Hepatic peliosis is a rare benign vascular condition characterized by dilatation of sinusoidal blood-filled spaces within the liver. There may be involvement of other organs, most commonly the spleen and bone marrow. It can be seen in a variety of settings and is important as appearances may m...
Hepatic pseudolesions near the falciform ligament show abnormal attenuation without mass effect. They may be seen on contrast-enhanced CT scans as either a region of high or low attenuation relative to the rest of the liver. They are typically located in the medial segment of the left lobe of th...
Hepatic siderotic nodules are a type of regenerative nodule formed in a cirrhotic liver. They occur in hepatic hemosiderosis. The nodules have an increased iron content compared with other regenerative nodules. They may be non-dysplastic or dysplastic.
The reason why these nodules co...
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.
Hepatic solitary fibrous tumors (hepatic SFTs) are rare mesenchymal tumors.
Fewer than 60 cases have been reported in the literature. Female predominance (~70%). There is a mean age of 52 years at presentation, but a wide range of incidence (16-84 years).
Hepatic steatosis refers to an increase of intracellular fat in the liver. It is widely mischaracterized by both radiologists and sonographers as 'fatty infiltration' but the fat is in the hepatocytes and not in the extracellular matrix. On imaging grounds, it can broadly be divided into two gro...
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 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.
Three large intrahepatic veins drain the liver parenchyma, into the inferior vena cava (IVC), and are named the right hepatic vein, middle hepatic vein and left hepatic vein. The veins are important landmarks, running in between and defining the segments of the liver. There are separate smaller ...
Hepatic venous pressure gradient measurement is a safe and minimally invasive method to indirectly measure portal vein pressure in chronic liver disease patients suspected of developing portal vein hypertension.
diagnosis of liver fibrosis and risk stratification
Hepatisation of the gallbladder is a sonographic entity in which the gallbladder lumen is entirely filled with tumefactive sludge giving the gallbladder a similar appearance to liver parenchyma. It is one of the causes of non-visualization of the gallbladder on sonography.
In the set...
Hepatitis B virus (HBV) is a circular DNA virus endemic in many parts of the world. It is a risk factor for the development of hepatocellular carcinoma (HCC).
Acute HBV infection is most often subclinical and asymptomatic. Symptomatic patients (~33%) may experience fever,...
Hepatitis C virus (HCV) is an RNA virus and a member of the Flaviviridae family. It is a risk factor for the development of hepatocellular carcinoma (HCC).
Route of transmission
The most common route of transmission is through blood products and contaminated needles. Unprotected sex...
LI-RADS (Liver Imaging Reporting and Data System) is both a set of standardized terminology and a classification system for imaging findings in liver lesions. The LI-RADS score for a liver lesion is an indication of its relative risk for hepatocellular carcinoma (HCC). The classification system ...
Hepatobiliary imaging in nuclear medicine can be accomplished with multiple different radiotracers to help evaluate the liver, gallbladder and the biliary ducts. The choice of tracer depends on the clinical question.
Common tracers include:
Tc-99m IDA (iminodiacetic acid) analogs: most commonl...
Hepatobiliary MRI contrast agents are specialized contrast agents used to aid diagnosis in MRI.
They are separated into three categories: gadolinium-based agents, manganese-based agents and superparamagnetic iron oxide particles.
Gadolinium (Gd) based contrast agents ...
The hepatobiliary system consists of the:
biliary tree (both intra- and extra-hepatic)
The pancreas is included by some.
Hepatoblastoma is the most common primary malignant liver tumor in children under four years of age who usually present with painless abdominal mass and raised AFP. It is tumor of embryonic origin.
Most cases are seen during the first 18 months of life and diagnosis in adulthood i...
Although hepatoblastomas can be histologically classified into a variety of subtypes, it is important to remember that with the possible exception of small cell undifferentiated subtype, prognosis is independent of histology when adjusted for stage gender and age 1.
As expected there are a number of different staging systems for hepatoblastoma.
PRETEXT grouping system of pediatric liver tumors
not specific to hepatoblastoma; used in all pediatric liver tumors
Intergroup staging system
specific for hepatoblastoma (see below)
Intergroup staging ...
Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. It is strongly associated with cirrhosis, from both alcohol and viral etiologies. HCC constitutes approximately 5% of all cancers partly due to the high endemic rates of hepatitis B infection 1.
Hepatocellular carcinoma staging classifications supersede the typical TNM staging system seen in most other epithelial cancers, as the TNM staging system has been found to not be as prognostically useful for stratification of patients with hepatocellular carcinoma. Several substitute staging sy...
Hepatocellular carcinoma surveillance programs have been adopted by some health systems in attempts to effect an early diagnosis of hepatocellular carcinoma in high-risk populations.
The idea behind hepatocellular carcinoma screening, as with any screening program, is to detect clin...
The hepatoduodenal ligament is a peritoneal ligament of lesser omentum containing the portal triad 1.
The hepatoduodenal ligament is a thickening of the right edge of the lesser omentum and forms the anterior margin of the epiploic foramen. It extends from the porta hepatis to t...
Hepatofugal or non-forward portal flow (NFPF) is an abnormal flow pattern in which the portal venous flow is from the periphery of the liver towards the porta and backwards along the portal vein. This phenomenon is not uncommon in patients with liver disease 3.
It is the opposite of hepatopetal...
Hepatolithiasis is the presence of bile duct stones within the intrahepatic bile ducts, specifically proximal to the confluence of the right and left hepatic ducts.
Hepatolithiasis is common in Asia and the Pacific, with a prevalence of ~40%. It is rare in the West with a prevale...
Hepatomegaly refers to an increase in size or enlargement of the liver.
Hepatomegaly can result from a vast range of pathology including, but not limited to, the following:
Hepatopetal denotes flow of blood towards the liver, which is the normal direction of blood flow through the portal vein. The term is typically used when discussing the portal vein or recanalized vein of the ligamentum teres in patients with suspected portal hypertension.
It is the opposite of ...
Hepatopulmonary syndrome (HPS) is a clinical syndrome defined by the presence of the following:
dilation of pulmonary vasculature
may involve pulmonary capillaries, pulmonary arteriovenous malformations, or pleural AVMs
abnormalities in oxygenation
elevation in the alveolar-ar...
Hepatosplenic candidiasis is a manifestation of disseminated candidiasis in immunosuppressed patients, particularly those receiving chemotherapy for hematological malignancies. Both hepatic and splenic infection usually happens simultaneously, the reason why they are approached together.
Hepatosplenomegaly is simply the simultaneous presence of a pathologically-enlarged liver (hepatomegaly) and spleen (splenomegaly).
Many, many infections can produce a mild concurrent enlargement of the liver and spleen. This list is by no means exhaustive!
Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterized by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system.
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...
Hereditary pancreatitis is a rare subtype of chronic pancreatitis that has an autosomal dominant inheritance and is one of the main causes of pancreatitis in childhood.
As a congenital condition, a presentation with acute pancreatitis attacks typically occurs in childhoo...
Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening.
The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...
HNF 1 alpha mutated hepatic adenomas are a genetic and pathologic subtype of hepatic adenoma. Their appearance and prognosis are different from other subtypes.
They are the second most common (30-35%) hepatic adenoma, after the inflammatory subtype. They occur only in female patie...
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
A Hutson loop, also known as an access loop, is variation of the Roux-en-Y choledochojejunostomy whereby a longer segment of jejunum is used to construct the hepatobiliary limb, and the upstream end is tacked to the anterior abdominal wall ("stomatization") 4.
The goal is to simplify future end...
Hyalinised hepatic hemangiomas, also known as sclerosing/sclerosed hepatic hemangiomas, are a rare variant of hepatic hemangioma. Because of their unusual imaging features, they cannot be reliably differentiated from a malignant tumor without a biopsy. Liver capsular retraction is a common featu...
A hyperattenuating gallbladder may occur from a number of different etiologies:
sludge in the gallbladder
vicarious excretion of intravenous contrast (iodinated contrast or gadolinium contrast)
medications I.e ceftriaxone associated gallbladder...
A hyperechoic liver lesion on ultrasound can arise from a number of entities, both benign and malignant. A benign hepatic hemangioma is the most common entity encountered, but in patients with atypical findings or risk for malignancy, other entities must be considered.
Hypertension refers to an increase in blood pressure above the 'normal' for the age, sex, and ethnicity of the patient. This can be specified according to the vascular system involved. Although generally when it is not specified it is assumed to refer to the systemic type.
Hypertriglyceridemia-induced pancreatitis is an uncommon form of acute pancreatitis caused by high levels of circulating triglycerides in the blood.
Hypertriglyceridemia-induced pancreatitis accounts for around 1-4% of cases of acute pancreatitis and is the third most common cause...
Hypertrophy of the caudate lobe is seen in a number of conditions, including:
cirrhosis: most common
primary sclerosing cholangitis (end stage)
congenital hepatic fibrosis
cavernous transformation of the portal vein
The caudate-right lobe ratio m...
Hypervascular liver lesions may be caused by primary liver pathology or metastatic disease.
hepatocellular carcinoma (HCC)
most common hypervascular primary liver malignancy
early arterial phase enhancement and then rapid wash out
rim enhancement of c...
IgG4-related disease (IgG4-RD) is a systemic disease that is characterized by fibroinflammatory infiltration of various organs, including by plasma cells that express IgG4 (immunoglobulin G subclass 4).
This condition has been known by many other names in the past, such as IgG4-rel...
IgG4-related sclerosing cholangitis, also known as autoimmune cholangiopathy, is part of the spectrum of IgG4-related disease but can also occur in isolation. It is a separate entity to primary sclerosing cholangitis.
The pathogenesis is poorly understood. The disease is characteriz...
Imaging in liver transplantation is aimed to evaluate donor and recipient for successful transplantation and its outcome.
volume of liver
parenchymal disease (diffuse or focal)
Increased splenic density can be due to a number of processes. The density may be due to calcification (most common) or other compounds (iron, Thorotrast), and can be seen (often incidentally) on abdominal radiographs and CT. On CT the usual splenic attenuation is 35-55 HU or ~10 HU 6 lower than...
Infantile hepatic hemangiomas (IHH) are liver lesions composed of large endothelial-lined vascular channels seen in fetuses and neonates. Not to be confused with hepatic epithelioid hemangioendothelioma, which occurs in older patients.
These benign tumors were previously referred t...
The inferior pancreaticoduodenal artery is the first branch of the superior mesenteric artery (SMA).
It usually arises at the inferior border of the pancreas or with the first jejunal artery as part of the pancreaticoduodenojejunal trunk.
It anastomoses with branches of the superior pancreati...
Inferior vena cava (IVC) webs are an uncommon condition characterized by obstruction of the hepatic segment of the inferior vena cava by a membrane or fibrous band. This is often associated with occlusion of one or more of the hepatic veins.
If there is hepatic vein invol...
Infiltrative hepatocellular carcinoma (HCC), also known as diffuse hepatocellular carcinoma, is an infrequent subtype of HCC, which has particular imaging characteristics. Because of these characteristics, it has been called cirrhotomimetic-HCC or cirrhosis-like HCC.
Inflammatory hepatic adenomas are a genetic and pathological subtype of hepatic adenoma. Their appearance and prognosis is different than other subtypes and has the highest incidence of hemorrhage amongst hepatic adenoma subtypes.
Most common subtype of hepatic adenoma (40-50%). O...
Inflammatory myofibroblastic tumors (IMT), also known as plasma cell granulomas, are rare neoplasms that have a diverse spectrum of biological behavior.
These tumors were previously referred to as inflammatory pseudotumor.
They can occur at any age and there is cu...
Insulinomas are the most common sporadic endocrine tumor of the pancreas.
On imaging, they usually present as small well-defined hypervascular tumors that may be found anywhere in the pancreas.
Account for 40% of syndromic pancreatic endocrine tumors. The overall incidence is of...
Interstitial edematous pancreatitis is one of the two subtypes of acute pancreatitis. It is normally referred to as "acute pancreatitis" or "uncomplicated pancreatitis" in day-to-day use. Please refer to the article on acute pancreatitis for further details.
Intrabiliary rupture of hepatic hydatid cyst is a common complication associated with hepatic hydatid cysts. It is important to appreciate the direct and indirect signs of this condition.
The radiological features of intrabiliary rupture of a hepatic hydatid cyst can be c...
Intracholecystic papillary neoplasms (ICPN), also known as intracholecystic papillary-tubular neoplasms, are rare, recently described, preinvasive neoplasms of the gallbladder.
On imaging, these lesions resemble adenomas of the gallbladder or have features suspicious for gallbladder carcinoma, ...
The intraductal neoplasms of the bile ducts are divided into those lesions that are a precursor to adenocarcinoma of the bile ducts, also referred to as preinvasive lesions, and the invasive tumors, which are cholangiocarcinomas of intraductal growing type.
Intraductal papillary mucinous neoplasms or tumors (IPMNs or IMPTs) are epithelial pancreatic cystic tumors of mucin-producing cells that arise from the pancreatic ducts. They are most commonly seen in elderly patients.
On imaging, particularly MRCP, they are characterized by single or multipl...
Intraductal papillary neoplasm of the bile duct (IPNB) is a preinvasive biliary tree neoplasm considered to be a precursor of cholangiocarcinoma.
Biliary papillary adenoma and non-invasive papillary carcinoma of the biliary tract were terms used to refer to localized low-grade and...
Intraductal tubulopapillary neoplasms of the bile ducts are rare intraluminal masses forming pre-invasive biliary neoplasms with no mucin production.
Intraductal tubulopapillary neoplasm of the bile ducts are rare tumors of unknown incidence, found more frequently in women at the...
Intrahepatic arterioportal shunts represent abnormal flow between the portal venous system and a hepatic arterial system within the liver. They can be a reversible cause of portal hypertension.
Clinical features will depend on the size and other underlying pathology. Smal...
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...
Intrahepatic cholangiocarcinoma staging is conducted most commonly in accordance with 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. Th...
Irreversible electroporation (IRE), also known as non-thermal irreversible electroporation (NTIRE), is a non-invasive soft-tissue ablation technique used for tumor ablation in regions that require very high precision and preservation of surrounding collagenous structures (vessels and ducts) and ...
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...
Jaundice refers to a clinical sign of hyperbilirubinemia (serum bilirubin >2.5 mg/dL) which has many causes. It is often a clue to a diagnosis. It can be largely divided into two types:
non-obstructive, i.e. prehepatic and hepatic causes
obstructive, i.e. posthepatic causes
Imaging has a majo...
Kasai classification is used to describe the three main anatomical types of biliary atresia.
type I: obliteration of common bile duct (patent cystic and common hepatic duct)
IIa: obliteration of common hepatic duct (patent cystic and common bile duct), sometimes with a...
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.
Klatskin tumor is a term that was traditionally given to a hilar (perihilar) cholangiocarcinoma, occurring at the bifurcation of the common hepatic duct. Typically, these tumors are small, poorly differentiated, exhibit aggressive biologic behavior, and tend to obstruct the intrahepatic bile duc...
Komi classification of bile duct cysts divides anomalous union of the pancreatico-bile ducts (AUPBD) into three types based on the angle of union of the ducts 1.
type I: union of the ducts at a right angle to each other
type Ia: without dilatation or
type Ib: with dilatation ...
KRAS (shortened name for the gene Kirsten RAt Sarcoma viral oncogene homolog) mutations are associated in a number of malignancies including:
certain adenocarcinomas of the lung
colorectal carcinoma 1
pancreatic ductal adenocarcinoma
Several germline KRAS mutations have also been found to b...
The Krenning score is a proposed semi-quantitative method of assessing the degree of tracer uptake on octreotide scintigraphy.
Initially designed for assessment of 111In-DTPA on planar imaging, the Krenning score is applicable to SPECT or PET/CT using various radiopharmaceuticals.
This article lists a series of labeled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
CT head: venogram axial
The term lamellated (or laminated which means the same thing) is a radiopathological term used to describe the layered appearance of many calculi, including those of the renal tract, the salivary glands, and the biliary tree. The internal structure of these calculi has been likened to that of an...
The left hepatic artery (LHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver.
The proper hepatic artery bifurcates into the left and right hepatic arteries at or before reac...
The left triangular ligament is a peritoneal suspensory ligament of the liver. It is formed by the fusion of the superior and inferior reflections of the coronary ligament.
It is shorter than the right triangular ligament and does not separate the left subphrenic space from the subhepatic space.
Leishmaniasis refers to zoonoses caused by parasites of the genus Leishmania. There are three main forms of leishmaniasis:
visceral (also known as kala-azar or dum-dum fever)
Leishmaniasis is a truly global disease with a higher burden in t...
Lemmel syndrome is defined as obstructive jaundice caused by a periampullary duodenal diverticulum compressing the intrapancreatic common bile duct with resultant bile duct dilatation.
Patients may present with recurrent episodes of jaundice, pancreatitis and/or cholangit...
Leptospirosis results from infection by the zoonotic Leptospira spp. The condition can have multiorgan manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Leukemic infiltration of the liver can occur with several forms of leukemia inclusive of acute myeloid leukemia (AML), acute lymphoid leukemia (ALL) and chronic myeloid leukemia (CML).
Described features are non-specific but include:
periportal low att...
The ligamentum venosum is a fibrous remnant which travels superiorly from the porta hepatis of the liver to the inferior vena cava. It is often obliterated in adults.
In the fetus, it is patent and known as the ductus venosus which shunts blood returning from the placenta in the umbilical vein...
The light bulb sign of a hepatic hemangioma is a feature than can be seen on MRI imaging with a classic hepatic hemangioma. This refers to marked hyperintensity seen on heavily T2 weighted sequences that has been likened to a glowing light bulb.
light bulb sign - shoulder
light bulb ...
Limy bile stands for the presence of a viscous substance in the dependent parts of the gallbladder and/or bile ducts, almost entirely composed of calcium carbonate, and therefore highly radiopaque.
The terms limy bile and calcium milk gallbladder can be used interchangeably for inc...
Lipase, more specifically pancreatic lipase, is an enzyme produced in the pancreas and is responsible for the digestion of fat molecules. It may be raised (hyperlipasemia) in numerous pancreatic, hepatobiliary and other diseases but is most commonly associated with acute pancreatitis.
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...
Liquefactive necrosis is a form of necrosis where there is transformation of the tissue into a liquid viscous mass.
In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes leading to a soft, circumscribed lesion which can consist of fluid with remains...
Liver Imaging Reporting and Data System (LI-RADS) is both a set of standardized terminology and a classification system for imaging findings in liver lesions. The LI-RADS score for a liver lesion is an indication of its relative risk for hepatocellular carcinoma (HCC).
The classification system...
Littoral cell angioma of the spleen is a rare, benign primary vascular tumor of the spleen.
Littoral cell angiomas may occur at any age and have no gender predilection.
Littoral cell angiomas have been diagnosed in association with various malignancies outside the s...
The liver is the largest abdominal organ. It plays a major role in metabolism and has a number of functions, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. It is one of the very few organs that has the ability to re...