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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.

1,214 results found
Article

Transverse sinus

The paired left and right transverse sinuses are major dural venous sinuses and arise from the confluence of the superior sagittal, occipital and straight sinuses at the torcular herophili (confluence of sinuses). On each side, the transverse sinus then runs in the lateral border of the tentori...
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Traumatic aortic injury

Traumatic aortic injury (TAI) is most often caused by blunt trauma (referred to as BTAI) and is best described in terms of injury location, type and severity: abdominal aortic injury aortic pseudoaneurysm thoracic aortic injury minimal aortic injury See traumatic aortic injury in the exam.
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Traumatic aortic injury in the exam

Getting a film with traumatic aortic injury in the exam is one of the many exam set-pieces that can be prepared for.  This is one of the cases you should look and not speak for 10 seconds as there tends to be a lot of findings on the film of patients with a traumatic aortic injury. Description...
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Tributaries of the inferior vena cava (mnemonic)

A useful mnemonic to remember the tributaries of the inferior vena cava is: I Like To Rise So High Mnemonic I: common iliac veins L: lumbar veins T: right testicular (gonadal) vein R: renal veins S: suprarenal veins H: hepatic veins
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Trident appearance (disambiguation)

The trident appearance (or sign) can refer to a variety of entities: trident acetabulum trident hand trident sign (osmotic demyelination) trident sign (persistent trigeminal artery) History and etymology The trident is a three-pronged lance employed for spearing fish, and in Classical myth...
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Trident sign (persistent primitive trigeminal artery)

The trident sign of a persistent primitive trigeminal artery refers to the appearance of the intracranial circulation on lateral projection. The internal carotid artery, the abnormal vessel and superior portion of the basilar artery resemble the Greek letter tau (thus tau sign). This configurati...
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Triple-rule-out CT

Triple-rule-out CT (TRO CT) angiography may be ordered in the setting of acute chest pain to examine the thoracic aorta and the coronary and pulmonary arteries. The protocol helps exclude life-threatening causes of acute chest pain, especially if atypical, or if alternative causes to acute coron...
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True aneurysm

In a true aneurysm, the aneurysm is bound by all three layers of the vessel wall (intima, media and adventitia). The wall may be attenuated. The risk of rupture is proportional to the size of the aneurysm. Pathology Etiology congenital atherosclerosis hypertension vasculitis hereditary...
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Tuberculous aortitis

Tuberculous aortitis is a rare cause of aortitis in the context of disseminated tuberculosis. It usually is a result of direct seeding from a contiguous lymph node or via hematogenous or lymphatic spread of distant infection. Fatal outcomes of tuberculous aortitis are commonly reported despite a...
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Tulip bulb sign

Tulip bulb sign refers to the characteristic appearance of annuloaortic ectasia as seen on CT angiography. There is symmetric dilatation of the three sinuses of Valsalva, with extension into the ascending aorta and effacement of the sinotubular junction.  It is seen especially in Marfan syndro...
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Tumor necrosis factor receptor-associated periodic syndrome

Tumor necrosis factor receptor-associated periodic syndrome (or sometimes abbreviated as TRAPS) is a condition characterized by recurrent (periodic) episodes of fever as well as spectrum of dermatologic findings, including migratory patches, edematous plaques, periorbital edema, and/or conjuncti...
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Tumors of blood vessels

Blood vessel derived tumors may arise from: endothelial cells hemangioma lymphangioma angiosarcoma cells supporting or surrounding blood vessels  glomus tumor of finger hemangiopericytoma Most arise in the soft tissues or viscera. Primary tumors of the large vessels (eg. aorta, IVC) are ...
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Tumor thrombus

Tumor thrombus is defined as tumor extending into a vessel, typically a vein. It occurs in a wide variety of malignancies. It is vital to distinguish tumor thrombus from "bland" thrombus (free of neoplastic cells) in the setting of neoplasia, as this often impacts staging and treatment approach....
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Tunica (disambiguation)

Tunica is a word used in anatomy to refer to a type of covering.  tunica adventitia (also known as tunica externa) tunica albuginea tunica albuginea (clitoris) tunica albuginea (ovary) tunica albuginea (penis) tunica albuginea (testis) tunica intima tunica media tunica vaginalis tunica...
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Tunnel syndrome

A tunnel syndrome refers to pain, paresthesia and weakness due to neurovascular compression, friction or traction within a confined anatomical passageway. The tunnel may be bordered by bone, muscle or tendoligamentous structures or a combination of these. Various specific syndromes exist and ar...
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Type I endoleak

Type I endoleaks are a subgroup of endoleaks which occur at graft ends, often due to an inadequate seal.  Pathology They occur as a result of poor apposition between one of the attachment sites of a stent-graft and the native aortic or iliac artery wall. Blood can leak through this defect into...
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Type II endoleak

A type II endoleak is a commonest form of endoleak are after an abdominal aortic repair.  Epidemiology They are the most common types of endoleaks and may occur in 10-44% of patients having repairs and can comprise around half of all endoleaks 1. Pathology They may be simple or complex. Simp...
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Type III endoleak

A type III endoleak is a type of endoleak which usually occurs through a defect in the graft. It may be divided into two components.  IIIa: junctional separation of the modular components IIIb: fractures or holes involving the endograft Epidemiology It is relatively uncommon and only occurs ...
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Type IV endoleak

Type IV endoleaks are a type of endoleak which usually occurs secondary to graft porosity and are typically seen in the immediate post operative angiogram following an endovascular aneurysm repair. Epidemiology Type IV endoleaks are extremely rare and studies report a prevalence of 0.3%. This ...
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Ulnar artery

The ulnar artery is a terminal branch of the brachial artery, arising at the proximal aspect of the forearm. Along with the radial artery, it is one of the main arteries of the forearm.  Summary origin: terminal branch of the brachial artery location: inferior aspect of the cubital fossa sup...
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Ulnar vein

The ulnar vein is one of the two major deep veins of the forearm, along with the radial vein. As is usual in the upper and lower limbs, there are often two veins (venae comitantes) that run on either side of the ulnar artery and anastomose freely with each other. It forms in the hand from the d...
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Ultrasound assessment of carotid arterial atherosclerotic disease

Ultrasound assessment of carotid arterial atherosclerotic disease has become the first choice for carotid artery stenosis screening, permitting the evaluation of both the macroscopic appearance of plaques as well as flow characteristics in the carotid artery. This article focus on internal caro...
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Ultrasound-guided peripheral intravenous cannulation

Peripheral intravenous cannulation under ultrasound guidance is the placement of a cannula into a peripherally-located vein under the direct vision of ultrasound. This process allows the cannulation of veins that are unable to be visualized or palpated without ultrasound. In trained individuals ...
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Umbilical arterial aneurysm

An umbilical arterial aneurysm (UAA) is an extremely rare but potentially lethal vascular anomaly which is usually detected in utero.  Pathology Location It tends to favor the placental end of the umbilical artery in the cord. Associations Concurrently associated anomalies are thought to be...
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Umbilical arterial catheters

Umbilical arterial catheters (UACs) are used in neonatal care for arterial sampling and need to be carefully assessed on all neonatal films.  Position The catheter should pass through the umbilicus, travel inferiorly through the umbilical artery, then in the anterior division of the internal i...
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Umbilical artery

The umbilical artery gives rise to both a nonfunctional remnant of the fetal circulation and an active vessel giving supply to the bladder. In the adult, the obliterated area of the vessel is identifiable as the medial umbilical ligament and the patent segment is the superior vesical artery. Su...
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Umbilical cord

The umbilical cord is a fetal organ that connects the placenta to the developing fetus and is a vital passage for nutrients, oxygen and waste products to and from the fetus. Gross anatomy The umbilical cord inserts into the center of the placental bulk and into the fetus at the umbilicus. Vari...
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Umbilical vein

The umbilical vein is the conduit for blood returning from the placenta to the fetus until it involutes soon after birth. The umbilical vein arises from multiple tributaries within the placenta and enters the umbilical cord, along with the (usually) paired umbilical arteries. Once it enters the...
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Umbilical vein varix

Umbilical vein varix (UVV) refers to a focal dilatation of the umbilical vein. Epidemiology Associations UVVs were initially thought to have a high association with other anomalies which include: chromosomal anomalies: 5-12% with FIUVV 2,3 Down syndrome   underlying congenital cardiovascul...
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Umbilical venous catheters

Umbilical venous catheters (UVCs) are commonly used in neonates for vascular access and should be carefully assessed for position on all neonatal films.  Position An umbilical venous catheter generally passes directly superiorly and remains relatively anterior in the abdomen. It passes through...
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Umbilicus

The umbilicus is the fibrous remnant of the fetal attachment of the umbilical cord after birth. Gross anatomy All layers of the anterior abdominal wall fuse at the umbilical ring, a small round defect in the linea alba located just inferior to the midpoint between the xiphoid process of the st...
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Unfolded aorta

The term unfolded aorta refers to the widened and 'opened up' appearance of the aortic arch on a frontal chest radiograph. It is one of the more common causes for apparent mediastinal widening and is seen with increasing age. It occurs due to the discrepancy in the growth of the ascending aorta...
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Unilateral pulmonary artery atresia

Unilateral pulmonary artery atresia (UPAA), also known as unilateral absence of the pulmonary artery (UAPA) or proximal interruption of the pulmonary artery, is a variant of pulmonary artery atresia.  Terminology The term interruption is preferred by some to absence or atresia because the anom...
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Unilateral pulmonary vein atresia

Unilateral pulmonary vein atresia is a type of pulmonary vein atresia. Clinical presentation The condition usually present in infancy or childhood with recurrent episodes of pneumonia and/or hemoptysis. Presentation in adulthood does occur but is uncommon. Pathology It results from failure o...
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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 Causes peptic ulcer gastritis esophagitis duodenitis Mallory-Weiss tear varices tumor vascular abnormality vascular ectasia angiodysplasia Dieulafoy lesion vascular malformation...
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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. Clinical presentation The presentation can vary. UAVMs can cause life-threatening massive bleeding in young women....
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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 evidenc...
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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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Vein of Galen

The vein of Galen, also known as the great cerebral vein or great vein of Galen, is a short valveless trunk formed by the union of the two internal cerebral veins and basal veins of Rosenthal. Gross anatomy It lies in the quadrigeminal cistern and curves backward and upward around the posterio...
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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 cordis minimae

The venae cordis minimae (singular: vena cordis minima), meaning "smallest cardiac veins", also known as thebesian veins (as these are eponymous, they are sometimes capitalized as Thebesian veins) are a small group of valveless myocardial coronary veins within the walls of each of the four cardi...
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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. Often despite thrombosis of the SMV, small bowel necrosis 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 peripheries of the thoracic cage back into systemic circulation. Gross anatomy Anterior thoracic wall Anterior intercostal veins The anterior intercostal veins originate from the intercostal space just inferio...
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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: deep vein thrombosis (DVT) pulmonary embolism (PE) dural venous sinus thrombosis Lemierre syndrome tumor thrombus
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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. It is potentially lethal and can be difficult to diagnose clinically and radiologically. Epidemiology Vertebral artery dissections have an incidence of 1-5 per...
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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...
Article

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.
Article

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 primary thrombophilia factor V Leiden protein S deficiency protein C deficiency antithrombin III de...
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Visceral artery aneurysm

Visceral artery aneurysms are abnormal focal dilatations of 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 discussed separate...
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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...
Article

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 alternatively as WCH or WCHT), 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 readi...
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Williams syndrome

Williams syndrome (WS) 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 2 pulmonary artery stenosis 3 renal insuff...

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