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...
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...
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
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...
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...
Hypoglycemia describes an abnormally low blood glucose level (<4 mmol/L). It is a common clinical problem in diabetics overtreated with glucose lowering agents.
Signs of hypoglycemia include:
tremors, palpitations and anxiety
Reynolds pentad is a combination of clinical signs found in acute cholangitis. It consists of Charcot triad 2-4:
fever and/or chills
as well as:
delirium or lethargy, and
Sensitivity of Reynolds pentad from a large systematic review of nine studies was ...
The enlarged hilar periportal space sign refers to the widening of the periportal space seen on MRI in early liver cirrhosis.
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...
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...
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.
Absolute ethanol (most commonly use...
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
The features of fibrolamellar hepatocellular carcinoma can be recalled using this mnemonic:
S: scar (fibrotic)
Y: young patients
C: capsular retraction
H: huge and heterogenous
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...
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.
Reye syndrome is usually seen between the ...
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.
They can considerably vary in size with one study reporting a range of 8 mm to 8 cm 1.
Interstitial lung disease associated with primary biliary cholangitis can occur in a variable pattern that can include 1:
lymphoid interstitial pneumonia
non-specific interstitial pneumonia
bronchiolitis obliterans with organizing pneumonia
It may occur in a...
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 ...
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...
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.
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...
Fluid-fluid levels in liver lesions are a rare appearance of both benign and malignant conditions.
complicated hepatic cyst 2
hepatic abscess 2
chronic hepatic hematoma 3
biliary cystadenoma 3
hepatic hemangioma (very rare) 2
The cystic veins (TA: venae cysticae) are the main venous drainage of the gallbladder. They subsequently drain into the portal vein.
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...
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.
external anal sphincter
internal anal sphincter
lower esophageal sphincter
Hepatic small vessel neoplasms (HSVN) are low-grade vascular lesions of uncertain malignant potential.
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 ...
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.
It has been esti...
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.
Rosenbach also gave...
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...
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...
Cullen sign refers to superficial edema visible as periumbilical discolouration and is most commonly seen in patients with acute pancreatitis 1-3.
Clinically patients with pancreatitis present with epigastric pain that radiates to the umbilical/periumbilical region and th...
The AJCC (American Joint Committee on Cancer) 8th edition gallbladder cancer staging system was introduced in 2018.
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
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...
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 ...
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...
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.
The term bird's beak sign is used in a number of other contexts: see bird beak sign (disambiguation).
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.
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.
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.
High levels of serum lipase, due to hypersecretion syndrome, resulting in sub...
Cystic artery pseudoaneurysms are rare and most commonly related to acute cholecystitis 1.
liver biopsy 6
laparoscopic cholecystectomy 3-5
The most common clinical manifestations are 4,5,9:
The term centrilobular in imaging may refer to:
centrilobular pattern (ultrasound liver)
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.
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 ...
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 ...
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...
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...
Ascitic fluid cholesterol level estimation is a simple and precise test for differentiating malignant ascites from non-malignant (cirrhotic) ascites 5-9.
Ascites is the abnormal collection of fluid within the peritoneal cavity. Malignant ascites comprises ~10% and is usually seconda...
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 ...
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...
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...
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...
Several normal anatomical structures and rare organ variants have been described as being horseshoe-shaped.
horseshoe pancreas 1
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).
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.
Emphysematous hepatitis is extremely rare, with less than 10 reported cases in the lite...
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...
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.
failed endoscopic transpapillary biliary drai...
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 ...
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.
Conditions that increase one's risk of developing m...
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.
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.
The major manifestation is he...
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
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...
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
The Strasberg classification of bile duct injury is a widely used system to anatomically define these injuries by location 1.
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...
Hepatic sinusoidal dilatation is a rare hepatic vascular lesion that is the result of dilatation of the hepatic capillaries.
Hepatic sinusoidal dilatation can be caused by hepatic venous outflow obstruction (more commonly) or extrahepatic inflammatory conditions 2.
Abdominal tuberculosis can manifest in almost every abdominopelvic organ:
jejunal and ileal tuberculosis
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.
Actinomycosis is endemic worldwide. It has no predilection for age, gender, ethnicity or climat...
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.
This technique consists of mobilizing...
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.
Tyrosinemia type 1 is an autosomal recessive disorder of metabolic origin. Progressive renal tubular defects and hepatocellular carcinoma are the primary manifestations.
More common in Turkey, India and Europe.
Presentation is typically in the first few mon...
Hepatic teratomas are extremely rare and represent either intraperitoneal or retroperitoneal teratomas that have invaded the liver. Hepatic teratomas comprise <1% of all teratomas.
These are extremely rare with only a few case reports have been described in the literature. The ma...
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.
Hepatic myelolipomas are ...
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...
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 ...
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
The most common technique is right hemihepatectomy, wit...
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...
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...
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...
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...
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...
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.
Arguably lipomatous pseudohypertrophy may be considered a distinct clinicopathologi...
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...
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 (semicircular ducts)
ampulla of ...
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 ...
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.
The incidence of microgallbladder varies considerably in the literature, however most ...
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)
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 ...
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...
The biological/medical term agenesis (plural: ageneses) refers to failure of an organ to grow or develop during the embryological period.
corpus callosum agenesis
dental agenesis (anodontia)
Thickening of the gallbladder wall, usually considered >3 mm, is a non-specific sign of various conditions.
Gallbladder wall thickening can be caused by inflammatory, benign, and malignant etiologies. Pseudothickening caused by the normal postprandial state of the contracted gallblad...
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...
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...
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...
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...
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.