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.

14,837 results found
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Why upload cases to Radiopaedia.org

Radiopaedia.org is more than just an amazing collaborative resource, it is also the perfect place to keep your case library.  Here are a few reasons why you should upload your cases to Radiopaedia.org: free registration unlimited storage capacity for all your cases support for scrollable sta...
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Wiberg classification of patella shape

Wiberg classification is a system used to describe the shape of the patella based mainly on the asymmetry between the patellar medial and lateral facets on axial views of the patella. Increasing number type indicates a larger degree of asymmetry. Classification Wiberg type 1 or a roughly symm...
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Widened intercondylar notch

A widened intercondylar notch on knee radiographs is a sign associated with: haemophilic arthropathy (most commonly bilateral) juvenile rheumatoid arthritis (most commonly bilateral) tuberculous arthropathy (usually unilateral) 3
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Widening of interpedicular distance

The interpedicular distance, which is the distance measured between the pedicles on frontal/coronal imaging, can be widened in a number of situations. Pathology Etiology diastematomyelia syringomyelia conditions that can cause dural ectasia (can potentially cause widening) Marfan syndrome ...
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Widening of the diploic space

Widening of the diploic space refers to expansion of the cancellous (spongy) bone between the inner and outer tables of the calvaria. The diploic space is the medullary cavity of the skull, and a location of normal physiologic hematopoiesis in adults. Thus, expansion of this structure most commo...
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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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Widow's peak hair anomaly

Widow's peak hair anomaly refers to a frontal hairline projection. Epidemiology Associations Aarskog syndrome Opitz syndrome Waardenburg syndrome frontonasal dysplasia craniofrontonasal dysplasia Clinical presentation Prominent V-shaped hairline projection. Ocular hypertelorism might be...
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Wildervanck syndrome

Wildervanck syndrome, also known as cervico-ocular-acoustic dysplasia, consists of the triad of: Klippel-Feil syndrome congenital ossicular anomalies: usually diffuse ossicular ankylosis and sensorineural deafness Duane syndrome: an ocular motility disturbance due to fibrosis of the extraocul...
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Wilhelm Roentgen

Wilhelm C Roentgen (1845-1923) was a German physicist who is celebrated globally for his discovery of x-rays on 8 November 1895. Early life Wilhelm Conrad Roentgen (Röntgen in German) was born on 27 March 1845 in Lennep, Germany. He attended the primary and secondary school run by Martinus Her...
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William D Coolidge

William D Coolidge (1873-1975) was an American physicist who revolutionised radiology with his groundbreaking x-ray tube, the underlying technology of which remains at the core of every machine more than a century later. Early life William David Coolidge was born on 23 October 1873 on a small ...
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Williams-Campbell syndrome

Williams-Campbell syndrome (WCS) is a rare form of congenital cystic bronchiectasis, in which distal bronchial cartilage is defective. Clinical presentation Williams-Campbell syndrome may present with recurrent pneumonia, wheezing, barrel-chest deformity, and Harrison sulcus 8. Pathology It ...
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Williams syndrome

Williams syndrome (WS), sometimes called Williams-Beuren syndrome, is characterized by some or all of the following features: craniofacial dysmorphism (e.g. elfin facies) oral abnormalities short stature (50% of cases) mild to moderate intellectual disability  supravalvular aortic stenosis ...
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Will Rogers phenomenon

The Will Rogers phenomenon is encountered in many disciplines but is particularly relevant to radiology in the setting of staging scans and is due to reclassifying borderline individuals also known as stage migration 1. The most common example in medicine is upstaging certain patients with mali...
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Wilms tumor

Wilms tumor, also known as nephroblastoma, is a malignant pediatric renal tumor. Epidemiology Wilms tumors are the most common pediatric renal mass, accounting for over 85% of cases 1,8 and accounts for 7% of all childhood cancers 12. It typically occurs in early childhood (1-11 years) with pe...
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Wilms tumor (staging)

Wilms' tumor staging is largely anatomical and relates to the invasion and spread of the tumor. Where there is invasion or metastasizes, prognosis is poorer. Wilms tumor, is one of the more common childhood malignancies. stage I confined to kidney complete resection possible stage II local ...
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Wilson disease

Wilson disease, also known as hepatolenticular degeneration, is a rare autosomal recessive disorder of copper metabolism affecting multiple systems.  Epidemiology Wilson disease is commonly found in Japan. It affects 1 in 30,000-40,000 individuals 12. 1 in 90 individuals are a heterozygous car...
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Wilson disease (CNS manifestations)

Wilson disease, also known as hepatolenticular degeneration, is a multisystem disease due to abnormal accumulation of copper. It is characterized by early onset liver cirrhosis with CNS findings most frequently affecting the basal ganglia and midbrain. This article aims to discuss the central n...
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Wilson disease (hepatobiliary manifestations)

Hepatobiliary manifestations of Wilson disease vary largely from fatty changes to cirrhosis and occasionally fulminant hepatic necrosis. They result from accumulation of copper in the liver. For a general discussion of the underlying condition, please refer to the article Wilson disease.  Epid...
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Wilson disease (musculoskeletal manifestations)

Wilson disease, also known as hepatolenticular degeneration, is a multisystem disease, which rarely has musculoskeletal manifestations secondary to the accumulation of copper in the articular cartilage.  Radiographic features Plain radiographs Reported manifestations include 1-3 premature os...
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Wilson Mikity syndrome

Wilson Mikity syndrome (WMS) refers to chronic lung disease in premature infants, characterized by early development of cystic interstitial emphysema (PIE). This is now sometimes considered as part of the spectrum of bronchopulmonary dysplasia. History and etymology Almost 51 years ago, Wilson...
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Wiltse classification (spondylolisthesis)

Spondylolisthesis can be classified according to broad etiologies as described by Wiltse in 1981 1. Typically when reporting studies with spondylolisthesis the Wiltse type is merely stated without referring to its number, whereas the grade of spondylolisthesis is explicitly stated: e.g. "Grade 1...
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Wimberger ring sign

Wimberger ring sign, often simply just called Wimberger ring, refers to a circular calcification surrounding the osteoporotic epiphyseal center of ossification in scurvy, which may result from bleeding. It must not be confused with Wimberger sign, pathognomonic for congenital syphilis. History...
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Wimberger sign

The Wimberger sign, also called Wimberger corner sign, refers to localized bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign for congenital syphilis. It must not be mixed up with Wimberger ring sign seen in scurvy, which is sometimes also confusingly re...
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Windmill artifact

In CT imaging, the windmill artifact is an image distortion in the axial plane, encountered during helical multidetector acquisitions. The telltale appearance is characterized by equally distanced bright streaks diverging from a focal high-density structure. The streaks seemingly rotate while sc...
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Windowing (CT)

Windowing, also known as grey-level mapping, contrast stretching, histogram modification or contrast enhancement is the process in which the CT image greyscale component of an image is manipulated via the CT numbers; doing this will change the appearance of the picture to highlight particular st...
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Windsock sign (aortic dissection)

The windsock sign refers to appearances seen in type A thoracic aortic dissections on contrast CT. It results from intimointimal intussusception between the true and false dissected lumens of the thoracic aorta. The altering density of contrast between the dissection lumens which taper distally ...
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Windsock sign (disambiguation)

The windsock sign can refer to different anatomical structures or pathologies: windsock sign (duodenal web) windsock sign (aortic dissection)
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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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Windswept pelvis

Windswept pelvis fracture is a complex bony pelvic injury caused by a combination of unilateral AP compression (open book) injury with a contralateral lateral compression injury.  It occurs when the internal rotation of one iliac wing causes a unilateral sacral compression fracture, while the s...
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Winking owl sign (spine)

The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent 5. The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to...
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Winquist classification of femoral shaft fractures

The Winquist classification of femoral shaft fractures is based on fracture comminution and was proposed by Winquist in 1980. This classification is used with regards to management decision making, in determining whether a fracture requires an intramedullary nail or open reduction.  Type 0: no ...
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Wirsungocele

Wirsungocele refers to a cystic dilatation of the pancreatic duct of Wirsung, which is the portion of ventral duct between the dorsal-ventral junction and major duodenal papilla. It is believed to be analogous to a choledochocele and santorinicele. Clinical presentation It may be an incidental...
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Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency disease. Epidemiology The incidence currently quoted is approximately 4 per million live male births, although there can be regional variation. Rarely occurs in females. Clinical presentation It has a characteristic phenotype that inc...
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Woggle technique (interventional procedure)

The Woggle technique is the purse-string suture modified using to close a puncture site after a percutaneous procedure. Techniques common to all procedure include: a purse-string suture is done around the introducer sheath (the short plastic tube placed within a vein or artery) cut the needle...
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Wolff-Chaikoff effect

Wolff-Chaikoff effect is an autoregulatory phenomenon, whereby a large amount of ingested iodine acutely inhibits thyroid hormone synthesis within the follicular cells, irrespective of the serum level of thyroid-stimulating hormone (TSH) 1.  Pathology The Wolff-Chaikoff effect is thought to be...
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Wolffian duct

The Wolffian duct (also known as the mesonephric duct) is one of the paired embryogenic tubules that drain the primitive kidney (mesonephros) to the cloaca. It also gives off a lateral branch forming the ureteric bud. In both the male and the female, the Wolffian duct develops into the trigone o...
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Wolff-Parkinson-White syndrome

The Wolff-Parkinson-White syndrome describes paroxysmal tachydysrhythmias in the presence of a specific accessory pathway which allows direct electrical connection between the atria and ventricles, which usually exclusively occurs via the atrioventricular (AV) node. The accessory pathway is usua...
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Wolff's law

Wolff's law summarizes the dynamic nature of the 3D microarchitecture of bone. Mechanical forces (or the lack of them) dynamically alter the thickness of cortical bone and the thickness and orientation of trabeculae.  Lack of sufficient mechanical loading (e.g. bed rest) results in resorption a...
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Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is an extremely rare chromosomal anomaly characterized by partial deletion of the p arm of chromosome 4 (4p16.3). Clinical presentation There is a large clinical spectrum: CNS agenesis of the corpus callosum hypertelorism coloboma seizures 4 craniofacial c...
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Wolfram syndrome (type one)

Wolfram syndrome type one, also known as DIDMOAD, is a disease caused by an autosomal recessive genetic trait, caused by mutations in the WFS1 gene, with incomplete penetrance. The syndrome presents with early onset of insulin-dependent diabetes mellitus, progressive optic atrophy, diabetes ins...
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Wolman disease

Wolman disease is a rare autosomal recessive inborn error of metabolism resulting in the deposition of fats in multiple organs.  Clinical presentation Patients with Wolman disease typically present during the first two months of life with failure to thrive, diarrhea and vomiting. Abdominal dis...
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Woodruff plexus

Woodruff plexus is a venous plexus located in the posterior end of the inferior meatus on lateral wall of nasal cavity 1,2. It accounts for between 5-10% of epistaxis and are associated with hypertension and use of aspirin and warfarin 2. These bleeds typically do not respond to anterior nasal p...
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Words we never use

There are a number of words we never use at Radiopaedia.org. This may be the result of an international consensus on correct spelling, other times it is a local decision about how we can improve consistency on the site. The term orthography is the formal term for the system of spelling for any l...
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World Health Organization (WHO)

The World Health Organization (WHO) is an agency of the United Nations (UN) that was established in 1948 and acts as the leader in coordinating global health, especially in relation to the developing world. From a radiology perspective, a key role of the WHO is in spearheading international radi...
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World Radiography Day

World Radiography Day (WRD) is an annual event held on 8 November to celebrate the anniversary of the discovery of x-rays by Wilhelm Roentgen, on 8 November 1895, and is organized by the International Society of Radiographers and Radiological Technologists (ISRRT) 1. World Radiography Day occur...
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Wormian bone

Wormian bones (also knows as intrasutural bones) is the name given to the additional small bones sometimes found between the cranial sutures of the bones of the skull vault, most commonly in relation to the lambdoid suture. Some reserve the term Wormian bones to just the intrasutural bones proxi...
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Wormian bones (mnemonic)

A mnemonic to remember ten of the numerous conditions associated with Wormian bones is: PORKCHOPS Mnemonic P: pyknodysostosis O: osteogenesis imperfecta R: rickets K: kinky hair syndrome C: cleidocranial dysostosis H: hypothyroidism/hypophosphatasia O: otopalatodigital syndrome P: prim...
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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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Wrisberg rip

Wrisberg rips, also known as zip tears or zipper tears, are longitudinal vertical meniscal tears. They occur at the junction of the ligament of Wrisberg and the posterior horn of the lateral meniscus and are commonly associated with anterior cruciate ligament tears 1.  Pathology The ligament o...
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Wrist

The wrist is a complex synovial joint formed by articulations of the radius, the articular disc of the distal radioulnar joint and the carpal bones. Gross anatomy Articulations The wrist is made up of three joint articulations 1: radiocarpal: concave distal surface of the radius and the atta...
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Wrist (carpal bridge view)

The carpal bridge view an additional view of the three view series of the wrist and carpal bones. It is a specialized projection that involves keeping the patient's wrist in flexion. Indications The carpal bridge view is requested to assess the dorsal aspect of the scaphoid, lunate and the tri...
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Wrist (carpal tunnel view)

The carpal tunnel view is an axial projection to demonstrate the medial and lateral prominences and the concavity. Indications This carpal tunnel view is seldom performed however it can be utilized to investigate potential hook of hamate, pisiform and trapezium factures. Patient position pat...
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Wrist (clenched fist view)

The clenched fist view is an additional projection used to evaluate suspected widening of the scapholunate interval, often performed bilaterally it is a functional view that requires the patient to clench both hands.  Patient position patient is seated in front of the table  both hands are pl...
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Wrist (horizontal beam lateral view)

The horizontal beam lateral wrist view is a modified lateral projection when performing the three view series of the wrist and carpal bones in trauma Indications This is not a requested view, rather an adaptation to a tricky situation. Most often this projection is conducted on patients who ar...
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Wrist (lateral view)

The lateral wrist view is part of a three view series of the wrist and carpal bones. It is the orthogonal projection of the PA wrist. Indications The lateral wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infective processes, injuries the distal...
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Wrist ligaments

The intrinsic and extrinsic wrist ligaments play a vital role in the stability of the wrist joint. There are numerous ligaments but included below are the most clinically significant. Wrist ligaments are best assessed with dedicated wrist MRI. Gross anatomy intrinsic ligaments (only attach to ...
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Wrist (oblique view)

The oblique wrist view is part of a three view series of the wrist and carpal bones. It is not generally performed in follow-up studies unless specifically requested. Indications The oblique wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infecti...
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Wrist (PA view)

The PA wrist view is part of a three view series of the wrist and carpal bones. Although performed PA the view can often be referred to an AP view. Indications The PA wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infective processes, injuries t...
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Wrist protocol (MRI)

The MRI wrist protocol encompasses a set of MRI sequences for the routine assessment of the wrist joint. Note: This article aims to frame a general concept of an MRI protocol for the assessment of the wrist. Protocol specifics will vary depending on MRI scanner type, specific hardware and softw...
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Wrist (radial deviation view)

The wrist PA radial deviation view is specialized projection employed to better demonstrate the carpal bones that lay on the ulnar aspect of the wrist. Indications Suspected abnormality at the ulnar aspect of the wrist, or in conjunction with a PA and ulnar deviation view to assess carpal move...
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Wrist radiograph

Wrist radiographs are ubiquitous in the emergency departments. They are commonly performed in the pediatric and elderly populations after a fall on an outstretched hand as well as in patients after higher force trauma. Moreover, they may be performed as part of a skeletal survey looking for meta...
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Wrist radiograph (an approach)

Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy!  Systematic review Choosing a search strategy and utilizing it consistently is a helpful method to overcome common errors seen in diagnostic radiology. The order in which you ...
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Wrist radiograph (approach)

Wrist x-rays are commonly used for the assessment of the wrist following trauma. This is usually a fall onto an outstretched hand. Systematic review It is useful to have a systematic approach; I tend to start proximally and work distally looking at structures on both views together: distal ra...
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Wrist radiograph (checklist)

The wrist radiograph checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting. Radiograph Wrist ...
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Wrist radiograph (summary approach)

This is a basic article for medical students and other non-radiologists Wrist radiographs are commonly used for the assessment of the wrist following trauma.  Summary approach alignment AP distal radius and ulna have smooth joint surface carpal arcs are smooth carpal bones do not overlap ...
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Wrist series

The wrist series is comprised of a posteroanterior, oblique, and lateral projection. The series examines the carpal bones that are consisting of the scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate. It also examines the radiocarpal and distal radiocarpal joint al...
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Wrist series (pediatric)

The wrist series for pediatrics often consist of a posteroanterior and lateral view only in order to minimize radiation dose to the patient. Depending on departmental protocols, the oblique view may also be included as a standard view.  Indications trauma with suspected fracture suspected dis...
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Wrist series (summary)

This is a basic article for medical students and other non-radiologists A wrist series (or wrist x-ray) may be performed for a multitude of reasons. However, they are most commonly used in the assessment of trauma, by clinical teams within the Emergency Department or Orthopedic service. Refere...
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Wunderlich syndrome

Wunderlich syndrome is a rare condition in which spontaneous non-traumatic renal hemorrhage occurs into the subcapsular and perirenal spaces. Clinical presentation Wunderlich syndrome is clinically characterized by Lenk's triad: acute flank pain flank mass hypovolemic shock ​Mnemonic F: f...
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Wyburn-Mason syndrome

Wyburn-Mason syndrome (also known as Bonnet-Dechaume-Blanc syndrome) is a rare, nonhereditary neurocutaneous disorder that typically presents with unilateral vascular malformations that primarily involve the brain, orbits and facial structures. It is currently classified as a craniofacial arteri...
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Xanthogranulomatous cholecystitis

Xanthogranulomatous cholecystitis (XGC) is an uncommon inflammatory disease of the gallbladder that may be difficult to differentiate from malignancy, both on imaging and pathologically. It is characterized by the presence of multiple intramural nodules. Epidemiology It is seen predominantly i...
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Xanthogranulomatous pyelonephritis

Xanthogranulomatous pyelonephritis (XGP) is a rare form of chronic pyelonephritis and represents a chronic granulomatous disease resulting in a non-functioning kidney. Radiographic features are usually specific. Epidemiology Xanthogranulomatous pyelonephritis is seen essentially in all age gro...
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Xanthomatous meningioma

Xanthomatous meningiomas are rare histological variants of meningiomas grouped into the subtype of metaplastic meningiomas, being WHO grade I tumors. They are characterized by cells with a lipid-filled vacuolated cytoplasm. Although reported numbers are too small to confirm that this is definit...
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XCCL view

An XCCL view is a supplementary mammographic view. It is a type of exaggerated cranio-caudal view. It is particularly good for imaging the lateral aspect of the breast.  It is often done when a lesion is suspected on a MLO view but cannot be seen on the CC view. In this view, the lateral aspect...
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XCCM view

An XCCM view is a supplementary mammographic view. It is a type of exaggerated cranio-caudal view. It is particularly good for imaging the medial portion of the breast. In this view, the medial portion of the breast is placed forward. A negative 15° tube tilt is suggested. An optimal XCCM view ...
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Xenon-127

Xenon-127 is a radiopharmaceutical principally used when a performing VQ scan. It is not a widely used alternative to xenon-133 with the main advantage being a higher proton energy allowing for post perfusion scanning.  photon energy: 203 KeV physical half life: 36.3 days
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Xenon-133

Xenon-133 is a radiopharmaceutical principally used when a performing VQ scan. Inhalation of this gas can also be used to assess cerebral blood flow. Mode of decay: Beta decay photon energy: 81 KeV physical half-life: 5.27 days biological half-life: 30 seconds normal distribution: lungs <1...
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Xerostomia

Xerostomia is the medical term for a dry mouth, and is most commonly due to hyposalivation. Epidemiology Xerostomia is the most frequently observed salivary abnormality in clinical practice 1. Clinical presentation dryness of the mouth uncomfortable swallowing vocalisation difficulties: to...
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Xiphisternal joint

The xiphisternal joint (or more rarely, the sternoxiphoid joint) is a symphysis between the inferior margin of the body of the sternum and the superior margin of the xiphoid process. In most people it ossifies with age, usually becoming fully fused by the age of 40 years, forming a synostosis.  ...
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Xiphisternum

The xiphisternum (also known as the xiphoid process or simply the xiphoid) is the smallest of the three parts of the sternum (manubrium, body or gladiolus, and xiphisternum). It arises from the inferior and posterior margin of the sternal body and projects inferiorly. It is a small cartilaginous...
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Xiphoid shape variations

There is considerable anatomic variation in the shape of the xiphoid of the sternum: xiphoid ending is classified as single, double, or triple. xiphoid size varies (e.g. elongated process) xiphoid morphology (e.g. ventral or dorsal deviation, hook-like, reverse S-shape). Clinical presentatio...
Article

X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy is an inherited metabolic peroxisomal disorder and one of the more common leukodystrophies in both children and adults. It is characterized by a lack of oxidation of very long chain fatty acids (VLCFAs) that results in severe inflammatory demyelination typically of ...
Article

X-linked Opitz G/BBB syndrome

X-linked Opitz G/BBB syndrome (XLOS) is an x-linked disorder with a spectrum of congenital anomalies. Anomalies that may be seen are: facial anomalies  ocular hypertelorism prominent forehead widow's peak broad nasal bridge anteverted nares cleft lip and/or palate  laryngotracheoesophage...
Article

X-marks-the-spot sign (large bowel volvulus)

The X-marks-the-spot sign of large bowel volvulus 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 obstruction...
Article

X-ray artifacts

X-ray artifacts can present in a variety of ways including abnormal shadows noted on a radiograph or degraded image quality, and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.  There are common and distinct artifacts for fi...
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X-ray film

X-ray film displays the radiographic image and consists of emulsion (single or double) of silver halide (silver bromide (AgBr) is most common) which when exposed to light, produces a silver ion (Ag+) and an electron. The electrons get attached to the sensitivity specks and attract the silver ion...
Article

X-ray interaction with matter

X-rays in the diagnostic range interact with matter primarily via two major processes, which are fundamental in understanding how an image is formed in a radiographic exam. These processes are the: photoelectric effect  Compton scatter 
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X-ray production

X-rays are produced due to sudden deceleration of fast-moving electrons when they collide and interact with the target anode. In this process of deceleration, more than 99% of the electron energy is converted into heat and less than 1% of energy is converted into x-rays. Definitions Generator ...
Article

X-ray quantity and quality

X-ray photon quantity refers to the number of photons produced during an exposure. Factors influencing x-ray quantity includes: peak voltage (kVp): beam quantity is approximately proportional to the square of the tube potential generator type/voltage waveform: reducing ripple increases beam q...
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X-rays

X-rays (or much more rarely, and usually historically, x-radiation or Roentgen rays) represent a form of ionizing electromagnetic radiation. They are produced by an x-ray tube, using a high voltage to accelerate the electrons produced by its cathode. The produced electrons interact with the anod...
Article

X-ray tube

An x-ray tube functions as a specific energy converter, receiving electrical energy and converting it into two other forms of energy: x-radiation (1%) and heat (99%). Heat is considered the undesirable product of this conversion process; therefore x-radiation is created by taking the energy from...
Article

Yasargil classification of vein of Galen aneurysmal malformations

The Yasargil classification is one of the two common systems for classifying vein of Galen malformations that is currently in use at the time of writing (mid 2016).  Classification type I: small pure cisternal fistula between the vein of Galen (voG) and either the pericallosal arteries (anteri...
Article

Yaws

Yaws, also known as framboesia, is a tropical disease produced by the Treponema pallidum subspecies pertenue. Epidemiology Yaws is a tropical disease. Infections have declined dramatically over the last century, however the disease is still present in several countries in Africa and Asia 1. Y...

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