Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

671 results found
Article

SPACE (MRI sequence)

The SPACE MRI sequence is an abbreviation for Sampling Perfection with Application optimized Contrasts using different flip angle Evolution adopted by Siemens. SPACE is a single slab three-dimensional turbo spin echo (TSE) sequence with a slab selective, variable excitation pulse. It is useful...
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Central scar in hepatic lesions

The central scar in hepatic lesions most frequently has been described in focal nodular hyperplasia which the scar is T2 hyperintense and usually non-calcified, and fibrolamellar hepatocellular carcinoma, where the scar is T2 hypointense and often calcified. Scars do not have to be exactly centr...
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Gastropancreatic fistula

A gastropancreatic fistula is a rare form of gut fistulation where there is a fistulous communication between the stomach and the pancreas. It has been described in association with chronic pancreatitis 1 / severe pancreatitis intraductal papillary mucinous neoplasm (IPMN) 4 peptic ulcers 2 ...
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Post-TARE assessment of hepatocellular carcinoma

Post-TARE (transarterial radioembolization) assessment of hepatocellular carcinomas is essential for evaluating the success of the therapy.  Hepatocellular carcinomas that are not amenable to definitive therapy with thermal ablation or resection can be treated with trans-arterial radioembolizat...
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Post-TACE assessment of hepatocellular carcinoma

Post-TACE assessment of hepatocellular carcinomas is essential for evaluating the success of the therapy.  Hepatocellular carcinomas that are not amenable to definitive therapy with thermal ablation or resection can be treated with trans-arterial chemoembolization (TACE). The end goal may be pa...
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Hypoglycemia

Hypoglycemia describes an abnormally low blood glucose level (<4 mmol/L). It is a common clinical problem in diabetics overtreated with glucose lowering agents. Clinical presentation Signs of hypoglycemia include: dizziness tremors, palpitations and anxiety hunger sweating confusion fati...
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Reynolds pentad

Reynolds pentad is a combination of clinical signs found in acute cholangitis. It consists of Charcot triad 2-4: fever and/or chills RUQ pain jaundice as well as: delirium or lethargy, and shock Usefulness Sensitivity of Reynolds pentad from a large systematic review of nine studies was ...
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Enlarged hilar periportal space sign

The enlarged hilar periportal space sign refers to the widening of the periportal space seen on MRI in early liver cirrhosis. Usage Enlarged hilar periportal space sign is one of the early signs of cirrhosis and may be used to detect fibrotic changes in the liver in patients who do not yet hav...
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Zebra sign (disambiguation)

The evocative appearance of the coat of a zebra has been used for several distinctive signs in radiology: zebra sign: cerebellar hemorrhage 1 zebra sign: amyotrophic lateral sclerosis 2 zebra spleen: arterial phase appearance of normal spleen 4,5 zebra stripe sign: treated osteogenesis imper...
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Chemical ablation

Introduction Chemical ablation is a technique in which chemical ablative substances are used to cause cell death in neoplastic tissue. It is used as a standalone procedure or in combination with other techniques like TACE and radiofrequency ablation. Agents Absolute ethanol (most commonly use...
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Complications of radiation therapy

Radiation therapy has the potential to cause complications in many organ systems, many of which, especially in the thorax, are important for radiologists to be aware of.  acute radiation syndrome complications of cranial radiation therapy radiation-induced cerebral vasculopathy radiation-ind...
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Fibrolamellar hepatocellular carcinoma (mnemonic)

The features of fibrolamellar hepatocellular carcinoma can be recalled using this mnemonic: PSYCH Mnemonic P: pseudocapsule S: scar (fibrotic) Y: young patients C: capsular retraction H: huge and heterogenous
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Portal venous flow

Portal venous flow is normally towards the liver (hepatopetal), with the normal main portal vein peak systolic velocities usually ranging between 20-40 cm/s. In pathological situations, the flow velocity may decrease or even invert resulting in hepatofugal flow. The flow waveform is usually sm...
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Reye syndrome

Reye syndrome is a rare pediatric condition characterized by acute onset encephalopathy, severe vomiting and fatty liver failure. It typically presents in children recovering from a viral illness, most commonly influenza or chickenpox 1.  Epidemiology Reye syndrome is usually seen between the ...
Article

Intramural pseudocyst

Intramural pseudocysts are a rare form of pancreatic pseudocysts that occur within the wall of the upper gastrointestinal tract. They may result in gastric outlet obstruction. Pathology Size They can considerably vary in size with one study reporting a range of 8 mm to 8 cm 1. Location Repo...
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Interstitial lung disease associated with primary biliary cholangitis

Interstitial lung disease associated with primary biliary cholangitis can occur in a variable pattern that can include 1: pulmonary fibrosis lymphoid interstitial pneumonia non-specific interstitial pneumonia bronchiolitis obliterans with organizing pneumonia Epidemiology It may occur in a...
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CT four-phase liver (protocol)

The four-phase liver CT protocol is a useful examination in the assessment of focal liver lesions, hypervascular liver metastasis and endocrine tumors. It is a triple-phase liver with an initial non-contrast component included before the intravenous contrast medium is given, often requested if ...
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CT triple-phase liver (protocol)

The triple-phase liver CT protocol is a useful examination in the assessment of focal liver lesions, hypervascular liver metastases and endocrine tumors. It involves a dedicated late arterial phase, portal venous phase and delayed phase acquisition. Not to be confused with a four-phase which in...
Article

Cholecystocolonic fistula

Cholecystocolonic fistulas are most commonly a rare late complication of gallstone disease, resulting from an abnormal communication between the gallbladder and the colon. It is the second most common cholecystoenteric fistula after cholecystoduodenal fistulas 1.  Clinical presentation These m...
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SMART-CT severity index

A SMART-CT severity index is a recent tool and an expansion of the original modified CT severity index of acute pancreatitis. This novel index that is nomogram based, predicts the clinical consequence with modest accuracy. Two components are mainly evaluated, the first ones are the components of...
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Fluid-fluid levels in liver lesions

Fluid-fluid levels in liver lesions are a rare appearance of both benign and malignant conditions. Differential diagnosis benign complicated hepatic cyst 2 hepatic abscess 2 chronic hepatic hematoma 3 biliary cystadenoma 3 hepatic hemangioma (very rare) 2 malignant cystic/necrotic hepat...
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Cystic vein

The cystic veins (TA: venae cysticae) are the main venous drainage of the gallbladder. They subsequently drain into the portal vein. Gross anatomy The cystic veins begin as venules running over the surface of the fundus and body of the gallbladder which merge proximate to the neck of the gallb...
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Sphincter (disambiguation)

A sphincter (TA: musculus sphincter) is a term used in anatomy to refer a ring of muscle which narrows a tube or closes off a bodily orifice 1. anal sphincter ​external anal sphincter internal anal sphincter hepatic sphincter esophageal sphincter lower esophageal sphincter upper esophagea...
Article

Hepatic small vessel neoplasm

Hepatic small vessel neoplasms (HSVN) are low-grade vascular lesions of uncertain malignant potential.  Terminology Although also referred to as hepatic small vessel hemangiomas 3, this term may wrongly mislead HSVN to represent a subtype of hepatic hemangiomas and, therefore, will be avoided ...
Article

Tobacco abuse

Tobacco abuse, most commonly by smoking cigarettes, is a legal drug habit of many throughout the world. It is a significant risk factor for many malignancies, respiratory and cardiovascular diseases and is a major cause of premature mortality throughout the world. Epidemiology It has been esti...
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Rosenbach sign (aortic valve regurgitation)

Rosenbach sign is a clinical sign that is seen in severe aortic/tricuspid valve regurgitation. It is elicited as pulsation of the liver, during systole, and it is primarily due to the increased cardiac output and associated retrograde blood flow into the liver 1-3. See also Rosenbach also gave...
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Bile duct duplication

Bile duct duplication, also known as common bile duct duplication (although in some cases this latter terminology would be erroneous), is a rare congenital anomaly of the biliary system. A double bile duct is considered normal during early human development, but by birth, we expect to see the co...
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Tc99m mebrofenin

Tc99m-Mebrofenin: trimethyl bromo IDA, also known as TBIDA, or under the trade name Choletec, is a diagnostic radiopharmaceutical used in hepatobiliary imaging. It is one of the Tc99m IDA (iminodiacetic acid) analogs. It is taken up by hepatocytes through the same membrane transport mechanism as...
Article

Cullen sign

Cullen sign refers to superficial edema visible as periumbilical discolouration and is most commonly seen in patients with acute pancreatitis 1-3. Clinical presentation Clinically patients with pancreatitis present with epigastric pain that radiates to the umbilical/periumbilical region and th...
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Gallbladder cancer (staging - AJCC 8th edition)

The AJCC (American Joint Committee on Cancer) 8th edition gallbladder cancer staging system was introduced in 2018. TNM system T: primary tumor Tis: carcinoma in situ - tumor only within the epithelium (the inner layer of the gallbladder) T1: tumor invades the lamina propria or muscularis T...
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CT chest abdomen-pelvis (protocol)

The CT chest-abdomen-pelvis protocol serves as an outline for an examination of the trunk covering the chest,  abdomen and pelvis. It is one of the most common CT examinations conducted in routine and emergencies. It can be combined with a CT angiogram. Note: This article aims to frame a genera...
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CT abdomen-pelvis (protocol)

The CT abdomen-pelvis protocol serves as an outline for an examination of the whole abdomen including the pelvis. It is one of the most common CT protocols for any clinical questions related to the abdomen and/or in routine and emergencies. It forms also an integral part of trauma and oncologic ...
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CT pancreas (protocol)

The CT pancreas protocol serves as an outline for a dedicated examination of the pancreas. As a separate examination, it is usually conducted as a biphasic contrast study and might be conducted as a part of other scans such as  CT abdomen-pelvis, CT chest-abdomen-pelvis. Note: This article aims...
Article

Beak sign (gallbladder)

The beak sign of gallbladder volvulus describes tapering of the distended gallbladder lumen as it transitions to a fulcrum point at the pedicle, resembling a curved beak.  Terminology The term bird's beak sign is used in a number of other contexts: see bird beak sign (disambiguation). 
Article

Unclassified hepatic adenoma

Unclassified hepatic adenomas refer to the 5-10% of hepatocellular adenomas subtype that lack known genetic abnormalities 1,2. These adenomas cannot be further categorized genetically or histologically as inflammatory adenomas, HNF 1 alpha mutated adenomas or beta catenin mutated adenomas. The ...
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Periportal lymphadenopathy (differential)

Periportal lymphadenopathy can be a common observation during imaging of the upper abdomen. What is considered the exact upper limit of normal has been variable 1,3 among different publications but with many authors suggesting a cut-off of around 10 mm in short axis diameter. Pathology Etiolog...
Article

Acinar cell carcinoma of the pancreas

Pancreatic acinar cell carcinoma is a rare exocrine neoplasm that comprises ~1% of all pancreatic tumors. This tumor shows more aggressive behavior than the far more common adenocarcinoma 1,3,4. Clinical presentation High levels of serum lipase, due to hypersecretion syndrome, resulting in sub...
Article

Cystic artery pseudoaneurysm

Cystic artery pseudoaneurysms are rare and most commonly related to acute cholecystitis 1. Epidemiology Associations cholecystitis liver biopsy 6 biliary interventions pancreatitis laparoscopic cholecystectomy 3-5 Clinical presentation The most common clinical manifestations are 4,5,9: ...
Article

Centrilobular (disambiguation)

The term centrilobular in imaging may refer to: centrilobular (lungs) centrilobular pattern (ultrasound liver)
Article

Kasai portoenterostomy

Kasai portoenterostomy is the surgery that comprises exposing the porta hepatis by radical excision of all bile duct tissue up to the liver capsule and attaching a Roux-en-Y loop of jejunum to the uncovered liver capsule above the bifurcation of the portal vein creating a portoenterostomy 1. In...
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Nodular regenerative hyperplasia

Nodular regenerative hyperplasia of the liver is the histopathological entity characterized by transformation of normal hepatic parenchyma into small nodules of hyperplastic hepatocytes without intervening fibrosis. It falls within the spectrum of porto-sinusoidal vascular disease and is one of ...
Article

Target sign (cholangiocarcinoma)

The target sign of cholangiocarcinoma refers to the appearance of intrahepatic mass-forming cholangiocarcinoma on DWI consisting of a centrally hypointense area and peripherally hyperintense rim. The presence of this sign favors cholangiocarcinoma over hepatocellular carcinoma. It is present in ...
Article

Periportal halo sign (MRI)

The periportal halo sign on liver MRI is a specific sign of primary biliary cholangitis (formerly primary biliary cirrhosis) that is characterized by rounded low signal intensity around portal venous branches, 5-10 mm in size, on T1- and T2-weighted images. These lesions are usually numerous, in...
Article

Meniscus sign (cholangiography)

The meniscus sign on cholangiography suggests impacted choledocholithiasis and is characterized by a concave cutoff of the lower common bile duct lumen. When a stone is impacted in the distal duct, fluid may not be visualized on the sides of the stone and therefore the contour of the duct termin...
Article

Ascitic fluid cholesterol level

Ascitic fluid cholesterol level estimation is a simple and precise test for differentiating malignant ascites from non-malignant (cirrhotic) ascites 5-9.  Pathology Ascites is the abnormal collection of fluid within the peritoneal cavity. Malignant ascites comprises ~10% and is usually seconda...
Article

Chain of lakes sign

The chain of lakes sign is a radiological finding describing the appearance of the pancreatic ducts in cases of chronic pancreatitis. Due to repeated inflammation, fibrosis occurs and results in damage and atrophy of the pancreatic tissue as well as dilatation and beading of the main pancreatic ...
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Distal cholangiocarcinoma (staging)

Distal cholangiocarcinoma staging is defined according to the TNM staging classification of the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC). As of 2018, the staging criteria are in their 8th edition and reflected below 1. These criteria apply to cancer...
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Perihilar cholangiocarcinoma (staging)

Perihilar cholangiocarcinoma staging is, for prognostication, most commonly conducted using the TNM staging classification of the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC). As of 2018, the staging criteria are in their 8th edition and reflected below...
Article

Horseshoe pancreas

A horseshoe pancreas is a term that has been used for a rare anatomic variant of the pancreas in which the uncinate process is unusually elongated such that it extends along the whole 3rd part of the duodenum to mirror the tail superiorly forming a horseshoe-shaped gland 1. History and etymolog...
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Horseshoe-shaped (disambiguation)

Several normal anatomical structures and rare organ variants have been described as being horseshoe-shaped. Organ anomalies horseshoe kidney horseshoe lung horseshoe adrenal horseshoe appendix horseshoe pancreas 1 Horseshoe-shaped organs hyoid bone limbic lobe supramarginal gyrus tymp...
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Common variable immunodeficiency (hepatic manifestations)

Hepatic manifestations of common variable immunodeficiency are not uncommon and can be primarily related to nodular regenerative hyperplasia. For a general discussion of the underlying condition, please refer to the article on common variable immunodeficiency (CVID).  Epidemiology General liv...
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Emphysematous hepatitis

Emphysematous hepatitis is a very rare condition characterized by a gas-forming infection of the liver, which in all reported cases has been rapidly fatal. Diabetes mellitus commonly coexists.  Epidemiology Emphysematous hepatitis is extremely rare, with less than 10 reported cases in the lite...
Article

Emphysema (disambiguation)

Emphysema refers to any disease process involving an abnormal accumulation of air/gas in the tissues. When used alone, it is usually taken to mean the lung disease, pulmonary emphysema, which forms part of the spectrum of chronic obstructive pulmonary disease (COPD).  gastric emphysema: include...
Article

EUS-guided biliary drainage

Endoscopic ultrasound (EUS)-guided biliary drainage is an alternative to conventional transpapillary and percutaneous biliary drainage in where an extra-anatomic route is created between the biliary tree and the gastrointestinal tract.  Indications failed endoscopic transpapillary biliary drai...
Article

Hepar lobatum carcinomatosum

Hepar lobatum carcinomatous, also known as pseudocirrhosis of the liver, is a rare form of metastatic liver disease. It is most often secondary to invasive ductal and lobular breast cancer. It was, however, first described in tertiary syphilis. The exact pathogenesis is unclear, and both direct ...
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Multifocal hepatic steatosis

Multifocal hepatic steatosis (also known as multifocal nodular hepatic steatosis) is the uncommon finding of multiple foci of focal fat in the liver mimicking - and at times being confused with - hepatic metastases. Epidemiology Risk factors Conditions that increase one's risk of developing m...
Article

Bile plug syndrome

Bile plug syndrome, also known as inspissated bile syndrome, is an uncommon cause of jaundice in neonates. Refers to a rare extrahepatic mechanical obstruction of the major bile duct in the perinatal period caused by viscous bile (sludge) within its lumen 3.  Epidemiology Risk factors Risk fa...
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Cirrhosis (CNS manifestations)

There are several central nervous system complications that can arise in the setting of cirrhosis, which can be classified as those which are general (essentially hepatic encephalopathy) and those that are specific to the cause of cirrhosis. General manifestations The major manifestation is he...
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Cirrhosis (musculoskeletal manifestations)

There are several musculoskeletal complications that can arise in the setting of cirrhosis 1: stigmata of portal hypertension, mainly abdominal wall varices hemorrhagic complications due to coagulopathy: spontaneous rectus hematoma postparacentesis abdominal wall bleeding infective complica...
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Septate gallbladder

Septate gallbladder is a congenital variant where there may be a single septum or multiple septa in the gallbladder splitting its lumen into several parts. There may be communication between the separated parts of gallbladder through small pores. The condition is mostly asymptomatic and incident...
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Bare area (disambiguation)

Bare area is a term that may apply to: bare area of the liver bare area of the spleen glenoid bare area bare area of a joint where synovium is in direct contact with bone, the site of marginal joint erosion in some inflammatory arthritides
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Strasberg classification of bile duct injury

The Strasberg classification of bile duct injury is a widely used system to anatomically define these injuries by location 1.  Classification type A: injury to the cystic duct or from minor hepatic ducts draining the liver bed type B: occlusion of the biliary tree, commonly aberrant right hep...
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Hepatic sinusoidal dilatation

Hepatic sinusoidal dilatation is a rare hepatic vascular lesion that is the result of dilatation of the hepatic capillaries.  Pathology Hepatic sinusoidal dilatation can be caused by hepatic venous outflow obstruction (more commonly) or extrahepatic inflammatory conditions 2. Radiographic fea...
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Abdominal tuberculosis

Abdominal tuberculosis can manifest in almost every abdominopelvic organ: gastrointestinal tuberculosis esophageal tuberculosis gastric tuberculosis duodenal tuberculosis jejunal and ileal tuberculosis ileocecal tuberculosis colorectal tuberculosis tuberculous peritonitis tubercular lym...
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Actinomycosis of the gallbladder

Actinomycosis of the gallbladder is rare and caused by Actinomyces spp. bacteria. It may present as biliary colic, cholecystitis or pancreatitis. It is a mimic of gallbladder carcinoma. Epidemiology Actinomycosis is endemic worldwide. It has no predilection for age, gender, ethnicity or climat...
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Omental liver packs

Omental liver packs have been used in the surgical management of traumatic lacerations and hepatic lobectomy. Knowledge of this surgical technique could avoid misinterpretation or confusion of these findings with true postsurgical complications.  Technique This technique consists of mobilizing...
Article

Tamoxifen-induced reversible hepatic steatosis

Tamoxifen is an important anti-estrogen agent used for the treatment of hormone receptor-positive breast cancer and it may induce reversible hepatic steatosis. This is usually transient and may occasionally be associated with hepatic dysfunction. It only rarely leads to cirrhosis 1. Epidemiolog...
Article

Tyrosinemia type 1

Tyrosinemia type 1 is an autosomal recessive disorder of metabolic origin. Progressive renal tubular defects and hepatocellular carcinoma are the primary manifestations. Epidemiology More common in Turkey, India and Europe. Clinical presentation Presentation is typically in the first few mon...
Article

Hepatic teratoma

Hepatic teratomas are extremely rare and represent either intraperitoneal or retroperitoneal teratomas that have invaded the liver. Hepatic teratomas comprise <1% of all teratomas.  Epidemiology These are extremely rare with only a few case reports have been described in the literature. The ma...
Article

Hepatic myelolipoma

Hepatic myelolipoma is a rare, benign fat-containing lesion of the liver, usually asymptomatic and found incidentally. Its diagnosis by imaging remains difficult because of a lack of pathognomonic signs. The definite diagnosis is by resection or biopsy.  Epidemiology  Hepatic myelolipomas are ...
Article

Ischemic type biliary lesions

Ischemic type biliary lesions (ITBL) is a term used to describe non-anastomotic intra- or extrahepatic bile duct strictures after primarily successful liver transplantation, when there is no evidence of perfusion restriction or other cause of bile duct damage (i.e organ rejection or recurrence o...
Article

Percutaneous liver tumor ablation

Percutaneous liver tumor ablation techniques are well-established and effective therapeutic alternatives for the treatment of primary and secondary liver tumors. Hepatocellular carcinoma (HCC) and colorectal oligometastatic disease are the most common indications. There are specific indications ...
Article

Living donor liver transplantation

Living donor liver transplantation (LDLT) is a lengthy and complex operation in which lobe or segment from the potential donor is resected and transplanted into the recipient patient after excision of the diseased liver Techniques Adults The most common technique is right hemihepatectomy, wit...
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CT liver volumetry (protocol)

CT liver volumetry is an essential imaging study in preoperative assessment for living donor liver transplantation. NB: This article is intended to outline some general principles of protocol design. The specifics will vary depending on CT hardware and software, radiologists' and referrers' pre...
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CT liver volumetry in living donor liver transplantation (approach)

CT liver volumetry in living donor liver transplantation is essential imaging studies in preoperative assessment. Liver volumetry is performed for the donor liver to calculate the graft volume and remnant liver volume. Preoperative measurement of liver volume is important to avoid graft mismatc...
Article

Filling defect

A filling defect is a general term used to refer to any abnormality on an imaging study which disrupts the normal opacification (filling) of a cavity or lumen. The opacification maybe physiological, for example, bile in the gallbladder or blood in a dural venous sinus, or maybe due to the instal...
Article

Exclamation mark sign (limy bile)

The exclamation mark sign is a pathognomonic imaging sign of the rare diagnosis of limy bile on plain abdominal radiography. It occurs when there is both limy bile and a gallstone in the common bile duct. The linear vertical radiopaque bile forms the line of the exclamation mark (i.e. !), whilst...
Article

MR elastography

MR elastography (MRE) is an MRI technique that can be used to assess liver stiffness. This is useful not only to detect the development of fibrosis in diffuse liver disease but also to quantify it and monitor liver fibrosis change with (or without) therapy. The main advantage over ultrasound el...
Article

Lipomatous pseudohypertrophy of the pancreas

Lipomatous pseudohypertrophy of the pancreas is a rare, benign entity characterized by focal or diffuse enlargement of the pancreas due to the replacement of exocrine parenchyma with adipose tissue. Terminology Arguably lipomatous pseudohypertrophy may be considered a distinct clinicopathologi...
Article

Champagne sign (gallbladder)

The champagne sign (also known as the effervescent gallbladder sign) is a pathognomonic sonographic sign of gas in the gallbladder. The sign refers to multiple small echogenic foci which are seen to migrate from a dependent to non-dependent position within the gallbladder as the patient changes...
Article

Ampulla (disambiguation)

Ampulla (plural: ampullae) is an anatomical term used for tubular structures with a short segmental bulbous dilatation: ampulla (fallopian tube) ampulla (lacrimal system) ampulla (esophagus): a.k.a. phrenic ampulla ampulla (rectum) ampulla (semicircular ducts) ampulla (spleen) ampulla of ...
Article

Bile duct enhancement (differential)

Bile duct enhancement can be seen in a number of biliary inflammatory conditions. The bile ducts are supplied by the hepatic artery, so enhancement is often best seen in an arterial phase, but enhancement can also be seen in a portal venous phase. Smooth and long segment enhancement This sort ...
Article

Microgallbladder

Microgallbladder is a common abdominal manifestation of cystic fibrosis. It defines a gallbladder that has a length less than 2-3 cm and a width less than 0.5-1.5 cm on sonographic evaluation 1. Epidemiology The incidence of microgallbladder varies considerably in the literature, however most ...
Article

Starry sky appearance (disambiguation)

Starry sky appearance is a radiological sign used to describe the appearance of the liver on two different imaging modalities: starry sky appearance (ultrasound) starry sky appearance (MRI) starry sky artifact (MRI)
Article

Caput medusae sign (disambiguation)

The caput medusae sign may refer to: caput medusae sign (portal hypertension) caput medusae sign (developmental venous anomaly) History and etymology Caput is the Latin for head, and the sign literally translates as head of Medusa 3. The appearance is reminiscent of the hair of Medusa, one ...
Article

Compression-type hepatic pseudolesions

Compression-type hepatic pseudolesions occur typically when an extrinsic structure, during the patient's deep inspiration breath-hold at the time of CT acquisition, causes transient focal compression of a subcapsular region of the liver and subsequent decreased portal perfusion and minimal chang...
Article

Agenesis (general)

The biological/medical term agenesis (plural: ageneses) refers to failure of an organ to grow or develop during the embryological period. Examples include: appendiceal agenesis cerebellar agenesis corpus callosum agenesis dental agenesis (anodontia) diaphragmatic agenesis dorsal pancreati...
Article

Gallbladder wall thickening

Thickening of the gallbladder wall, usually considered >3 mm, is a non-specific sign of various conditions. Pathology Gallbladder wall thickening can be caused by inflammatory, benign, and malignant etiologies. Pseudothickening caused by the normal postprandial state of the contracted gallblad...
Article

Starry sky appearance (MRI)

Starry sky appearance on MRI refers to the appearance of small innumerable T2 hyperintense bile duct hamartomas and biliary microhamartomas, scattered throughout the T2 hypointense hepatic parenchyma, which resembles a “starry sky”. The high T2 signal lesions represent Von Meyenburg complexes se...
Article

Third inflow

Third inflow refers to anatomical variants leading to an additional venous inflow to the liver apart from the usual dual blood supply (portal vein and hepatic artery). They tend to be associated with parenchymal pseudolesions (focal hyperenhancement on post-contrast imaging, focal fat infiltrati...
Article

Intrahepatic arteriovenous shunt

Intrahepatic arteriovenous shunts, also referred to as intrahepatic arteriovenous malformations (AVMs) or hepatic arteriosystemic venous shunts, represent a spectrum of abnormal communications between the hepatic arterial system and the hepatic veins.  Please note that arterioportal shunts, whi...
Article

Hereditary hemorrhagic telangiectasia (liver manifestations)

Hepatic manifestations of Hereditary hemorrhagic telangiectasia (HHT), which is also known as Osler-Weber-Rendu syndrome, are typically seen on imaging as multiple telangiectasias and arteriovenous malformations (i.e. arteriovenous and portovenous shunts). These multiple shunts lead to a hyperdy...
Article

Hepatic vascular and perfusion disorders

Hepatic vascular and perfusion disorders are a broad group of conditions that radiologists should be familiar with, as some of them are quite frequently seen in the daily practice. The aim of this article is to be a collection of articles that represent the core knowledge in the matter. Patholo...

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