Gastrointestinal neuroendocrine tumors (GI NETs) can be functional or non-functional:
functional NETs can be challenging to localize as:
they are often small in size at the time of diagnosis
arise in many sites throughout the body
non-functioning and/or malignant NETs often are larger at p...
Gastrointestinal nodular lymphoid hyperplasia is a type of nodular lymphoid hyperplasia that can be found elsewhere in the body. It is formed out of gut-associated lymphoid tissue (GALT), and most often is a diagnostic dilemma for radiologists in the stomach and terminal ileum.
Gastrointestinal schwannomas are extremely rare mesenchymal neoplasms which arise in relation to the gastrointestinal tract.
They are reported to typically present at about the 3rd to 5th decades of life 4.
Patients are often asymptomatic but may occasional...
Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. They account for ~5% of all sarcomas, and are mostly found within stomach and mid-distal small bowel. They respond remarkably well to chemotherapy.
Previously these tumors h...
The gastrointestinal tract includes any part of the oral cavity, oropharynx, hypopharynx, esophagus, stomach, small bowel, colon, rectum and anal canal.
Gastrointestinal tract lipomas are not uncommon and can be found anywhere along the entire length of the gastrointestinal tract.
Gastrointestinal tract lipomas are most frequently encountered between the ages of 50 and 70 years 3.
The majority of lipomas a...
Gastrointestinal tuberculosis refers to the infection of abdominal organs with Mycobacterium tuberculosis. It generally affects the following organs:
ileocecal junction (terminal ileum and cecum): most commonly due to the abundance of lymphoid tissue 1
The gastro-esophageal junction (GEJ) (also known as the esophagogastric junction) is the part of the gastrointestinal tract where the esophagus and stomach are joined.
The GEJ is normally mostly intra-abdominal and is 3-4 cm in length. To some extent, the esophagus slides in and ...
Gastro-esophageal reflux disease (GERD) is a spectrum of disease that occurs when gastric acid refluxes from the stomach into the lower end of the esophagus across the lower esophageal sphincter (LES).
Common clinical features in adults include epigastric and retrosternal...
This is a basic article for medical students and other non-radiologists
Gastric-esophageal reflux disease (GERD) is a spectrum of disease that occurs when gastric acid refluxes into the lower esophagus
This is a summary article; read more in our article on gastro-esophageal ...
A gastro-pleural fistula is a very rare situation characterized by a pathological communication between the stomach and the pleural cavity.
They can occur in number of situations:
trauma (stab injuries 3)
iatrogenic (following bariatric, pulmonary or esophageal surgery 1)
Gastroschisis refers to extra-abdominal herniation (evisceration) of fetal or neonatal bowel loops (and occasionally portions of the stomach and or liver) into the amniotic cavity through a para-umbilical anterior abdominal wall defect.
The estimated incidence is at around 1-6 p...
The gastrosplenic ligament is a peritoneal ligament which is formed by ventral part of dorsal mesentery.
The gastrosplenic ligament extends from the greater curvature of the stomach to the hilum of the spleen. It contains the short gastric arteries.
Gaucher disease (GD) is the most common lysosomal storage disorder in humans. It is an autosomal recessive, multisystem disease arising from a deficiency of glucocerebrosidase or beta-glucosidase activity, resulting in the accumulation of a glycolipid (glucocerebroside) within the lysosomes of m...
A mnemonic to remember the causes of generalized colitis is:
I: infectious colitis e.g. E. coli, cytomegalovirus
I: inflammatory, e.g. pseudomembranous colitis, Crohn disease, ulcerative colitis
I: ischemic colitis
N: neoplastic, e.g. lymphoma
R: radiation colitis
To facilitate clinical description, the general topography of the abdomen is divided into four quadrants or nine regions by lines on the surface of the anterior abdominal wall. The four quadrants are created by vertical and horizontal lines passing through the umbilicus, whereas the nine regions...
Geophagy is the intentional ingestion of earth, soil or clay and is a form of pica. This practice is not uncommon in the southern regions of the United States or provinces of Africa. It may be seen in pregnant or iron-deficient patients 3. Although geophagia may be seen in the context of a varie...
Giant colonic diverticula, also referred to as giant colonic pseudodiverticula, are an uncommon form of presentation of colonic diverticulosis and are characterized by large diverticular masses, usually filled with stool and gas, that communicate with the colonic lumen.
Globus pharyngeus is the subjective feeling of a lump in the throat which can have a variety of causes. In modern practice globus is often evaluated by flexible nasoendoscopy in the first instance since many patients present to otolaryngology services. If no cause is identified or if nasoendosco...
Glucagon is a polypeptide hormone central to the regulation of glucose homeostasis, acting as an antagonist to insulin. In imaging it is used as an antiperistaltic agent in GI studies, although its clinical efficacy is controversial.
Glucagon is a 29-amino acid polypeptide hormone t...
Glucagonomas are pancreatic endocrine tumors that secrete glucagon. Most lesions are malignant.
They are very rare with an incidence of ~0.000005% or less than 1 case per 20 million. Equal incidence in middle-aged men and women.
Most patients present with ...
Gluten-related disorders are a collection of conditions that are the result of a reaction to the consumption of gluten a protein found in wheat, barley and rye 1.
Gluten-related disorders can be broadly divided into 1,2:
celiac disease: most common and most widely recognized
Glycogenic acanthosis is a benign finding on esophagography in elderly patients.
It most commonly occurs in patients >40 years of age and incidence and numbers of lesions increase by age. No gender predilection exists. Typically patients are asymptomatic.
It occurs fr...
Glycogen storage disease type I (GSD-I), also known as von Gierke disease, is a type of glycogen storage disease where there is excess deposition of glycogen primarily in the liver, but also in the kidney and small bowel.
It occurs approximately one in every 100,000 live births 2,...
A gossypiboma, also called textiloma or cottonoid, refers to a foreign object, such as a mass of cotton matrix or a sponge, that is left behind in a body cavity during an operation. It is an uncommon surgical complication.
The manifestations and complications of gossypibomas are so variable tha...
Graft versus host disease (GvHD) is a frequent complication of allogeneic post hematopoietic stem cell transplantation, commonly known as bone marrow transplantation. Anti-rejection drugs have reduced the incidence, although it does still frequently occur.
Graft versus host disease ...
Granular mucosal pattern of the esophagus represents very fine nodularity of the esophageal mucosal surface. This finding is non-specific and may represent:
reflux esophagitis (most common)
superficial spreading esophageal carcinom...
The great vessel space is the fourth retroperitoneal space along with the anterior and posterior pararenal spaces, and the perirenal space 1,2. Unlike other retroperitoneal spaces, it is not well-defined by fascial planes and thus disease processes affecting other retroperitoneal spaces can also...
The Griffiths point, also known as Griffiths critical point, refers to the site of watershed anastomosis between the ascending left colic artery and the marginal artery of Drummond occurring in the region of the splenic flexure. Most anatomy texts describe the location as two-thirds along the tr...
Gullo syndrome, also known as benign pancreatic hyperenzymaemia, is characterized by the abnormal elevation of the serum levels of most or all of the pancreatic enzymes without any evidence of underlying pancreatic pathology. All other laboratory assays and imaging studies are unremarkable.
A gastrointestinal fistula is an abnormal connection between the gut and another epithelial / endothealial - lined surface, such as another organ system, the skin surface, or elsewhere along the gastrointestinal tract. Some authors exclude fistulas involving the large bowel and esophagus when cl...
The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall.
The bowel wall has five layers, composed of alternating hyperechoic and hypoechoic appearances. Anatomically these layers are as follows (innermost to o...
Hemangiopericytomas of the spleen are very rare vascular neoplasm with only a few case reports available at the time of writing.
Splenic hemangiopericytomas are typically asymptomatic or can result in splenomegaly.
These are soft tissue vascular neoplasms aris...
Abdominal complications of hematopoietic stem cell transplantation can occur early (0-100 days) or late (>100 days) post-transplant.
bacterial infections, e.g. pseudomembranous colitis
fungal infections, often affecting the esophagus or as hepatic/splenic microabscesses
Pancreatic manifestations of hemochromatosis typically occur with primary hemochromatosis, as the organ is usually spared in the secondary form of the disease.
For a general discussion, and for links to other system specific manifestations, please refer to the article on hemochromatosis.
Hemoperitoneum (plural: haemoperitoneums) is the presence of blood within the peritoneal cavity.
penetrating or non-penetrating abdominal trauma (often with associated organ injury) 1
ruptured ectopic pregnancy
ovarian cyst rupture
aneurysm or pseudoaneurysm rupture
Hemorrhagic pancreatitis is characterized by bleeding within or around the pancreas, and is usually considered a late sequela of acute pancreatitis.
Hemorrhage can occur in patients with severe necrotizing pancreatitis or as a result of pancreatic pseudoaneurysm rupture when it const...
Haemosuccus pancreaticus, also known as pseudohaemobilia or haemoductal pancreatitis, is defined as upper gastrointestinal tract hemorrhage originating from the pancreatic duct into the duodenum via the ampulla of Vater, or major pancreatic papilla.
male:female ratio is 7:1
The Haggitt level is a histopathological term used for describing the degree of infiltration from a malignant polypoidal lesion.
Levels of invasion
0: carcinoma in situ or intramucosal carcinoma
1: invasion of the submucosa, but limited to the head of the polyp
2: invasion extending into the...
Hair artifact and hair-product artifacts are artifacts produced by the presence of the patient's hair across the field of view during acquisition of an image, which can affect all modalities to varying degrees. For example, in mammography, hair may appear as curvilinear white lines or may simula...
The Hampton line is a thin millimetric radiolucent line seen at the neck of a gastric ulcer in barium studies (profile view), indicating its benign nature. It is caused by a thin line of mucosa overhanging the ulcer's crater.
History and etymology
It was originally described by Aubrey Otis Ham...
Hartmann pouches are a technique in colon surgery. After a segment of colon is resected, there are generally two options with regards to what to do with the two ends of the colon:
both the upstream end of the colon (the end of the colon through which fecal contents would pass) and the downstr...
Hartmann procedure (HP) (or proctosigmoidectomy) is an operation in which the sigmoid colon is resected and the distal colon brought out as a colostomy in the left iliac fossa. The remnant rectum stump is sewn shut. It is a quick and straightforward intervention and currently finds most favor in...
The haustral folds (Latin: haustrum, plural: haustra) represent folds of mucosa within the colon. The haustra refer to the small segmented pouches of bowel separated by the haustral folds. They are formed by circumferential contraction of the inner muscular layer of the colon.
The outer longitu...
Haustral markings are the radiological appearance of the haustral folds within the colon. Disappearance of the haustral folds results in the lead pipe appearance of ulcerative colitis.
Hepatic and splenic tuberculosis refers to tuberculosis affecting the liver and the spleen. It generally occurs due to haematogenous spread from the primary site of infection, commonly from pulmonary tuberculosis.
Two types of lesions are known:
The hepatic edge sign is a radiographic sign of pneumoperitoneum seen on a supine plain abdominal radiograph. It is represented by a cigar-shaped pocket of free air in the subhepatic region, which tracks superomedial following the contour of the liver.
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...
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 th...
The hepatogastric (gastrohepatic) ligament is a peritoneal ligament that together with the hepatoduodenal ligament forms the lesser omentum. It derives from the embryonic ventral mesentery.
The hepatogastric ligament extends from the fissure of the ligamentum venosum and porta he...
Hepatorenal syndrome refers to a form of acute kidney injury caused by changes in renal blood flow regulation due to liver pathology 1. Although the syndrome occurs mainly in cirrhotic livers it has been reported in patients with acute fulminant liver failure as well 1.
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 breast and ovarian cancer (HBOC) syndrome is caused by a mutation to either BRCA1 or BRCA2 genes. These patients have an increased risk of breast cancer, ovarian cancer, pancreatic cancer and prostate cancer. However, these gene mutations are not the only cause of hereditary breast ca...
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.
Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is an inherited condition which predisposes to a host of malignancies, including colorectal carcinoma. It is considered the most frequent form of hereditary colorectal cancer. Diagnosis requires evaluation using cl...
Hereditary pancreatitis is a rare subtype of chronic pancreatitis that has an autosomal dominant inheritance. Imaging plays a role in excluding underlying abnormalities.
As a congenital condition, presentation with acute pancreatitis attacks typically occurs in childhood,...
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...
Herpes esophagitis is one of the infectious esophagitis that usually affects immunocompromised patients.
It occurs as an opportunistic infection in immunocompromised patients, particularly those with AIDS. It has also been described in immunocompetent individuals 3.
Heyde syndrome is an association between aortic valve stenosis and gastrointestinal hemorrhage.
The etiology of the gastrointestinal bleeding in this setting is uncertain, but it is thought to be related to intestinal angiodysplasia. The strength of this association independent of age-related d...
Hiatus hernias occur when there is herniation of abdominal contents through the esophageal hiatus of the diaphragm into the thoracic cavity.
The prevalence of hiatus hernia increases with age, with a slight female predilection.
Many patients with hiatus her...
Hiccups (or hiccoughs), medical term singultus (rarely used), are an unpleasant phenomenon, experienced by everyone on occasion, and usually self-limiting. However the much rarer intractable chronic form can be extremely debilitating.
Hiccups are a symptom that has probably been e...
The hide-bound bowel sign refers to an appearance on a barium study of the small bowel in patients with scleroderma. The sign describes the narrow separation between the valvulae conniventes which are of normal thickness despite dilatation of the bowel lumen.
Although the term hide-bound is u...
High-grade appendiceal mucinous neoplasms (HAMN) are rare mucinous tumors of the appendix showing high-grade cytologic atypia, cf. low-grade appendiceal mucinous neoplasms (LAMN). The distinction between both LAMN and HAMN is done on histological grounds and these tumors look the same on imaging...
Edward John Hinchey et al. 3 proposed a classification for acute diverticulitis, (anywhere along the bowel, not just the colon) that has been variously adapted, and is useful not only in academia but also in outlining successive stages of severity.
stage Ia: phlegmon
stage Ib: ...
Hirschsprung disease is the most common cause of neonatal colonic obstruction (15-20%). It is commonly characterized by a short segment of colonic aganglionosis affecting term neonates, especially boys.
Hirschsprung disease affects approximately 1:5000-8000 live births. In short ...
Acquired immunodeficiency syndrome (AIDS) is an immunosuppressed state, caused by infection with the human immunodeficiency virus (HIV). It is characterized by opportunistic infections, neoplasms, and neurological manifestations.
According to the United Nations programme on HIV/AI...
Gastrointestinal manifestations of AIDS are protean and can be broadly divided into opportunistic infections and tumors:
herpes simplex virus (HSV)
primary infection with HIV
HIV-associated neoplasms are numerous and can be broadly divided into two groups:
associated but not AIDS defining malignancies
The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4:
HIV esophagitis is a possible cause of odynophagia in immunosuppressed patients with HIV.
The actual incidence and prevalence of Idiopathic esophagitis of HIV are unknown. Most of the patients have acquired immunodeficiency syndrome (AIDS) and CD4 count <100 3.
The Howship-Romberg sign refers to obturator nerve neuropathy due to compression of the obturator nerve by an obturator hernia. Patients present with pain and paraesthesia along the inner aspect of the thigh, down to the knee.
History and etymology
Named after Moritz Heinrich Romberg (1795-187...
Hydatid cysts result from infection by the Echinococcus species, and can result in cyst formation anywhere in the body.
Cystic echinococcosus has a world wide geographical distribution. The Mediterranean basin is an important endemic area 6,7.
There are two main specie...
Hyoscine-N-butylbromide, more commonly known by its brand name, Buscopan®, is an antimuscarinic agent, widely used in radiology as an antispasmodic agent. It is employed to freeze bowel motion as part of many fluoroscopic, CT and MRI studies (its main use for many years was for barium GI studies...
The hyperattenuating ring sign is a sign that has been described with epiploic appendagitis and refers to a hyperattenuating ring of visceral peritoneum surrounding an inflamed epiploic appendage 1. On CT it can be seen as a ring of soft tissue surrounding a region of fat attenuation adjacent to...
Hypercontracting (nutcracker) esophagus is a motility disorder of the esophagus. This condition is primarily diagnosed with manometry with high intra-esophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.
Hypercontracting esophagus ("nutcracker esophagus")...
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...
Hypertrophic pyloric stenosis can be characterized on ultrasound by the measurements of the hypertrophic muscle. Although the criteria can vary from publication to publication, an easy way to keep in mind the values is using a mnemonic which relies upon remembering the first digits of the number...
The ice pick sign is a smooth tapered narrowing of the upstream pancreatic duct distal to the pancreatic lesion seen frequently in benign pancreatic lesions such as a focal autoimmune pancreatitis, this is due to the extrinsic narrowing of the duct secondary to periductal fibrosis and inflammati...
Idiopathic eosinophilic esophagitis is an inflammatory disease of the esophagus characterized by eosinophilia that can involve all the layers of the esophagus.
It is most commonly seen in males aged 20-40. It is an uncommon disease; however not rare.
IgG4-related disease (IgG4-RD) is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs.
This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
Ileal atresia is a congenital abnormality where there is significant stenosis or complete absence of a portion of the ileum. There is an increased incidence in those with chromosomal abnormalities.
This article will focus on ileal atresia alone but bear in mind that some cases correspond to jej...
The ileocecal valve separates the terminal ileum from the cecum and functions to regulate flow between these two structures and prevent reflux from the cecum into the small intestine.
The ileocecal valve consists of two muscular layers of ileum, an upper and lower lip, that are ...
The ileocolic artery is a branch of the superior mesenteric artery (SMA) that runs obliquely to the ileocecal junction.
It divides into an ileal branch that supplies the terminal ileum and anastomoses with the terminal SMA and a colic branch that supplies the proximal ascending colon and anasto...
Ileovesicostomy (also known as "cutaneous ileocystostomy", "ileal chimney", or "bladder chimney") is an uncommon urologic diversion in which a loop of small bowel is anastomosed/augmented to the dome of the bladder. This loop of bowel then exits through a urostomy. The diversion is not continent...
The ileum is the final part of the small intestine, following the duodenum and jejunum.
The ileum is not to be confused with the ilium - the associated plural/adjectival forms are ilea/ileal and ilia/ilial respectively.
The ileum is 2-4 m in length and is separated ...
The medical terms ileum and ilium have been causing great confusion to medical students and junior doctors alike for decades now. Only separated by one letter, the second vowel, the pronunciation may be identical, or differ slightly with the i sound resembling that in "bit" for ilium (ɪlɪəm) or ...
Incarcerated (also referred to as irreducible) is used to describe herniae, in which their contents are unable to pass back through the hernial opening to their anatomical site of origin.
Incarceration is a risk factor for bowel obstruction and strangulation, and therefore usually necessitates...
The majority of splenic lesions are benign and when an incidental splenic lesion is found in an asymptomatic patient, it may pose a dilemma in workup because imaging findings are often nonspecific.
benign imaging features: no follow up
Incisional hernias are relatively common and along with parastomal hernias, umbilical hernias, paraumbilical hernias and spigelian hernias, they are usually anterior abdominal hernias.
Usually develop within a few months of surgery but a small proportion can remain clinically sile...
Indeterminate colitis is considered a somewhat controversial term. It was originally used by pathologists when no specific features for either Crohn disease (CD) or ulcerative colitis (UC) were seen. Over the years the term has been adopted to describe patients in whom a diagnosis of UC or CD ca...
Indirect inguinal hernias are the most common type of abdominal hernias.
It is five times more common than a direct inguinal hernia, and is seven times more frequent in males, due to the persistence of the processus vaginalis during testicular descent.
In children, the vast majo...
Indium-111 OncoScint is a radiopharmaceutical used in SPECT imaging. It is a labeled monoclonal antibody that is directed against TAG-72, which is a tumor-associated antigen associated with ~95% of colorectal carcinomas and 100% of ovarian carcinomas 1,2. Background hepatic uptake limits sensiti...
Infectious colitis refers to inflammation of the colon due to an infective cause, including bacterial, viral, fungal, or parasitic infections.
In Western countries, bacterial infection is the most common cause, while in developing countries parasitic infection is much more common....
The inferior lumbar triangle, also known as the Petit triangle, is an anatomical space through which inferior lumbar hernias can occur.
inferiorly: iliac crest
anteriorly: external oblique muscle
posteriorly: latissimus dorsi muscle
floor: internal oblique muscle