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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
16,879 results found
Article
Abductor digiti minimi muscle (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 the fifth metatarsal
in...
Article
Abductor digiti minimi muscle (hand)
The abductor digiti minimi muscle overlies the opponens digiti minimi muscle, 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 tend...
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 muscle
The abductor pollicis brevis muscle 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 ten...
Article
Abductor pollicis longus muscle
The abductor pollicis longus (APL) muscle is 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 ext...
Article
Abernethy malformation
Abernethy malformations are rare vascular anomalies of the splanchnic venous system. They consist of congenital portosystemic shunts resulting from the embryonic vessels' persistence.
Epidemiology
Type I malformations are thought to occur only in females, while type II has a male predominance...
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, also known as arachnoid pits, 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 and may be seen in idiopathic intracranial hypertension. Occ...
Article
Aberrant internal carotid artery
Aberrant internal carotid artery is a variant of the internal carotid artery and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the internal carotid artery 5.
Gross anatomy
There is consequent enlargement of the usually sma...
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 among the commonest aortic arch anomalies.
Epidemiology
The estimated incidence is 0.5-2% 1.
Associations
as can be expected from the embryological development of the artery, the right recurrent laryngeal nerve...
Article
Aberrations in the normal development and involution of the breast
Aberrations in the Normal Development and Involution (ANDI) of the breast is an overarching term used to describe a wide spectrum of benign breast disease. As the name suggests, it is based on the theory that most of the encountered benign breast disorders are aberrations in the normal developme...
Article
Ablepharon macrostomia syndrome
Ablepharon macrostomia syndrome is a very rare genetic disorder characterized by macrostomia, wide mouth and microblepharon.
Clinical presentation
A few of the clinical features of this syndrome are:
syndactyly
zygomatic hypoplasia
delayed speech
microtia
hypoplastic nipples
excessive ...
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:
FED UP
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. "A wave" reversal can be seen in 5% of euploid fetuses 9.
Pathology
Abnormal waveforms in fetal ductus venosus flow assessment can occur in a number of situ...
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 (bowe...
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:
interstitial ectopic pregnancy 1
normally implanted pregnancy in a
bicornu...
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...
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