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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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Superior vena cava obstruction

Superior vena cava obstruction (SVCO) can occur from extrinsic compression, intrinsic stenosis, or thrombosis of the superior vena cava. Malignancies are the main cause and are considered an oncologic emergency. Superior vena cava syndrome (SVCS) refers to the clinical syndrome with symptoms tha...
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Superior vena cava obstruction (grading)

SVC obstruction can cause SVC syndrome which is the most common condition affecting this vessel. It can be secondary to extrinsic compression or intraluminal thrombosis/stenosis. Collateral pathways, with the azygos vein being the most important collateral vessel, form in response to severe narr...
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Superior vesical artery

The superior vesical artery is a branch of the anterior division of the internal iliac artery. It supplies part of the bladder, ureter, seminal vesicle and ductus deferens. Summary origin: anterior division of internal iliac artery location: pelvis supply: superior bladder, ureter, ductus de...
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Supermicrosurgery

Supermicrosurgery is the specialized surgical technique employed to anastomose blood vessels and nerves measuring 0.3 to 0.8 mm in caliber (so-called microneurovascular anastomosis) 1. The instruments developed for these demanding procedures are very fine microsurgical devices. Microsurgery as a...
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Supraduodenal artery

The supraduodenal artery (SDA) is a branch of the gastroduodenal artery (GDA). It arises soon after the origin of the GDA posterior to the first part of the duodenum and supplies the anterosuperior part of the first and second parts of the duodenum, contributing to the rich arterial anastomotic ...
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Supraorbital artery

The supraorbital artery is a branch of the ophthalmic artery supplying part of the orbit and face.  Gross anatomy Origin The supraorbital artery originates from the ophthalmic artery, upon branching it lies medial to the optic nerve. Course The supraorbital artery courses superiorly and med...
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Suprascapular artery

The suprascapular artery is 1 of the 4 branches of the thyrocervical trunk (off the first part of the subclavian artery). It traverses inferiorly and laterally in the lower anterior neck superficial to the anterior scalene muscle and phrenic nerve before crossing the third part of the subclavia...
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Supratrochlear artery

The supratrochlear artery, also known as the frontal artery, originates from the ophthalmic artery as one of its terminal branches. Gross anatomy After arising from the ophthalmic artery, it pierces the orbital septum and courses in the superior and medial aspect of the orbit, medial to the su...
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Supreme intercostal arteries

The supreme intercostal arteries, or superior intercostal arteries, are formed as a direct result of the embryological development of the intersegmental arteries. These arteries are paired structures of the upper thorax which normally form to provide blood flow to the first and second posterior ...
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Suzuki staging system for Moyamoya

The staging system for moyamoya disease first described by Suzuki and Takaku in their seminal 1969 article 1 is still in use today. Formally, the staging refers to findings on conventional angiography, although there are efforts to apply similar systems to MR angiography 2. Suzuki stage appears...
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Syndromes with a vascular component

Ataxia-telangiectasia CREST syndrome Lemierre syndrome Maffucci syndrome PHACE syndrome Stewart-Treves syndrome Sturge-Weber syndrome von Hippel-Lindau disease Wyburn-Mason syndrome
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Syphilitic aortitis

Syphilitic aortitis is a form of aortitis which occurs due to syphilis. It usually occurs in tertiary syphilis often 10-30 years after initial infection. Complications progression into a luetic aneurysm aortic valvular insufficiency coronary ostial involvement with coronary ostial stenosis ...
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Systemic hypertension

Systemic hypertension is defined medically as a blood pressure greater than 140/90 mmHg. Recently the American College of Cardiology (ACC) and American Heart Association (AHA) have changed guidelines to indicate that pressures above 130/80 mmHg will be considered hypertension, however the Europe...
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Systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multisystem involvement. Although abnormalities in almost every aspect of the immune system have been found, the key defect is thought to result from a loss of self-tolerance to autoantigens. Epidemiology There is a strong...
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Systemic lupus erythematosus (CNS manifestations)

Central nervous system manifestations of systemic lupus erythematosus (CNS lupus) describe a wide variety of neuropsychiatric manifestations that are secondary to systemic lupus erythematosus (SLE) in the central nervous system (CNS). For a general discussion, and for links to other system spec...
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Takayasu arteritis

Takayasu arteritis (TAK), also known as idiopathic medial aortopathy or pulseless disease, is a granulomatous large vessel vasculitis that predominantly affects the aorta and its major branches. It may also affect the pulmonary arteries. The exact cause is not well known but the pathology is tho...
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Takeuchi procedure

The Takeuchi procedure refers to a direct anastomosis of the anomalous left coronary artery from the pulmonary artery directly to the aorta was described in the 1970s and currently remains the procedure of choice. An intrapulmonary aortocoronary tunnel or baffle was performed by Takeuchi prior ...
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Tandem lesion (cerebrovascular)

Tandem lesion (or tandem occlusion) is a term used in cerebrovascular imaging and intervention to refer to the simultaneous presence of high-grade stenosis or occlusion of the cervical internal carotid artery and thromboembolic occlusion of the intracranial terminal internal carotid artery or it...
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Tangential calcium sign

A tangential calcium sign is a sign seen with an aortic aneurysm rupture. The calcified intimal rim is discontinuous and is seen to tangentially point away from the aneurysmal lumen. This sign is seen at the point of breach. There is associated retroperitoneal leakage.
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Tardus parvus

Tardus parvus refers to a pattern of Doppler ultrasound spectral waveform resulting from arterial stenosis. The phenomenon is observed downstream to the site of stenosis, and is due to reduced magnitude of blood flow through the narrowed vessel during ventricular systole 7. This characteristic ...
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Teardrop sign (superior mesenteric vein)

The teardrop sign of the superior mesenteric vein is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer. Radiographic feat...
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Tela choroidea

The tela choroidea is the thin, highly vascularized, loose connective tissue portion of pia mater that gives rise to the choroid plexus. Thus, it is basically the lamina propria of the ependyma and lies directly adherent to it, without any tissue in between the two 6. Gross anatomy Being part ...
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Telangiectasias

A telangiectasia commonly refers to a group of abnormally prominent capillaries that occur close to a mucosal surface. Rarely they are also referred to denote vascular malformations at other non-mucosal sites (e.g capillary telangiectasias of the brain 1) Associations There are numerous condit...
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Temporal tap maneuver

Temporal tap maneuver consists in tapping over the ipsilateral superficial temporal artery while assessing the carotid bifurcation on Doppler ultrasound aiming to produce a reflected flow in the external carotid artery (ECA) and thus helping to distinguish which vessel is being assessed: externa...
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Temporopolar artery

The temporopolar artery is usually a dorsolateral branch from the M1 segment of the middle cerebral artery (MCA) and supplies the polar and anterolateral portions of the temporal lobe.  This artery may arise as a branch from the anterior temporal artery 1.  
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Tentorial angle

The tentorial angle is measured between a line connecting the nasion with the tuberculum sellae and the angle of the straight sinus. Normally it should measure between 27° and 52°. Abnormalities of the posterior fossa or base of skull can alter this. For example, this angle is elevated in achon...
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Terson syndrome

Terson syndrome refers to vitreous hemorrhage associated with subarachnoid hemorrhage, however, some authors include retinal hemorrhage as well. The syndrome is a poor prognostic marker in patients with subarachnoid hemorrhage. Epidemiology Terson syndrome has been reported to occur in 13-50% ...
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Testicular arteries

The testicular arteries (also known as the spermatic arteries) are the long, small-diameter gonadal arteries in the male that supply the testis alongside the cremasteric artery and the artery to the ductus deferens.  Gross anatomy Origin As paired structures they arise symmetrically, slightly...
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Thalamostriate veins

Thalamostriate veins are formed by the joining of anterior caudate vein and the vein of stria terminalis. They join the septal veins and form internal cerebral veins. Related pathology The thalamostriate veins can be compressed in preterm neonates who have had germinal matrix hemorrhage. This ...
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Third inflow

Third inflow refers to anatomical variants leading to an additional venous inflow to the liver apart from the usual dual blood supply (portal vein and hepatic artery). They tend to be associated with parenchymal pseudolesions (focal hyperenhancement on post-contrast imaging, focal fat infiltrati...
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Thoracic aorta

The thoracic aorta is the most superior division of the aorta and is divided into three sections: ascending aorta aortic arch descending aorta The thoracic aorta begins at the aortic valve, located obliquely just to the left of the midline at the level of the third intercostal space. It term...
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Thoracic aortic aneurysm

Thoracic aortic aneurysms are relatively uncommon compared to abdominal aortic aneurysms. There is a wide range of causes, and the ascending aorta is the segment most commonly affected. Both CTA and MRA are the modalities of choice to image this condition. Terminology The normal aortic diamete...
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Thoracic aortic dilatation (differential)

There is a broad differential for thoracic aortic dilatation. Differential diagnosis senile ectasia hypertension post-stenotic dilatation, e.g. bicuspid aortic valve thoracic aortic aneurysm atherosclerosis (usually descending thoracic aorta) collagen disorders Marfan syndrome Ehlers-Da...
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Thoracic aortic injury

Thoracic aortic injury is the most common type of traumatic aortic injury and is a critical life-threatening, and often life-ending event.  Clinical presentation Approximately 80% of patients with thoracic aortic injury die at the scene of the trauma. In those who make it to hospital, clinical...
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Thoracic aortic stenosis (differential)

The differential for thoracic aortic stenosis includes: atherosclerosis aortitis (especially Takayasu arteritis) radiotherapy coarctation pseudocoarctation Williams syndrome: supravalvular aortic stenosis congenital rubella syndrome: supravalvular aortic stenosis
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Thoracic duct

The thoracic duct is the main lymphatic vessel for the return of chyle/lymph to the systemic venous system. It drains lymph from both lower limbs, abdomen (except the convex area of the liver), left hemithorax, left upper limb and left side of face and neck. Gross anatomy The thoracic duct is ...
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Thoracic endovascular aneurysm repair

A thoracic endovascular aneurysm repair (TEVAR) is a type of endovascular aneurysm repair that involves the thoracic aorta. Indications It is a commonly applied treatment strategy for various thoracic aortic pathologies inclusive of both: type A and type B thoracic aortic dissections penetra...
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Thoracic outlet syndrome

Thoracic outlet syndrome refers to a group of clinical syndromes caused by congenital or acquired compression of the brachial plexus or subclavian vessels as they pass through the superior thoracic aperture 11.  Clinical presentation Clinical presentation will depend on the structure compresse...
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Thoracic plane (mnemonic)

A handy mnemonic to remember the structures found at the level of the thoracic plane (also known as the plane of Ludwig) is: CLAPTRAP RAT PLANT Mnemonic CLAPTRAP C: cardiac plexus L: ligamentum arteriosum A: aortic arch (inner concavity) P: pulmonary trunk T: tracheal bifurcation (carin...
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Thoracoacromial artery

The thoracoacromial artery is a vessel arising from the axillary artery at the axilla. Summary origin: first branch of the second part of the axillary artery 1 location: axilla supply: pectoralis major and minor, anterior part of the deltoid, and dermal sensation overlying the clavipectoral ...
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Thoracoacromial artery (mnemonic)

Some useful mnemonics to remember the branches of the thoracoacromial artery are: Cadavers Are Dead People PACkeD Mnemonics Cadavers Are Dead People C: clavicular A: acromial D: deltoid P: pectoral PACkeD P: pectoral A: acromial C: clavicular D: deltoid
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Thorax

The thorax (plural: thoraces) also known as the chest, refers to that anatomical region of the body containing the heart and lungs, thoracic aorta, great vessels and surrounding structures, all contained within the thoracic cavity. It also includes the thoracic skeleton, including the thoracic s...
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Threads and streaks sign

The threads and streaks sign refers to an angiographic appearance of a vascularized tumor thrombus extending into the ipsilateral renal vein or the inferior vena cava from a renal cell carcinoma. This gives an appearance of linear, thread-like or string-like appearance of the involved vessel.  ...
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Thrombolysis in cerebral infarction (TICI) scale

The thrombolysis in cerebral infarction (TICI) grading system was described in 2003 by Higashida et al. 1 as a tool for determining the response of thrombolytic therapy for ischemic stroke. In neurointerventional radiology it is commonly used for patients post endovascular revascularization. Lik...
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Thrombus fissuration sign (aortic aneurysm)

Thrombus fissuration is a sign of impending rupture of an aortic aneurysm. It reflects blood dissecting into the intramural thrombus. This sign is observed on contrast-enhanced CT as a linear contrast infiltration from the aneurysm lumen through the intramural thrombus. Thrombus fissurations ext...
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Thyrocervical trunk

The thyrocervical trunk is one of the 3 branches of the first part of the subclavian artery and gives off numerous branches to supply viscera of the neck, the brachial plexus, neck muscles and the scapular anastomosis. Gross anatomy Origin The trunk arises lateral to the vertebral artery from...
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Thyroidea ima artery

The thyroidea ima artery is an uncommon variant of the blood supply to the inferior aspect of the thyroid gland. It is reported in ~7.5% (range 1.5-12.2%) of individuals and can arise from: brachiocephalic trunk (most common: 1.9-6.0%) right common carotid artery aortic arch internal thoraci...
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Thyrolingual trunk

A thyrolingual trunk is an anatomical variant in which the superior thyroid artery and lingual artery share a common trunk 1. This is in contrast to the typical pattern of both vessels emerging independently from the external carotid artery. Other variations of origin include a linguofacial trun...
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Thyrolinguofacial trunk

A thyrolinguofacial trunk is a very rare pattern of branching of the anterior branches of the external carotid artery. Rather than the facial artery, lingual artery, and superior thyroid artery having their own distinct origins, all three vessels originate from a common trunk of the external car...
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Tibioperoneal trunk

The tibioperoneal or TP trunk, which occasionally referred to as the tibiofibular​ trunk is the direct continuation of the popliteal artery in the posterior upper leg after the anterior tibial artery origin. It is a short trunk that bifurcates into two terminal branches. Summary origin: contin...
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Time of flight angiography

Time of flight angiography (TOF) is an MRI technique to visualize flow within vessels, without the need to administer contrast. It is based on the phenomenon of flow-related enhancement of spins entering into an imaging slice. As a result of being unsaturated, these spins give more signal than s...
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TIPS evaluation

TIPS evaluation is useful to ensure that a transjugular intrahepatic portosystemic shunt (TIPS) is working properly and that no stenosis has occurred within the stent. Ultrasound is often used as a first-line modality. Radiographic features Ultrasound The normal TIPS should show color Doppler...
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Top of the basilar syndrome

Top of the basilar syndrome, also known as rostral brainstem infarction, occurs when there is thromboembolic occlusion of the top of the basilar artery. This results in bilateral thalamic ischemia due to occlusion of perforator vessels. Clinical presentation Clinically, top of the basilar synd...
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Transjugular intrahepatic portosystemic shunt

Transjugular intrahepatic portosystemic shunt (TIPS or TIPSS) is a treatment for portal hypertension in which direct communication is formed between a hepatic vein and a branch of the portal vein, thus allowing some proportion of portal flow to bypass the liver. The target portosystemic gradient...
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Transposition of inferior vena cava

Transposition of inferior vena cava (also known as left-sided IVC) refers to a variant course of the inferior vena cava. It is the most common anomaly of IVC and occurs due to persistence of left supracardinal vein. Diagnosis of left sided inferior vena cava is important for: planning of vascu...
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Transposition of the great arteries

Transposition of the great arteries (TGA) (also known as transposition of the great vessels (TGV)) is the most common cyanotic congenital cardiac anomaly presenting during the newborn period, with cyanosis in the first 24 hours of life. It accounts for up to 7% of all congenital cardiac anomalie...
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Transverse cervical artery

The transverse cervical artery, also known as the cervicodorsal trunk, is 1 of the 4 branches of the thyrocervical trunk (off the first part of the subclavian artery). It is a short artery that bifurcates into the superficial and deep branches, both which course superficially and laterally acro...
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Transverse pancreatic artery

The transverse pancreatic artery, also known as the inferior pancreatic artery, is a branch of the splenic artery that supplies the pancreatic tail and body. It arises from the proximal splenic artery and descends a short distance to run to the left along the posterior margin of the pancreas ne...
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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 a spectrum of dermatologic findings that includes migratory patches, edematous plaques, periorbital edema, and/or conj...
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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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Ulcer-like projection (aorta)

Ulcer-like projections (ULPs) are sometimes seen on contrast-enhanced CTs obtained in patients with a recent intramural aortic hematoma. They represent new intimal disruption and have a negative effect on prognosis.  Ulcer-like projections are seen in approximately 40% of patients with intramur...
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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 decreased curvature of the aortic arch on a frontal chest radiograph giving an ‘opened up’ appearance. It is one of the more common causes for apparent mediastinal widening and is seen with increasing age, usually associated with aortic calcifica...
Article

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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