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12,604 results found

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 ...

≤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 ...

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

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...

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...

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...

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 (i.e. 19q) and is recognized as a genetic marker predictive of therapeutic response to both chemotherapy and combined chemoradiotherapy and overall longer survival in patients ...

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...

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...

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 ...

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...

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...

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...

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...

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...

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.

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/gynecologic exams) and to potentially re...

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...

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...

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.

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: ...

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...

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...

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) ...

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...

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...

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 ...

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...

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 ...

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 ...

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...

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...

Abdomen (oblique view)

AP oblique supine radiograph is normally performed when localizing 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...

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...

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...

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...

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.

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...

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...

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...

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...

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...

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...

Abdominal compartment syndrome

Abdominal compartment syndrome (ACS) is the life-threatening clinical state of increased intra-abdominal compartment pressure (IAP). Radiological diagnosis is difficult and usually raised when a collection of imaging findings are present in the appropriate clinical setting or if the signs on seq...

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 ...

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...

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 ...

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...

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...

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...

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)

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...

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...

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...

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...

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,...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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:...

Abductor digiti minimi (hand)

The abductor digiti minimi muscle overlies the opponens digits minima, within the hypothenar eminence, and is one of the intrinsic muscles of the hand. Occasionally an accessory abductor digiti minimi muscle of the hand is present. Summary origin: pisiform, pisohamate ligament, and tendon of f...

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 ...

Abductor pollicis brevis

The abductor pollicis brevis is a thin subcutaneous muscle located laterally in the thenar eminence of the hand, and is one of the intrinsic muscles 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

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. It is one of the e...

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...

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...

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...

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. Gross anatomy There is consequent enlargement of the usually small collaterals...

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...

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...

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...

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...

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

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%...

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...

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...

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

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...

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...

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...

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 ...

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...

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...

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...

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...

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