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.

Create new article

Filtered (1)Done (clear)

×Systems

+Article Sections

+Sort By

1,052 results found

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 haemangioendothelioma

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

Pulmonary gas embolism

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

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 oedema due to air embolism

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

Pulmonary-renal syndromes

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

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 characterised 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 aetiologies. Clinical presentation Often the signs and symptoms are non-specific and can range from acute (pulmonary infarction) to more insidious (progressive or recurrent pulmonary oede...

Pulsatile portal venous flow

Pulsatile portal venous flow pattern can result from both physiological and pathological causes. Usually, 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 correlation to body ...

Pulsatile tinnitus

The clinical symptom of pulsatile tinnitus can occur from a number of causes. They include vascular congenital venous dehiscent jugular bulb high riding jugular bulb laterally placed sigmoid sinus venous diverticulum abnormal mastoid emissary veins arterial aberrant internal carotid ...

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. Clinical presentation Clinical symptoms are broad and depend on the underlying vasculopathy. Radiation-induced telangie...

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 haematoma

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

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 tumours. Epidemiology The demographics of affected patients will depend on the underlying cause, although as most ...

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 ha...

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 tumour thrombus (extension of tumor into the vein). There are numerous aetiologies for bland thrombus, but it most commonly occurs in the hypercoagulable nephrotic syndrome. Renal vein thrombus is commoner on the left side, presumably ...

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 haematuria. Pathology Aetiology chronic renal vein thrombosis nutcracker syndrome retroaortic ...

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 Aetiology There are a number of condit...

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 proced...

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 haemorrhage

Retroperitoneal haemorrhage 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 featur...

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...

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 PHA bifurcates into the right and left hepatic arteries at or before reaching the porta he...

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 characterised 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...

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. It has many predisposing aetiologies, but is most often due to large osteophytes, atla...

Ruptured berry aneurysm

Rupture of a berry aneurysm, also known as a saccular aneurysm, usually results in a subarachnoid haemorrhage (SAH) but can, depending on the location of the rupture and presence of adhesions to the aneurysm, also result in cerebral haematoma, subdural haematoma and/or intraventricular haemorrha...

Saccular cerebral aneurysm

Saccular cerebral aneurysms, also known as berry aneurysms, are intracranial aneurysms with a characteristic rounded shape and account for the vast majority of intracranial aneurysms. They are also the most common cause of non-traumatic subarachnoid haemorrhage. Terminology When larger than 25...

Sano shunt

The Sano shunt is a palliative surgical technique sometimes used as a step in Norwood procedure for hypoplastic left heart syndrome. The procedure involves placement of an extracardiac conduit between the right ventricle and main pulmonary artery stump. This technique prevents the reduced diast...

Scapular anastomosis

The pectoral girdle has a rich plexus of arterial vessels that anastomose around the scapula and its muscles known as the scapular anastomosis. It functions to allow blood to flow around the scapula and shoulder joint if there is injury or occlusion. Contributing branches arise from as proximal...

Scimitar sign of cystic adventitial disease

Scimitar sign traditionally referred to a catheter angiographic appearance, although it can also be seen on MRA and CTA. It denotes lateral displacement and stenosis of the popliteal artery in patients with cystic adventitial disease.

Scimitar syndrome (lungs)

Scimitar syndrome, also known as hypogenetic lung syndrome, is characterised by a hypoplastic lung that is drained by an anomalous vein into the systemic venous system. It is a type of partial anomalous pulmonary venous return and is one of the several findings in congenital pulmonary venolobar ...

Secondary pulmonary arterial hypertension

Secondary pulmonary arterial hypertension includes all cases of pulmonary arterial hypertension except for those for which no cause is identified with are then termed idiopathic pulmonary arterial hypertension. The classification of pulmonary arterial hypertension into primary and secondary ha...

Segmental arterial mediolysis

Segmental arterial mediolysis (SAM) is an increasingly recognised vascular disease of the middle-aged and elderly and a leading cause of spontanoeus intra-abdominal haemorrhage. It is characterised by fusiform aneurysms, stenoses, dissections and occlusions within splanchnic arterial branches. I...

Sentinel clot sign

The sentinel clot sign is a useful CT finding for the evaluation of probable anatomic sites of haemorrhage. On CT, acute clotted haemorrhage typically has high attenuation (45 to 80 HU), whereas surrounding areas of acute non-clotted haemorrhage or more chronic haemorrhage have either lower att...

Septal cerebral veins

Septal cerebral veins originate at the lateral aspect of the anterior horns of the lateral ventricles then pass medially, inferior to the genu of the corpus callosum. They then turn backwards and traverse along the septum pellucidum and enter the internal cerebral vein behind the foramen of Monr...

Serpentine aneurysm

Serpentine aneurysm is a rare subtype of intracranial aneurysm with a distinct appearance. It consists of a partially thrombosed giant intracranial aneurysm (≥ 25 mm) traversed by a patent serpiginous intra-aneurysmal vascular channel. This vascular channel has an entry and an exit point, differ...

Shmoo sign

Shmoo sign refers to the appearance of a prominent, rounded left ventricle and dilated aorta on a plain AP chest radiograph giving the appearance of Shmoo, a fictional cartoon character in the comic strip Li'l Abner, which first appeared in 1948. This sign is indicative of left ventricular enlar...

Shone syndrome

Shone syndrome, also known as Shone complex, is a rare syndrome characterised by left-sided, obstructive congenital heart defects. Epidemiology Shone syndrome is thought to be very rare, accounting for less than 1% of all congenital heart disease 1. Clinical presentation Patients, usually ne...

Short gastric arteries

The short gastric arteries are a group of short arteries arising from the terminal splenic artery and the left gastroepiploic artery which supply the fundus of the stomach along it's greater curvature. The vessels are short in length, variable in number and course through the gastrosplenic liga...

Shrinking lung syndrome

Shrinking lung syndrome (SLS) refers to a rare complication of systemic lupus erythematosus (SLE), and is characterised by: unexplained dyspnoea restrictive pattern on pulmonary function tests elevated hemidiaphragm Epidemiology As with SLE in general, it is thought to carry a increased fem...

Sickle cell disease

Sickle cell disease (SCD) is a hereditary (autosomal recessive) condition resulting in the formation of abnormal haemoglobin (a haemoglobinopathy), which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia. Epidemiology There is no recognised gender predilection. ...

Sickle cell disease (abdominal manifestations)

Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs. For a general discussion, please refer to sickle cell disease. Splenic splenomegaly may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in the spleen, resulting ...

Sigmoid arteries

The sigmoid arteries are branches, between two-to-four, of the inferior mesenteric artery (IMA) and supply the sigmoid colon. Summary origin: inferior mesenteric artery course: after arising from IMA, these branches descend to the left in the sigmoid mesocolon anastomosis: superiorly with ...

Sigmoid sinus

The sigmoid sinus is a paired structure and one of the dural venous sinuses. It is the continuation of the transverse sinus (which is similarly variable in size) and becomes the sigmoid sinus as the tentorium ends. It is here that the sinus receives the superior petrosal sinus. It passes inferi...

Signal flare phenomenon

The signal flare phenomenon is a useful sign to identify active bleeding in a liquefied haematoma with haematocrit effect on dynamic CT scan images. When active arterial haemorrhage is present in a liquefied haematoma that has a haematocrit effect, a signal flare phenomenon may be seen as a lin...

Sildenafil citrate-induced penile Doppler

In the past 15 years sildenafil citrate-induced penile Doppler has emerged as a technique for evaluating erectile dysfunction. It has greater patient acceptability than the usual papaverine-induced colour Doppler and is safer. Sildenafil citrate is a popular vasodilator drug used in treatment o...

Single coronary artery

Single coronary arteries are rare (incidence 0.03-0.07%), with a higher incidence in patients with congenital heart disease (in particular truncus arteriosus and pulmonary atresia). They occur when there is a single ostia arising from the aorta with no ectopic ostia. There is a wide variety of c...

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.