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.
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12,463 results found
Article
11-13 week antenatal scan
11-13 week antenatal scan is considered a routine investigation advised for the fetal well being as well as for early screening in pregnancy (see antenatal screening).
It includes multiple components and is highly dependent on the operator. Traditionally three factors are used to calculate the ...
Article
≤11 ribs (differential)
≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including:
Down syndrome, Trisomy 21
campomelic dysplasia
kyphomelic dysplasias
asphyxiating thoracic dysplasia (Jeune syndrome)
short rib polydactyly syndromes
trisomy 18
chromosome 1q21.1 deletion ...
Article
1-2-3 rule (ovary)
The 1-2-3 rule is a simple aide memoire describing the nomenclature of any small simple anechoic structure in the ovary on ultrasound:
<1cm: follicle
1-2cm: dominant follicle
>3cm: cyst
Article
14-3-3 protein
14-3-3 proteins are found in the cerebrospinal fluid (CSF), and are currently used to help identify patients with sporadic Creutzfeldt-Jakob disease (sCJD).
Seven distinct 14-3-3 proteins have been found in humans.
In diagnosing sCJD, the sensitivity of 14-3-3 protein is 92% and its specifici...
Article
1.5 T vs 3.0 T
Comparing 1.5 T vs 3.0 T (1.5 tesla vs 3.0 tesla) MRI systems identifies a number of differences; a 3 T system has
increased signal-to-noise ratio (SNR)
increased spatial resolution
increased temporal resolution
increased specific absorption rate (SAR)
increased acoustic noise
Signal-to-n...
Article
18q-deletion syndrome
18q-deletion syndrome is a rare chromosomal anomaly where there is a deletion of part of the long arm of chromosome 18. Associated symptoms and findings vary widely, as do their severity. Characteristic clinical features include short stature, mental retardation, hypotonia, facial and distal ske...
Article
1p19q codeletion
1p19q codeletion stands for the combined loss of the short arm chromosome 1 (i.e. 1p) and the long arm of chromosome 19 (19q) and is recognised as a genetic marker predictive of therapeutic response to both chemotherapy and combined chemoradiotherapy and overall longer survival in patients with ...
Article
1p36 deletion syndrome
1p36 deletion syndrome, or monosomy 1p36, is a chromosomal abnormality characterized most commonly by a deletion in the distal segment of the short arm of chromosome one 1.
Epidemiology
The 1p36 deletion syndrome is present in approximately 1 in 5000 live births. It is the most common terminal...
Article
2001 WHO classification of hepatic hydatid cysts
The 2001 World Health Organization (WHO) classification of hepatic hydatid cysts is used to assess the stage of hepatic hydatid cyst on ultrasound and is useful in deciding the appropriate management for it depending on the stage of the cyst. This classification was proposed by the WHO in 2001 a...
Article
2005 WHO histological classification of odontogenic tumors
The 2005 WHO histological classification of odontogenic tumors lays out a classification system for neoplasms and other tumors related to the odontogenic apparatus. At the time of writing (2016), it is still the most widely used classification system although a new revision is due to come up in ...
Article
2014 WHO classification of endometrial stromal tumors
Endometrial stromal tumors (EST) constitute <2% of all uterine tumors and <10% of uterine mesenchymal neoplasms 1.
Over the past four decades, EST classification has gone through various modifications, starting from the earliest study by Norris and Taylor 2. This was primarily due to the rarit...
Article
2016 Histiocyte Society classification of histiocytoses
The 2016 Histiocyte Society classification of histiocytoses and neoplasms of macrophage-dendritic cell lineages is a proposed revision of the organization's initial classification system from 1987.
Terminology
Histiocytes are mononuclear phagocytes that reside in tissues, including macrophages...
Article
20° oblique projection
20° oblique projection is a troubleshooting projection used in mammography, especially in young women and in follow-up patients.
Technique
The C-arm is turned approximately 20° for a superomedial-inferolateral oblique. With the patient's feet pointing towards the unit and her torso turned slig...
Article
22q11.2 deletion syndrome
22q11.2 deletion syndrome, also known as the DiGeorge syndrome or velocardiofacial syndrome, is a syndrome where a small portion of the chromosome 22 is lost and results in a variable but a recognisable pattern of physical and behavioral features.
Epidemiology
The estimated incidence is at ~ 1...
Article
2-hydroxyglutarate
2-hydroxyglutarate is a metabolite that accumulates in the brains of patients with IDH-1 mutated (IDH-1 positive) brain tumors, particularly diffuse low-grade gliomas. Although not in widespread clinical use, it is likely that 2-hydroxyglutarate, which resonates at 2.25 ppm, will be able to be d...
Article
3-6-9 rule (bowel)
The 3-6-9 rule is a simple aide memoire describing the normal bowel caliber:
small bowel: <3 cm
large bowel: <6 cm
cecum: <9 cm
Above these dimensions, obstruction should be considered.
Article
3D ultrasound
Three-dimensional (3D) ultrasound is a technique that converts standard 2D grayscale ultrasound images into a volumetric dataset. The 3D image can then be reviewed retrospectively. The technique was developed for problem-solving (particularly in obstetric/gynaecologic exams) and to potentially r...
Article
4D syndrome
4D syndrome is a term used to describe a manifestation of syndromic glucagonomas, a type of pancreatic endocrine tumor.
D: dermatitis 2
necrolytic migratory erythema - a widespread rash, tending to involve perioral and perigenital regions
oral rashes (angular stomatitis, cheilitis)
tend to r...
Article
5-F risk factors for cholelithiasis (mnemonic)
The 5-F rule refers to risk factors for the development of cholelithiasis in the event of upper abdominal pain:
fair: more prevalent in the Caucasian population 1
fat: BMI >30
female
fertile: one or more children
forty: age ≥40
cholelithiasis can occur in young patients with a positive fam...
Article
5th metacarpal pit
The 5th metacarpal pit refers to the normal exaggeration of the pit-like depression in the head of fifth metacarpal.
It should not be mistaken for a fracture (old or new) or an erosion.
Article
5-tier ACR system of radiologic breast findings
The 5-tier ACR system was a previously used system for classification of radiologic breast findings, proposed by the American College of Radiology (ACR). It is no longer in widespread use, having been gradually superseded by the 6-tier BI-RADS classification system first published in 1992.
5: ...
Article
60/60 sign (echocardiography)
The 60/60 sign in echocardiography refers to the coexistence of a shorted right ventricular acceleration time with a discordant, low velocity tricuspid regurgitant jet. A finding 94% specific for acute cor pulmonale due to pulmonary embolism, the tricuspid regurgitant (TR) jet will be <60 m/s (a...
Article
Aarskog syndrome
Aarskog syndrome or Aarskog–Scott syndrome (also known as the facio-digito-genital syndrome) is a rare anomaly characterized by short stature in association with a variety of structural anomalies involving mainly the face, distal extremities, and external genitalia.
Epidemiology
Population pre...
Article
Aase-Smith syndrome
Aase-Smith syndrome (or Aase syndrome) is an extremely rare congenital disorder.
Clinical presentation
congenital hypoplastic anemia - fetal anemia
triphalangeal thumbs
broad thumb
abnormal clavicles
cleft lip or cleft palate
hypoplastic radii
hydrocephalus (due to Dandy-Walker anomaly)
...
Article
AAST injury scoring scales
The American Association for the Surgery of Trauma (AAST) injury scoring scales are the most widely accepted and used system of classifying and categorizing traumatic injuries. Injury grade reflects severity, guides management, and aids in prognosis. Currently (early 2019), 32 different injury s...
Article
AAST kidney injury scale
The American Association for the Surgery of Trauma (AAST) renal injury scale, most recently updated in 2018, is the most widely used grading system for renal trauma.
The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criteria for viscera...
Article
AAST liver injury scale
The AAST (American Association for the Surgery of Trauma) liver injury scale, most recently revised in 2018, is the most widely used liver injury grading system 3.
The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criteria for visceral ...
Article
AAST spleen injury scale
The American Association for the Surgery of Trauma (AAST) splenic injury scale, most recently revised in 2018, is currently the most widely used grading system for splenic trauma.
The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criter...
Article
ABC/2
ABC/2 is a fast and simple method for estimating the volume of intracerebral hemorrhage (or any other ellipsoid lesion for that matter) which does not require volumetric 3D analysis or software. Intracerebral hemorrhage volume is an important predictor of morbidity and mortality (and thus trial ...
Article
Abdomen (AP supine view)
AP supine radiograph can be performed as a standalone projection or as part of an acute abdominal series, depending on the clinical question posed, local protocol and the availability of other imaging modalities.
Patient position
the patient is supine, lying on their back, either on the X-ray ...
Article
Abdomen (dorsal decubitus view)
The dorsal decubitus view is a supplementary projection often replacing the lateral decubitus view in the context of an unstable patient who is unable to roll nor stand. Used to identify free intraperitoneal gas (pneumoperitoneum). It can be performed when the patient is unable to be transferred...
Article
Abdomen (lateral decubitus view)
The lateral decubitus abdominal radiograph is used to identify free intraperitoneal gas (pneumoperitoneum). It can be performed when the patient is unable to be transferred to, or other imaging modalities (e.g. CT) are not available. The most useful position for detecting free intraperitoneal ai...
Article
Abdomen (oblique view)
AP oblique supine radiograph is normally performed when localising foreign bodies or lines within the abdominal cavity. Additionally, the oblique abdominal series can be utilized in the assessment of the upper intestinal tract during barium studies.
Patient position
the patient is laying 30 de...
Article
Abdomen (PA erect view)
The PA erect abdominal radiograph is often obtained in conjunction with the AP supine abdominal view in the acute abdominal series of radiographs. When used together it is a valuable projection in assessing air fluid levels, and free air in the abdominal cavity.
The erect abdominal radiograph h...
Article
Abdomen (PA prone view)
PA prone radiograph is rarely performed, often utilized when a patient is unable to lay supine. The projection is adequate for the examination of the abdominal cavities, however, not as practical for the renal structures due to magnification.
Patient position
the patient is prone, either on th...
Article
Abdominal adhesions
Abdominal adhesions are bands of scar tissue (fibrous or fibrous fatty), most often occurring as a complication of previous abdominal surgery.
Pathology
Adhesions often occur with
multiple abdominal operations or previous postoperative intra-abdominal complications
history of intra-abdominal i...
Article
Abdominal and pelvic anatomy
Abdominal and pelvic anatomy encompasses the anatomy of all structures of the abdominal and pelvic cavities.
This anatomy section promotes the use of the Terminologia Anatomica, the global standard for correct gross anatomical nomenclature.
Article
Abdominal aorta
The abdominal aorta is the main blood vessel in the abdominal cavity that transmits oxygenated blood from the thoracic cavity to the organs within the abdomen and to the lower limbs.
Summary
origin: continuation of descending thoracic aorta at T12
course: descends anterior and slightly to th...
Article
Abdominal aortic aneurysm
Abdominal aortic aneurysms (AAA) are focal dilatations of the abdominal aorta measuring 50% greater than the proximal normal segment, or >3 cm in maximum diameter.
Epidemiology
represent the tenth most common cause of death in the Western world
prevalence increases with age
~10% patients old...
Article
Abdominal aortic aneurysm rupture
Abdominal aortic aneurysm (AAA) rupture is a feared complication of abdominal aortic aneurysm and is a surgical emergency. It is part of the acute aortic syndrome spectrum.
Epidemiology
Abdominal aortic aneurysms are common and affect ~7.5% of patients aged over 65 years 6.
Clinical presentat...
Article
Abdominal aortic aneurysm (summary)
This is a basic article for medical students and other non-radiologists
Abdominal aortic aneurysms (AAA) are focal dilatations of the abdominal aorta that are 50% greater than the proximal normal segment or >3 cm in maximum diameter.
Reference article
This is a summary article; read more in o...
Article
Abdominal aortic injury
Abdominal aortic injuries are a very rare form of traumatic aortic injury and are much less common than thoracic aortic injury.
Epidemiology
Aortic injury occurs in <1% of blunt trauma patients, with abdominal aortic injury representing only ~5% of all aortic injuries 1. Males are more freque...
Article
Abdominal cavity
The abdominal cavity is divided into two major compartments, the peritoneum and retroperitoneum, early in fetal development.
The parietal peritoneum is reflected over the peritoneal organs to form a series of supporting peritoneal ligaments, mesenteries and omenta. The peritoneal reflections ca...
Article
Abdominal ectopic pregnancy
Abdominal ectopic pregnancies are an extremely rare type of ectopic pregnancy.
Epidemiology
They are thought to represent ~1% of all ectopic pregnancies 6 with an estimated incidence of 1:1000-10,000 births.
Pathology
It is often thought that they most frequently result from a tubal rupture ...
Article
Abdominal hernia
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
Article
Abdominal imaging (dual energy CT)
The role of dual energy CT is becoming increasingly more prevalent abdominal imaging due to the availability of scanners and increasing field of research.
Acute bowel ischemia
The addition of iodine maps and 40-keV monoenergetic images to standard single energy CT images was found to increase ...
Article
Abdominal (lateral view)
The lateral view abdominal radiograph is a useful problem-solving view that can complement frontal views of the abdomen, often utilized in the context of foreign bodies or to better visualize lines such as a shunt. It is different from the lateral decubitus view of the abdomen and looks more lik...
Article
Abdominal migraine
Abdominal migraine (AM) is a syndrome which presents as recurrent episodes of severe abdominal pain, coupled with vasomotor symptoms, nausea and emesis. Historically it has tended to be a pediatric diagnosis, but is now increasingly seen in adults. It is one of the functional gastrointestinal di...
Article
Abdominal opacities
An opacity projecting over the abdomen has a broad differential. Possibilities to consider include:
foreign bodies
ingested, e.g. coins, batteries, bones, etc
artifacts, e.g. object attached to the cloth of the patient like a safety pin or button
iatrogenic, e.g. hemostatic clips, gastric ba...
Article
Abdominal organ echogenicity (mnemonic)
This mnemonic helps to remember the relative echogenicity of abdominal organs on ultrasound:
Darling Parents So Love Kids
Mnemonic
From most to least echogenic:
D: diaphragm
P: pancreas
S: spleen
L: liver
K: kidneys (cortex)
Article
Abdominal paracentesis
Abdominal paracentesis, more commonly referred to as an ascitic tap, is a procedure that can be performed to collect peritoneal fluid for analysis or as a therapeutic intervention.
Indications
diagnostic: especially for newly-diagnosed ascites
determine etiology of ascites
assess for bacteri...
Article
Abdominal radiography
Abdominal radiography can be useful in many settings. Before the advent of computed tomography (CT) imaging, it was a primary means of investigating gastrointestinal pathology and often allowed indirect evaluation of other abdominal viscera.
Indications
Although abdominal radiography has lower...
Article
Abdominal radiology for students (curriculum)
This is a basic article for medical students and other non-radiologists
Abdominal radiology curriculum for medical students is broadly split into content that refers to imaging (the test and findings) and conditions that are considered key for this stage of training.
Some non-abdominal conditi...
Article
Abdominal surface anatomy
Abdominal surface anatomy can be described when viewed from in front of the abdomen in 2 ways:
divided into 9 regions by two vertical and two horizontal imaginary planes
divided into 4 quadrants by single vertical and horizontal imaginary planes
These regions and quadrants are of clinical imp...
Article
Abdominal trauma
Abdominal trauma is usually divided into blunt and penetrating trauma.
Findings of abdominal trauma
haemoperitoneum
splenic trauma: most common
hepatic trauma
renal trauma
pancreatic trauma
gastrointestinal tract (bowel) trauma:
proximal jejunum is most commonly affected by blunt trauma,...
Article
Abdominal x-ray air (summary)
This is a basic article for medical students and other non-radiologists
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where A refers to the assess...
Article
Abdominal x-ray - an approach (summary)
This is a basic article for medical students and other non-radiologists
Abdominal radiographs can be challenging examinations to look at. It is always best to approach radiographs in a systematic way.
Bowel gas pattern
Gas within the bowel forms a natural contrast with surrounding tissues sin...
Article
Abdominal x-ray artifacts (summary)
This is a basic article for medical students and other non-radiologists
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where X refers to the assess...
Article
Abdominal x-ray bowel (summary)
This is a basic article for medical students and other non-radiologists
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where B refers to the assess...
Article
Abdominal x-ray densities (summary)
This is a basic article for medical students and other non-radiologists
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where D refers to the assess...
Article
Abdominal x-ray organs (summary)
This is a basic article for medical students and other non-radiologists
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where O refers to the assess...
Article
Abdominal x-ray review: ABDO X (summary)
Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review:
A: air - where it should and shouldn't be
B: bowel - position, size and wall thickness
D: dense st...
Article
Abdominal x-ray (summary)
This is a basic article for medical students and other non-radiologists
Abdominal radiographs can be a useful examination, but you need to think about the question you are asking before getting the test. Before the advent of computerized tomography (CT) imaging, it was a primary means of invest...
Article
Abdominoschisis
Abdominoschisis refers to a split or in the abdominal wall. Some authors use the term synonymously with a gastroschisis. When the defect continues into the thoracic region it is termed a thoraco-abdominoschisis. A large abdominoschisis is considered part of the limb body wall complex 2.
See als...
Article
Abducens nerve
The abducens nerve is the sixth cranial nerve. It courses from its nucleus located in the dorsal pons to its innervation of the lateral rectus muscle and can be divided into four parts:
nucleus and intraparenchymal portion
cisternal portion
cavernous sinus portion
orbital portion
Gross anat...
Article
Abducens nerve palsy
Abducens nerve palsies, or sixth nerve palsies, results in weakness of the ipsilateral lateral rectus muscle.
Clinical presentation
Patients present with horizontal diplopia with an inability to abduct the ipsilateral eye, thereby resulting in an esotropia (nasal deviation of the eye).
Pathol...
Article
Abductor digiti minimi (foot)
The abductor digiti minimi muscle is on the lateral side of the foot and contributes to the large lateral plantar eminence on the sole.
Summary
origin: lateral and medial processes of calcaneal tuberosity, and band of connective tissue connecting calcaneus with base of metatarsal V
insertion:...
Article
Abductor digiti minimi (hand)
The abductor digiti minimi muscle overlies the opponens digits minima, within the hypothenar eminence.
Summary
origin: pisiform, the pisohamate ligament, and tendon of flexor carpi ulnaris
insertion: 5th proximal phalanx
action: abducts 5th finger at metacarpophalangeal joint
arterial suppl...
Article
Abductor hallucis muscle
The abductor hallucis muscle forms the medial margin of the foot and contributes to a soft tissue bulge on the medial side of the sole.
Summary
origin: medial process of calcaneal tuberosity
insertion: medial side of base of proximal phalanx of great toe
action: abducts and flexes great toe ...
Article
Abductor pollicis brevis
The abductor pollicis brevis is a thin subcutaneous muscle located laterally in the thenar eminence of the hand.
Summary
origin: mainly from the flexor retinaculum
few fibers originate from the tubercles of scaphoid and trapezium and tendon of abductor pollicis longus
accessory slips may ori...
Article
Abductor pollicis longus
The abductor pollicis longus (APL) is a muscle found in the deep layer of the posterior compartment of the forearm. As it descends, it becomes superficial and passes under the extensor retinaculum and through the 1st extensor compartment of the wrist before attaching distally.
Summary
origin: ...
Article
Abernethy malformation
Abernethy malformations are rare vascular anomalies of the splanchnic venous system. They consist of congenital portosystemic shunts and result from persistence of the embryonic vessels.
Epidemiology
Type I malformations are thought to occur only in females, while type II have a male predomin...
Article
ABER position
The ABER position relates to MR arthrography of the shoulder joint and is a mnemonic for ABduction and External Rotation.
In this position, labral tears are made conspicuous by tightening the inferior glenohumeral labroligamentous complex (which are also the most important glenohumeral ligament...
Article
Aberrant arachnoid granulations
Aberrant arachnoid granulations are arachnoid granulations that penetrated the dura but failed to migrate normally in the venous sinus. They are most often located in the greater wing of the sphenoid bone. Occasionally, they are seen in the posterior temporal bone wall.
Clinical presentation
A...
Article
Aberrant internal carotid artery
Aberrant internal carotid artery is a variant of the internal carotid artery (ICA) and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the ICA 5.
There is consequent enlargement of the usually small collaterals which course t...
Article
Aberrant left pulmonary artery
Aberrant left pulmonary artery, also known as pulmonary sling, represents an anatomical variant characterized by the left pulmonary artery arising from the right pulmonary artery and passing above the right main bronchus and in between the trachea and esophagus to reach the left lung. It may lea...
Article
Aberrant right subclavian artery
Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are the commonest of the aortic arch anomalies 2.
Epidemiology
The estimated incidence is 0.5-2%.
Clinical presentation
They are often asymptomatic, but around 10% of people may complain of tracheo-esophageal symptoms...
Article
Aberrations in the normal development and involution of the breast
Aberrations in the Normal Development and Involution of the breast (ANDI) is an all-encompassing term that is used to describe a wide spectrum of the benign breast diseases. As the name suggests, it is based on the theory that most of the encountered benign breast disorders are essentially minor...
Article
Abnormal bowel wall attenuation patterns
Abnormal bowel wall attenuation patterns on CT scan can be grouped under five categories:
white enhancement
gray enhancement
water halo sign
fat halo sign
black attenuation
The first three patterns are seen on contrast studies.
White enhancement
It is defined as uniform enhancement of th...
Article
Abnormal collection of barium anywhere (mnemonic)
A mnemonic used for abnormal collection of barium anywhere in the body:
FEDUP
Mnemonic
F: fistula
E: extravasation
D: diverticulum
U: ulcer
P: perforation
Article
Abnormal ductus venosus waveforms
Abnormal ductus venosus waveforms can arise in a number of conditions ranging from aneuploidy to vascular malformations and fetal tumors.
Pathology
Abnormal waveforms in fetal ductus venosus flow assessment can occur in a number of situations:
aneuploidic anomalies
Down syndrome: around 80%...
Article
Abnormal intra-abdominal gas
Abnormal intra-abdominal gas is an important radiologic finding with many potential causes. It may be seen on a chest radiograph, abdominal radiograph, CT or MRI.
pneumoperitoneum
retropneumoperitoneum
pseudopneumoperitoneum
abnormally located bowel, e.g. Chilaiditi syndrome (bowel interpose...
Article
Abnormally eccentric gestational sac
An eccentrically-located gestational sac towards the fundus of the uterus is the normal sonographic appearance; however an abnormally eccentric gestational sac on ultrasound may be apparent due to a number of causes
They include
interstitial ectopic pregnancy 1
normally implanted pregnancy in...
Article
Abnormally low sac position
An abnormally low sac position can result from several possibilities which include
impending/ongoing miscarriage
cervical ectopic pregnancy
Cesarean scar ectopic pregnancy
fundal fibroid or other mass compressing the sac downward
Article
Abnormally thickened endometrium (differential)
Abnormally thickened endometrium on imaging may occur for a number of reasons which may be categorized based on whether or not they are related to pregnancy. Etiologies may also be classified based on whether the patient is premenopausal or postmenopausal.
Differential diagnosis
Pregnancy-rela...
Article
Abnormal renal rotation
Abnormal renal rotation (renal malrotation) refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.
Epidemiology
Malrotation is...
Article
Abnormal ultrasound findings in rheumatological diseases (definitions)
The OMERACT ultrasound group published a consensus in 2005 of widely accepted definitions of abnormal ultrasound findings in rheumatological diseases:
erosion: an intra-articular discontinuity of the bone surface that is visible in two orthogonal planes
joint effusion: abnormal hypoechoic or a...
Article
ABR certifying exam
The ABR certifying exam is the second of two exams necessary for certification in diagnostic and interventional radiology in the United States of America (the first is the core exam). It is taken 15 months after the end of the PGY 5 year (or three months after a one year PGY 6 fellowship).
The ...
Article
ABR core exam
The ABR core exam is the first of two exams necessary for certification in diagnostic and interventional radiology in the United States of America. It is taken at the end of the PGY 4 year of radiology residency training.
The exam is computer-based and occurs in two sessions (7.5 hours and 6 ho...
Article
Abrodil
Abrodil (marketed as Skiodan in the US) was a water-based iodinated contrast medium introduced for clinical use in 1930 3. It was developed by Bronner, Hecht and Schueller in Germany. Chemically, Abrodil is the sodium salt of monoiodomethanesulfonic acid.
It was initially employed for intraveno...
Article
Abscess
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Article
Absent bow tie sign (knee)
The absent bow tie sign represents the loss of the normal appearance of the menisci on parasagittal MRI images and is suggestive of meniscal injury.
Normally the medial and lateral menisci appear as low signal bow-tie-shaped structures between the femoral condyles and tibial plateaux. As the no...
Article
Absent ductus venosus
Agenesis of the ductus venosus (ADV) is a rare fetal vascular anomaly.
Epidemiology
According to the data obtained from the screening tests performed at 11-14 weeks of pregnancy, its incidence is reported to be 1/2500 12.
Pathology
In a large case series, Acherman et al. 13 defined five drai...