery is most often involved, followed by the rightvand left hepatic arteries. Most of the hepatic artery aneurysms may be attributed to atherosclerosis. Before the widespread use of antibiotics, mycotic hepatic artery aneurysms were common and often secondary to streptococcus or staphylococcus endocarditis. Mycotic aneurysms now account for only 0.1% of all arterial aneurysms. Hepatic artery pseudoaneurysms may develop secondary to trauma, surgery, or indwelling biliary catheter. The arterial intimal layer is damaged, with subsequent formation of a saccular outpouching. These aneurysms may rarely be caused by iatrogenic causesas well, including radiofrequency ablation and hepatobiliary or vascular surgery.”
Imaging Vascular Disorders of the Liver
Nandan Keshav, Michael A. Ohliger
Radiol Clin N Am 60 (2022) 857–871 - “Hepatic artery aneurysms are usually asymptomatic and are often incidentally discovered on cross-sectional imaging. When symptomatic, a triad of epigastric pain, obstructive jaundice, and hemobilia, referred to as Quincke triad, may be seen in up to one-third of patients and is secondary to erosion of the aneurysm through the biliary tree. On CT, a focal outpouching may be seen within the hepatic artery. Treatment is indicated if the size of the aneurysm exceeds 2 cm or if the patient is symptomatic. Treatment also varies by location of the aneurysm: intrahepatic aneurysms are amenable to coil embolization, whereas direct surgical repair is recommended for most extrahepatic aneurysms.Coil embolization is recommended for intrahepatic pseudoaneurysms.”
Imaging Vascular Disorders of the Liver
Nandan Keshav, Michael A. Ohliger
Radiol Clin N Am 60 (2022) 857–871 - “Vasculitis refers to inflammation and necrosis of vessel walls. These disorders are classified by the Chapel Hill classification by the size of the vessel involved, number of organs involved, and by association with systemic disease, among other categories. Polyarteritis nodosa refers to necrotizing arteritis of medium-sized vessels; the liver is the third most common site of involvement, after the kidneys and gastrointestinal tract. On imaging, multiple microaneurysms may be seen. Other imaging appearances include vessel wall thickening and perivascular stranding, as well as hepatic parenchymal infarctions.”
Imaging Vascular Disorders of the Liver
Nandan Keshav, Michael A. Ohliger
Radiol Clin N Am 60 (2022) 857–871 - “The underlying hepatic vascular physiology as well as a diverse imaging spectrum of vascular disorders of the liver was reviewed in this article, including pathologies related to outflow, inflow, and arteriovenous connections. Outflow abnormalities include Budd-Chiari syndrome, sinusoidal obstruction syndrome, and congestive hepatopathy. Inflow abnormalities include hepatic infarction, portal venous bland and tumor thrombus, pylephlebitis, hepatic arterial aneurysms, and vasculitis. Aberrant arteriovenous connections include hereditary hemorrhagic telangiectasia, arterioportal shunts, and Abernethy malformation. Other vascular disorders and mimics of disease include peliosis, shunting secondary to parenchymal mass lesions, and enhancing quadrate lobe secondary to superior vena cava obstruction.”
Imaging Vascular Disorders of the Liver
Nandan Keshav, Michael A. Ohliger
Radiol Clin N Am 60 (2022) 857–871
- “Hepatic artery aneurysms account for 20% of all visceral aneurysms, with 20% being intrahepatic. These can develop secondary to atherosclerotic disease. Calcified atherosclerotic disease is seen 30% of the time. At unenhanced CT, these calcifications are curvilinear and typically seen in the vessel wall . After IV contrast agent administration, the hepatic artery lumen and outpouching arising from the hepatic artery forming the aneurysm will opacify except for areas of thrombosis. An important complication of these aneurysms is rupture, with a mortality rate of 21%. Therefore, it is important to avoid potential misinterpretation of these lesions for a calcified liver lesion.”
Liver Calcifications and Calcified Liver Masses: Pattern Recognition Approach on CT Madhavi Patnana et al AJR 2018; 211:76–86 - “Thorium dioxide was a contrast agent previously used for medical imaging between 1928 and 1955, but was discontinued in the 1960s because of its carcinogenic effects resulting in various cancers, including liver-related malignancy (e.g., cholangiocarcinoma, angiosarcoma, and HCC), around 20 years after injection. The exact cause is not known but is thought to be secondary to long-term low-dose α-irradiation leading to gene mutations . At CT, high-density deposits are typically seen in the liver, lymph nodes, and spleen and can feature a reticular pattern.”
Liver Calcifications and Calcified Liver Masses: Pattern Recognition Approach on CT Madhavi Patnana et al AJR 2018; 211:76–86
- “Vascular mesenchymal neoplasms can further be characterized as benign (cavernous hemangioma, angiomyolipoma), malignant potential (epithelioid hemangioendothelioma, perivascular epithelioid cell tumor, solitary fibrous tumor), and malignant (angiosarcoma), depending on histology.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359 - “Patients often do not have symptoms, but if the hemangioma is large, it may be palpable or cause abdominal pain. Rarely, cavernous hemangiomas can rupture or be implicated in Kasabach-Merritt syndrome, a consump- tive coagulopathy triggered by the vascular abnormality. Treatment is generally con- servative, with surgical treatment reserved for large, symptomatic lesions.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359 - “Vascular mesenchymal neoplasms with progressive enhancement include cavernous hemangioma, epithelioid hemangioendothelioma, and angiosarcoma. Two additional entities with progressive enhancement that can mimic primary vascular neoplasms are hepatic peliosis and solitary brous tumor.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359 - “Epithelioid hemangioendothelioma (EHE) is a rare vascular mesenchymal tumor with low to intermedi- ate malignancy potential. Incidence of EHE is less than 1 per million [14]. Patients have nonspeci c symptoms, such as right upper quadrant pain, hepatomegaly, or weight loss, or no symptoms at all. Tumor markers, including α-fetoprotein (AFP), carcinoembryonic antigen, and cancer antigen (CA) 19–9, are usually at normal levels.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359 - “The characteristic imaging appearance of EHE is multiple confluent tumor nodules or masses with peripheral, targetlike, or rim enhancement. Contrast-enhanced dynamic imaging is useful for show- ing initial enhancement of the peripheral cellular rim followed by progressive, lamellar enhancement of the central brous stroma. On unenhanced CT, lesions are hypodense compared with the normal hepatic parenchyma. Intralesional calci cations are sometimes seen.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359 - “Angiosarcoma is a malignant neoplasm of the vascular or lymphatic endothelium that accounts for less than 2% of all primary neoplasms but is the most common primary sarcoma in the liver. It most commonly occurs in patients 60–70 years of age with a male-to-female ratio of 4:1.”
Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation Hailey Hye-In Choi et al. AJR 2017; 209:W350–W359
- “The liver is the largest organ in the adult human body, weighing approximately 1.5 kg. It is divided into eight independent segments on the basis of the fact that each segment has a separate vascular inflow and outflow. The hepatic inflow consists of the hepatic artery and portal vein in the center of each hepatic segment, and the outflow consists of the hepatic veins in the periphery of the segment. The portal vein, which supplies 75% of the blood supply to the liver, provides deoxygenated blood that has drained from the spleen, pancreas, and gastrointestinal tract. The hepatic artery, a branch of the celiac artery, supplies 25% of the blood to the liver and provides the liver with oxygenated blood.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - “The portal vein and hepatic artery each divide into right and left lobar branches, which further divide into segmental, then lobular branches. The smallest portal vein and hepatic artery branches are located at the corners of hepatic lobules. The hexagonal hepatic lobules represent the small microscopic units of the liver. Each lobule is formed of radiating hepatocytes and many specialized capillaries, known as sinusoids. In the sinusoids, the blood is processed by hepatocytes, which can absorb or release nutrients and metabolize toxic chemicals. Deoxygenated blood flows out of the lobules through the central veins (located at the center of each lobule) to, in order, the hepatic veins, IVC, and right atrium.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - “Portal vein thrombosis can be seen with many conditions, including cirrhosis, abdominal tumors, intraabdominal inflammatory processes such as Crohn disease, diverticulitis and appendicitis, hypercoagulable states, and trauma . Recently, portal vein thrombosis was found to be associated with metabolic syndrome, especially with central abdominal obesity. A thrombus may be either bland or tumoral, with venous invasion from adjacent malignancies.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - “Transient hepatic attenuation differences (THADs) and THIDs refer to perfusional changes usually resulting from portal venous occlusion, with THAD being seen at CT and THID at MR imaging. These perfusional changes generally appear as segmental wedge-shaped areas of enhancement during the arterial phase, which become isoattenuating/isointense during the portal venous phase. This results from an increase in hepatic arterial inflow in response to decreased portal venous flow, resulting in relative hyperenhancement during arterial-phase imaging. Causes of THAD and THID include bland and tumor thrombi, extrinsic compression (such as from adjacent tumors), surgical ligation, flow diversion from shunts or anomalous blood supply, and inflammation of the biliary ducts or adjacent organs.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - “A portal venous aneurysm, or varix, is a localized fusiform or saccular dilatation of the portal vein measuring greater than 2 cm in diameter. This cutoff was derived from a sonographic study by Doust and Pearce in which no portal vein measured more than 1.5 cm in diameter in patients with healthy livers, or more than 1.9 cm in patients with cirrhotic livers. Intrahepatic portal veins are considered to be aneurysmal when there is a diameter of greater than 0.7 cm in a patient with a healthy liver and 0.85 cm in a patient with a cirrhotic liver. The extrahepatic portal vein is the most commonly involved vein in the portal venous system to form aneurysms, followed by the splenomesenteric venous confluence, intrahepatic portal vein, splenic vein, superior mesenteric vein, and inferior mesenteric vein. Although a portal venous aneurysm is often incidentally discovered during imaging, the most common presentation is abdominal pain . Complications of aneurysms include thrombosis, compression of the biliary tree or duodenum, and rupture.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - “The most common cause of portal venous gas is bowel ischemia, which can result from arterial or venous mesenteric thrombosis, hypoperfusion, aortic dissection, embolic disease, or intestinal obstruction. Bowel distention and intra-abdominal sepsis have also been implicated as sources of portal venous gas . At CT, portal venous gas appears as linear branches of air coursing in the expected location of the portal venous system to the periphery of the liver . The feature of peripheral branching air at CT helps differentiate portal venous gas from pneumobilia, which typically is more central. The sonographic appearance of portal venous gas is multiple tiny high-amplitude transient intraluminal echogenic foci, resulting in characteristic high-amplitude spikes at Doppler spectral analysis. The air bubbles in the portal vein are strong acoustic reflectors, which cause blooming of the color flow in the portal vein and are noted to move during real-time imagings.”
A Comprehensive Approach to Hepatic Vascular Disease Khaled M. Elsayes et al. RadioGraphics (in press) - Portal Vein Thrombosis: Causes
• cirrhosis
• abdominal tumors
• intraabdominal inflammatory processes such as Crohn disease, diverticulitis and appendicitis
• hypercoagulable states
• trauma - Portal Venous Air: Causes
• bowel ischemia, which can result from arterial or venous mesenteric thrombosis, hypoperfusion, aortic • dissection, embolic disease, or intestinal obstruction
• bowel distention
• intra-abdominal sepsis
- “Communication between a hepatic arterial branch and the portal vein at the level of the trunk, sinusoids, or peribiliary venules results in redistribution of arterial flow into a focal region of portal venous flow. Arterioportal shunts may be posttraumatic, occurring after blunt or penetrating injury, biopsy, or instrumentation (eg, placement of a transhepatic biliary drainage catheter).”
CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders Torabi M et al. RadioGraphics 2008; 28:1967–1982 - “The prevalence of arterioportal shunts in patients with large hepatocellular carcinomas is as high as 63%. In patients with cirrhosis, the majority of small arterioportal shunts are pseudolesions; that is, they involve no pathologic alteration.”
CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders Torabi M et al. RadioGraphics 2008; 28:1967–1982 - “Contrast-enhanced arterial phase CT usually shows small, peripheral, nonspherical, enhancing foci, which become isoattenuating to the liver and vasculature in the portal venous phase. Early enhancement of the peripheral portal vein occurs during the hepatic arterial phase and before the opacification of the main portal vein.”
CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders Torabi M et al. RadioGraphics 2008; 28:1967–1982 - “It may be difficult to distinguish an arterioportal shunt from a small hepatocellular carcinoma. In such situations, repeat imaging in 6 months usually demonstrates the resolution or stability of an arterioportal shunt, as opposed to growth for a hepatocellular carcinoma. Moreover, on portal venous and delayed phase images, a hepatocellular carcinoma usually becomes hypoattenuated to liver and vessels, but an arterioportal shunt has the same attenuation as the vessels.”
CT of Nonneoplastic Hepatic Vascular and Perfusion Disorders Torabi M et al. RadioGraphics 2008; 28:1967–1982
- “Hepatic arterial thrombosis (HAT) is a potentially devastating arterial complication following transplantation and also the most common vascular complication. Undetected HAT can result in biliary ischemia, necrosis, bilomas, sepsis, fulminant hepatic necrosis, and graft failure. Although early diagnosis of HAT may enhance the success of attempts at revascularization with surgical thrombectomy or thrombolysis, most patients with HAT will require retransplantation. Absence of hepatic arterial flow on Doppler ultrasonography should raise concern for hepatic arterial thrombosis and prompt further evaluation with CTA, magnetic resonance angiography, or catheter angiography.”
Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation Price M, Patino M, Sahani D Radiol Clin N Am 54 (2016) 55–70 - “MDCT serves as an excellent noninvasive imaging modality for diagnosis and surveillance of hepatic artery aneurysms (HAAs). HAAs are the second most common type of visceral artery aneurysm, after splenic artery aneurysms. Most HAAs are incidentally detected with cross-sectional imaging and patients will be asymptomatic unless the aneurysm ruptures. Unlike splenic artery aneurysms, HAAs most frequently occur in men.25 When imaging HAAs, it is critical to assess for the presence of any anatomic vascular variants, particularly in the presence of planned endovascular or surgical intervention.”
Computed Tomography Angiography of the Hepatic, Pancreatic, and Splenic Circulation Price M, Patino M, Sahani D Radiol Clin N Am 54 (2016) 55–70