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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.

1,278 results found
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Upper gastrointestinal bleeding

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

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

Upper limb anatomy encompasses the anatomy of the shoulder, arm, elbow, forearm, wrist and hand. This anatomy section promotes the use of the Terminologia Anatomica, the international standard of anatomical nomenclature. 
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Uterine arteriovenous malformation

Uterine arteriovenous malformations (UAVM) result from the formation of multiple arteriovenous fistulous communications within the uterus without an intervening capillary network. Epidemiology Associations Acquired UAVM disease is associated with conditions such as 4,7: multiple pregnancies ...
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Uterine artery

The uterine artery is seen bilaterally and is a branch of the anterior division of the internal iliac artery. Gross anatomy Course It runs medially in the pelvis, within the base of the broad ligament, to the outer surface of the uterus. From lateral to medial it has a descending, transverse ...
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Uterine artery embolization

Uterine artery embolization (UAE) is an interventional radiological technique to occlude the arterial supply to the uterus and is performed for various reasons. History Uterine artery embolization has been practised for more than 20 years for controlling hemorrhage following delivery/abortion,...
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Uterine artery embolization: MRI assessment

Uterine artery embolization (UAE) is used as an alternative to hysterectomy in selected patients and MRI assessment is key in allowing not only pre-procedure assessment but also assessing post-procedural outcome.   For a general discussion of the underlying condition refer to the article on ute...
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Uterine artery flow notching

Uterine artery flow notching refers to a phenomenon observed in uterine arterial Doppler ultrasound assessment. Pathology Associations The presence of notching after 22 weeks is associated with several other conditions including adverse pregnancy outcomes. These include pregnancy induced hyp...
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Uterine artery pseudoaneurysm

Uterine artery pseudoaneurysm (UAP) is a rare cause of secondary postpartum hemorrhage.  Clinical presentation UAP usually presents as delayed (secondary) postpartum hemorrhage, that is per vaginal bleeding which occurs more than 24 hours and up to 6 weeks postpartum. However, some reported ca...
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Uterine venous plexus

The uterine venous plexus is a network of veins surrounding the uterus and has extensive anastomoses with the vaginal venous plexus inferiorly and ovarian venous plexuses laterally. Gross anatomy The uterine venous plexus lies along the lateral aspects and superior angles of the uterus within ...
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Vaginal artery

The vaginal artery is a branch of the anterior division of the internal iliac artery, and should not to be mistaken with the vaginal branch of the uterine artery. It is often considered to be a homolog of the inferior vesical artery, which is present only in males. Summary origin: anterior div...
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Valsalva maneuver

The Valsalva maneuver is the forced expiration of air against a closed airway, resulting in increased intra-abdominal, intrathoracic, and pharyngeal pressure. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling. It is commonly u...
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Valveless vein

The valveless veins are veins that lack venous valves. Most veins contain valves (known as the valvula venosa in the TA) to prevent backflow, i.e. ensuring that blood flow is always towards the heart 1. Recent evidence shows that veins that were previously thought to be valveless, are now known...
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Variant anatomy of the aortic arch

Variant anatomy of the aortic arch occurs when there is failure of normal aortic development. It results in a number of heterogenous anomalies of the aorta and its branch vessels. Gross anatomy Normally, the aorta ascends in the superior mediastinum to the level of the sternal notch before arc...
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Variant hepatic arterial anatomy

Variation in hepatic arterial anatomy is seen in 40-45% of people. Classic branching of the common hepatic artery from the celiac artery, and the proper hepatic artery into right and left hepatic arteries to supply the entire liver, is seen in 55-60% of the population.  Terminology An accessor...
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Varicocele

Varicocele is the dilatation of the pampiniform plexus of veins, a network of many small veins found in the male spermatic cord. It is the most frequently encountered mass of the spermatic cord. Epidemiology The estimated incidence is at ~15% of the general male population and ~40% of subferti...
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Varicocele embolization

Varicocele embolization is a minimally invasive method of treating varicoceles by embolizing the testicular vein (internal spermatic veins). Indications symptomatic varicocele infertility/subfertility failed surgical ligation Contraindications Relative contraindications include: intraveno...
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Varicocele grading on color Doppler

Varicocele grading on color Doppler can be done variably. The most elaborate and widely-accepted grading was given by Sarteschi, as below.  For a general discussion of this condition refer to the article: varicocele. Evaluation baseline greyscale study in supine position and measure the diame...
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Varicose veins

Varicose veins are dilated tortuous superficially located venous channels that accompany the superficial veins of the upper or lower limbs. Epidemiology Varicose veins are more common in women than men and are more common in the lower limb than in the upper limb 5. Risk factors include: pregn...
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Vascular anatomical variants

Vascular anatomical variants are common: aortic variants thoracic aorta ascending aorta aortic arch descending aorta abdominal SVC and IVC - caval variants intracranial arteries - variants
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Vascular compression disorders

Vascular compression disorders are numerous and can be divided into those cases where a vascular structure is the "compress-er" or the "compress-ee" . Some conditions fall into both categories, where one vessel compresses another.  Compression of a vascular structure  Eagle syndrome thoracic ...
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Vascular Ehlers Danlos syndrome

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

Vascular malformations and tumors are a heterogeneous group of lesions that may affect the arterial, capillary, venous or lymphatic system or any combination thereof. They encompass a bewildering range of lesions,  syndromes, and masses ranging from the relatively common (e.g. infantile hemangio...
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Vascular pathology

Vascular pathologies are common and include: arteriosclerosis hypertension fibromuscular dysplasia inherited disorders of the vessel wall aneurysms dissection thromboembolism vasculitis vasospasm vascular trauma intimal hyperplasia tumors of blood vessels congenital vascular anomali...
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Vascular rings and slings

Vascular rings and slings refer to the congenital vascular encirclement of the esophagus and/or trachea by anomalous/aberrant vessels.  Epidemiology Vascular rings are rare, occurring in <1% of patients 1. No gender or ethnic predispositions have been identified 3.  Clinical presentation Man...
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Vascular syndromes

The are numerous vascular syndromes that can occur in the body. They include: Syndromes principally involving the vascular system Budd-Chiari syndrome celiac artery compression syndrome hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) hypothenar hammer syndrome Kasabach-M...
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Vasculitis

Vasculitis describes generalized inflammation of vessels. Vasculitides carry a broad range of clinical presentations and as a whole can involve almost any organ system. Pathology Some vasculitides are due to direct vessel injury from an infectious agent. However, a large proportion show eviden...
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Vasculopathies caused by varicella zoster virus

Vasculopathies caused by varicella zoster virus (VZV) represent a group of illnesses involving both small and large CNS arteries caused by a inflammatory process involving the media and the vascular endothelium. Usually it occurs in immunocompromised individuals due the viral reactivation and sp...
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Vasospastic angina

Vasospastic angina (VSA), variant angina or Prinzmetal angina is a clinical entity that refers to a hyper-reactive response of the epicardial coronary arteries to vasoconstrictor stimuli. Epidemiology Incidence and prevalence seem not entirely explored and are highly variable between certain p...
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Vein of Galen aneurysmal malformation

Vein of Galen aneurysmal malformations (VGAMs), probably better termed as median prosencephalic arteriovenous fistulas, are uncommon intracranial anomalies that tend to present dramatically during early childhood with features of a left-to-right shunt and high-output cardiac failure. Epidemiolo...
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Vein of Marshall

The vein of Marshall, oblique vein of Marshall or the oblique vein of the left atrium is a small vein that descends on and drains the posterior wall of the left atrium. It drains directly into the coronary sinus at the same end as the great cardiac vein, marking the origin of the sinus. It repr...
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Velocity encoding

Velocity encoding or Venc is referred to as an operator-controlled parameter for the determination of the maximum velocity within a velocity encoded phase contrast imaging study. Usage Velocity-encoding (Venc) gradients are used to generate a phase shift in magnetic resonance phase contrast im...
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Vena caval foramen

The vena caval foramen is one of the three major apertures in the diaphragm. It is the highest of the three and situated at the level of T8-9. It is quadrilateral and placed at the junction of the right and middle leaflets of the central tendon. It transmits several structures between the thora...
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Venae cavae

In human anatomy, the venae cavae is the collective term for the main venous great vessels that return deoxygenated blood to the right heart from the venous side of the systemic circulation, i.e. the superior vena cava (SVC) and inferior vena cava (IVC). Both venae cavae do not contain any valve...
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Venae cordis minimae

The venae cordis minimae (singular: vena cordis minima), meaning "smallest cardiac veins", also known as Thebesian veins (variably capitalized in the literature) are a small group of valveless myocardial coronary veins within the walls of each of the four cardiac chambers that drain venous blood...
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Veno-occlusive mesenteric ischemia

Veno-occlusive mesenteric ischemia is most often the result of superior mesenteric vein (SMV) thrombosis and is a less common cause of acute mesenteric ischemia. Despite thrombosis of the SMV, small bowel necrosis often does not occur, presumably due to persistent arterial supply and some venous...
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Venous circle of Trolard

The anastomotic venous circle of the base of the brain 1, also referred to as the venous circle of Trolard 2,3,5, is an inconsistently found venous homologue of the better-known arterial circle of Willis. It should not be confused with other venous structures also described by Trolard such as t...
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Venous drainage of the foot

Venous drainage of the foot can be divided into two main components. Plantar veins, draining the sole (plantar surface) of the foot, and the dorsal veins which drain the dorsal surface of the foot. The veins of the foot are susceptible to several pathologies, including corona phelbectatica, vari...
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Venous drainage of the hand

Venous drainage of the hand is predominantly via the dorsal venous network in the superficial fascia, which extends proximally across the dorsal aspect of the metacarpus to drain laterally into the cephalic vein, and medially into the basilic vein 1. An accessory cephalic vein commonly drains pa...
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Venous drainage of the lower limb

The anatomy of the venous drainage of the lower limbs is extremely variable. However, there is order in the variability. The veins of the lower extremities are arranged in three systems: the superficial, the deep, and the perforating venous systems. These are located in two main compartments: th...
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Venous drainage of the thoracic wall

The venous drainage of the thoracic wall drains deoxygenated venous blood from the periphery of the thoracic cage back into the systemic circulation. Gross anatomy Anterior thoracic wall Anterior intercostal veins The anterior intercostal veins originate from the intercostal space just infer...
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Venous thoracic outlet syndrome

The venous thoracic outlet syndrome is the second commonest form of thoracic outlet syndrome (with neurogenic thoracic outlet syndrome being the commonest and the arterial thoracic outlet syndrome being the least common). Clinical presentation It may develop suddenly, often after unusual and t...
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Venous thromboembolism

Venous thromboembolism covers a wide spectrum of diseases. Individual conditions and complicating condition include: head and neck cerebral vein thrombosis dural venous sinus thrombosis cavernous sinus thrombosis deep cerebral vein thrombosis cortical vein thrombosis superior ophthalmic v...
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Vertebral artery

The vertebral arteries (VA) are paired arteries, each arising from the respective subclavian artery and ascending in the neck to supply the posterior fossa and occipital lobes, as well as provide segmental vertebral and spinal column blood supply. Summary origin: branches of the 1st part of th...
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Vertebral artery dissection

Vertebral artery dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima of the vertebral artery. It is potentially lethal and can be difficult to diagnose clinically and radiologically. Epidemiology Vertebral artery dissections have...
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Vertebral artery ectasia

Vertebral artery ectasia refers to an abnormal dilatation of the vertebral artery. It is also known as a dolichoarterial loop (of Danziger). Clinical presentation Symptoms occur due to radicular compression or pathologic fracture (rare) from extensive bone erosion. Generally, patients present ...
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Vertebral artery loop

Vertebral artery loops occur when a portion of the vertebral artery contains an unusual coil. It can be a rare anatomical variant or can be acquired. Epidemiology Vertebral artery loops tend to be mostly diagnosed in the 5th and 6th decades. Its prevalence is uncertain but is thought to be pre...
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Vertebral artery thrombosis

Vertebral artery thrombosis results in complete or partial occlusion of the vertebral artery and alteration of blood flow to the posterior cerebral circulation. Ischemia or infarction to structures supplied by these arteries may result in a range of symptoms. brainstem cerebellum occipital lo...
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Vertebral venous plexus

The vertebral venous plexus is a highly anastomotic network of valveless veins running along the entire length of the vertebral column from the foramen magnum to the sacral hiatus. Gross anatomy The vertebral venous plexus is comprised of three interconnected divisions: internal vertebral ven...
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Vertebrobasilar insufficiency

Vertebrobasilar insufficiency is a clinical syndrome caused by transient ischemia of the vertebrobasilar circulation, formed by the vertebral and basilar arteries, which forms the posterior circulation of the brain 1.  Epidemiology Vertebrobasilar insufficiency is largely caused by atheroscler...
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Vestibule (disambiguation)

A vestibule is an anatomical term and refers to a small cavity at the proximal end of a tube. It may refer to: vestibule (aorta) vestibule (ear) vestibule (larynx) vestibule (mouth) vestibule (nose) vestibule (esophagus) vestibule (vulva) History and etymology Vestibule derives ultimate...
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Vidian artery

There are two arteries passing through Vidian canal from the pterygopalatine fossa to the petrous portion of the ICA. One is a branch of the internal maxillary artery (itself a branch of the ECA) and the other is from the C2 segment of the ICA. It therefore forms one of the ICA to ECA anastamoses.
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Vieussens' arterial ring

Vieussens' arterial ring is a rare anatomic variant consisting of an anastomotic connection between the conus artery and branch vessels of the left coronary artery.  Gross anatomy The artery arises from the conus artery, a branch of the right coronary artery, and connects to the proximal right...
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Virchow triad

Virchow triad refers to the factors which can promote thrombosis, these are useful to consider when thinking about the possible causes in a particular situation. They are: hypercoagulability endothelial injury disturbance of flow It is still believed that the simultaneous presence of at leas...
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Viscera

The viscera (singular: viscus) refers to all the internal organs within the major cavities of the thorax, abdomen and pelvis. Therefore it does not include organs of the CNS, head and neck or musculoskeletal compartments nor does it encompass non-internal organs (e.g. the skin) 1. Splanchnology...
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Visceral artery aneurysm

Visceral artery aneurysms are abnormal focal dilatations of splanchnic arteries supplying abdominal organs. Visceral artery aneurysms include both true aneurysms and pseudoaneurysms. Owing to different clinical manifestations and a unique, specific, pathology, renal artery aneurysms are discuss...
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Walnut kernel microbleed pattern

The walnut kernel microbleed pattern along with the starfield pattern and corpus callosum diffusion restriction appears to be the most important imaging markers of cerebral fat embolism 1-3. In this pattern, there is a diffuse presence of round microbleeds (punctate focal hypointensities) of si...
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Wells criteria for deep venous thrombosis

Wells criteria for deep venous thrombosis is a risk stratification score and clinical decision rule to estimate the pretest probability for acute deep venous thrombosis (DVT). It is intended to be combined with noninvasive diagnostic tests (e.g. ultrasound or D-dimer) for suspected cases. D-dime...
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Westermark sign

Westermark sign is a sign of pulmonary embolus seen on chest radiographs. It is one of several described signs of pulmonary embolus on chest radiographs. Pathology The theory behind the sign is either obstruction of the pulmonary artery or distal vasoconstriction in hypoxic lung 3. In one stu...
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WFNS grading system

The WFNS (World Federation of Neurosurgical Societies) grading system uses the Glasgow Coma Scale and presence of focal neurological deficits to grade the clinical severity of subarachnoid hemorrhage. This grading system was proposed in 1988, and this is one of the accepted systems (although not...
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White coat effect

The white coat effect (WCE), not to be confused with white coat hypertension, is a measure of change that is commonly defined as the difference between in-clinic and out-of-clinic blood pressure readings 1,2.  Alternatively, the white coat effect can be defined as the increase in the arterial b...
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White coat hypertension

White coat hypertension (abbreviated either as WCH or WCHT), and not to be confused with the white coat effect (WCE), is commonly defined as typical in-clinic blood pressure (BP) measurements of 140/90 mm Hg or more in the presence of multiple daytime out-of-clinic home or ambulatory BP readings...
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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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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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Winslow pathway

The Winslow pathway is a type of collateral vessel communication which connects the mammary arteries through the internal thoracic arteries to the inferior epigastric arteries and then into the external iliac arteries. It may recanalize in conditions such as aortoiliac occlusive disease.
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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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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...
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Yellow nail syndrome

The yellow nail syndrome (YNS) is a rare disorder principally affecting the lymphatic system. It is characterized by a clinical triad: nail discolouration (chromonychia): yellow to dark green slow-growing dystrophic nails (scleronychia) 9 lymphedema (peripheral/primary) pulmonary disease: se...
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Yin-yang sign (vascular)

The yin-yang sign, also known as the Pepsi sign, is a radiological sign described in both true and false aneurysms on various imaging modalities. Radiographic features Ultrasound On Doppler ultrasound, the yin-yang sign indicates bidirectional flow due to the swirling of blood within the true...

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