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.

587 results found
Article

Mickey Mouse appearance

In medical imaging literature, a Mickey Mouse appearance has been given to imaging features that depict that of Mickey Mouse when viewed from the front. It has been described in the following: anencephaly 2 progressive supranuclear palsy 1 synonymously with a finger in glove sign the flared ...
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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 ...
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Middle hepatic artery

The middle hepatic artery (MHA) is an intrahepatic hilar arterial branch, usually arising from the left hepatic artery, which supplies segments IVa and IVb. It runs towards the right side of the umbilical fissure. Variant anatomy it may arise from the right hepatic artery 1,2 it may arise as ...
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Milan criteria in liver tranplantation

The Milan criteria are a generally accepted set of criteria used to assess suitability in patients for liver transplantation with cirrhosis and hepatocellular carcinoma. In order to be suitable for a liver transplantation, one needs to have 1: single tumor with a diameter of ≤5 cm, or up to 3 ...
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Milk of calcium (disambiguation)

The term milk of calcium (MOC) is given to dependent, sedimented calcification within a cystic structure or hollow organ. This sort of colloidal calcium suspension layering can occur in various regions: renal: milk of calcium in renal cyst (most common) breast: milk of calcium in breast cyst ...
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Mirizzi syndrome

The Mirizzi syndrome refers to an uncommon phenomenon which results in extrinsic compression of an extrahepatic biliary duct from one or more calculi within the cystic duct or gallbladder. It is a functional hepatic syndrome but can often present with biliary duct dilatation and can mimic other ...
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MR elastography

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

MR liver iron quantification is a non-invasive means of measuring liver iron concentration, a key indicator in the management of patients with hemochromatosis (primary or secondary). Advantages Apart from being non-invasive, sampling occurs in a large cross-section of the liver, as opposed to ...
Article

Mucinous cystic neoplasm of the gallbladder

Mucinous cystic neoplasms of the gallbladder are extremely rare epithelial cystic tumors formed by mucin-producing cells. They are histologically similar to the other mucinous cystic tumors found elsewhere in the body. For the lesions involving the bile ducts, please refer to: biliary cystaden...
Article

Mucocele

A mucocele simply refers to accumulation and expansion of a structure by mucus. It occurs in a variety of locations which are discussed separately: paranasal sinus mucocele oral cavity e.g. ranula, mucous retention cysts mucocele of the appendix 1 mucocele of the gallbladder mucocele of the...
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Multiple biliary hamartomas

Multiple biliary hamartomas (MBH's) are a rare cause of multiple benign hepatic lesions. The condition is also known as von Meyenburg complexes, multiple bile duct hamartomas and biliary microhamartomas. MBH is asymptomatic and usually found incidentally, where it is important to differentiate f...
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Multiple focal nodular hyperplasia syndrome

Multiple focal nodular hyperplasia occurs in approximately 20-25% of patients with focal nodular hyperplasia (FNH). It is defined by The International Working Party as consisting of two or more FNHs in combination with 1: liver hemangioma or vascular malformations (most frequent types: hepatic...
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Neimeier classification of gallbladder perforation

The classification of gallbladder perforation was proposed by Neimeier and later modified by Anderson et al. in 1987, which at the time of writing (July 2016) remains the most widely accepted classification for gall bladder perforation. According to this classification, there are three main cli...
Article

Niacin (vitamin B3) excess

In general taking large doses of water-soluble vitamins has not been found to have a deleterious clinical effect. However niacin (vitamin B3) excess can be problematic, usually when greater than 100 mg niacin is taken per day. To put this in context the recommended daily allowance (RDA) in the U...
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Niemann-Pick disease

Niemann-Pick disease (NPD) is actually a collection of a number of distinct autosomal recessive lysosomal storage diseases. They are divided into two groups of two based on the underlying metabolic deficiency: deficiency of acid sphingomyelinase 1,3,4 Niemann-Pick disease type A (NPD-A) sever...
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Niemann-Pick disease type A

Niemann-Pick disease type A (NPD-A) is one of a group of autosomal recessive lysosomal lipid storage disorders (see Niemann-Pick disease) that presents in early childhood and usually progresses to death within a few years. It shares the same enzyme deficiency as Niemann-Pick disease type B (NPD-...
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Niemann-Pick disease type C

Niemann-Pick disease type c (NPD-C or just NPC) is an autosomal recessive lysosomal storage disorder classed under Niemann-Pick disease on account of clinical similarities, namely hepatosplenomegaly and variable involvement of the central nervous system.  Epidemiology NPD-C is inherited as an ...
Article

Nodule-in-nodule appearance (liver)

In hepatic imaging, a nodule-in-nodule appearance represents foci of abnormal arterial enhancement within a liver lesion, in cases of a liver regenerative nodule with a focus of hepatocellular carcinoma or high-grade dysplastic nodule. It is so called because of the nodular arterial enhancement ...
Article

Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) occurs when fat is deposited into hepatocytes without a known cause (such as with alcoholic fatty liver disease). The deposition of fat may lead to hepatic inflammation (hepatitis) and may eventually lead to cirrhosis. Terminology "Non-alcoholic fatty ...
Article

Non-neoplastic solid lesions of the pancreas

Non-neoplastic solid lesions of the pancreas are conditions which may mimic pancreatic neoplasms on imaging. They include: focal pancreatitis autoimmune pancreatitis fatty infiltration-replacement intrapancreatic accessory spleen peripancreatic lymph node congenital anomalies prominent pa...
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Non-visualization of the fetal gallbladder

Non-visualization of the fetal gallbladder is often a transient finding and in most cases, the gallbladder can be eventually detected. However non-visualization can be rarely associated with certain pathological conditions. Associations cystic fibrosis aneuploidy agenesis of the gallbladder ...
Article

Normal hepatic vein Doppler

The hepatic veins have a characteristic spectral Doppler waveform. Alterations in the normal hepatic vein waveform may reveal or confirm abnormalities in the heart or liver. Terminology The key factor in the shape of the hepatic vein spectral Doppler waveform is the motion of the heart. Multip...
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Normal hepatobiliary imaging examples

This article lists examples of normal imaging of the liver and biliary tree and surrounding structures, divided by region and modality. Liver Plain radiographs liver silhouette: example Ultrasound liver ultrasound example 1 with shear wave elastography liver Doppler ultrasound: example ne...
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Nubbin sign

Nubbin sign (also called as cystic duct sign) is an important sign in a HIDA scan (cholescintigraphy using iminodiacetic acid analogs) that may be seen in cases of gallbladder neck obstruction. The "nubbin" refers to a small amount of radiotracer activity in the cystic duct, with absence of trac...
Article

Nutmeg liver

A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...
Article

Obstructive jaundice (summary)

This is a basic article for medical students and other non-radiologists Obstructive jaundice represents a set of conditions that cause jaundice by obstructing the flow of bile into the duodenum anywhere along the intrahepatic or extrahepatic biliary tree. Reference article This is a summary a...
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Esophageal varix

Esophageal varices describe dilated submucosal veins of the esophagus, and are an important portosystemic collateral pathway. They are considered distinct from gastric varices, which are less common. Epidemiology Esophageal varices are present in ~50% of patients with portal hypertension 1,2. ...
Article

Okuda staging system

The Okuda staging system was an advance on earlier hepatocellular (HCC) staging classifications, in that it incorporated both cancer-related variables and liver function related variables to determine prognosis 1: disease involving >50% of hepatic parenchyma ascites albumin ≤3 mg/dL bilirubi...
Article

Omentum

An omentum is a double layer of peritoneum that attaches the stomach to another viscus: the greater omentum hangs from the greater curvature of the stomach like an apron the lesser omentum attaches the lesser curvature of the stomach to the liver superiorly Gross anatomy Greater omentum The...
Article

Organ Procurement and Transplantation Network (OPTN) classification

Organ Procurement and Transplantation Network (OPTN) is the unified transplantation network in the United States and runs under the administration of United Network for Organ Sharing (UNOS). OPTN classification is the part of the imaging policy of UNOS that consists of in order to determine the ...
Article

Pediatric benign liver tumors

Pediatric benign liver tumors are a relatively rare, but important group of conditions. Importantly, the commonest cause of a benign liver tumor is specific to the pediatric population. The list in descending order of frequency is: infantile hepatic hemangioma (previously hemangioendothelioma) ...
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Pediatric liver tumor (PRETEXT grouping system)

The PRETEXT system proposed by the International Childhood Liver Tumors Strategy Group (previously called Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumor Study Group - SIOPEL) aims for staging and risk stratification of liver tumors at diagnosis.  It is used to describe ...
Article

Pancreas

The pancreas (plural: pancreata) is a retroperitoneal organ that has both endocrine and exocrine functions: it is involved in the production of hormones (insulin, glucagon and somatostatin), and also involved in digestion by its production and secretion of pancreatic juice. Gross anatomy The p...
Article

Pancreas divisum

Pancreas divisum represents a variation in pancreatic ductal anatomy that can be associated with abdominal pain and idiopathic pancreatitis. It is characterized, in the majority of cases, by the dorsal pancreatic duct (main pancreatic and Santorini ducts) directly entering the minor papilla with...
Article

Pancreatic atrophy

Pancreatic atrophy is non-specific and is common in elderly patients, although in younger patients it can be a hallmark of pathology. Most commonly it is associated with aging, obesity and end-stage chronic pancreatitis.  It occurs principally with fatty replacement of the pancreas (pancreatic ...
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Pancreatic calcifications

Pancreatic calcifications can arise from many etiologies. Punctate intraductal calcifications chronic pancreatitis alcoholic pancreatitis (20-40%) 2  intraductal, numerous, small, irregular preponderant cause of diffuse pancreatic intraductal calcification gallstone pancreatitis (2%) 2 ​m...
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Pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma makes up the vast majority (~90%) of all pancreatic neoplasms and remains a disease with a very poor prognosis and high morbidity. On imaging, it usually presents as a hypodense mass on CT that is poorly marginated, which may encase vessels and the common bile d...
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Pancreatic ductal adenocarcinoma (staging)

Staging of pancreatic ductal adenocarcinoma is traditionally done according to American Joint Committee on Cancer (AJCC) / Union for International Cancer Control (IUCC) TNM system.  In 2017 new edition (8th edition) AJCC published with some major changes; now exocrine and endocrine tumors of the...
Article

Pancreatic duct diameter

The diameter of the (main) pancreatic duct is a commonly assessed parameter in imaging. Gross anatomy The duct diameter is greatest at the head and neck region and is slightly narrower towards the body and tail. Its normal reported value ranges between 1-3.5 mm 5,8: head: 3.5 mm body: 2.5 mm...
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Pancreatic ducts

The ductal embryology of the pancreas is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant. Gross anatomy The normal arrangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vate...
Article

Pancreatic intraepithelial neoplasia

Pancreatic intraepithelial neoplasia (PanIN) is a precursor lesion to pancreatic ductal adenocarcinoma, but the frequency at which this transition occurs is unknown.  Epidemiology Increasing incidence with age 1. Risk factors: obesity pancreatic lipomatosis 3 Pathology Mostly flat lesions ...
Article

Pancreatic lipomatosis

Pancreatic lipomatosis refers to fat accumulation in the pancreatic parenchyma. This finding is most often associated with obesity and aging.  It tends to be the commonest pathological condition involving the pancreas. The condition may occasionally simulate a mass-like lesion particularly when...
Article

Pancreatic lymphoma

Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma. Epidemiology Pancreatic lymphoma is typically seen in middle-aged patients with a mean age of around 55 years old and is more common in immunocompromised patients. Clinical presentation Symptoms are often non-spe...
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Pancreatic metastases

Pancreatic metastases are uncommon and are only found in a minority (3-12%) of patients with widespread metastatic disease at autopsy. They account for only 2-5% of all pancreatic malignancies. Epidemiology Demographics will match those of the primary tumor, but in general, will be in elderly ...
Article

Pancreatic neoplasms

There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components. Classification Classification based on function exocrine: ~99% of all primary pancreatic neoplasms pancreatic ductal adenocarcinoma ~90-95% cystic neoplasm intraductal papillary muc...
Article

Pancreatico-pleural fistula

Pancreatico-pleural fistulas are a rare complication of acute or chronic pancreatitis whereby enzymatic pancreatic fluid, either from a pancreatic pseudocyst or directly from a disrupted duct, dissects into the pleural cavity. Pancreaticopleural fistulas may also develop in the setting of trauma...
Article

Pancreatic pseudocyst

Pancreatic pseudocysts are common sequelae of acute pancreatitis or chronic pancreatitis, and the most common cystic lesion of the pancreas. They are important both in terms of management and differentiation from other cystic processes or masses in this region. Terminology The following are th...
Article

Pancreatic trauma

The pancreas is uncommonly injured in blunt trauma. However, pancreatic trauma has a high morbidity and mortality. Imaging features range from subtle to obvious. Epidemiology The pancreas is injured in ~7.5% (range 2-13%) of blunt trauma cases 1,3. Motor vehicle accidents account for the vast ...
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Pancreatic trauma injury grading

A number of pancreatic injury grading systems have been proposed. Classifications American Association for the Surgery of Trauma (AAST) grade 1: hematoma with minor contusion/laceration but without duct injury grade 2: major contusion/laceration but without duct injury grade 3: distal lacer...
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Pancreatitis

Pancreatitis (plural: pancreatitides) refers to inflammation involving the pancreas.  It has various forms which can be classified in many many ways according to time of onset, etiological agent or associated pathology. acute pancreatitis interstitial edematous pancreatitis necrotizing pancr...
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Pancreatoblastoma

Pancreatoblastomas are rare pediatric tumors of the pancreas. However, they are the most common pancreatic neoplasm of childhood and are often associated with a raised alpha-fetoprotein. Epidemiology There is slight male predilection. Usually occurs in the first decade of life with a mean age ...
Article

Papillary process of the caudate lobe

The papillary process of the caudate lobe, also known as the medial papillary process, represents a division of the inferior caudate lobe of the liver 1. The inferior aspect of the caudate may be divided into medial and lateral processes.  While the lateral or caudate process is contiguous with ...
Article

Paracaval lipoma

Paracaval lipoma (juxtacaval fat collection or pseudolipoma of the inferior vena cava) can be a frequent finding on CT and can be seen in up to 0.5% of examinations 1. Some even consider this as a normal variation 5. It occurs at the medial aspect of the intrahepatic portion of the inferior vena...
Article

Paraduodenal pancreatitis

Paraduodenal pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum and the common bile duct. Terminology The following entities with which it shares clinicopathological features are unified by this term and should no ...
Article

Paraumbilical veins

The paraumbilical veins are small veins around the falciform ligament that drain venous blood from the anterior part of the abdominal wall and diaphragm directly into the liver, and communicate with other anterior abdominal wall veins. This flow is considered the cause of focal fatty infiltratio...
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Passive hepatic congestion

Passive hepatic congestion, also known as congested liver in cardiac disease, describes the stasis of blood in the hepatic parenchyma, due to impaired hepatic venous drainage, which leads to the dilation of central hepatic veins and hepatomegaly.  Passive hepatic congestion is a well-studied re...
Article

Pearl necklace sign

The pearl necklace sign occurs in adenomyomatosis of the gallbladder, on both oral cholecystograms and MRCP. It represents the contrast/fluid-filled intramural mucosal diverticula (Rokitansky-Aschoff sinuses); lined up, these are reminiscent of pearls on a necklace. It is synonymous with the CT ...
Article

Pepper syndrome

Pepper syndrome is of interest only (the term is not readily used in day-to-day practice), and refers to primary adrenal neuroblastoma with extensive liver metastases 1. In essence, it refers to stage 4S neuroblastoma (see staging of neuroblastoma). 
Article

Percutaneous cholecystostomy

Percutaneous cholecystostomy is an image-guided placement of drainage catheter into gallbladder lumen. This minimally invasive procedure can aid the stabilization of a patient to enable a more measured surgical approach with time for therapeutic planning. A 2018 study 11 demonstrate no differen...
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Percutaneous transhepatic biliary drainage

Percutaneous transhepatic biliary drainage is an interventional radiology procedure undertaken for those with biliary obstruction. It is almost exclusively performed in those with a malignant obstruction, such as cholangiocarcinoma, ampullary and pancreatic malignancies when retrograde access v...
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Percutaneous transhepatic cholangiography

Percutaneous transhepatic cholangiography (PTC) is a radiographic technique employed in the visualization of the biliary tree and can be used as the first step in a number of percutaneous biliary interventions (e.g. percutaneous transhepatic biliary stent placement) Indications Purely diagnost...
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Periampullary diverticulum

A periampullary diverticulum is a location-specific type of duodenal diverticulum.  Epidemiology The incidence is reported to increase with age with reported rates as high as 27%. Pathology It is located close to the region of the duodenum often involving the D2 segment.  Associations can ...
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Periampullary tumors

Periampullary tumors are those that arise within 2 cm of the ampulla of Vater in the duodenum. Tumors that fall under this group include four main types of tumors 1,4 that will be approached in their specific articles: pancreatic head/uncinate process tumors: includes pancreatic ductal adenoca...
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Peribiliary cyst

Peribiliary cysts occur in the setting of chronic liver disease where it is a rare, benign and often asymptomatic disorder. It occurs when there is cyst formation around the intrahepatic biliary ductules primarily in a hilar distribution 1. Unlike choledochal cysts (for example in Caroli disease...
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Peripancreatic pseudoaneurysm

Peripancreatic pseudoaneurysm refers to the formation of a pseudoaneurysm around the pancreatic gland. It is a rare but potentially lethal complication 5. Epidemiology Formation of pseudoaneurysm can occur in as many as 10% of cases of pancreatitis. The time interval is variable, ranging from ...
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Periportal halo (liver)

Periportal halo or periportal collar sign refers to a zone of low attenuation seen around the portal veins on contrast-enhanced CT or hypoechogenicity on liver ultrasound. It likely represents periportal edema, which is often used as a synonymous term. Periportal haloes may occur around the cent...
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Periportal hyperechogenicity

Periportal hyperechogenicity can result from many causes including: pneumobilia cholecystitis schistosomiasis of the portal region recurrent pyogenic cholangitis (oriental) inflammatory bowel disease: has been described to give "echo-rich" periportal cuffing 2​
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Periportal hypoechogenicity

Periportal hypoechogenicity can result from many causes: orthotopic liver transplant rejection congestive hepatomegaly malignant lymphatic obstruction cholangitis viral hepatitis See also periportal hyperechogenicity periportal halo
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Peritoneal hydatidosis

Peritoneal hydatidosis occurs secondary to seeding of echinococcosis to the peritoneum, usually secondary to rupture of hydatid disease of liver. Pathology Seeding involves the entire peritoneum and gives appearance of a multiloculated mass.  Classification Peritoneal hydatidosis can be prim...
Article

Phrygian cap

Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance. Radiographic findings A Phrygian cap may be identified on ultrasound, multiphase CT/MRI or ch...
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Pleuro-biliary fistula

Pleuro-biliary fistulae refer to abnormal fistulous communications between the biliary tree and pleural space. It forms the large portion of thoraco-biliary fistulas and can occur in various situations such as with complications secondary to trauma, infection, malignancy, biliary disease, or per...
Article

Pneumobilia

Pneumobilia, also known as aerobilia, is the accumulation of gas in the biliary tree. It is important to distinguish pneumobilia from portal venous gas, the other type of branching hepatic gas. There are many causes of pneumobilia and clinical context is often important to distinguish between th...
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Pneumobilia vs portal venous gas (mnemonic)

Pneumobilia and portal venous gas are two causes of an intrahepatic branching gas pattern. The two have different causes and implications and need to be distinguished on imaging, and a simple mnemonic can help. Mnemonic A simple mnemonic for remembering the difference in appearance is: portal...
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Point-of-care ultrasound (curriculum)

The point-of-care ultrasound (PoCUS) curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core applications of ultrasonography in a point-of-care setting. Point-of-care ultrasound refers to ultrasonography which may be simultaneously performed,...
Article

Polyarteritis nodosa

Polyarteritis nodosa (PAN) is a systemic inflammatory necrotizing vasculitis that involves small to medium-sized arteries (larger than arterioles).  Epidemiology PAN is more common in males and typically presents around the 5th to 7th decades. 20-30% of patients are hepatitis B antigen positiv...
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Polycystic liver disease

Polycystic liver disease (PCLD) is a hereditary condition that may arise either in patients with autosomal dominant polycystic kidney disease (ADPKD) or in patients with a different genetic mutation that results solely in autosomal dominant polycystic liver disease. Clinical presentation Most ...
Article

Porcelain gallbladder

Porcelain gallbladder refers to extensive calcium encrustation of the gallbladder wall. The term has been used to emphasize the blue discolouration and brittle consistency of the gallbladder wall at surgery but is often an incidental finding on multiple different imaging modalities.  Clinical p...
Article

Porta hepatis

The porta hepatis is a deep fissure in the inferior surface of the liver through which all the neurovascular structures (except hepatic veins) and hepatic ducts enter or leave the liver 1. It runs in the hepatoduodenal ligament and contains: right and left hepatic ducts right and left branches...
Article

Portal biliopathy

Portal biliopathy or portal ductopathy refers to biliary obstruction that is associated with cavernous transformation of the portal vein due to portal vein thrombosis 1.2. Clinical presentation Portal bilopathy may present as jaundice, cholangitis due to bile duct obstruction, or rarely as hem...
Article

Portal hypertension

Portal hypertension is defined as hepatic venous pressure gradient (HVPG) greater than 5 mmHg. HVPG is a surrogate for the portosystemic pressure gradient. Clinically significant portal hypertension is defined as a gradient greater than 10 mmHg and variceal bleeding may occur at a gradient great...
Article

Portal hypertensive gastropathy / enteropathy / colopathy

In portal hypertension, chronic portal venous congestion leads to dilatation and ectasia of the submucosal vessels in the stomach (portal hypertensive gastropathy), small bowel (portal hypertensive enteropathy) and/or large bowel (portal hypertensive colopathy). This may result in upper or lower...
Article

Portal vein

The portal vein (PV) (sometimes referred to as the main or hepatic portal vein) is the main vessel in the portal venous system and drains blood from the gastrointestinal tract and spleen to the liver. Gross anatomy The portal vein usually measures approximately 8 cm in length in adults with a ...
Article

Portal vein embolization

Portal vein embolization (PVE) is a technique used to selectively occlude the blood supply to one of the liver lobes, diverting portal blood flow to the other lobe, the future liver remnant (FLR). This diversion will increase the size of the post-hepatectomy future liver remnant (FLR) which imp...
Article

Portal vein thrombosis

Portal vein thrombosis may be seen in a variety of clinical contexts, and when acute can be a life-threatening condition. It is a major cause of non-cirrhotic presinusoidal portal hypertension. Portal vein thrombus may be either bland and/or malignant (i.e. tumor thrombus), and it is a critical ...
Article

Portal venous gas

Portal venous gas is the accumulation of gas in the portal vein and its branches. It needs to be distinguished from pneumobilia, although this is usually not too problematic when associated findings are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, centr...
Article

Portopulmonary hypertension

Portopulmonary hypertension (POPH/PPHTN) refers to pulmonary artery hypertension that develops in the setting of portal hypertension (with or without underlying liver disease). It falls under group 1.4 of the Dana point 2008 pulmonary hypertension classification system. Epidemiology The preval...
Article

Portosystemic collateral pathways

Portosystemic collateral pathways (also called varices) develop spontaneously via dilatation of pre-existing anastomoses between the portal and systemic venous systems. This facilitates shunting of blood away from the liver into the systemic venous system in portal hypertension, as a means for r...
Article

Posterior parahepatic cyst

Posterior parahepatic cysts are an incidental finding of a small, isolated, nodular structure adjacent to the posterior segment of the right hepatic lobe.  Pathology Due to the benign imaging characteristics and stability on long-term imaging, no pathologic diagnosis of these lesions has been ...
Article

Posterior right subhepatic space

The posterior right subhepatic space (also known as the hepatorenal fossa or Morison pouch) separates the liver from the right kidney. It is a potential space that is not filled with any fluid in normal conditions. Gross anatomy The posterior right subhepatic space is a subcompartment of the s...
Article

Posttransplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD), also referred as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the WHO classification of tumors of hematopoietic and lymphoid tissues. It can be a ...
Article

Primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic progressive cholestatic liver disease that is the cause of 1-2% of deaths from cirrhosis and constitutes the third most common indication for liver transplantation in adults. Terminology The name of this disease was changed from primary biliary ci...
Article

Primary effusion lymphoma

Primary effusion lymphoma is a rare form of non-Hodgkin lymphoma (diffuse large cell B cell lymphoma) characterized by malignant fluid accumulation in the absence of lymphadenopathy. Typical sites of accumulation include pleural space pericardium peritoneal space Associations immunodeficie...
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Primary hepatic lymphoma

Primary hepatic lymphoma (PHL) is rare, with roughly 100 described cases. If it is being considered as a diagnosis, distal lymphadenopathy, splenomegaly, bone marrow disease, and leukemia should not be present for at least 6 months after the liver tumor is detected (see: secondary hepatic lympho...

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