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...
Wind-swept pelvis fracture is a combination a 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 same forces cause external rotation of t...
The (absent) pedicle sign, also called the winking owl sign, occurs on plain film when a pedicle is absent.
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other open eye, and the spinous process to the beak of the animal on ...
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 choledochocele and santorinicele.
It may be an incidental f...
Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency disease with a characteristic clinical phenotype that includes:
X-linked recessive and only occurs in boys
petechiae, bloody diarrhoea, epistaxis due to thrombocytopaenia with small platelets
eczema starts in first month of life
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. In both the male and the female the Wolffian duct develops into the trigone of the urinary bladder.
In the female, in...
Wolf-Hirschhorn syndrome (WHS) is an extremely rare chromosomal anomaly characterised by partial deletion of the p arm of chromosome 4 (4p16.3).
agenesis of the corpus callosum
cleft lip + / - palate...
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, diarrhoea and vomiting. Abdominal di...
Wormian bones (a.k.a. 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 proximate to...
A mnemonic to remember ten of the numerous conditions associated with Wormian bones is:
P - pyknodysostosis
O - osteogenesis imperfecta
R - rickets
K - kinky hair syndrome
C - cleidocranial dysostosis
H - hypothyroidism/hypophosphatasia
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 are longitudinal vertical meniscal tears. They occur at the 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 carpal bridge view an additional view to the three view series of the wrist and carpal bones. It is used to assess the dorsal aspect of the scaphoid, lunate and the triquetrum.
the patient is seated alongside the table
dorsal aspect of affected wrist is placed on the dete...
The carpal tunnel view is an axial projection to demonstrate the medial and lateral prominences and the concavity. It can be utilised to investigate potential hook of hamate, pisiform and trapezium factures.
patient stands with the back facing the table
palmar surface of hand...
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. It is the orthogonal projection of the PA wrist without any patient movement, making it the most appropriate projection for patients in pain.
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.
patient is seated alongside the table
the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table
abduct the hum...
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.
patient is seated alongside the table
the affected arm if possible is flexed at 90° so the arm and wrist can ...
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.
patient is seated alongside the table
the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table
Wrist radiographs are ubiquitous in the emergency departments. They are commonly performed in the paediatric 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 a skeletal survey looking for metabolic d...
Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy!
Distal radial contour
Check the contour of the distal radius:
the distal radial articular surface should cup the carpals
the articular surface should ...
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:
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
apart from pisiform and trapezium
metacarpals do not overlap and distal...
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...
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 Orthopaedic service.
This is a summary article. For more information, you can re...
Wunderlich syndrome is a rare condition, in which spontaneous nontraumatic renal haemorrhage occurs into the subcapsular and perirenal spaces 2.
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 is an uncommon inflammatory disease of the gallbladder which may be difficult to differentiate from malignancy, both on imaging and pathologically. It is characterised by presence of multiple intramural nodules.
It is seen predominantly in female ...
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 tumours. They are characterised by cells with a lipid-filled vacuolated cytoplasm.
Although reported numbers are too small to confirm that this is defini...
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 an not 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.
photon energy: 81 KeV
physical half-life: 5.27 days
biological half-life: 30 seconds
normal distribution: lungs
<15% of inhaled gas is absorb...
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 ...
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 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...
Artifacts can present in a variety of ways including abnormal shadow 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 film, comp...
X-ray film displays the radiographic image and consists of emulsion (single or double) of silver halide (AgBr is most common) which when exposed to light, produces silver ion (Ag+) and electron. The electrons get attached to the sensitivity specks and attract the silver ion. Subsequently, the si...
X-rays in the diagnostic range interact with matter primarily via two processes, which are fundamental in understanding how an image is formed in a radiographic exam. These process 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-rays represent a form of electromagnetic radiation. They are produced by the x-ray tube, using the high voltage to accelerate the electrons produced by the cathode. The produced electrons interact with the anode, thus producing x-rays. The x-rays produced include Bremsstrahlung and the charact...
An x-ray tube functions as a specific energy converter, receiving the electrical energy and converting it into two other forms of energy: x-radiation and heat. Heat is considered the undesirable product of this conversion process; therefore x-radiation is created by taking the energy from the el...
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...
The yellow nail syndrome (YNS) is rare disorder principally affecting lymphatic system
It is characterised by
nail discolouration: yellow slow growing dystrophic nails
peripheral / primary lymphoedema
exudative pleural effusions (least common manifestation)
The yin-yang sign is a radiological sign described in both true and false aneurysms on various imaging modalities.
The yin-yang sign indicates bidirectional flow due to swirling of blood within the (true or false) aneurysm.
Yolk sac is the first anatomical structure identified within the gestational sac. It plays a critical role in embryonal development by providing nutrients, serving as the site of initial haematopoiesis, providing endocrine, metabolic and immunological functions and contributing to the developmen...
The Young and Burgess classification is a modification of the Tile classification 1. It is the recommended 5 and most widely used classification system for pelvic ring fractures.
It takes into account force type, severity, and direction, as well as injury instability.
Young's modulus is a relationship between elasticity, strain, and stress:
elasticity x (change in length / original length) = (force / area)
put another way, this is
elasticity x (strain) = stress
elasticity = stress / strain
The units of elasticity are in kPa.
This relationship is fun...
Young syndrome shares similar clinical and radiological findings to primary ciliary dyskinesia and cystic fibrosis, however the underlying pathogenesis yet to be fully elucidated. Obstructive azoopsermia at the level of the epididymis is thought to be the cause of infertility. The commonly refer...
The Y sign refers to a common appearance in lumbar epidural lipomatosis where excess fat in the extradural space compresses the dural sac into the shape of the letter "Y".
Yunis Varón syndrome is a rare skeletal dysplasia. It is thought to be autosomal recessive.
severe neurologic impairment
diastasis of sutures
absent thumbs and distal phalanges of fingers
The Zabramski classification of cerebral cavernomas has been proposed as a way of classifying cerebral cavernous malformations, and although not used in clinical practice it is useful in scientific publications that seek to study cavernous malformations.
The classification was proposed in 1994 ...
The Z deformity is one of the musculoskeletal manifestation of rheumatoid arthritis in hand:
radial deviation at the wrist
ulnar deviation of the digits, and often
palmar subluxation of the proximal phalanges
The zebra sign has been termed to describe the finding of layering of blood in amongst the folia of the cerebellum, particularly in the setting of remote cerebellar haemorrhage.1
This type of haemorrhage is characterised by a streaky pattern, like a zebra's stripes, due to blood spreading in th...
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.
Zebra stripes/artifacts appear as alternating bright and dark bands in a MRI image. The term has been used to describe several different kind of artifacts causing some confusion.
Artifacts that have been described as a zebra artifact include the following:
Moire fringes 1,2
The zebra stripe sign occurs where children with osteogenesis imperfecta have been treated with cyclical bisphosphonate therapy, e.g. pamidronate. When the drug is delivered in cycles, dense bone is formed while treatment is being given. This results in dense stripes across the metaphyses of bon...
Zellweger syndrome (ZS), also known as the cerebrohepatorenal syndrome, is a multisystem metabolic abnormality. As the name implies it primarily affects the central nervous system (CNS), liver and kidneys.
The condition typically presents in neonates with poor feeding and/or seiz...
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.
More than 50% of the affected patients present in 60-80 year...
Zero fill artifact is one of many MRI artifacts and is due to data in the K-space array missing or set to zero during scanning. The abrupt change from signal to no signal results in artifacts in the images showing alternating bands of shading and darkness, often in an oblique direction.
Zero filling interpolation (ZIP) is the substitution of zeroes for unmeasured data points in order to increase the matrix size of the new data prior to Fourier transformation of MR data. This results in pixels smaller than the actual resolution of the image. The zero filling occurs in the periph...
Zimmerman-Laband syndrome is a rare congenital syndrome, characterized primarily by gingival hypertrophy and skeletal abnormalities.
The molecular basis of the syndrome is currently unknown. An autosomal dominant mutation with high mutation rate and rare instances of germinal mosaic...
Zinner syndrome is a triad of Wolffian duct anomalies that include unilateral renal agenesis, ipsilateral seminal vesicle cyst, and ejaculatory duct obstruction 1.
Patients are typically diagnosed at 3rd or 4th decade of life and often present with perineal pain, recurren...
In MR imaging, zipper artifact refers to a type of MRI artefact where one or more spurious bands of electronic noise extend perpendicular to the frequency encode direction and is present in all images of a series.
There are various causes for zipper artifacts in images. Most of them are...
Zollinger-Ellison syndrome (ZES) is a clinical syndrome that occurs secondary to a gastrinoma.
Diagnosis of ZES is often delayed by 5-7 years after the onset of symptoms 2.
Gastrinomas are usually multiple and typically located in the duodenum (more common) ...
The zona orbicularis are circular fibres of the hip joint capsule and form a collar around the femoral neck. Though partly blended with the pubofemoral and ischiofemoral ligaments, these fibres are not directly attached to bone.
Z-scores are a way to translate individual data points into terms of a standard deviation.
Z = (X - Xbar) / σ
X: individual data point
Xbar: the arithmetic mean
σ: the standard deviation
The purpose of the Z-score is to allow comparison between values in different normal distributions. Two...
Zuckerkandl tubercle is a normal variant of the thyroid and may be mistaken for a thyroid nodule, mass or lymph node. It is a projection of normal thyroid tissue from the posterior aspect of the lateral lobes of the thyroid gland.
The tubercle is also an important surgical landmark due to its ...
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...
The zygoma (or zygomatic bone) is an important facial bone which forms the prominence of the cheek. It is roughly quadrangular in shape.
Zygoma has three surfaces, five borders, and two processes.
anterolateral surface is convex, pierced at its orbital border by the zy...
The zygomatic arch is formed by the union of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone at the zygomaticotemporal suture.
Le Fort type 3 fracture
zygomaticomaxillary complex fracture
The zygomatic nerve is a main branch of the maxillary division of the trigeminal nerve. It should not be confused with the zygomatic branch of the facial nerve.
The zygomatic nerve divides off the maxillary division just after emerging from the foramen rotundum to enter the ptery...
The zygomaticofacial foramen is a small foramen in the mid lateral surface of the zygomatic bone that transmits the zygomaticofacial nerve (a branch of the zygomatic nerve from the maxillary division of the trigeminal nerve) and zygomaticofacial vessels.
The zygomaticofacial nerve is the smaller of the two branches of the zygomatic nerve, from the maxillary division of the trigeminal nerve. It is sometimes referred to as the malar branch of the zygomatic nerve. It leaves the inferolateral aspect of the extraconal space of the orbit through the z...
Zygomaticomaxillary complex (ZMC) fractures, also known as a tripod, tetrapod, quadripod, malar or trimalar fractures, are seen in the setting of traumatic injury to the face. They comprise fractures of the:
inferior orbital rim, and anterior and posterior maxillary sinus walls
The zygomaticomaxillary suture is between the zygomatic process of the maxilla and the maxillary margin of the zygomatic bone.
The zygomaticotemporal foramen is a small foramen in the anteromediall surface of the zygomatic bone that transmits the zygomaticotemporal nerve (a branch of the zygomatic nerve from the maxillary division of the trigeminal nerve) and zygomaticotemporal vessels.
The zygomaticotemporal nerve is the larger of the two branches of the zygomatic nerve, from the maxillary division of the trigeminal nerve. It is primarily sensory but also relays parasympathetic fibres to the lacrimal nerve from the pterygopalatine ganglion which reach the lacrimal gland. It le...