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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.
Wiberg type 1 or a
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
The interpedicular distance, which is the distance measured between the pedicles on frontal/coronal imaging, can be widened in a number of situations.
conditions that can cause dural ectasia (can potentially cause widening)
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...
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....
Widow's peak hair anomaly refers to a frontal hairline projection.
Prominent V-shaped hairline projection. Ocular hypertelorism might be...
Wildervanck syndrome, also known as cervico-ocular-acoustic dysplasia, consists of the triad of:
congenital ossicular anomalies: usually diffuse ossicular ankylosis and sensorineural deafness
Duane syndrome: an ocular motility disturbance due to fibrosis of the extraocul...
Wilhelm C Roentgen (1845-1923) was a German physicist who is celebrated globally for his discovery of x-rays on 8 November 1895.
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...
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.
William David Coolidge was born on 23 October 1873 on a small ...
Williams-Campbell syndrome (WCS) is a rare form of congenital cystic bronchiectasis, in which distal bronchial cartilage is defective.
Williams-Campbell syndrome may present with recurrent pneumonia, wheezing, barrel-chest deformity, and Harrison sulcus 8.
Williams syndrome (WS), sometimes called Williams-Beuren syndrome, is characterized by some or all of the following features:
craniofacial dysmorphism (e.g. elfin facies)
short stature (50% of cases)
mild to moderate intellectual disability
supravalvular aortic stenosis ...
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...
Wilms tumor, also known as nephroblastoma, is a malignant pediatric renal tumor.
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...
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.
confined to kidney
complete resection possible
Wilson disease, also known as hepatolenticular degeneration, is a rare autosomal recessive disorder of copper metabolism affecting multiple systems.
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...
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...
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.
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.
Reported manifestations include 1-3
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...
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...
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.
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...
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...
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...
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 ...
The windsock sign can refer to different anatomical structures or pathologies:
windsock sign (duodenal web)
windsock sign (aortic dissection)
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...
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...
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...
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 ...
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.
It may be an incidental...
Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency disease.
The incidence currently quoted is approximately 4 per million live male births, although there can be regional variation. Rarely occurs in females.
It has a characteristic phenotype that inc...
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...
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.
The Wolff-Chaikoff effect is thought to be...
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...
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...
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...
Wolf-Hirschhorn syndrome (WHS) is an extremely rare chromosomal anomaly characterized by partial deletion of the p arm of chromosome 4 (4p16.3).
There is a large clinical spectrum:
agenesis of the corpus callosum
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...
Wolman disease is a rare autosomal recessive inborn error of metabolism resulting in the deposition of fats in multiple organs.
Patients with Wolman disease typically present during the first two months of life with failure to thrive, diarrhea and vomiting. Abdominal dis...
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...
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...
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...
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...
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...
A mnemonic to remember ten of the numerous conditions associated with Wormian bones is:
O: osteogenesis imperfecta
K: kinky hair syndrome
C: cleidocranial dysostosis
O: otopalatodigital syndrome
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.
Presentation may be with pain (e.g. sternal dehiscence), or...
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.
The ligament o...
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.
The wrist is made up of three joint articulations 1:
radiocarpal: concave distal surface of the radius and the atta...
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.
The carpal bridge view is requested to assess the dorsal aspect of the scaphoid, lunate and the tri...
The carpal tunnel view is an axial projection to demonstrate the medial and lateral prominences and the concavity.
This carpal tunnel view is seldom performed however it can be utilized to investigate potential hook of hamate, pisiform and trapezium factures.
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 is seated in front of the table
both hands are pl...
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
This is not a requested view, rather an adaptation to a tricky situation. Most often this projection is conducted on patients who ar...
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.
The lateral wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infective processes, injuries the distal...
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.
intrinsic ligaments (only attach to ...
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.
The oblique wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infecti...
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.
The PA wrist radiograph is requested for myriad reasons including but not limited to trauma, suspected infective processes, injuries t...
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...
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.
Suspected abnormality at the ulnar aspect of the wrist, or in conjunction with a PA and ulnar deviation view to assess carpal move...
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...
Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy!
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 ...
Wrist x-rays are commonly used for the assessment of the wrist following trauma. This is usually a fall onto an outstretched hand.
It is useful to have a systematic approach; I tend to start proximally and work distally looking at structures on both views together:
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.
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.
distal radius and ulna have smooth joint surface
carpal arcs are smooth
carpal bones do not overlap
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...
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.
trauma with suspected fracture
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.
Wunderlich syndrome is a rare condition in which spontaneous non-traumatic renal hemorrhage occurs into the subcapsular and perirenal spaces.
Wunderlich syndrome is clinically characterized by Lenk's triad:
acute flank pain
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...
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.
It is seen predominantly i...
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.
Xanthogranulomatous pyelonephritis is seen essentially in all age gro...
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...
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...
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 ...
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
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
Xerostomia is the medical term for a dry mouth, and is most commonly due to hyposalivation.
Xerostomia is the most frequently observed salivary abnormality in clinical practice 1.
dryness of the mouth
vocalisation difficulties: to...
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.
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...
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).
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 ...
X-linked Opitz G/BBB syndrome (XLOS) is an x-linked disorder with a spectrum of congenital anomalies. Anomalies that may be seen are:
broad nasal bridge
cleft lip and/or palate
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...
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...
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...
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:
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.
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...
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...
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...
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).
type I: small pure cisternal fistula between the vein of Galen (voG) and either the pericallosal arteries (anteri...
Yaws, also known as framboesia, is a tropical disease produced by the Treponema pallidum subspecies pertenue.
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...