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.

1,080 results found
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Tissue tropism

Tissue tropism is a phenomenon by which certain host tissues preferentially support the growth and proliferation of pathogens. This concept is central to the radiological evaluation of infectious disease.  Pathology As infections that display tissue tropism will thrive in certain tissue locati...
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Toxic megacolon

Toxic megacolon is a complication that can be seen in both types of inflammatory bowel disease, and less commonly in infectious colitis, as well as in some other types of colitis. Terminology Toxic colitis is preferred by many now as the colon is not always dilated.  Pathology The mechanisms...
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Toxoplasmosis

Toxoplasmosis is a common worldwide parasitic disease caused by the protozoan Toxoplasma gondii. It is usually an asymptomatic infection, but it is related with several sequelae when acquired in-utero or related with cerebral abscesses due to its reactivation in immunocompromised patients (e.g. ...
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Tracheo-oesophageal fistulation

Tracheo-oesophageal fistula is a pathological communication between the trachea and oesophagus. It can be broadly classified into two types: congenital tracheo-oesophageal fistula acquired tracheo-oesophageal fistula: from malignancy/tuberculosis
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Transhiatal oesophagectomy

Transhiatal oesophagectomy is a type of oesophagectomy, a surgery that removes the distal oesophagus, usually for oesophageal carcinoma. Removal of the oesophagus can be performed through the chest wall (a transthoracic oesophagectomy), but the thoracotomy is a major component of patient pain a...
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Transient intussusception

Transient (non-obstructing) intussusception without a lead point is known to occur in both adults and children and occurs more frequently than was previously reported. Transient intussusception of the small bowel has been reported in adults with coeliac disease and Crohn disease but is most fre...
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Transpyloric plane

The transpyloric plane, also known as Addison's plane, is an imaginary axial plane located midway between the jugular notch and superior border of pubic symphysis, at approximately the level of L1 vertebral body. It an important landmark as many key structures are visualised at this level, altho...
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Transverse colon

The transverse colon is the longest and most mobile part of the large intestine. It measures up to 45 cm in length.  Gross anatomy The transverse colon is the continuation of the ascending colon from the right colic flexure. It passes from the right to left hypochondrium in a downward convex p...
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Transverse mesocolon

The transverse mesocolon is a broad, meso-fold of peritoneum, which connects the transverse colon to the posterior wall of the abdomen. It is continuous with the two posterior layers of the greater omentum, which, after separating to surround the transverse colon, join behind it, and are contin...
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Traumatic abdominal wall hernia

Traumatic abdominal wall hernia describes traumatic disruption of musculature and fascia of anterior abdominal wall without skin penetration. Clinical presentation Abdominal skin ecchymosis or abrasions may be seen. Pathology Traumatic abdominal wall hernia is caused by blunt trauma to the a...
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Triple bubble sign

The triple bubble sign is the classic radiographic appearance observed in jejunal atresia 1,2. The appearance is due to a proximal obstruction caused by the atretric jejunum. It is equivalent to the double bubble sign, but a third bubble is seen because of proximal jejunal distention.
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Troisier sign

Troisier sign is the clinical finding of a hard and enlarged left supraclavicular node (Virchow node), and is considered a sign of metastatic abdominal malignancy. Terminology It is sometimes referred to as the Virchow node, which is the name given by Rudolf Virchow (1821-1902) 6, a German pat...
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Tropical pancreatitis

Tropical pancreatitis is a subtype of chronic pancreatitis associated with malnutrition, tropical countries, and a young age of onset. There are characteristic, large ductal calculi, which may measure up to a few centimeters in size. This is in contrast to the small, speckled calculi more common...
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Tuberculous peritonitis

Tuberculous peritonitis is a result of peritoneal involvement in tuberculosis. It is frequently seen in association with other forms of gastrointestinal tuberculosis 6. Epidemiology Tuberculosis is usually confined to the respiratory system but may involve any organ system, particularly in imm...
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Tumours of the small intestine

The small intestine is rarely the site of malignant tumours, although it accounts for ~75% of the entire length of the GI tract and more than 90% of the mucosal surface. Approximately 40 different histologic tumour types have been described.  In this article, an overview will be given of the mo...
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Tumour-to-tumour metastasis

A tumour-to-tumour metastasis, also known as a collision tumour, is a rare metastatic process in which a primary malignant tumour ('donor') metastasises to another tumour ('recipient'), most commonly a benign tumour such as a meningioma. Epidemiology Tumour-to-tumour metastasis is considered v...
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Turcot syndrome

Turcot syndrome is one of the variations in polyposis syndromes. It is characterised by multiple colonic polyps and an increased risk of colon and primary brain cancers. Epidemiology Turcot syndrome is a rare disease. Patients typically present in the second decade 3. Pathology Turcot syndro...
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Twinkling artifact

Twinkling artifact is the result of intrinsic machine noise seen with colour Doppler ultrasound 1. It occurs as a focus of alternating colours on Doppler signal behind a reflective object (such as calculi), which gives the appearance of turbulent blood flow 2. It appears with or without an assoc...
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Typhlitis

Typhlitis, also called caecitis or neutropaenic colitis, is a necrotising inflammatory condition which typically involves the caecum and, sometimes, can extend into the ascending colon or terminal ileum. Epidemiology Typhlitis was first described in children with leukaemia and severe neutropae...
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Ulcerative colitis

Ulcerative colitis is an inflammatory bowel disease that not only predominantly affects the colon, but also has extraintestinal manifestations. Epidemiology Typically ulcerative colitis manifests in young adults (15-40 years of age) and is more prevalent in males but the onset of disease after...
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Ultrasound-guided biopsy

Ultrasound-guided biopsy is one form of image-guided biopsy, typically performed by a radiologist. It is the most common form of image-guided biopsy, offering convenience and real-time dynamic observation with echogenic markers on cannulae allowing for precise placement. It can potentially be u...
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Ultrasound guided percutaneous drainage

Ultrasound guided percutaneous drainage is one form of image guided procedure, allowing minimally invasive treatment of collections that are accessible by ultrasound study. It has several advantages and disadvantages over CT, which include: Advantages is a dynamic study, allowing greater prec...
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Umbilical hernia

Umbilical hernias are the most common ventral hernia and occur in the midline. Epidemiology Ten times more common in females 2 and represent ~5% of all abdominal hernias 4. Clinical presentation Umbilical hernias present in the midline as painless or painful mass.  Pathology Umbilical hern...
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Upper gastrointestinal bleeding

Upper gastrointestinal bleeding (UGIB) is defined as bleeding proximal to the ligament of Treitz. Epidemiology The incidence of acute upper GI bleeding is ~100 per 100,000 adults per year. Upper GI bleeding is twice as common in men as in women and increases in prevalence with age 5. The demog...
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Upper gastrointestinal bleeding (differential)

An upper gastrointestinal bleed usually refers to bleeding proximal to the ligament of Treitz. Pathology Causes peptic ulcer gastritis oesophagitis duodenitis Mallory-Weiss tear varices tumour vascular abnormality vascular ectasia angiodysplasia Dieulafoy lesion vascular malformati...
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Upper GI study

Upper GI studies are a fluoroscopic evaluation of the oesophagus, stomach, and duodenum.  Indications There are a number of indications for an upper GI study, including: upper abdominal pain with a possible gastric or duodenal origin ulcer gastritis or duodenitis gastric outlet obstruction...
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Urachus sign

The urachus sign is a radiographic sign of pneumoperitoneum. It represents the outline of the median umbilical ligament with free abdominal gas in a supine patient, as seen on a plain abdominal radiograph.
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US abdomen (summary)

This is a basic article for medical students and other non-radiologists Ultrasound abdomen is one of the tests that is commonly used in the assessment of patients with abdominal pain. It is particularly useful for the assessment of solid organs and fluid-filled structures. Reference article T...
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Valentino syndrome

Valentino syndrome, or Valentino appendix, refers to a clinical syndrome of right lower quadrant or right iliac fossa pain secondary to a perforated peptic ulcer. It is an important differential diagnosis for acute appendicitis. Epidemiology Although thought to be a very rare manifestation of ...
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Valvulae conniventes

The valvulae conniventes, also known as Kerckring folds, plicae circulares or just small bowel folds, are the mucosal folds of the small intestine, starting from the second part of the duodenum, they are large and thick at the jejunum and considerably decrease in size distally in the ileum to di...
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Vascular Ehlers Danlos syndrome

Vascular Ehlers-Danlos syndrome (EDS) or type IV Ehlers-Danlos syndrome (EDS 4) is the most malignant form of Ehlers-Danlos syndrome. This form is often accompanied by neurovascular complications secondary to vessel dissections and/or aneurysms. Epidemiology Vascular EDS represents about 4% of...
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Veiled right kidney sign

The veiled right kidney sign is a sonographic sign described in pneumoretroperitoneum, most commonly due to duodenal perforation. It refers to the appearance of the right kidney on transabdominal ultrasound 1-4. On ultrasound, there is difficulty in obtaining images of the right kidney due to i...
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Vertical-banded gastroplasty

Vertical-banded gastroplasty (VBG) is an older, purely restrictive procedure used to treat morbid obesity. Procedure It involves creating a small gastric pouch, based on the lesser curvature of the stomach (which is thicker and less resistant to stretching than the greater curvature), by using...
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Vestibule (disambiguation)

A vestibule is an anatomical term and refers to a small cavity at the proximal end of a tube. vestibule (aorta) vestibule (ear) vestibule (larynx) vestibule (mouth) vestibule (nose) vestibule (oesophagus) vestibule (vulva) History and etymology Vestibule derives ultimately from the Lati...
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Vicarious contrast material excretion

Vicarious contrast material excretion (VCME) defines excretion of water-soluble contrast material in a way other than via normal renal secretion.  The most common vicarious excretion of water-soluble contrast material is via the liver, resulting in increased bile density seen in the gallbladder...
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VIPoma

VIPomas are a very rare type of pancreatic endocrine tumour that secrete, and get their name from, vasoactive intestinal peptide (VIP). The clinical syndrome resulting from these tumours is commonly known as WDHA syndrome, as an acronym of the cardinal symptoms of watery diarrhoea, hypokalaemia,...
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Virgin abdomen

Virgin abdomen is used to describe the abdomen of a patient who has never had any surgical procedure on their abdomen. It is usually used in the context of someone presenting with an acute small bowel obstruction and whether adhesions might be the underlying aetiology. The conventional wisdom be...
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Vitamin B3

Vitamin B3 (niacin or nicotinic acid) is a water-soluble vitamin that is an important part of the coenzyme nicotinamide adenine dinucleotide (NAD+) which is involved in many reactions of cellular metabolism. Related pathology pellagra is the clinical syndrome of niacin deficiency, and may affe...
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Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterised by the development of numerous benign and malignant tumours in different organs (at least 40 types 1) due to mutations in the VHL tumour suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-5...
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Walled-off pancreatic necrosis

Walled-off pancreatic necrosis (WOPN) is a late complication of acute pancreatitis, although it can occur in chronic pancreatitis or as a result of pancreatic trauma. Differentiation of WOPN from pancreatic pseudocyst is essential because management differs. WOPN may need aggressive treatment to...
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Wandering spleen

Wandering spleen is a rare condition in which the spleen migrates from its usual anatomical position, commonly to the lower abdomen or pelvis. Epidemiology Wandering spleen is rare, with a reported incidence of <0.5%. Diagnosis is most commonly made between ages 20 and 40 years and is more co...
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Water siphon test

The water siphon test may be performed as part of a barium swallow to assess for gastro-oesophageal reflux. It is performed in the supine RPO position with the patient drinking water continuously. The test is said to be positive if there is visible barium reflux in the oesophagus, and is more se...
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Whipple disease

Whipple disease is a rare infectious multisystem disorder caused by the actinobacteria Tropheryma whipplei. Epidemiology The incidence of Whipple disease is not truly known, one Swiss study estimated it at approximately 1 per 1.5 million per year 7. The peak age for presentation is in the fif...
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Whipple disease (gastrointestinal manifestations)

Gastrointestinal manifestations are a key component of Whipple disease.  The gastrointestinal manifestations of Tropheryma whipplei are also known as intestinal lipodystrophy. Pathology Extensive infiltration of the lamina propria with large macrophages infected by intracellular T. whipplei ca...
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Whipple procedure

The Whipple procedure (or partial pancreaticoduodenectomy) is considered the definitive surgical operation to resect carcinoma in the head of the pancreas, periampullary carcinoma, or duodenal carcinoma 1. Procedure In the procedure, the head of the pancreas and adjacent duodenum is resected. ...
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Whipple triad

Whipple triad is the clinical presentation of pancreatic insulinomas and consists of: fasting hypoglycemia (<50 mg/dl) symptoms of hypoglycemia immediate relief of symptoms after the administration of IV glucose History and etymology As a good piece of trivia, one would suspect that Whipple...
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Whirlpool sign (mesentery)

The whirlpool sign of the mesentery, also known as the whirl sign, is seen when the bowel rotates around its mesentery leading to whirls of the mesenteric vessels.  Terminology The term whirlpool sign is used in other contexts: see whirlpool sign (disambiguation). Radiographic features It is...
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WHO classification of anal canal tumours

The World Health Organisation classifies anal canal neoplasms into intraepithelial neoplasms and invasive neoplasms which are further divided to epithelial and non-epithelial tumours and secondary lesions: Epithelial tumours squamous cell carcinoma of anal canal adenocarcinoma of anal canal ...
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WHO classification of anal margin tumours

The WHO classification of anal margin tumours or perianal skin tumours is: intraepithelial tumours Bowen disease (precursor of squamous cell carcinoma) Paget's disease (precursor of adenocarcinoma) invasive tumours squamous cell carcinoma adenocarcinoma basal cell carcinoma  verrucous ca...
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Widening of the presacral space (differential)

Widening of the presacral space is one of the diagnostic indicators of the diseases involving pelvic pathology and rectal involvement. It is ideally measured on barium studies at the level of S3/4 disc level on lateral radiographs and the normal value of the presacral space is <15 mm in adults.​...
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Windsock sign (duodenal web)

The windsock sign is a typical appearance of a duodenal web (intraluminal duodenal diverticulum) on upper gastrointestinal contrast series which consists of an intraduodenal barium contrast-filled sac that is surrounded by a narrow lucent line (web or intraluminal mucosal diaphragm) which is wel...
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Wound dehiscence

Wound dehiscence is a surgical complication whereby there is rupture of a wound along the surgical scar (dehiscence, refers to "splitting open"). This may occur on the skin surface, or along a deeper suture line. Clinical presentation Presentation may be with pain (e.g. sternal dehiscence), or...
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X-marks-the-spot sign (large bowel volvulus)

The X-marks-the-spot is a sign of complete bowel volvulus and refers to the crossing loops of the bowel at the site of the transition. It has been reported to improve diagnostic confidence in detecting caecal and sigmoid volvulus. This is in contrast to the split-wall sign which indicates partia...
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Zebra spleen

Zebra spleen, also referred to as psychedelic spleen or more correctly inhomogeneous splenic enhancement refers to the transient heterogeneous parenchymal enhancement of the spleen during the arterial or early portal venous phases of contrast enhancement in CT, MRI, or ultrasound imaging. It is...
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Zenker diverticulum

Zenker diverticulum, also known as a pharyngeal pouch, is a posterior outpouching of the hypopharynx, just proximal to the upper oesophageal sphincter through a weakness in the muscle layer called the Killian dehiscence. Epidemiology More than 50% of the affected patients present in 60-80 year...
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Zollinger-Ellison syndrome

Zollinger-Ellison syndrome (ZES) is a clinical syndrome that occurs secondary to a gastrinoma.  Clinical presentation Diagnosis of ZES is often delayed by 5-7 years after the onset of symptoms 2.  Pathology Gastrinomas are usually multiple and typically located in the duodenum (more common) ...
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Zuelzer-Wilson syndrome

The Zuelzer-Wilson syndrome (total colonic aganglionosis) is a subset of Hirschsprung disease, in which the whole colon is aganglionic. It is uncommon and accounts for 2-13% of cases of Hirschsprung disease 3. Multiple procedures have been devised to treat the condition, including proctocolectom...

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