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Proteus syndrome

Proteus syndrome is a rare congenital, multisystemic, hamartomatous condition characterized by asymmetrical overgrowth of almost any part of the body and a broad spectrum of manifestations. It can affect tissue from any germinal layer. It is suspected to be a genetic condition, but a particular ...

Proximal brachial artery

The proximal brachial artery represents the initial portion of the brachial artery as it arises as a continuation of the axillary artery at the inferior edge of teres major. There is no anatomic difference between the proximal and more distal brachial artery. However, the functional response to...

Pseudocoarctation of the aorta

Pseudocoarctation of the aorta is a very rare anomaly characterized by kinking or buckling of the descending aorta at the level of the ligamentum arteriosum without a pressure gradient across the lesion. Pathology It is thought to be of congenital origin, and characterized by elongation and ki...

Pseudovein sign (bowel)

The pseudovein sign can occur with active gastrointestinal bleeding where contrast extravasation during angiography may have a curvilinear appearance as it pools in the gastric rugae or mucosal folds of bowel, mimicking the appearance of a vein. However, contrast in the “pseudovein” persists bey...

Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE), also known as Grönblad–Strandberg syndrome, is a systemic condition characterized by the degeneration of elastic fibers. It has multiorgan manifestations. Epidemiology Its prevalence is estimated to be around 1 in 25,000 9. Clinical presentation Patients may ...

Psoas sign (abdominal x-ray)

The psoas sign is a classic non-specific finding on the abdominal radiograph, potentially representing retroperitoneal pathology. Normally on an abdominal radiograph, the lateral margins of both the psoas muscles are clearly visible due to adjacent fat. When the lateral edge of one, or both, ps...

Puff of smoke sign

The puff of smoke sign describes the characteristic angiographic appearance of tiny abnormal intracranial collateral vessel networks in moyamoya disease. Progressive narrowing of the supraclinoid internal carotid arteries and circle of Willis vessels results in extensive small collateral arteria...

Pulmonary arterial aneurysm

Pulmonary arterial aneurysms refer to a focal dilatation of the pulmonary arterial system. Epidemiology Overall it is considered a rare entity with autopsy prevalence rates of around 1 in 14,000 to 100,000 4,5. Pathology A true pulmonary artery aneurysm results from dilatation of all three l...

Pulmonary arterial atherosclerosis

Pulmonary artery atherosclerosis is less common than systemic arterial atherosclerosis in the thorax. It has been shown to correlate with the following factors age right ventricular dilatation right ventricular hypertrophy pulmonary emphysema aortic atherosclerosis pulmonary hypertensio...

Pulmonary arterial calcification

Pulmonary arterial calcification is the phenomenon which is usually seen in the setting of advanced pulmonary hypertension. It can however be uncommonly present in those without pulmonary hypertension. Pathology The general mechanism in the vast majority is thought to be from high end pulmonar...

Pulmonary arterial dissection

Pulmonary arterial dissection is extremely rare but can be a fatal situation. Only a handful of cases have been described in live patients. Pathology It is mostly described in those with chronic pulmonary arterial hypertension. It can progress to a pulmonary artery aneurysm and fatal spontan...

Pulmonary arteriovenous malformation

Pulmonary arteriovenous malformations (PAVMs) are rare vascular anomalies of the lung, in which abnormally dilated vessels provide a right-to-left shunt between the pulmonary artery and vein. They are generally considered direct high flow, low-resistance fistulous connections between the pulmona...

Pulmonary artery atresia

Pulmonary artery atresia (or sometimes known as pulmonary atresia) is a congenital cardiovascular anomaly in which there is complete disruption between the right ventricular outflow tract (RVOT) and the pulmonary trunk. Epidemiology The estimated incidence is 1 in 10,000 births. Pathology Th...

Pulmonary artery banding

Pulmonary artery banding is a palliative surgical procedure used to decrease excessive pulmonary blood flow. It is usually used for neonates and infants with left-to-right shunts unable to withstand complete surgical correction. Some indications include: single ventricle multiple ventricula...

Pulmonary artery catheter

Pulmonary artery catheters (or Swan-Ganz catheters) are balloon flotation catheters that can be inserted simply, quickly, with little training and without fluoroscopic guidance, at the bedside, even in the seriously ill patient. Historically they were widely used to measure right heart haemodyna...

Pulmonary artery pseudoaneurysm

Pulmonary artery pseudoaneurysm refers to a pseudoaneurysm arising from the pulmonary arteries. Pathology Unlike a true aneurysm it does not involve all three layers of the the arterial wall. They can arise from a number of causes including infection, associated neoplasms and trauma. Locat...

Pulmonary artery sarcoma

Pulmonary artery sarcomas are extremely rare tumors that originate from the intimal mesenchymal cells of the pulmonary artery. It is frequently misdiagnosed as pulmonary thromboembolism. Epidemiology Primary malignant tumors of the pulmonary arteries are very rare with an incidence of 0.001–...

Pulmonary artery stenosis types

A pulmonary arterial stenosis can be classified into several types 1,2: type I: involving main pulmonary artery type II: involving bifurcation type III: multiple peripheral stenoses type IV: central and peripheral stenoses See also congenital pulmonary stenosis

Pulmonary capillaritis

Pulmonary capillaritis is a general term given to inflammation of the pulmonary capillaries. It is essentially a histopathological diagnosis 3. Pathology The underlying inflammation leads to the disruption alveolar-capillary basement membrane integrity with resultant flooding of the alveoli wi...

Pulmonary embolism

Pulmonary embolism (PE) refers to embolic occlusion of the pulmonary arterial system. The majority of cases result from thrombotic occlusion, and therefore the condition is frequently termed pulmonary thromboembolism which is what this article mainly covers. Other embolic sources include: air ...

Pulmonary epithelioid hemangioendothelioma

Pulmonary epithelioid hemangioendothelioma is a rare vascular tumor of the lung with low malignant potential. Epidemiology Rare tumor, with ~50 cases reported. Patient age at presentation ranges from 25-54 years old. Female predilection. Clinical presentation Often asymptomatic and discovere...

Pulmonary gas embolism

Pulmonary gas emboli are a specific type of pulmonary emboli. Clinical presentation Presentation can vary dependent on the degree of air emboli where patients with small amount of air can be asymptomatic. Commonly reported clinical manifestations include sudden dyspnea, chest pain, hypotensio...

Pulmonary hypertension

Pulmonary hypertension is defined as a resting mean pulmonary arterial pressure of 25 mmHg or greater at right heart catheterisation, which is a haemodynamic feature that is shared by all types of pulmonary hypertension. A resting mean pulmonary arterial pressure of 20 mmHg or less is considered...

Pulmonary hypertension (2003 classification)

There are numerous causes of pulmonary hypertension, and thus not surprisingly there have been many classification systems. In 2003, the 3rd World Symposium on PAH met in Venice and produced an updated classification system (this has been further revised in the Dana Point classification of pulm...

Pulmonary hypertension (differential)

Pulmonary hypertension has many causes, and these can be divided in many ways. A simple and systematic approach is to proceed along the cardiopulmonary pulmonary circulation, as causes are found at each site (for a more official classification system see 2003 third world symposium on pulmonary a...

Pulmonary infarction

Pulmonary infarction is one of the key complications of pulmonary embolism (PE). Epidemiology Pulmonary infarction occurs in the minority (10-15%) of patients with PE 2. Although in a necropsy study of those with lethal PE, 60% of cases developed infarction 7. Until recently it was felt that...

Pulmonary edema due to air embolism

Pulmonary edema due to air embolism is one for the uncommon causes of non-cardiogenic pulmonary edema. It usually occurs as an iatrogenic complication of an invasive procedure. Rarely, it may also be associated with open or closed chest trauma. Pathology Air may enter into the low-pressure ve...

Pulmonary-renal syndromes

Pulmonary-renal syndromes refer to a group of conditions that can affect the lung and kidneys. These conditions are typically characterized by diffuse alveolar hemorrhage and glomerulonephritis. Diseases that can result in a pulmonary-renal syndrome includes: certain pulmonary vasculitides c...

Pulmonary trunk

The pulmonary trunk or main pulmonary artery is the solitary arterial output from the right ventricle, transporting deoxygenated blood to the lungs for oxygenation. Gross anatomy The pulmonary trunk is approximately 50 mm long and 30 mm wide (most authors use 29 mm width as the cut-off of norm...

Pulmonary vasculitis

Pulmonary vasculitis refers to vasculitides that affect the lung or pulmonary vessels. If this definition is used, a large group of conditions can fall into this category. The respiratory system may be potentially involved in all systemic vasculitides, although to a variable degree. Pathology ...

Pulmonary vein atresia

Pulmonary vein atresia represents to a spectrum of disorders where the pulmonary veins fail to form to varying degrees. It can be broadly divided into: unilateral pulmonary vein atresia bilateral pulmonary vein atresia - common pulmonary vein atresia See also anomalous pulmonary venous drai...

Pulmonary veins

The pulmonary veins drain oxygenated blood from the lungs to the left atrium. A small amount of blood is also drained from the lungs by the bronchial veins Gross anatomy There are typically four pulmonary veins, two draining each lung: right superior: drains the right upper and middle lobes ...

Pulmonary vein stenosis

Pulmonary vein stenosis refers to a spectrum of conditions characterized by narrowing of the pulmonary veins. It can be congenital or acquired. primary pulmonary vein stenosis - occurs in children secondary pulmonary vein stenosis - occurs in adults and usually associated with some identifiabl...

Pulmonary vein thrombosis

Pulmonary vein thrombosis is a rare but potentially serious condition with a number of underlying possible etiologies. Clinical presentation Often the signs and symptoms are non-specific and can range from acute (pulmonary infarction) to more insidious (progressive or recurrent pulmonary edema...

Pulsatile portal venous flow

A pulsatile portal venous flow pattern can result from both physiological and pathological causes. In well subjects mild pulsatility, or in rare situations, even marked pulsatility has been described, particularly in thin subjects, with a venous pulsatility index of >0.5 with an inverse correla...

Pulsatile tinnitus

The clinical symptom of pulsatile tinnitus can occur from a number of causes. They include vascular venous jugular bulb diverticulum dehiscent jugular bulb high riding jugular bulb sigmoid sinus diverticulum sigmoid sinus dehiscence laterally placed sigmoid sinus abnormal mastoid emiss...

Pulsatility index (ultrasound)

The pulsatility index is a calculated flow parameter in ultrasound, derived from the maximum, minimum, and mean Doppler frequency shifts during a defined cardiac cycle. Along with the resistivity index (RI), it is typically used to assess the resistance in a vascular system. Terminology Pulsat...

Pulsus bisferiens

Pulsus bisferiens or double pulse refers to a wave pattern where there is the presence of two systolic peaks that can be seen in pressure tracings of the the ascending aorta, the aortic arch, and the carotid artery. It can occur in patients with aortic valve pathology: aortic regurgitation wit...

Radial artery

The radial artery is a terminal branch of the brachial artery and arises at the cubital fossa of the forearm. It is one of the two main arteries of the forearm, along with the ulnar artery. Summary origin: terminal branch of the brachial artery location: inferior aspect of the cubital fossa ...

Radial collateral artery

The radial collateral artery is one of the two terminal branches of the deep brachial artery. As it descends in the distal part of the posterior compartment of the arm, it pierces the lateral intermuscular septum and contributes to the arterial anastomosis of the elbow specifically the radial re...

Radialis indicis artery

The radialis indicis artery is a branch of the radial artery in the hand that supplies the radial aspect of the index finger (2nd digit). It arises from the radial artery in the plam just after the origin of the princeps pollicis artery. The artery courses distally along the radial (lateral) pal...

Radial recurrent artery

The radial recurrent artery is the largest lateral branch of the radial artery in the forearm, arising just after its origin. It courses proximally on supinator from its origin to form an arterial arcade with the anterior branch (radial collateral artery) of the profunda brachii (deep brachial) ...

Radial vein

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

Radiation-induced cerebral vasculopathy

Radiation-induced cerebral vasculopathy encompasses a complex and broad range of effects on the intra- and extracranial vessels resulting from injury from radiation exposure. Manifestations can include hemorrhages and ischemic strokes, cavernoma and capillary telangiectasias, and large vessel st...

Ramus intermedius artery

The ramus intermedius is a variant coronary artery resulting from trifurcation of the left main coronary artery 1. It is present in ~20% (range 15-30%) 2-3 of the population. It can have a course similar to the obtuse marginal branches of the left circumflex artery or the diagonal branches of t...

Rapid ultrasound in shock

The rapid ultrasound in shock (RUSH) protocol is a structured point-of-care ultrasound (POCUS) examination performed at the time of presentation of a shocked patient. It is a more detailed and longer exam than the FAST scan, with the aim to differentiate between hypovolemic, cardiogenic, obstruc...

Rasmussen aneurysm

Rasmussen aneurysm (not to be confused with Rasmussen encephalitis) is an uncommon complication of pulmonary tuberculosis and represents a pulmonary artery aneurysm adjacent or within a tuberculous cavity. Epidemiology It can be present in up to 5% of patients with chronic cavitary tuberculos...

Rastelli procedure

The Rastelli procedure is a surgical procedure to correct certain combinations of cardiovascular defects in patients with cyanotic congenital heart disease. Rationale The operation is based on a redirection of ventricular outflows using an intracardiac baffle that tunnels the left ventricle to...

Raymond–Roy occlusion classification of intracranial aneurysms

The Raymond–Roy occlusion classification (RROC) is an angiographic classification scheme for grading the occlusion of endovascularly treated intracranial aneurysms 1. It is also known as the Raymond class, Montreal scale or the Raymond Montreal scale. class I: complete obliteration class II: r...

Raynaud phenomenon

Raynaud phenomenon describes a localised vasculopathy whereby there is an exaggerated vascular response to cold temperature or emotional stresses. Terminology Raynaud phenomenon is classified as being either 'primary' or idiopathic, or 'secondary' to another underlying condition (as discussed ...

Rectus sheath hematoma

Rectus sheath hematomas, as the term implies, occur when a hematoma forms in the rectus abdominis muscle/rectus sheath. It is most common in its lower segment and is generally self-limiting. Epidemiology Rectus sheath hematomas are more common in women with a 3:1 F:M ratio. Clinical presentat...

Recurrent artery of Heubner

Recurrent artery of Heubner, also known as the medial striate artery or long central artery, is the largest perforating branch from the proximal anterior cerebral artery (ACA), and is the only one routinely seen on angiography. Gross anatomy Origin and course Its origin is near the A1-ACOM-A2...

Recurrent tibial arteries

Posterior tibial recurrent artery Origin and course Inconstant branch that arises before the anterior tibial reaches the extensor compartment Ascends anterior to popliteus with the recurrent nerve to that muscle, anastomosing with the inferior genicular branches of the popliteal artery Suppl...

Renal arterial cut-off sign

Renal arterial cut-off sign, as the name suggests, is an abrupt termination of the contrast-opacified lumen of the renal artery. It may or may not be associated with contrast extravasation. It is seen in a vascular injury, e.g. segmental or main renal artery thrombosis or occlusion.

Renal arterial resistive index

The renal arterial resistive index (RI) is a sonographic index to assess for renal arterial disease. It is measured as RI = (peak systolic velocity - end diastolic velocity ) / peak systolic velocity the normal value is ≈ 0.60 with 0.70 being around the upper limits of normal Technique M...

Renal arteriovenous fistula

Renal arteriovenous fistulae (AVFs) are anomalous direct communications between arteries and veins in the kidney, which may be confused with a renal arteriovenous malformation (AVM). Epidemiology The incidence of renal AVF is variable, estimated at 0.3-19% in native kidneys and 6-8% in ren...

Renal arteriovenous malformation

Renal arteriovenous malformations (renal AVMs) are an uncommon vascular anomaly, which may be confused with a renal arteriovenous fistula (renal AVF). Pathology Like arteriovenous malformations elsewhere in the body, a renal AVM is formed by a connection between the arterial and venous structu...

Renal artery

The renal arteries originate from the abdominal aorta and enter the renal hila to supply the kidneys. Any variant in arterial supply is important to clinicians undertaking surgery or other interventional renal procedures. Gross anatomy Origin They arise from the abdominal aorta at the L1-2 ...

Renal artery aneurysm

Renal artery aneurysms (RAA) are considered the second most common visceral aneurysm (15-22%), most common being splenic artery aneurysm (60%). They are more common in females. Most of the lesions are saccular and tend to occur at the bifurcation of main renal artery. Epidemiology RAAs occur i...

Renal artery dissection

Renal artery dissection may occur as a result of the following processes 1: aortic dissection extending to involve the renal artery iatrogenic (e.g. catheterisation) trauma atherosclerosis fibromuscular dysplasia connective tissue disease (eg. Marfan syndrome) idiopathic

Renal artery occlusion (acute)

Renal artery occlusion can happen acutely due to in-situ thrombus, embolism, or dissection. Unless immediately treated, it can lead to renal infarction 1. Epidemiology The condition is more common in the elderly, however, it may be seen in a younger age group if they have risk factors (describ...

Renal artery pseudoaneurysm

Renal artery pseudoaneurysms are uncommon vascular finding, with the majority occuring after a renal intervention. Pathology A renal artery pseudoaneurysm differs from a renal artery true aneurysm (as might occur in fibromuscular dysplasia) in that it does not involve all three layers of the a...

Renal artery stenosis

Renal artery stenosis (RAS) refers to a narrowing of a renal artery. When the process occurs slowly, it leads to secondary hypertension. Acute renal artery stenosis does not lead to hypersecretion of renin. Pathology When the stenosis occurs slowly, collateral vessels form and supply the kidne...

Renal infarction

Renal infarction results from interruption of the normal blood supply to part of, or to the whole kidney. The main imaging differential diagnosis includes pyelonephritis and renal tumors. Epidemiology The demographics of affected patients will depend on the underlying cause, although as most c...

Renal sympathetic denervation

Renal sympathetic denervation (RSDN), also known as renal denervation, is an interventional procedure that uses radiofrequency ablation to destroy the nerve endings in the wall of the renal arteries. Endovascular (trans-catheter) techniques are an alternative to surgical sympathectomy. Indicat...

Renal vascular pedicle injury

Renal vascular pedicle injury is a severe form of renal trauma, which if not recognised and treated expediently with lead to the loss of the kidney. Radiographic features CT Contrast enhanced CT is the Imaging modality of choice. On CT it is recognised as a non-enhaning kidney. Perirenal he...

Renal vein

The renal veins are asymmetric paired veins that drain the kidneys. Gross anatomy Course The renal vein is formed by the union of two-to-three renal parenchymal veins in the renal sinus. It emerges from the renal hilum anterior to the renal artery and drains into the inferior vena cava at th...

Renal vein anomalies

There are several variations in renal venous anatomy. Some of these are specific to the left renal vein. Left renal vein anomalies are generally classified into four types 2: type I the ventral pre-aortic limb of the left renal vein is obliterated, but the dorsal retro-aortic limb persists a...

Renal vein thrombosis

Renal vein thrombosis can be either from "bland" thrombus or tumor thrombus (extension of tumor into the vein). There are numerous etiologies for bland thrombus, but it most commonly occurs in the hypercoagulable nephrotic syndrome. Renal vein thrombus is commoner on the left side, presumably du...

Renal vein varices

Renal vein varices develop for various reasons and are usually asymptomatic. Clinical presentation Renal vein varices are usually asymptomatic. Some patients may present with flank pain and/or hematuria. Pathology Etiology chronic renal vein thrombosis nutcracker syndrome retroaortic le...

Renovascular hypertension

Renovascular hypertension (RVH) is a type of secondary hypertension, where high blood pressure develops secondary to renal artery disease. Epidemiology Approximately 2.5% (range 0.5-5%) of hypertensive patients will have RVH as a cause 2,3. Pathology Etiology There are a number of conditi...

Reporting tips for aortic aneurysms

When issuing an MRI or CT report on a patient with an aortic aneurysm, whether it be thoracic or abdominal, a number of features should be mentioned to aid the referring clinician in managing the patient. Reporting tips for aortic aneurysms include 1-2: size and shape sac dimensions (outer sur...

Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations

Retinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic manifestations (RVCL-S) is an autosomal dominant microvasculopathy of the brain, retina, and other organ systems. Terminology RVCL-S was described by Stam and colleagues in 2016 to encompass several previously described condit...

Retro-aortic left brachiocephalic vein

The retro-aortic left brachiocephalic vein is a rare vascular variant where the left brachiocephalic vein passes more inferiorly through the superior mediastinum, coursing inferior to the aortic arch and posterior to the ascending aorta to join the right brachiocepahilc vein forming the superior...

Retroaortic left renal vein

Retroaortic left renal vein (RLRV) is a normal anatomical variant where the left renal vein is located between the aorta and the vertebra and drains into the inferior vena cava. Its recognition is important in order to avoid complications during retroperitoneal surgery or interventional procedu...

Retromandibular vein

The retromandibular vein runs through the substance of the parotid gland. Gross anatomy Origin and course The retromandibular vein is formed, usually within the parotid, by the confluence of the maxillary vein and the superficial temporal vein. It lies deep to the facial nerve and superficial...

Retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF), is a condition that has previously been described as chronic periaortitis. It is an uncommon fibrotic reaction in the retroperitoneum that typically presents with ureteric obstruction. The disease is part of a spectrum of entities that have a common pathogenic pr...

Retroperitoneal hemorrhage

Retroperitoneal hemorrhage can be a source of significant yet occult blood loss. Clinical presentation The clinical features are varied depending on the amount of hemorrhage present, rate of onset and ability of the surrounding structures to contain the hemostatic system. The classical feature...

Reverse figure 3 sign

The reverse figure 3 sign (also known as the E sign) is seen on barium swallows in patients with a coarctation of the aorta and is the medial equivalent of the figure 3 sign seen on plain chest radiographs. It is formed by prestenotic dilatation of the ascending aorta, indentation of the coarcta...

Reversible cerebral vasoconstriction syndrome

Reversible cerebral vasoconstriction syndrome (RCVS) is a group of conditions with a common clinical and radiologic presentation. It is characterized by thunderclap headache and reversible vasoconstriction of the cerebral arteries. Terminology Numerous and varied terms have been used to descri...

Revised International Chapel Hill Consensus Conference nomenclature of vasculitides

Following months of preparation, experts in the field of vasculitis from 12 different countries proposed an update to the 1994 International Chapel Hill Consensus Conference nomenclature of vasculitides. This 2012 update at the time of writing (mid-2016) remains the most widely used system for d...

Rhupus syndrome

Rhupus syndrome is a term traditionally used to describe patients uncommonly having the coexistence of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA)

Right colic artery

The right colic artery may arise directly from the superior mesenteric artery (SMA) but often arises from a common trunk with the ileocolic artery or middle colic artery. It courses to the right to the ascending colon and divides into a descending branch that supplies the lower portion of the a...

Right coronary artery

The right coronary artery (RCA) is one of the two main coronary arteries that supply the heart with oxygenated blood. Gross anatomy Origin It is a branch of the ascending aorta, with its normal origin in the right aortic sinus, just superior to the aortic valve Course The RCA courses to th...

Right gastric artery

The right gastric artery is a branch of the common hepatic artery which supplies the lesser curvature of the stomach. Gross Anatomy Course The right gastric artery branches off from the common hepatic artery as it turns into the lesser omentum. It runs along the lesser curvature of the stomac...

Right gastroepiploic artery

The right gastroepiploic artery (RGA) arises from the gastroduodenal artery as it divides into its two terminal branches, the right gastroepiploic artery and the superior pancreaticoduodenal artery. Gross Anatomy Course The RGA passes between the first part of the duodenum and the pancreas, ...

Right hepatic artery

The right hepatic artery (RHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver. Gross anatomy The proper hepatic artery bifurcates into the right and left hepatic arteries at or before rea...

Right marginal artery

The right marginal artery, also known as the right intermediate atrial branch, supplies the surrounding right atrial tissues 1,2 and, in 10-15% of cases, provides the main arterial supply to the sinus node 3,4. Terminology It also sometimes known as a the acute marginal artery or margo acutus ...

Right pulmonary artery

The right pulmonary artery (RPA) is one of the branches of the pulmonary trunk, branching at the level of the transthoracic plane of Ludwig. It is longer than the left pulmonary artery and courses perpendicularly away from the pulmonary trunk and left pulmonary artery, between the superior vena ...

Right sided aortic arch

Right-sided aortic arch is a type of aortic arch variant characterized by the aortic arch coursing to the right of the trachea. Different configurations can be found based on the supra-aortic branching patterns, with the two most common patterns being the right-sided aortic arch with mirror imag...

Right-to-left shunt (mnemonic)

A useful mnemonic to remember the differential diagnoses associated with right-to-left cardiovascular shunts is: 1-5 Mnemonic 1: a combination vessel; truncus arteriosus 2: number of arteries involved; transposition of the great arteries 3: "tri-" means 3, the number of leaflets involved; t...

Rim sign in renal vascular compromise

Rim sign in renal vascular compromise is seen in major renal vascular compromise. It can be seen in: renal artery obstruction from embolism, thrombosis or dissection renal vein thrombosis acute tubular necrosis Radiographic features At contrast-enhanced CT or MRI, a thin (1-3 mm) rim of su...

Rotational vertebral artery occlusion syndrome

Rotational vertebral artery occlusion syndrome, also known as bow hunter's syndrome, is a rare form of vertebrobasilar insufficiency secondary to dynamic compression of the usually-dominant vertebral artery. Pathology It has many predisposing etiologies, but is most often due to large osteoph...

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