Hughes-Stovin syndrome (HSS) is a vasculitis that predominantly affects large vessels. The disease bears some resemblance to Behçet disease.
It occurs predominantly between the 2nd to 4th decades. There is a recognized male predilection.
The Hunt and Hess scale describes the severity of subarachnoid hemorrhage resulting from the rupture of an intracerebral aneurysm and is used as a predictor of survival.
asymptomatic or minimal headache and slight neck stiffness
moderate to severe headache; neck...
The hyperdense MCA sign refers to focal hyperdensity of the middle cerebral artery (MCA) on non-contrast brain CT and is the direct visualization of thromboembolic material within the lumen. It is thus the earliest visible sign of MCA infarction as it is seen within 90 minutes after the event 1....
Hyperperfusion syndrome after carotid endarterectomy (CEA) or carotid artery stenting (CAS) is a rare complication.
Hyperperfusion occurs in ~7.5% (range 1-14%) of patients but only a minority (~1.5%) of patients are symptomatic 1,2, with incidence being reported slightly more af...
Hyperreninaemic hypertension may have many causes including:
renal artery stenosis
renal secreting tumor, e.g. renal cell carcinoma, reninoma
renal compression: large renal mass, subcapsular hemorrhage (Page kidney)
Hypertension refers to an increase in blood pressure above the 'normal' for the age, sex and ethnicity of the patient. This can be specified according to the vascular system involved. Although generally when it is not specified it is assumed to refer to the systemic type.
Hypervascular liver lesions may be caused by primary liver pathology or metastatic disease.
hepatocellular carcinoma (HCC)
most common hypervascular primary liver malignancy
early arterial phase enhancement and then rapid wash out
rim enhancement of c...
Hypothenar hammer syndrome occurs from trauma to the distal ulnar artery or proximal portion of superficial palmar arch as a result of repetitive trauma to the hypothenar eminence. Originally described in patients using hammers and screwdrivers, it is also seen in various athletes such as basket...
Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly comprising of pulmonary trunk enlargement with or without dilatation of the right and left pulmonary arteries.
For this diagnosis, exclusion of pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and confirma...
Idiopathic pauci immune pulmonary capillaritis (IPIPC) is considered a rare type of pulmonary vasculitis. Some authors consider this due be an organ specific subset of microscopic polyangiitis 3. It can result in diffuse alveolar hemorrhage.
It is an isolated small vessel vasculitis ...
Idiopathic portal hypertension (non-cirrhotic portal hypertension or Banti syndrome) is a term that has been given to portal hypertension occurring without hepatic cirrhosis, parasitic infection, or portal venous thrombosis.
Rare condition. More common in India and Japan.
Idiopathic pulmonary arterial hypertension is uncommon, representing only a tiny fraction of all cases of pulmonary arterial hypertension, which has a very long list of secondary causes (see causes of pulmonary arterial hypertension).
Older terms for this entity include primary pul...
Idiopathic retroperitoneal fibrosis, also known as Ormond disease, is a subtype of retroperitoneal fibrosis where no obvious cause is found. It includes a spectrum of diseases which are characterized by fibroinflammatory tissue encasing the abdominal aorta and the iliac arteries. This process ma...
IgA vasculitis (formerly known as Henoch-Schonlein purpura (HSP)) is a type of non-thrombocytopenic immune-mediated small vessel acute leukocytoclastic vasculitis.
It tends to occur in the pediatric population (peak incidence 3-10 years) 3.
In order to differentiate from other types of vasculi...
IgG4-related cardiovascular disease is one of the many manifestations of IgG4-related disease and may present as:
aortitis and periaortitis
arteritis and periarteritis of small to medium-sized arteries
coronary arteritis and periarteritis
The ileocolic artery is a branch of the superior mesenteric artery (SMA) that runs obliquely to the ileocecal junction.
It divides into an ileal branch that supplies the terminal ileum and anastomoses with the terminal SMA and a colic branch that supplies the proximal ascending colon and anasto...
Iliac arterial aneurysms are focal dilatations of the iliac artery.
Although the dimensions that define the aneurysm are dependent on the sex of the patient and the portion of the artery involved, a common iliac artery (CIA) with a diameter ≥1.7 cm in males or ≥1.5 cm in females is considered ...
Iliac artery endofibrosis is a rare condition that affects young endurance athletes, characterized by a non-atherosclerotic stenosis of the iliac artery.
It is a rare entity that affects highly trained endurance athletes, mostly cyclists and long-distance runners 4. The disease ha...
Iliac vein occlusion can be due to a variety of causes including:
catheter dissection injuries
IVC filter insertion
direct tumor invasion
enlarged lymph nodes
Iliofemoral deep vein thrombosis (iliofemoral DVT) occurs when a thrombus in the iliac vein (common, external or internal) or common femoral vein obstructs the venous outflow from the lower limb leading to marked edema; DVT of the IVC or the more distal lower limb veins may be present.
The iliolumbar artery is one of three branches of the posterior division of the internal iliac artery.
origin: posterior division of the internal iliac artery
supply: ilium, iliacus muscle, psoas major muscle, quadratus lumborum muscle, erector spinae muscle, anterio...
Implantable ports, also known as chemoports, totally implantable central venous access ports or Port-A-Caths®, are a type of central venous catheter for patients requiring long-term venous access. They offer the ability to have long-term central venous access with some of the advantages over per...
Incomplete double aortic arch is a rare vascular ring anomaly wherein a segment of the minor aortic arch, usually the left, is atretic.
As in the case of other vascular rings, this anomaly can cause 1:
Some patients may reach adulthood with...
Indocyanine green (ICG) lymphangiography is an emerging imaging technique used to visualize lymphatic vessels and map their course as they drain to sentinel lymph nodes.
Indocyanine green is a fluorescent dye discovered by researchers at Kodak working on near-infrared photography in 1...
Infantile hemangiomas are benign vascular neoplasms that are the most common head and neck tumors of infancy. They can occur virtually anywhere, but the majority are found in the head and neck regions.
This article aims to be a generic discussion of the condition, for detailed and more specific...
The infarct core denotes the part of an acute ischemic stroke which has already infarcted, or is irrevocably destined to infarct regardless of reperfusion. It is also referred to as established infarct and is in distinction from the penumbra which remains potentially salvageable.
The inferior adrenal (suprarenal) artery is one of three adrenal arteries that supplies the adrenal gland.
Ipsilateral renal artery (usually before the terminal division of the renal artery)
The course of the inferior suprarenal artery depends on its origin. Re...
The inferior alveolar artery is a branch of the maxillary artery. It runs with the inferior alveolar nerve as it descends through the infratemporal fossa and enters the mandibular canal and supplies mandibular teeth. In the region of the first premolar it bifurcates into the incisive and mental ...
The inferior epigastric artery arises from the external iliac artery and is an important artery supplying the anterior abdominal wall. If a superficial inferior epigastric artery is present, as seen in about two-thrids of cases, then the inferior epigastric artery is referred to as the deep infe...
The inferior gluteal artery is a branch of the anterior division of the internal iliac artery. It originates in the pelvis and supplies the gluteal region and thigh.
origin: anterior division of the internal iliac artery
location: pelvis, gluteal region, back of thigh
The inferior hypophyseal arterial circle, also known as the inferior capsular arterial rete, is an anastamotic arterial network formed around the base of the pituitary gland by branches from three vessels, themselves branches off the cavernous portion of the carotid artery. They are:
The inferior hypophyseal artery is a branch from the meningohypophyseal trunk, a branch of the C4 segment of the internal carotid artery. It is usually single on each side and divides into medial and lateral branches contributing to the inferior hypophyseal arterial circle.
The inferior hypoph...
The inferior interventricular artery (also known as the posterior interventricular artery or posterior descending artery, PDA) is an artery that extends along the inferior interventricular sulcus. The artery supplies the posterior third of the interventricular septum through posterior septal per...
The inferior mediastinum is the box-shaped space in the mediastinum below the transthoracic plane of Ludwig between the wedge-shaped superior mediastinum above and the diaphragm and inferior thoracic aperture below. There are no physical structures that divide the superior and inferior mediastin...
The inferior mesenteric artery (IMA) is one of the three non-paired major visceral arteries in the abdominal cavity arising from the abdominal aorta and supplying the hindgut. It is the smallest of the three anterior visceral branches of the abdominal aorta.
Inferior mesenteric artery aneurysms are among the rarest of all visceral artery aneurysms.
Aneurysms of the inferior mesenteric artery (IMA) only account for <1% of all visceral artery aneurysms 1,2. These aneurysms are more common in men than in women 3.
The inferior mesenteric vein drains blood from the distal portion of the colon as well as the rectum (i.e. the hindgut).
Origin and course
The inferior mesenteric vein drains the mesenteric arcade of the hindgut (comprising of distal transverse, descending, and sigmoid colon). ...
The inferior pancreaticoduodenal artery is the first branch of the superior mesenteric artery (SMA), though it often arises from the first jejunal branch.
It anastomoses with branches of the superior pancreaticoduodenal artery (from the gastroduodenal artery) and it supplies the head of the pan...
The inferior petrosal sinus is one of the dural venous sinuses. It is often a plexus of venous channels rather than a true sinus and drains blood from the cavernous sinus to the jugular bulb through the jugular foramen (pars nervosa) or sometimes via a vein which passes through the hypoglossal c...
The inferior phrenic arteries (IPA) are paired branches of the abdominal aorta / celiac trunk supplying the diaphragm. Their importance lies with the fact that the right IPA is the most common extrahepatic arterial supply of a hepatocellular carcinoma.
origin: abdominal aorta or celia...
The inferior rectal artery is an artery that supplies the lower anal canal including the external anal sphincter.
origin: from internal pudendal artery, just after it enters the pudendal canal
course: runs anteromedially through the ischioanal fossa to reach the deep portion of the ex...
The inferior sagittal sinus is one of the dural venous sinuses and runs along the inferior (free) edge of the falx cerebri. It runs from anterior to posterior, the same as the superior sagittal sinus, and drains into the straight sinus. It receives tributaries from the falx itself as well as som...
The inferior thoracic aperture connects the thorax with the abdomen.
The inferior thoracic aperture is irregular in shape and is more oblique and much larger than the superior thoracic aperture. The diaphragm occupies and closes the inferior thoracic aperture, thereby separating ...
The inferior thyroid artery is a branch of the thyrocervical trunk (85%) or subclavian artery (15%) and ascends to enter the thyroid gland on its posterior surface, as well as supplying both the superior and inferior parathyroid glands 1. The nerve is closely related to the ascending limb of the...
The inferior ulnar collateral artery is a vessel arising from the brachial artery at the distal-most part of the upper arm.
origin: branch of the brachial artery superior to the medial epicondyle 1
location: distal lower arm
supply: brachialis, biceps brachii, and coracobrachialis 1
The inferior vena cava (IVC) drains venous blood from the lower trunk, abdomen, pelvis and lower limbs to the right atrium of the heart.
The inferior vena cava is formed by the confluence of the two common iliac veins at the L5 vertebral level. The IVC has a retroperitoneal cours...
Inferior vena cava filter, or just IVC filter, is an endovascular device which is typically placed in the infrarenal inferior vena cava (IVC) to prevent pulmonary embolism in selected patients. This procedure is most often performed by interventional radiologists under fluoroscopic guidance.
Inferior vena cava leiomyosarcomas are the most common type of retroperitoneal leiomyosarcoma and most common primary malignancy of the inferior vena cava.
Three-quarters of cases occur in women, usually aged 40-60 years 2.
When symptomatic, patients most c...
Inferior vena caval (IVC) thrombosis is an essential diagnosis while evaluating any neoplastic lesion, or portal hypertension. It is also important to differentiate bland thrombus from tumor thrombus.
Patient can present with many features which include
bilateral pedal edema...
Inferior vena cava (IVC) webs are an uncommon condition characterized by obstruction of the hepatic segment of the inferior vena cava by a membrane or fibrous band. This is often associated with occlusion of one or more of the hepatic veins.
If there is hepatic vein invol...
The inferior vesical artery is a branch of the anterior division of the internal iliac artery.
Some texts state it is only present in males and may be replaced by a vaginal artery in females. Note, the vaginal artery which is most commonly described, is often a branch of the uterine artery.
The inferolateral trunk, along with the meningohypophyseal trunk, is a branch of the C4 segment of the internal carotid artery. It is identified in up to 80% of dissection specimens but is less frequently seen on imaging.
It is also referred to as the artery to the inferior cavernous sinus, ari...
Inflammatory abdominal aortic aneurysm (IAAA) is a variant of abdominal aortic aneurysm (AAA) characterized by inflammatory thickening of the aneurysm wall, perianeurysmal fibrosis and adherence to surrounding structures.
They account for ~5 to 10% of all AAAs.
The infraorbital artery is a branch of the third part of the maxillary artery. It runs through the inferior orbital fissure, orbit, infraorbital canal then the infraorbital foramen. Here it gives off the anterior superior alveolar artery which supplies the anterior teeth and the anterior part of...
An infundibulum (plural: infundibula) is a conical outpouching from an artery (usually intracranial), with a broad base narrowing to an apex from which a vessel originates. The most common location for an infundibulum is the origin of the posterior communicating artery (PCOM) from the supraclino...
Infusothorax (plural: infusothoraces), also known as a chemothorax, is a complication of central venous catheter malposition where the catheter tip is located in the pleural space and the infusion of the fluid collects inadvertently in the pleural space in the form of a pleural effusion. Longer ...
Innominate artery compression syndrome, also known as brachiocephalic artery compression syndrome, is a rare cause of tracheal stenosis that occurs in the pediatric population.
The brachiocephalic artery usually takes its origin to the left of the trachea. The artery subs...
An interarterial course of the left coronary artery is defined as origination of the left main or left anterior descending coronary artery from the right coronary sinus of Valsalva, with a course between the ascending aorta and the pulmonary artery trunk.
An interarterial course i...
Interarterial course of the right coronary artery, may occur if the right coronary artery (RCA) has an aberrant origin from the left coronary sinus. The interarterial course occurs because the artery passes between the ascending aorta and the pulmonary trunk.
It is an uncommon anatomic variant ...
The intercavernous sinuses (anterior, posterior, and inferior) are variable dural venous sinuses that connect the left and right cavernous sinuses. Some authors also include in this group the basilar venous plexus (basilar sinus) and sinus of the dorsum sellae 2. The anterior, posterior, and inf...
The internal carotid artery (ICA) is a terminal branch of the common carotid artery.
It arises most frequently between C3 and C5 vertebral level, where the common carotid bifurcates to form the internal carotid and the external carotid artery (ECA). Just superior to its ...
Internal carotid artery (ICA) dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima 1 and is a common cause of stroke in younger patients.
Dissection may occur at any age but is a common cause of stroke in young patien...
The internal carotid artery segments, according to the Bouthillier classification, can be recalled by the following mnemonic:
C'mon Please Learn Carotid Clinical Organizing Classification
C: cervical segment
P: petrous segment
L: lacerum segment
C: cavernous segment
C: clinoid se...
The internal cerebral veins are paired, paramedian veins which course posteriorly along the roof of the third ventricle, between the two leaves of the velum interpositum.
Each is formed at the foramen of Monro by the confluence of the choroidal vein (draining the choroid plexus o...
The internal iliac artery (also known as the hypogastric artery) is the smaller terminal branch of the common iliac artery. It supplies the pelvic walls, pelvic viscera, external genitalia, perineum, buttock and medial part of the thigh.
The common iliac artery bifurcate...
The internal iliac vein (IIV) represents the union of veins and venous plexuses draining the pelvic viscera, pelvic wall, external genitalia, perineum, buttocks and medial thigh.
Above the greater sciatic notch.
Course and termination
Ascends out of pelvis to meet the...
The internal jugular vein (IJV) is the major venous return from the brain, upper face and neck.
Origin and course
It is formed by the union of inferior petrosal and sigmoid dural venous sinuses in or just distal to the jugular foramen (forming the jugular bulb). It descends in t...
A useful mnemonic to remember the branches of the internal jugular vein is:
Medical Schools Let Fun People In
From inferior to superior:
M: middle thyroid vein
S: superior thyroid vein
L: lingual vein
F: facial vein
P: pharyngeal vein
I: inferior petrosal sinus
The internal palpebral arteries, or medial palpebral arteries, are branches of the ophthalmic artery, with superior and inferior medial palpebral branches arising opposite the trochlear of the superior oblique muscle.
The internal palpebral arteries enter the superior and inferio...
The internal pudendal artery is a branch of the anterior division of the internal iliac artery and is the primary supply of the perineum. It is a larger vessel in males than in females.
origin: anterior division of internal iliac artery
location: pelvis, gluteal region, perineum
The internal pudendal veins are the set of accompanying veins to the internal pudendal artery draining the perineal region to empty into the internal iliac vein.
inferior rectal veins
penile bulb and scrotum vein
clitoris and posterior labial vein
The internal thoracic artery (previously called the internal mammary artery) supplies the anterior body wall and its associated structures from the clavicles to the umbilicus.
The internal thoracic artery arises from the first part of the subclavian artery in the base of ...
The internal thoracic vein (previously known as the internal mammary vein) arises from the superior epigastric vein. It drains the chest wall and breasts.
The internal thoracic vein arises from the superior epigastric vein. It forms venae comitantes to the internal thoracic arte...
The interosseous recurrent artery is a branch of the posterior interosseous artery just after its origin, within the proximal aspect of the posterior compartment of the forearm. It courses proximally between the lateral epicondyle of the humerus and olecranon of the ulna to anastomose with the m...
An interscalene brachial plexus block is indicated for procedures involving the shoulder and upper arm.
Ultrasound-guided brachial plexus nerve blocks entered the literature in 1989, when Ting et al. detailed their success with axillary nerve blocks in 10 patients 3.
This is a basic article for medical students and other non-radiologists
Intestinal ischemia refers to vascular compromise of the bowel which in the acute setting has a very high mortality if not treated expediently. Diagnosis is often straight forward provided appropriate imaging is obtained. T...
Intimal hyperplasia is not a true disease, but a physiologic healing response to injury to the blood vessel wall. It is the bane of endovascular intervention and vascular surgery.
When the endothelium is injured, endothelial cells release inflammatory mediators that trigger platelet aggregatio...
Intra-aortic balloon pumps (IABP) are used in the intensive care setting to provide hemodynamic assistance to patients in cardiogenic shock.
Function and physiology
The device is comprised of a catheter introduced via a femoral artery sheath, which extends retrogradely to the proximal descendi...
Intra-atrial course of the right coronary artery is an uncommon anatomic variation in the course of the right coronary artery, usually involving the mid and distal segments, where the vessel partially or completely courses through the right atrial chamber. It is the most common intracavitary (in...
Intracranial arteries have unique structure when compared to extracranial vessels of similar size: see general histology of blood vessels entry.
Proximal larger arteries
The proximal arteries, arising from the internal carotid and vertebral arteries have differing distribution of elastic fiber...
Intracranial arterial variants, of which there are many, are collectively common. Their clinical significance may be variable but knowledge and recognition of these variants is fundamental, especially if surgical or endovascular treatments (e.g. for acute stroke, aneurysms or other vascular path...
Intracranial mycotic aneurysms, or intracranial infectious aneurysms, describe aneurysms arising from infection of the arterial wall of intracranial vessels.
See mycotic aneurysm for a general discussion on infectious aneurysms.
The epidemiology of intracerebral mycotic aneurysms...
Intrahepatic arteriovenous shunts, also referred to as intrahepatic arteriovenous malformations (AVMs) or hepatic arteriosystemic venous shunts, represent a spectrum of abnormal communications between the hepatic arterial system and the hepatic veins.
Please note that arterioportal shunts, whi...
Intratesticular varicocele is a rare entity, occurring in ~2% of symptomatic population.
It is defined as dilated intratesticular veins seen in relation to the mediastinum testis and extending peripherally. It is usually seen in the presence of ipsilateral extratesticular varicocele....
Intravenous leiomyomatosis (IVLM) is characterized by the extension into venous channels of histologically benign smooth muscle tumor arising from either the wall of a vessel or from a uterine leiomyoma.
Intravenous leiomyomatosis should not be confused with benign metastasizing le...
This is a basic article for medical students and other non-radiologists
Limb ischemia is a relatively uncommon, but potentially limb (and life) threatening situation. There are many potential causes.
This is a summary article; we do not have a more in-depth reference article...
Ischemic colitis refers to inflammation of the colon secondary to vascular insufficiency and ischemia. It is sometimes considered under the same spectrum as intestinal ischemia. The severity and consequences of the disease are highly variable.
Ischemic bowel is typically a disease...
Ischemic stroke results from a sudden cessation of adequate amounts of blood reaching parts of the brain. Ischemic strokes can be divided according to territory affected or mechanism.
Stroke is the second most common cause of morbidity worldwide (after myocardial infarction) and i...
The Isikoff's view is a sonographic view which demonstrates the origins of the right and left renal arteries. It is taken in the longitudinal plane with the patient in the left lateral decubitus position 1.
Isolated periaortitis is a non-aneurysmal form of chronic periaortitis.
mesenteric arterial ischemia: abdominal pain, diarrhea, and gastrointestinal hemorrhage
renal artery stenosis: renovascular hypertension
vascular impairment ...
Isolated unilateral absence of the pulmonary artery (IUAPA) is the congenital absence of the left or right pulmonary artery. When found in combination with other congenital vascular abnormalities it is known as unilateral absence of the pulmonary artery (UAPA).
The ISSVA classification of vascular anomalies encompasses all vascular malformations and tumors in a framework of internationally consistent nomenclature. It is based on the initial classification published by Mulliken and Glowacki in 1982 and has since been updated with recognition of causal g...
Isthmus (plural isthmi) is an anatomical term and refers to a slender structure joining two larger components. Some of these uses of the word isthmus are now rarely used or only seen in older texts and articles:
isthmus (auditory tube)
isthmus (auricle of the ear)