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.

1,093 results found
Article

Target sign (pyloric stenosis)

The target sign of pyloric stenosis is a sign seen due to hypertrophied hypoechoic muscle surrounding echogenic mucosa, seen in pyloric stenosis. This is likened to that of a target. See also antral nipple sign cervix sign of pyloric stenosis shoulder sign of pyloric stenosis
Article

Tc-99m labeled RBC

Tc-99m labelled RBC is one of the technetium radiopharmaceuticals used in the assessment of GI bleeding. Characteristics photon energy: 140 KeV physical half life: 6 hours biological half life:  normal distribution: heart, vessels, spleen miscellaneous facts: threshold for detection is 0....
Article

Tc-99m pertechnetate

Tc-99m pertechnetate is one of the technetium radiopharmaceuticals used in imaging of thyroid, colon, bladder and stomach. Characteristics photon energy: 140 keV physical half-life biological half-life: 6 hours normal distribution: stomach, thyroid, salivary glands, (testicles) excretion: ...
Article

Tc-99m sulfur colloid

Technetium-99m sulfur colloid is one of the technetium radiopharmaceuticals. Characteristics photon energy: 140 keV physical half-life: 6 hours biological half-life normal distribution: liver: 85% spleen: 10% bone marrow: 5% excretion: hepatic target organ: liver, spleen pharmacokinet...
Article

Teardrop sign (superior mesenteric vein)

The teardrop sign of the superior mesenteric vein is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer. Radiographic feat...
Article

Telltale triangle sign

The telltale triangle sign, also known as the triangle sign or telltale triangle, is a radiographic sign seen on plain abdominal radiograph that signifies presence of pneumoperitoneum 1. It describes the appearance of a radiolucent triangle of gas formed between three loops of bowel or between t...
Article

Tension gastrothorax

Tension gastrothorax describes a rare life-threatening condition caused by mediastinal shift due to a distended stomach herniating into the thorax through a diaphragmatic defect.  Clinical presentation Presentation is generally with acute and severe respiratory failure, with clinical features ...
Article

Tension pneumoperitoneum

Tension pneumoperitoneum is a special and rare type of pneumoperitoneum, in which the free intra-abdominal peritoneal gas is under pressure. Pathology The mechanism is thought to be a ball-valve effect allowing the one-way accumulation of gas. This results in: elevation and splinting of the d...
Article

Terminal ileitis (differential)

The differential diagnosis for a terminal ileitis is quite extensive, and includes: inflammatory bowel disease Crohn disease (most common) backwash ileitis due to ulcerative colitis infectious colitis Yersinia spp.  Yersinia enterocolitica Yersinia pseudotuberculosis Salmonella spp. ​Sa...
Article

Terminal ileum

The terminal ileum is the most distal segment of small bowel. It immediately precedes the small bowel's connection with the colon through the ileocecal valve. It is of particular interest since a number of infectious and inflammatory processes preferentially involve the segment. location: the m...
Article

Thumbprinting

Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by edema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen. Pathology Etiology Th...
Article

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...
Article

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...
Article

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. ...
Article

Tracheo-esophageal fistulation

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

Transhiatal esophagectomy

Transhiatal esophagectomy is a type of esophagectomy, a surgery that removes the distal esophagus, usually for esophageal carcinoma. Removal of the esophagus can be performed through the chest wall (a transthoracic esophagectomy), but the thoracotomy is a major component of patient pain and com...
Article

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 celiac disease and Crohn disease but is most freq...
Article

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 visualized at this level, altho...
Article

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...
Article

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...
Article

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...
Article

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.
Article

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...
Article

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...
Article

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...
Article

Tumors of the small intestine

The small intestine is rarely the site of malignant tumors, 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 tumor types have been described.  In this article, an overview will be given of the most...
Article

Tumor-to-tumor metastasis

A tumor-to-tumor metastasis, also known as a collision tumor, is a rare metastatic process in which a primary malignant tumor ('donor') metastasises to another tumor ('recipient'), most commonly a benign tumor such as a meningioma. Epidemiology Tumor-to-tumor metastasis is considered very rare...
Article

Turcot syndrome

Turcot syndrome is one of the variations in polyposis syndromes. It is characterized 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...
Article

Twinkling artifact

Twinkling artifact is the result of intrinsic machine noise seen with color Doppler ultrasound 1. It occurs as a focus of alternating colors 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 associa...
Article

Typhlitis

Typhlitis, also called cecitis or neutropaenic colitis, is a necrotizing inflammatory condition which typically involves the cecum and, sometimes, can extend into the ascending colon or terminal ileum. Epidemiology Typhlitis was first described in children with leukemia and severe neutropaenia...
Article

Typhoid fever

Typhoid fever or just typhoid is an infectious disease caused by the Salmonella enterica serovar Typhi bacterium, usually spread by the orofecal route. The condition is characterized by severe fever, acute systemic symptoms, with occasionally serious enterocolic complications. Terminology Do n...
Article

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...
Article

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...
Article

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...
Article

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...
Article

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...
Article

Upper gastrointestinal bleeding (differential)

An upper gastrointestinal bleed usually refers to bleeding proximal to the ligament of Treitz. Pathology Causes peptic ulcer gastritis esophagitis duodenitis Mallory-Weiss tear varices tumor vascular abnormality vascular ectasia angiodysplasia Dieulafoy lesion vascular malformation...
Article

Upper GI study

Upper GI studies are a fluoroscopic evaluation of the esophagus, 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 ...
Article

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.
Article

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...
Article

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 ...
Article

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...
Article

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...
Article

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...
Article

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...
Article

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 (esophagus) vestibule (vulva) History and etymology Vestibule derives ultimately from the Latin...
Article

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...
Article

Videofluoroscopic swallow study

Videofluoroscopic swallow studies (also often called modified barium swallow studies) are a variation on traditional barium swallow studies. Although typical barium swallow studies / esophagrams evaluate the pharynx, the goal in these studies is to even more closely evaluate the oral cavity, pha...
Article

VIPoma

VIPomas are a very rare type of pancreatic endocrine tumor that secrete, and get their name from, vasoactive intestinal peptide (VIP). The clinical syndrome resulting from these tumors is commonly known as WDHA syndrome, as an acronym of the cardinal symptoms of watery diarrhea, hypokalemia, and...
Article

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 etiology. The conventional wisdom bei...
Article

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...
Article

Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterized by the development of numerous benign and malignant tumors in different organs (at least 40 types 1) due to mutations in the VHL tumor suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-50,...
Article

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...
Article

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...
Article

Water siphon test

The water siphon test may be performed as part of a barium swallow to assess for gastro-esophageal 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 esophagus, and is more sens...
Article

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...
Article

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...
Article

Whipple procedure

The Whipple procedure (or partial pancreaticoduodenectomy) is considered the definitive surgical operation to resect carcinoma of 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. ...
Article

Whipple triad

Whipple triad is the clinical presentation of pancreatic insulinoma and consists of: fasting hypoglycemia (<50 mg/dL) symptoms of hypoglycemia immediate relief of symptoms after the administration of IV glucose History and etymology The triad and also the Whipple procedure were both named a...
Article

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...
Article

WHO classification of anal canal tumors

The World Health Organization classifies anal canal neoplasms into intraepithelial neoplasms and invasive neoplasms which are further divided to epithelial and non-epithelial tumors and secondary lesions: Epithelial tumors squamous cell carcinoma of anal canal adenocarcinoma of anal canal mu...
Article

WHO classification of anal margin tumors

The WHO classification of anal margin tumors or perianal skin tumors is: intraepithelial tumors Bowen disease (precursor of squamous cell carcinoma) Paget's disease (precursor of adenocarcinoma) invasive tumors squamous cell carcinoma adenocarcinoma basal cell carcinoma  verrucous carcin...
Article

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 disk level on lateral radiographs and the normal value of the presacral space is <15 mm in adults.​...
Article

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...
Article

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...
Article

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 cecal and sigmoid volvulus. This is in contrast to the split-wall sign which indicates partial...
Article

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...
Article

Zenker diverticulum

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

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) ...
Article

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...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.