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.

13,606 results found
Article

Anderson and D'Alonzo classification of odontoid process fracture

The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2. Classification type I rare fracture of the upper part of the odontoid peg above the level of the transverse band of the cruciform ligament usually considered stable...
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Andersson lesion

Andersson lesions refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis. Epidemiology Rheumatic spondylodiskitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spondylitis, as detected at radiography. Patholog...
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Androgen deprivation therapy (ADT)

Androgen deprivation therapy (ADT), also called androgen suppression therapy, or is a form of treatment in prostate cancer, which basically aims to slow prostate cancer growth by blocking the effect of androgens e.g. testosterone. Such therapy is mainly used for treating men with intermediate- ...
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Androgen insensitivity syndrome

Androgen insensitivity syndrome (AIS), also known as the testicular feminization syndrome, results from end-organ resistance to androgens, particularly testosterone. AIS may be complete or incomplete with variable imaging findings.  Epidemiology The incidence may vary depending on whether it i...
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Anembryonic pregnancy

Anembryonic pregnancy is a form of a failed early pregnancy, where a gestational sac develops, but the embryo does not form. The term blighted ovum is synonymous with this but is falling out of favor and is best avoided.  Clinical presentation The patient may be asymptomatic, presenting for an...
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Anembryonic pregnancy in the exam

Getting a film with anembryonic pregnancy in the radiology fellowship examination is one of the many exam set-pieces that the candidate must be prepared for.  Description Transabdominal and transvaginal pelvic ultrasound shows a uterus with an intrauterine gestational sac. MSD is at least 25 m...
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Anencephaly

Anencephaly is the most severe form of cranial neural tube defect (NTD) and is characterized by an absence of cortical tissue (although the brainstem and cerebellum may be variably present) as well as an absence of the cranial vault. The morphological spectrum within anencephaly ranges from holo...
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Aneuploidy

Aneuploidy refers to an abnormal number of chromosomes, and is a type of chromosomal abnormality.There are large number potential aneuploidic anomalies. The most common three in obstetric practice are: trisomy 21: commonest aneuploidic anomaly trisomy 18 trisomy 13
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Aneurysm

Aneurysms are focal abnormal dilatation of a blood vessel. They typically occur in arteries, venous aneurysms are rare. Aneurysms may also occur in the heart. Pathology Pathological types true aneurysm false aneurysm (or pseudoaneurysm) Causes Atherosclerotic atherosclerosis Non-atherosc...
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Aneurysmal bone cyst

Aneurysmal bone cysts (ABC) are benign expansile tumor-like bone lesions of uncertain etiology, composed of numerous blood-filled channels, and mostly diagnosed in children and adolescents. Epidemiology Aneurysmal bone cysts are primarily seen in children and adolescents, with 80% occurring in...
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Aneurysms of the portal venous system

Aneurysms of the portal vein are extremely rare and represent only 3% of all aneurysms of the venous system. Clinical presentation Most patients are asymptomatic but may present with nonspecific abdominal pain as a major symptom 2-4. Pathology Both congenital and acquired causes have been pr...
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Angina

Angina or angina pectoris is cardiac chest pain that occurs as the result of myocardial ischemia. Clinical presentation Angina is classically described as substernal chest discomfort that is of a typical quality and duration (heavy, tight, ‘bandlike’ pain that lasts for minutes at a time). Ang...
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Angiocentric glioma

Angiocentric gliomas are rare superficial slow-growing brain tumors typically presenting in young patients with intractable partial epilepsy 1-6. They were first introduced in the 2007 (4th) edition of the WHO brain tumor classification, and are classified as WHO grade I tumors 1.  For a genera...
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Angioimmunoblastic T cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) (previously known as angioimmunoblastic lymphadenopathy with dysproteinemia) is a rare, aggressive (fast-growing) form of peripheral T-cell lymphoma. It only accounts for around 1-2% of all non-Hodgkin lymphoma. It is one of the more common subtypes of m...
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Angioinvasive aspergillosis

Angioinvasive aspergillosis is the most severe and aggressive form of invasive aspergillosis. It is a life-threatening condition that requires prompt treatment. Fortunately, it is not seen in the general population and only occurs in profoundly immunocompromised patients.  Epidemiology Angioin...
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Angiolipoma

Angiolipomas (also sometimes known as haemangiolipomas, vascular lipomas, and fibromyolipomas) are rare soft tissue tumors composed of mature adipocytes and vessels. They can occur essentially anywhere and can be subclassified into infiltrating and non-infiltrating variants 1.  Please refer to ...
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Angiomatous meningioma

Angiomatous meningiomas are a rare histological variant of WHO grade I meningiomas and account for only 2.1% of all meningiomas 1,3.  The epidemiology and clinical presentation of these tumors do not clearly deviate from that of more common histological variants of meningiomas and is thus not r...
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Angiomyofibroblastoma-like tumor of scrotum

Angiomyofibroblastoma-like tumor of the scrotum is a rare, well-defined, slow growing mesenchymal extratesticular nonepididymal tumor rarely seen in the perineum or scrotum of older male patients. A similar tumor can occur in females in the vulval region. Epidemiology  In males, they are seen ...
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Angiomyolipoma

Angiomyolipomas (AMLs)  refer to hamartomatous lesions composed of abnormal, thick-walled vessels (i.e. angio) and varying amounts of smooth muscle–like cells (i.e. myo) and adipose tissue (i.e. lipoma) They predominantly occur in the kidney (renal angiomyolipoma) but occasionally occur in other...
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Angiosarcoma

 Angiosarcomas (like hemangiopericytomas and hemangioendotheliomas) are tumors that arise from vascular structures. They are typically difficult to distinguish from one another on imaging alone. Angiosarcomas, are the most aggressive of the three, frequently having metastases at the time of dia...
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Angiosarcoma - bone

Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage are either radiation-induced or associated with bone infarction Epidemiology Mo...
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Angiosarcoma involving the lung

Angiosarcoma involving the lung includes: metastatic angiosarcoma to lung 1  commoner usual primary sites include the heart and breast 2 primary pulmonary angiosarcoma: very rare See also angiosarcoma
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Angiosarcoma of breast

Breast angiosarcomas are a rare vascular breast malignancy. Epidemiology As primary tumors of the breast, they account for ~0.04% 2 of all breast cancers and tend to occur in younger women, in their 3rd to 4th decades. Secondary angiosarcoma, related to prior therapy of breast cancer, has an ...
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Angiosarcoma of the spleen

Angiosarcomas of the spleen are rare malignant splenic neoplasms. The term is usually given to describe a primary angiosarcoma of the spleen although angiosarcoma elsewhere can also rarely metastasize to the spleen. Despite its absolute rarity, a splenic angiosarcoma is considered the most commo...
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Angiotensin converting enzyme

Angiotensin converting enzyme (ACE) a central component of the renin-angiotensin system (RAS) which assists in blood pressure control by regulating the volume of fluids in the body. Normal individuals can have small volume circulating in serum/blood. Measurement Normally measured as nanomoles...
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Angle of the longitudinal arch (foot)

The angle of the longitudinal arch (calcaneal–fifth metatarsal angle) is one of the angles drawn on the weight-bearing lateral foot radiograph. The angle is formed between the calcaneal inclination axis and a line drawn along the inferior edge of the 5th metatarsal: pes planus: >170° normal: ...
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Angular artery (disambiguation)

Angular artery (facial artery) Angular artery (MCA branch) History and etymology Angular is derived from the Latin root in angulus (for corner).
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Angular artery (facial artery branch)

The angular artery is the terminal branch of the facial artery. It becomes the angular artery after the lateral nasal artery branch from the facial artery. It courses superiorly along the lateral border of the external nose to the medial canthus. It is accompanied by the angular vein which drai...
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Angular artery (MCA branch)

The angular artery (MCA branch) is an M4 branch of middle cerebral artery. ( It is not the same as the facial artery angular artery branch.) The artery arises from the posterior part of the Sylvian fissure and runs posteriorly. On lateral angiogram it forms a downward concave curve while transv...
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Angular gyrus

The angular gyrus is a portion of the parietal lobe of the brain. It is one of the two parts of the inferior parietal lobule, the other part being the supramarginal gyrus. It plays a part in language and number processing, memory and reasoning 1. Gross anatomy Relations It lies as a horseshoe...
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Angular interface sign

The angular interface sign is used to characterize an exophytic renal mass, in which the exophytic renal mass has an angular interface with the renal parenchyma. In other words, the exophytic lesion has a tapered pyramidal contour or definite apex within the renal parenchyma. Due to its high se...
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Angular pregnancy

Angular pregnancies are those in which implantation occurs eccentrically along the fundus of the endometrial cavity, along with the lateral upper angle or cornua of the uterus. In contrast to interstitial tubal pregnancy, angular pregnancies have a more medial location and are considered an int...
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Angular vein

The angular vein drains the anterior region of the scalp 1. It is formed by the union of the supratrochlear and supraorbital veins and becomes the facial vein 1,2,3. Gross Anatomy The angular vein is formed at the medial canthus as the supratrochlear vein and supraorbital vein unite 1,2. The a...
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Anhydramnios

Anhydramnios is a term where there is a complete or near-complete lack of amniotic fluid (sometimes referred to as "liquor volume"). Pathology Anhydramnios can result in a number of situations: fetal renal tract anomalies Potter syndrome (bilateral renal agenesis): most common  large ureter...
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Animal and animal produce inspired signs

Animal and animal produce inspired signs may sound a little silly, but the radiology literature is replete with such signs, some more fanciful than others. Fish and seafood cluster of black pearls sign endosteal scalloping: medullary cavity masses, e.g. multiple myeloma fish vertebra (also k...
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Aniridia

Aniridia refers to either the clinical sign of a complete/partial absence of the iris, or more specifically to the disease entity classic aniridia. Rarely other genetic conditions may cause this sign. Epidemiology Classic aniridia is inherited as an autosomal dominant condition and is seen in ...
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Anisocoria

Anisocoria is present when an individual's pupils differ in size. If a person's pupils are symmetric there is said to be isocoria. Epidemiology The prevalence of transient physiological anisocoria of >0.4 mm is found in up to 20% population. However persistent anisocoria seems to be rarer, in ...
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Anisotropy

Anisotropy is an artefact encountered in ultrasound, notably in muscles and tendons during a musculoskeletal ultrasound. In musculoskeletal applications, the artefact may prompt an incorrect diagnosis of tendinosis or tendon tear. When the ultrasound beam is incident on a fibrillar structure as...
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Ankle and foot radiography

Ankle and foot radiography is the plain radiographic investigation of the distal tibia and fibula, the tarsal bones and metatarsals. Radiographic examination of the foot and ankle are often requested together, however, there is a plethora of literature to aid in the correct request of x-ray exam...
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Ankle (AP view)

Ankle AP view is part of a three view series of the distal tibia, distal fibula, proximal talus and proximal metatarsals. Patient position the patient may be supine or sitting upright with their leg straighten on the table the foot is in dorsiflexion the toes will be pointing directly toward...
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Ankle brachial index

Ankle brachial index (ABI) is a means of detecting and quantifying peripheral arterial disease (PAD). It can be performed in conjunction with ultrasound for better results. Indications Many patients with peripheral arterial disease may be asymptomatic (20-50%), but they may also present with ...
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Ankle fractures

Ankle fractures account for ~10% of fractures encountered in trauma, preceded only in incidence by proximal femoral fractures in the lower limb. They have a bimodal presentation, involving young males and older females. Ankle injuries play a major part in post multitrauma functional impairment t...
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Ankle (horizontal beam lateral view)

The ankle horizontal beam lateral view is a modified lateral view part of a three view ankle series; this projection is used to assess the distal tibia and fibula, talus, navicular, cuboid, the base of the 5th metatarsal and calcaneus. The horizontal beam lateral is a highly adaptable projectio...
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Ankle impingement syndromes

There are several ankle impingement syndromes. They are characterized by limited range of motion and pain on attempting specific movements about the joint and often in a load-bearing position. They have variable etiology and pathogenesis. They are best classified according to location. The key ...
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Ankle joint

The ankle joint (also known as the tibiotalar joint or talocrural joint) forms the articulation between the foot and the leg. It is a primary hinge synovial joint lined with hyaline cartilage. Gross anatomy The ankle joint is comprised of the tibia, fibula and talus as well as the supporting l...
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Ankle (lateral view)

Ankle lateral view is part of a three view ankle series; this projection is used to assess the distal tibia and fibula, talus, navicular, cuboid, the base of the 5th metatarsal and calcaneus. Patient position patient is in a lateral recumbent position on the table the lateral aspect of the kn...
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Ankle (mortise view)

Ankle AP mortise (mortice is equally correct) view is part of a three view series of the distal tibia, distal fibula, talus and proximal metatarsals. It is the most pertinent projection for assessing the articulation of the tibial plafond and two malleoli with the talar dome, otherwise known as ...
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Ankle radiograph (an approach)

Ankle radiographs are frequently performed in emergency departments, usually, after trauma, the radiographic series is comprised of three views: an anteroposterior, mortise, and a lateral. They may be performed to assess degenerative or inflammatory arthritis as well as to look for the sequela o...
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Ankle radiograph (checklist)

The ankle radiograph checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting. Radiograph The ma...
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Ankle series

The ankle series is comprised of an anteroposterior (AP), mortise and lateral radiograph. The series is often used in emergency departments to evaluate the distal tibia, distal fibula, and the talus; forming the ankle joint. See approach to an ankle series. Indications Ankle radiographs are p...
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Ankle x-ray (summary)

This is a basic article for medical students and other non-radiologists An ankle x-ray, also known as ankle series or ankle radiograph, is a set of two x-rays of the ankle joint. It is performed to look for evidence of injury (or pathology) affecting the ankle, often after trauma. Reference ar...
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Ankylosing spondylitis

Ankylosing spondylitis (less commonly known as Bechterew disease and Marie Strümpell disease) is a seronegative spondyloarthropathy, which results in fusion (ankylosis) of the spine and sacroiliac (SI) joints, although involvement is also seen in large and small joints. Epidemiology Traditiona...
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Ankylosing spondylitis: thoracic manifestations

Thoracic manifestations of ankylosing spondylitis can be varied. For a general discussion of the condition refer to the parent article on ankylosing spondylitis. It can affect the tracheobronchial tree and the lung parenchyma, and the disease spectrum includes: upper lobe fibrocystic changes -...
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Anlage

An anlage in biology refers to the primordial precursor of a tissue or organ, which is still recognisable as a collection of cells that will form that specific tissue. The term is commonly used in medicine to refer to organs, such as the pancreas, when one is describing anatomical variants and ...
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Ann Arbor staging system

The Ann Arbor staging system was the landmark lymphoma staging classification system for both Hodgkin lymphoma and non-Hodgkin lymphoma. It is named after the town of Ann Arbor in the US state of Michigan where the Committee on Hodgkin's Disease Staging Classification met in 1971 to agree on it....
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Annular fissure

Annular fissures are a degenerative deficiency of one or more layers that make up the annulus fibrosus of the intervertebral disc.  Terminology Many authors prefer the term annular fissure over annular tear, as the latter seems to imply acute injury 1,2. In the setting of severe trauma with di...
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Annular ligament (disambiguation)

The annular ligament can refer to: annular ligament of the stapes annular ligament of the proximal radio-ulnar joint
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Annular pancreas

Annular pancreas is a morphological anomaly which can cause duodenal obstruction. This condition is important to recognize, as radiologists are frequently the first to make the diagnosis. Epidemiology The incidence is probably 1 in 250, however its incidence is not accurately reported 1. It is...
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Annulo-aortic ectasia

Annulo-aortic ectasia refers to a proximal dilatation of the aortic root at the level of the aortic annulus, it is also the same level as the sinus of Valsalva. Pathology Annulo-aortic ectasia occurs with connective tissue diseases such as Marfan disease and Ehlers-Danlos syndrome. It is a cys...
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Annulus fibrosus

The annulus fibrosus (plural: annuli fibrosi) surrounds the nucleus pulposus and together they form the intervertebral disc. Gross anatomy The annulus comprises 15 to 20 collagenous (type I) laminae which run obliquely from the edge of one vertebra down to the edge of the vertebra below. The d...
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Annulus fibrosus calcification

Annulus fibrosus calcification is a form of intervertebral disc calcification where the peripheral annular portion (annulus fibrosus) can get calcified. This may occur in isolation or in conjunction with other sites of disc calcification. It could involve any portion of the spine. Some suggest t...
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Annulus of Zinn contents (mnemonic)

A mnemonic to remember the contents of the tendinous ring (also known as the annulus of Zinn) from superior to inferior is: "One Canal, Several Orbital Nerves In One Annulus" Mnemonic: OC: optic canal SO: superior division of oculomotor nerve N: nasociliary nerve IO: inferior division of o...
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Anode

The anode is the component of the x-ray tube where x-rays are produced. It is a piece of metal, shaped in the form of a bevelled disk with the diameter between 55 and 100 mm, and thickness of 7 mm, connected to the positive side of the electrical circuit. The anode converts energy of incident el...
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Anode angle

The anode angle refers to the angle the target surface of the anode sits at in relation to the vertical.  Most x-ray tubes have an anode angle of 12-15 degrees but greater or lesser angles can also be used depending on the application. The degree of angulation of the anode affects the effective...
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Anode heel effect

Anode heel effect refers to the lower field intensity towards the anode in comparison to the cathode due to lower x-ray emissions from the target material at angles perpendicular to the electron beam. Basic concept The conversion of the electron beam into x-rays doesn’t simply occur at the sur...
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Anomalous course of coronary arteries

Anomalous course of a coronary artery is a type of congenital coronary artery anomaly. It may represent a benign and incidental finding, but can also be a malignant course predisposing patients to life-threatening myocardial ischemia or arrhythmias, depending on where the artery runs.  Clinical...
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Anomalous left coronary artery from the pulmonary artery

Anomalous left coronary artery from the pulmonary artery (ALCAPA), also known as Bland-White-Garland syndrome (BWG), is a rare congenital coronary artery anomaly and is considered one of the most severe of such anomalies. There are two forms, based on onset of disease, each of which has differe...
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Anomalous pancreaticobiliary junction

An anomalous pancreaticobiliary junction, also known as pancreaticobiliary maljunction, describes the abnormal junction of the pancreatic duct and common bile duct that occurs outside the duodenal wall to form a long common channel (> 15 mm). Epidemiology Associations The anomalous junction i...
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Anomalous systemic arterial supply to normal lung

Anomalous systemic arterial supply to normal lung is an anatomical variant in which a portion of the lung (usually a basal segment) is supplied by a systemic vessel without a distinct pulmonary sequestration. Terminology It was traditionally (perhaps inappropriately since not a true sequestrat...
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Anomaly detection

Anomaly detection uses a large number of normal examples to train an algorithm which detects what is normal (based on the training examples) and what is not normal. Anomaly detection has features of both supervised and unsupervised learning, and is applicable to Radiology as it’s important to di...
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Anophthalmia

Anophthalmia refers to a complete absence of ocular development. It is often considered to represent the most severe form of microphthalmia. Pathology It can occur in three different situations: primary anophthalmia: complete absence of eye tissue due to a failure of the part of the brain tha...
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Anorectal disease (summary)

This is a basic article for medical students and other non-radiologists Anorectal disease is a group of conditions that affect the anus and rectum. The most common conditions in this group include hemorrhoids, anal fissures, anorectal abscess and anal fistula. Reference article This is a summ...
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Anorexia nervosa

Anorexia nervosa is a psychiatric disorder characterized by distorted self-perception of body weight leading to starvation, obsession with remaining underweight, and an excessive fear of gaining weight. One in five patients with anorexia dies due to complications of the disease. Epidemiology T...
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Anorexia nervosa (CNS manifestations)

CNS manifestations of anorexia nervosa are common but varied with most of the imaging features non-specific in their own right.  For a general discussion, and for links to other system specific manifestations, please refer to the article on anorexia nervosa. Epidemiology Studies have identifi...
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ANOVA

ANOVA (ANalysis Of VAriance) is a statistical technique commonly seen in radiology research. ANOVA analyzes are conceptually similar to the student t-test, but involve comparison of multiple groups at once. The alternative to an ANOVA would be multiple head-to-head t-tests, but this would likel...
Article

Anoxic brain injury

Anoxic brain injury, also known as global hypoxic-ischemic injury, is seen in all age groups (from antenatal to the elderly) as a result of numerous etiologies. The pattern of injury depends on a number of factors including: age of the patient (brain maturity) neonatal hypoxic-ischemic encepha...
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Ansa cervicalis

The ansa cervicalis (or ansa hypoglossi, an archaic synonym) is a component of the cervical plexus which gives muscular branches to the geniohyoid muscle of the suprahyoid group and most of the infrahyoid (strap) muscles (excluding the thyrohyoid muscle).  It lies within the carotid triangle, s...
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Ansa pancreatica

The ansa pancreatica is a rare type of anatomical variation of the pancreatic duct. It is a communication between the main pancreatic duct (of Wirsung) and the accessory pancreatic duct (of Santorini). Recently, the ansa pancreatica has been considered as a predisposing factor in patients with i...
Article

Anteater nose sign (foot)

The anteater nose sign refers to an anterior tubular elongation of the superior calcaneus which approaches or overlaps the navicular on a lateral radiograph of the foot. This fancifully resembles the nose of an anteater and is indicative of calcaneonavicular coalition 1,2.  History and etymolog...
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Antegrade ureteric stent

Antegrade ureteric stents are performed under fluoroscopic guidance, typically by an interventional radiologist or urologist. It is performed via percutaneous access from the kidney. It is usually performed using the access from a prior percutaneous nephrostomy, a so-called two-step procedure, a...
Article

Antenatal features of Down syndrome

Antenatal screening of Down syndrome (and other less common aneuploidies) should be available as a routine component of antenatal care. It allows families to either adjust to the idea of having a child with the condition or to consider termination of pregnancy. For a general description of Down...
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Antenatal screening

Antenatal screening and diagnosis are currently available for a few selected genetic conditions, including trisomy 21 (Down syndrome), trisomy 18 (Edward syndrome), trisomy 13 (Patau syndrome) and neural tube defects. For an overview of the conditions and their manifestations, please refer to t...
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Antenatal soft markers on ultrasound

Antenatal soft ultrasound markers are fetal sonographic findings that are generally not abnormalities as such but are indicative of an increased age adjusted risk of an underlying fetal aneuploidic or some non chromosomal abnormalities. Most of the described features do not constitute a structu...
Article

Antepartum hemorrhage

Antepartum hemorrhage (APH) refers to vaginal bleeding during the second half of pregnancy (> 20 weeks gestation). APH may occur in varying degrees from mild to severe, with concomitant risk to mother and baby and potential to result in severe maternal/fetal compromise, including death. Epidemi...
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Anterior abdominal wall

The anterior abdominal wall forms the anterior limit of the abdominal viscera and is defined superiorly by the xiphoid process of the sternum and costal cartilages and inferiorly by the iliac crest and pubic bones of the pelvis. Gross anatomy The anterior abdominal wall has seven layers (from ...
Article

Anterior angulation of the coccyx

Anterior angulation of the coccyx may be a normal variant but poses a diagnostic challenge for those considering coccygeal trauma. Classification Four types of coccyx have been described: type I: the coccyx is curved slightly forward, with its apex pointing caudally (~70%) type II: the coccy...
Article

Anterior ankle impingement syndrome

Anterior ankle impingement (AAI) syndrome is the result of chronic repetitive trauma with impingement of the anterior tibia against the talus. Clinical presentation Clinical features of anterior ankle impingement syndrome include painful and limited dorsiflexion and anterior joint line swellin...
Article

Anterior ankle tendons (mnemonic)

A mnemonic that refers to the order of the anterior ankle tendons around the ankle is: Tom Hates Dick The mnemonic can be used to remember the order of the tendons from medial to lateral as they pass under the extensor retinaculum of the ankle.  Mnemonic T: tibialis anterior H: extensor hal...
Article

Anterior atlanto-occipital membrane

The anterior atlanto-occipital membrane is a thin membrane that joins the upper border of the anterior arch of the atlas (C1) to the anterior inferior surface of the foramen magnum. It is a continuation of the anterior longitudinal ligament above the C1 level. It is immediately posterior to the ...
Article

Anterior bronchus sign

The anterior bronchus sign refers to the appearance of the anterior segmental bronchus of the upper lobes as seen on a frontal chest radiograph. Gross anatomy The anterior segment bronchus of the upper lobes courses anteriorly and laterally. When the orientation is predominantly anteriorly the...
Article

Anterior cardiac veins

The anterior cardiac veins are a group of parallel coronary veins that course over the anterior surface of the right ventricle, draining it and entering directly into the right atrium. They may occasionally drain into the small cardiac vein. 
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Anterior cardinal veins

The anterior cardinal veins are paired transient embryologic venous vessels which deliver venous return to the heart starting at about 4 weeks of gestation 1. Embryogenesis The anterior cardinal veins begin their embryological development as symmetric venous channels draining blood from the cr...
Article

Anterior center-edge angle

The anterior center-edge angle, also known as the vertical-center-anterior (VCA) angle, is a radiographic measurement of the anterior coverage of the femoral head by the acetabulum. It is used in assessing acetabular dysplasia and pincer type of femoroacetabular impingement. Radiographic featur...

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