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.

631 results found
Article

Liver and biliary interventional procedures

There is a wide range of liver and biliary interventional procedures, both diagnostic and therapeutic, most commonly using CT-guidance or ultrasound-guidance.   Vascular Interventions: transjugular intrahepatic portosystemic shunt (TIPS) transjugular liver biopsy (TJLB) Percutaneous interven...
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Liver biopsy (percutaneous)

Percutaneous liver biopsy, utilizing either ultrasound or CT guidance, allows for an accurate and reliable method of acquiring hepatic tissue for histopathological assessment. It is divided into two types: non-focal or non-targeted liver biopsy (used in the assessment and staging of the parench...
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Liver biopsy (transjugular)

Transjugular liver biopsy (TJLB) is an alternative to a percutaneous liver biopsy in patients with diffuse liver disease, coagulopathy and ascites. It is sometimes done in combination with a transjugular intrahepatic portosystemic shunt (TIPSS) or venography. Indications massive ascites coag...
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Liver cancer (BCLC staging)

Barcelona clinic liver cancer (BCLC) staging uses a set of criteria to guide the management of patients with hepatocellular carcinoma (HCC). The classification takes the following variables into account 1,2: performance status (PS)  Child-Pugh score radiologic tumor extent tumor size multi...
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Liver lesions

Liver lesions represent a heterogeneous group of pathology ranging from solitary benign lesions to multiple metastases from a variety of primary tumors. Liver lesions may be infiltrative or have mass-effect, be solitary or multiple, benign or malignant. Assessment of liver lesions takes into c...
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Liver lesions (pediatric)

Pediatric liver lesions are a heterogeneous group that includes infiltrative lesions and those that demonstrate mass-effect. Moreover, they may be solitary or multiple, benign or malignant: benign liver tumors malignant liver tumors Epidemiology There are differing frequencies of both benign...
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Liver lobules

Liver lobules are the basic functional units of the liver. They are classically described ('classic lobules') as hexagonal structures made of six vertically aligned portal canals with a central vein. However, microscopic evaluation of the liver usually shows a lack of classic liver lobule as a w...
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Liver protocol (MRI)

Examination of the liver with MRI requires numerous sequences and imaging at multiple times after the administration of contrast.   Note: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's...
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Liver sinusoid

Liver sinusoids are a type of fenestrated/porous blood vessel which compose the 'capillary bed' of the liver parenchyma. They receive terminal branches of the oxygen-rich hepatic artery (terminal hepatic arterioles) and nutrient-rich portal vein (terminal portal venules). They facilitate vascula...
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Liver trauma

The liver is one of the most frequently damaged organs in blunt trauma, and liver trauma is associated with a significant mortality rate. Epidemiology In blunt abdominal trauma, the liver is injured ~5% (range 1-10%) of the time 1,3. Clinical presentation Patients can present with right uppe...
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Liver tumors

Liver tumors, like tumors of any organ, can be classified as primary or secondary. Metastases Liver metastases are by far the most common hepatic malignancy, with many of the most common primaries readily seeding to the liver. This is especially the case with gastrointestinal tract tumors, due...
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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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Lollipop sign (hepatic epithelioid hemangioendothelioma)

The lollipop sign is seen in hepatic epithelioid hemangioendothelioma (HEHE). It represents hepatic/portal vein and/or their tributaries/branches tapering and terminating at or just within the edge of a well defined peripherally enhancing (or non-enhancing) lesion with an avascular core on CT or...
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Low phospholipid-associated cholelithiasis syndrome

Low phospholipid-associated cholelithiasis (LPAC) syndrome is one of the syndromes associated with ABCB4/MDR3 mutation. Characteristics of this syndrome include 1,2: intrahepatic microlithiasis/sludge symptomatic cholesterol stones with early onset (<40 years) recurrent symptoms post cholecys...
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LR2 cirrhosis-associated nodule

LR2 cirrhosis-associated nodules are defined as "probably benign" according to the LI-RADS classification system. They are a common finding in a cirrhotic liver and do not need to be mentioned in the report.  Radiographic features The nodule must demonstrate all of the following: diameter <20...
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Macroamylasemia

Macroamylasemia is the presence of serum amylase of a large molecular size, seen in both otherwise healthy individuals, and also in various diseases. Amylase seems to be able to self-polymerize and/or form complexes with other blood proteins, e.g. immunoglobulins. Epidemiology Macroamylasemia ...
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Macrolipasemia

Macrolipasemia is the presence of serum lipase of a large molecular size, seen occasionally in otherwise healthy individuals, but more commonly in various diseases. Lipase is able to self-polymerize and/or form complexes with other blood proteins e.g. immunoglobulins. Epidemiology Epidemiologi...
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Magnetic resonance cholangiopancreatography (MRCP)

Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive imaging technique to visualize the intra and extrahepatic biliary tree and pancreatic ductal system. It can provide the diagnostic range equivalent to the ERCP and so it can replace the ERCP in high risk patients to avoid sign...
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Malignant biliary tract obstruction (summary)

This is a basic article for medical students and other non-radiologists Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative. Reference art...
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Malignant liver tumors (pediatric)

Pediatric malignant liver tumors are rare, some of which occur only in children but that are similar to those that occur in adults. Epidemiology Malignant liver tumors account for ~1% of pediatric malignancies 2. Pathology Broadly, any malignant liver mass can be defined as a metastasis or p...
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Mallory bodies

Mallory bodies are cytoplasmic eosinophilic inclusions in hepatocytes, associated with ballooning and inflammation, found in: alcoholic fatty liver disease and hepatitis non-alcoholic fatty liver disease hepatocellular carcinoma (HCC) primary biliary cholangitis (PBC) cholestasis
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Mass-forming intrahepatic cholangiocarcinoma

Mass-forming intrahepatic cholangiocarcinomas (MF-ICC), also referred as peripheral cholangiocarcinomas, comprise one of the three recognized growth patterns of intrahepatic cholangiocarcinomas.  On imaging, these tumors usually present as large and relatively well-defined hepatic masses with l...
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Mastocytosis

Mastocytosis is characterized by excessive accumulation of mast cells in one or more organs. According to the World Health Organization classification, three clinical entities fall under the mastocytosis umbrella: cutaneous mastocytosis, systemic mastocytosis (with or without cutaneous manifesta...
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Meandering main pancreatic duct

Meandering main pancreatic duct (MMPD) comprises of a reverse Z-type and loop-type of pancreatic ducts. These ductal variants are found in ERCP and MRCP studies. The exact incidence is not known. Increased incidence of meandering pancreatic duct has been reported in patients with idiopathic re...
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Medical devices in the abdomen and pelvis

Medical devices in the abdomen and pelvis are important to be recognized, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications. Gastrointestinal tubes stomac...
Article

Meglumine iotroxate (Biliscopin)

Meglumine iotroxate (BiliscopinTM) is an iodinated, intravenous contrast agent that is preferentially excreted into the biliary tree and is used in CT intravenous cholangiography. The typical dose is 100 mL Biliscopin (105 mg meglumine iotroxate/mL; 5.0 g iodine), which is administered via slow...
Article

MELD score

The MELD score (Model for End-stage Liver Disease) is a classification used to grade liver dysfunction in preparation for liver transplantation. The score has prognostic value in terms of three month mortality and certain complications. The components of the score are: serum creatinine (mg/dl)...
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Melioidosis

Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei) and is a multisystem disorder which may affect the lungs, brain, visceral organs, or musculoskeletal system. Epidemiology Melioidosis is a disease of the monsoo...
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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...
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Mercedes-Benz sign (gallbladder)

In the gallbladder, the Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2. Fissures, usually fluid-filled, are present in close to 50% of gallstones. Less than half of these fissured gallstones contain some amo...
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METAVIR score

The METAVIR​ scoring system is a system used to assess the extent of inflammation and fibrosis by histopathological evaluation in a liver biopsy of patients with hepatitis C. The grade indicates the activity or degree of inflammation while the stage represents the amount of fibrosis or scarring....
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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 ...
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

Middle hepatic artery

The middle hepatic artery (MHA) is an intrahepatic hilar arterial branch, usually arising from the left hepatic artery, which supplies segments 4a and 4b. 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 a ...
Article

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 ...
Article

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) ureter: milk of calcium in the ureter 7 ...
Article

Mirizzi syndrome

Mirizzi syndrome refers to an uncommon phenomenon that 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 hepat...
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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. The main advantage over ultrasound el...
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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...
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Mucocele (general)

A mucocele simply refers to accumulation and expansion of a structure by mucus 1. It occurs in a variety of locations which are discussed separately: paranasal sinus mucocele  lacrimal mucocele 3 mucocele of the mastoid (rare) 4 mucocele of the oral cavity e.g. ranula, mucous retention cysts...
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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...
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Multiple biliary hamartomas

Multiple biliary hamartomas (MBHs) are a rare cause of multiple benign hepatic lesions. The condition is also known as von Meyenburg complexes, multiple bile duct hamartomas or biliary microhamartomas. Multiple biliary hamartomas are asymptomatic and usually found incidentally, when it is import...
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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

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

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 shape of the hepatic vein spectral Doppler waveform is primarily determined by pressure changes in the r...
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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

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...
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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...
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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 staging (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 ...
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...
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Pancreas transplant

A pancreas transplant is a procedure in which a donor pancreas is transplanted to a recipient. The donor pancreas is typically cadaveric, but may rarely be a segment from a living donor 1. The transplant is meant to establish normoglycemia in patients with diabetes mellitus, typically type 1, th...
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 (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...
Article

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

Pancreaticopleural fistula

Pancreaticopleural fistulae 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 rate. 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 ...
Article

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...
Article

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 panc...
Article

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 (a.k.a. juxtacaval fat collection or pseudolipoma of the inferior vena cava) is the apparent protrusion of paracaval fat into the inferior vena cava (IVC) and is commonly visible on CT; some believe it to be a normal anatomic variant 5.  Epidemiology Paracaval lipoma may be se...
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...
Article

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 a term not readily used in day-to-day practice and usually refers to primary adrenal neuroblastoma with extensive liver metastases 1. In essence, it refers to stage 4S neuroblastoma (see staging of neuroblastoma).  Cohen syndrome, a genetic disorder, is sometimes referred to a...
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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