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.

11,136 results found
Article

Absent fetal stomach on ultrasound (differential)

Non-visualisation of the fetal stomach on ultrasound can occur with various physiological as well as pathological processes. It becomes a significant sonographic observation >14 weeks of gestation (about the time the fetus begins to swallow). Causes include: physiological emptying: transient ...
Article

Absent infrarenal inferior vena cava

An absent infrarenal inferior vena cava (IVC) can be congenital due to the failure of development of the posterior cardinal and supracardinal veins, or acquired as result of intrauterine or perinatal inferior vena cava thrombosis. Epidemiology It is an extremely rare anomaly. Clinical present...
Article

Absent nasal bone

In fetal sonographic assessment, an absent nasal bone is a feature which can sometimes be used as an adjunctive marker for fetal aneuploidy. Radiographic assessment Antenatal ultrasound It is assessed on a midline sagittal view. In this section the nasal bone is often seen as a bright echogen...
Article

Absent patella

An absent patella is a rare finding and can be found with an equally rare set of associations: surgical removal of patella (patellectomy) nail patella syndrome 2 popliteal pterygium syndrome proximal focal femoral deficiency (PFFD) Meier-Gorlin syndrome 3
Article

Absent septum pellucidum

An absent septum pellucidum may rarely be an isolated finding, or more commonly be seen in association with a variety of conditions. Epidemiology The septum pellucidum is partly or entirely absent in 2 or 3 individuals per 100,000 in the general population.  Pathology An absent septum pelluc...
Article

Absent thumb

An absent thumb can have many associations. They include: Fanconi anaemia (pancytopenia-dysmelia syndrome) Franceschetti syndrome Holt-Oram syndrome phocomelia (e.g. thalidomide embryopathy) Poland syndrome (pectoral muscle aplasia and syndactyly) Rothmund-Thomson syndrome Seckel syndrome...
Article

Absent umbilical arterial end-diastolic flow

Absent end-diastolic flow (AEDF) in an umbilical artery Doppler assessment is a useful feature which indicates underlying fetal vascular stress if detected in mid or late pregnancy. It is often classified as Class II in severity in abnormal umbilical arterial Dopplers 9. Pathology The presence...
Article

Absent yolk sac

Absence of the yolk sac in the presence of an embryo on a transvaginal ultrasound is considered abnormal, and in general is associated with subsequent embryonic death. See also yolk sac
Article

Absorbed dose

Absorbed dose is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg or gray (Gy) where 1Gy = 1Jkg-1. The absorbed dose is not a good indicator of the likely biological effect. 1 Gy of alpha r...
Article

Absorption (ultrasound)

In ultrasound, absorption is the reduction in intensity of the sound waves as it passes through tissue. Most of the energy lost is in the form of heat.
Article

Acaeruloplasminaemia

Acaeruloplasminaemia is an autosomal recessive type of neurodegeneration with brain iron accumulation and disorder of iron metabolism caused by a mutation in the caeruloplasmin (CP) gene resulting in production of dysfunctional caeruloplasmin. Epidemiology Acaeruloplasminaemia is a very rare d...
Article

Acardiac twin

Acardiac twins (or recipient twins) are haemodynamically disadvantaged non-viable twins that undergo secondary atrophy in association with a twin reversed arterial perfusion sequence. Epidemiology Acardiac twinning is thought to affect 1 in 100 monozygotic twin pregnancies and 1 in 35,000 preg...
Article

Accepted abbreviations

There are a number of accepted abbreviations that we use on Radiopaedia.org. We would like the site to be as standardised as possible and we have therefore chosen our accepted abbreviations and would ask that where possible these are used: a.k.a. not aka (short for "also known as") cf. not c.f...
Article

Accessory appendicular artery

The accessory appendicular artery (or artery of Seshachalam) is a branch of the posterior caecal artery, which in turn arises from the ileocolic artery, and runs in the mesoappendix. The exact prevalence of this accessory artery and its impact upon the risk of appendicitis varies among studies....
Article

Accessory breast tissue

Accessory breast tissue is a relatively common congenital condition in which abnormal accessory breast tissue is seen in addition to the presence of normal breast tissue. This normal variant can present as a mass anywhere along the course of the embryologic mammary streak (axilla to the inguinal...
Article

Accessory fissures of the lung

Accessory fissures of the lung usually occur at the borders of bronchopulmonary segments. They are common normal variants but are less commonly seen on imaging.  Some of the more common accessory fissure include 1: azygos fissure: most commonly seen accessory fissure inferior accessory fissur...
Article

Accessory gallbladder

Accessory gallbladders are a rare anatomical variant occurring in 0.03% of cases (approximately 1 in 3000 people). They can arise from either the left or right hepatic ducts or both. Accessory gallbladders arise from a bifid diverticulum of the hepatic duct in the 5th or 6th week of development ...
Article

Accessory hemiazygos vein

The accessory (or superior) hemiazygos vein forms part of the azygos system and along with the hemiazygos vein, it is partially analogous to the right-sided azygos vein. It drains the left superior hemithorax.  Gross anatomy Origin and course The accessory hemiazygos vein is formed by the con...
Article

Accessory left atrial appendage

An accessory left atrial appendage is a frequent fortuitous finding in cardiac imaging, encountered in ~10% of patients. They are more often seen as a small diverticular structure projecting from the right upper side of the left atrial wall. Differential diagnosis it must not be confused with ...
Article

Accessory meningeal artery

The accessory meningeal artery is a branch of the maxillary artery but can also branch from the middle meningeal artery. The artery passes upwards through the foramen ovale to supply the trigeminal ganglion and the dura mater of Meckel's cave and the middle cranial fossa. It also usually suppli...
Article

Accessory middle cerebral artery

The accessory middle cerebral artery is a variant of the middle cerebral artery (MCA) that arises from the anterior cerebral artery (ACA). It is different from a duplicated middle cerebral artery, in which the duplicated vessel originates also from the distal end of the internal carotid artery (...
Article

Accessory navicular syndrome

Accessory navicular syndrome occurs when a type II accessory navicular (or "os tibiale externum") becomes painful due to movement across the pseudojoint between the ossicle and the navicular bone. Radiographic features Ultrasound It can be inferred on musculoskeletal ultrasound if a patient's...
Article

Accessory occipital bone sutures

The parietal and occipital bones in particular are common regions for accessory sutures because of their multiple ossification centres. The occipital bone has complex development, ossifying from six centres. The foramen magnum is surrounded by four ossification centres. On each side are the exo...
Article

Accessory ossicle of the anterior arch of the atlas

The accessory ossicle of the anterior arch of the atlas is a normal variant and is best appreciated on a lateral cervical/sagittal study. It is observed as a circular and corticated osseous density that articulates with the inferior aspect of the anterior arch of the atlas.  It is not associate...
Article

Accessory ossicles

Accessory ossicles are secondary ossification centres that are separate from the adjacent bone. They are usually round or ovoid in shape, occur in typical locations and have well defined smooth cortical margins on all sides. In most cases, they are congenital in origin, although they may occur ...
Article

Accessory ossicles of the foot

Accessory ossicles of the feet are common developmental variants with almost 40 having been described. The more common ones include: os peroneum os subfibulare os subtibiale os tibiale externum (accessory navicular) os trigonum os calcaneus secundaris os intermetatarseum pars peronea met...
Article

Accessory ossicles of the wrist

Accessory ossicles of the wrist are commonly seen on plain radiographs of the wrist and associated cross-sectional imaging. Over 20 were originally described 2, although the more common include 1: lunula: between TFCC and triquetrum os styloideum (carpal boss): on dorsal surface of 2nd or 3rd ...
Article

Accessory ossicles of the wrist (mnemonic)

Accessory ossicles of the wrist can be easily recalled with the mnemonic: LOTTEO 1 HOTELS Mnemonic   L: lunula O: os styloideum (carpal boss) T: (os) triangulare T: (os) trapezium secondarium E: (os) epilunate O: os hamuli propriu Another useful mnemonic is HOTELS H: (os) hamuli propr...
Article

Accessory parotid glands

Accessory parotid glands are a normal variant and represent ectopic salivary tissue separate from, but usually in close proximity to, the main parotid glands 1. Occasionally the accessory tissue is contiguous with the main glands. Epidemiology Accessory parotid glands are commonly picked up in...
Article

Accessory peroneal muscles

Accessory peroneal muscles are a group of accessory muscles that can occur in the foot region as a normal variant in some individuals. The peroneal compartment is known as the lateral compartment of the leg. Peroneus quartus muscle Originally, several accessory muscles were distinguished in th...
Article

Accessory renal artery

Accessory renal arteries are a common variant and are present in ~25% (range 20-30%) of the population. Their proper identification is of utmost importance for surgical planning prior to live donor transplantation 3,4 and renal artery embolisation for various reasons 5. The term extra renal art...
Article

Accessory right inferior hepatic vein

An accessory right inferior hepatic vein is the most common variation of the hepatic veins.  It is present in up to 48% of the population and drains the posterior part of the right lobe (mainly segments 6 and 7) directly into the inferior vena cava. Variations in hepatic vascular anatomy are pa...
Article

Accessory soleus muscle

The accessory soleus muscle is an anatomical variant characterised by an additional distinct muscle encountered along a normal soleus muscle. It is uncommon with a prevalence of ~3% (range 0.7-5.5%). Summary origin: fibula, soleal line of the tibia, or the anterior surface of the soleus muscle...
Article

Accessory superior acetabular notch

An accessory superior acetabular notch is a normal variant of the acetabulum, which can be seen on radiographs. It may lead to diagnostic confusion, especially in younger patients.  Radiographic features MRI appear as bilateral symmetric fluid-filled pits in the roof of the acetabulum with sh...
Article

Accordion sign (colon)

The accordion sign is seen on CT examinations of the abdomen and refers to the similarity between the thickened oedematous wall of pseudomembranous colitis and the folds of an accordion. This appearance is the result of oral contrast being trapped between oedematous haustral folds and pseudomemb...
Article

Ace-of-spades sign (heart)

Ace-of-spades sign refers to the pathognomonic configuration of the left ventricle as seen in apical hypertrophy 1-3. It consists of marked ventricular wall thickening at the apex resulting in cavity narrowing at the apex with a relatively normal appearance of the mid-ventricular to basal wall ...
Article

Acetabular angle

The acetabular angle is a radiographic measurement used when evaluating potential developmental dysplasia of the hip (DDH).  It is most useful in patients who have started to ossify the epiphysis since ossification diminishes the usefulness of ultrasound. The angle is formed by a horizontal lin...
Article

Acetabular foramen

The acetabular foramen is formed by the bony margins of the acetabular notch and completed by the transverse ligament of the hip. From its margins (both transverse ligament and acetabular notch) arises the ligamentum teres. Through it pass nutrient vessels to the femoral head epiphysis.
Article

Acetabular labral tears

Acetabular labral tears, as the name implies, are tears involving the acetabular labrum of the hip.   With the increasing use of hip arthroscopy in orthopaedic surgery since the 1970s pathologies of the acetabular labrum as a possible cause of chronic hip and groin pain have become more familia...
Article

Acetabular labrum

Acetabular labrum acts to deepen the acetabulum and increase contact between the pelvis and the femoral head. Its exact biomechanical role remains to be fully elucidated. Gross anatomy The acetabular labrum is a C-shaped fibrocartilaginous structure with an opening anteroinferiorly at the site...
Article

Acetabular notch

The acetablar notch is a depression in the margin of the acetabulum located anteroinferiorly. It is bridged by the transverse ligament, and thus forms the acteabular foramen. The ligamentum teres has part of its origin from the acetabular notch. 
Article

Acetabulum

The acetabulum (plural: acetabula) is the large cup-shaped cavity on the anterolateral aspect of the pelvis that articulates with the femoral head to form the hip joint. Gross anatomy All three bones of the pelvis (the ilium, ischium, and pubis) together form the acetabulum. The three bones ar...
Article

Achalasia

Achalasia (primary achalasia) refers to a failure of organised oesophageal peristalsis with an impaired relaxation of the lower oesophageal sphincter (LOS), resulting in often marked dilatation of the oesophagus and food stasis. Obstruction of the distal oesophagus (often due to tumour) has been...
Article

Acheiria

Acheiria refers to absence of one or both hands and can occur in a number of situations, including: amniotic band syndrome: particularly if unilateral Cornelia de Lange syndrome 1 fetal hydantoin syndrome 2  Epidemiology Rare defect occurring in 1:65 000 live births. See also absent thumb...
Article

Achilles tendinopathy

Achilles tendinopathy refers to a combination of pathological changes affecting the Achilles tendon usually due to overuse and excessive chronic stress upon the tendon. It can be seen both in athletes and non-athletes (weekend warriors). It is hard to differentiate clinically from a paratendinop...
Article

Achilles tendon ossification

Achilles tendon ossification (ATO) is an uncommon condition that consists of characteristic bone formation within the substance of the Achilles tendon.  Epidemiology Achilles tendon ossification is more common in males 4.  Pathology The aetiology is unknown but Achilles tendon ossification i...
Article

Achilles tendon tear

Achilles tendon tears are the most common ankle tendon injuries, and are most commonly seen secondary to sports-related injury, especially squash and basketball. Epidemiology There is strong male over-representation presumably as a result of the predominantly sport related aetiology. Patients ...
Article

Achilles tendon thickening

Achilles tendon thickening can occur for a number of reasons. The Achilles tendon has an average AP diameter of 6 mm 1. Thickening of the tendon is when it exceeds 8 mm in AP diameter and can result from: Achilles tendinosis/tear post-surgical thickening retrocalcaneal bursitis degeneration...
Article

Achilles tendon xanthoma

Achilles tendon xanthomas are painless soft tissue masses occurring most commonly at the distal one-third of the tendon and are usually bilateral and symmetrical. Pathology It is characterised by localised accumulation of lipid-laden macrophages, inflammatory cells and giant cells secondary to...
Article

Achondrogenesis

Achondrogenesis refers to a group of rare and extreme skeletal dysplasias. Epidemiology The estimated incidence is 1:40,000 with no recognised gender predilection. Pathology It is classified as an osteochondrodysplasia, meaning deficiency of both bone and cartilage development.  Subtypes T...
Article

Achondrogenesis 1A

Achondrogenesis type Ia, also known as the Houston-Harris subtype, is a subtype of achondrogenesis. It is an extremely rare lethal skeletal dysplasia (chondrodysplasia) with a characteristic severe disarrangement of endochondral ossification.  Pathology The growth plate cartilage completely la...
Article

Achondrogenesis 1B

Achondrogenesis type Ib, also known as Parenti-Fraccaro subtype, is a subtype of achondrogenesis and is an extremely rare skeletal dysplasia (chondrodysplasia).​​ Pathology Undersulphation has a pronounced effect on the composition of the extracellular matrix of cartilage, and this has been sh...
Article

Achondroplasia

Achondroplasia is a congenital genetic disorder resulting in rhizomelic dwarfism and is the most common skeletal dysplasia. It has numerous distinctive radiographic features.  Epidemiology It occurs due to sporadic mutations in the majority of cases but can be inherited as an autosomal dominan...
Article

Achondroplastic base of skull abnormalities

Achondroplasia is the most common cause of short-limb dwarfism. (For a general discussion, see the generic article on achondroplasia.) As the skull base forms by endochondral ossification whereas the skull vault by membranous ossification, there is a marked discrepancy in relative size as the s...
Article

Acinic cell carcinoma (lung)

Acinic cell carcinoma of the lung (also known as a Fechner tumour) is a type of lung carcinoma of the salivary gland type. It is extremely rare, especially when it presents in the form of primary acinic cell carcinoma. Pathology Histologically, they are comprised of clear cells with abundant g...
Article

Acinic cell carcinoma (salivary glands)

Acinic cell carcinomas of the salivary glands are rare malignant neoplasms that account for 1-3% of all salivary gland tumours.  Pathology Pathology may superficially resemble normal serous (acinar) cells of the salivary glands. It is considered a low-grade, indolent malignancy, but with a ten...
Article

Acoustic enhancement

Acoustic enhancement, also called posterior enhancement or enhanced through transmission, refers to the increased echoes deep to structures that transmit sound exceptionally well. This is characteristic of fluid filled structures such as cysts, the urinary bladder and the gallbladder. The fluid...
Article

Acoustic impedance

Acoustic impedance (Z) is a physical property of tissue. It describes how much resistance an ultrasound beam encounters as it passes through a tissue. Acoustic impedance depends on: the density of the tissue (d, in kg/m3) the speed of the sound wave (c, in m/s) and they are related by: Z = ...
Article

Acoustic schwannoma

Acoustic schwannomas (also known as vestibular schwannomas) are relatively common tumours that arise from the vestibulocochlear nerve (CN VIII) and represent ~80% of cerebellopontine angle masses. Bilateral acoustic schwannomas are strongly suggestive of neurofibromatosis type 2 (NF2). These tu...
Article

Acoustic shadowing

Acoustic shadowing on an ultrasound image is characterised by a signal void behind structures that strongly absorb or reflect ultrasonic waves. This happens most frequently with solid structures, as sound conducts most rapidly in areas where molecules are closely packed, such as in bone or stone...
Article

AC-PC line

The anterior commissure - posterior commissure line (AC-PC line), also referred as the bicommissural line, has been adopted as a convenient standard by the neuroimaging community, and in most instances is the reference plane for axial imaging in everyday scanning. The creation of a standard imag...
Article

Acquired aortic conditions

There are many acquired aortic conditions. These include aortic dissection aortic rupture / transection ascending aortic aneurysm aortitis thoracic aortic injury abdominal aortic aneurysm inflammatory abdominal aortic aneurysm
Article

Acquired cholesteatoma

Acquired cholesteatomas make up 98% of all middle ear cholesteatomas and are almost always closely related to the tympanic membrane, from which most are thought to arise.  Clinical presentation The vast majority of acquired cholesteatomas develop as a result of chronic middle ear infection and...
Article

Acquired cystic kidney disease

Acquired cystic kidney disease (ACKD) is a condition that occurs in patients with end-stage kidney disease (ESKD), especially when on dialysis treatment, and who do not have a history of other cystic renal disease.  Epidemiology Its incidence increases with the amount of time a patient is azot...
Article

Acquired hepatocerebral degeneration

Acquired hepatocerebral degeneration is an uncommon irreversible extrapyramidal neurodegenerative condition encountered in patients with cirrhotic chronic liver disease, resulting in widespread cerebral, basal ganglia and cerebellar damage.  Terminology Acquired hepatocerebral degeneration is ...
Article

Acquired tracheo-oesophageal fistula

An acquired tracheo-oesophageal fistula refers to a pathological communication between the trachea and oesophagus due to a secondary cause  Pathology Acquired causes of tracheo-oesophagal fistulae can be divided into those that are related to malignancy (common) and those from other causes (un...
Article

Acquisition time

The time of acquisition for a conventional spin echo or gradient echo sequence is the product of the repetition time, phase encoding steps, and number of averages (TR x phase steps x NEX). For example, with a one second TR, 128 phase steps, and two averages we would get an acquisition time of ab...
Article

Acrania

Acrania is a rare lethal congenital anomaly characterised by an absence of the calvaria. Epidemiology The estimated incidence is at ~1:1000 pregnancies 4.  Pathology  The condition is thought to result from abnormal migration of mesenchymal tissue, which normally covers the cerebral hemisphe...
Article

Acrania anencephaly sequence

Acrania anencephaly sequence is the progression from a relatively normal-appearing exposed brain due to an absent cranium (acrania) to an amorphous brain mass (exencephaly) to no recognisable brain tissue (anencephaly) 1. Epidemiology The acrania anencephaly sequence begins with acrania, which...
Article

Acrocephalopolysyndactyly

Acrocephalopolysyndactyly (ACPS) syndrome is comprised of a rare group of disorders collectively characterised by: calvarial anomalies: e.g. craniosynostoses digital anomalies: syndactyly and polydactyly While there can be some overlap in features, they can be primarily classified into the fo...
Article

Acrocephalosyndactyly

Acrocephalosyndactyly syndromes (ACS) is a rare group of disorders collectively characterised by: calvarial anomalies, e.g. craniosynostoses digital anomalies, e.g. syndactyly Classification While there can be some overlap in features, they can be primarily classified into the following majo...
Article

Acrodysostosis

Acrodysostosis is a rare skeletal dysplasia characterised by growth retardation, nasal hypoplasia, brachydactyly, midfacial deficiency, mental retardation and deafness. Pathology Most cases are sporadic. Few cases with autosomal dominant transmission have been reported. It is believed to occur...
Article

Acromegaly

Acromegaly is the result of excessive growth hormone production in skeletally mature patients, most commonly from a pituitary adenoma. The same excess of growth hormone in individuals whose epiphyses have not fused will result in gigantism (excessively tall stature).   It is most commonly diagn...
Article

Acromial apophysiolysis

Acromial apohysiolysis is a finding on shoulder MRI that may be encountered in patients with an unfused acromial apophysis. It is associated with athletes in throwing sports. Clinical presentation Presents with superior shoulder tenderness in a patient <25 years old, often in a young throwing ...
Article

Acromial types

The shape of the acromion had been initially divided into three types (which was known as the Bigliani classification) 3, to which a fourth has been added 2. They are useful as a standardised way of describing the acromion, as well as predicting to a degree the incidence of impingement.  Classi...
Article

Acromioclavicular injury

Acromioclavicular joint injuries are common and range from a mild sprain to complete disruption of the acromioclavicular joint (ACJ) and injury to surrounding structures.  Pathology Mechanism Acromioclavicular joint injuries usually occur from a direct blow or following a fall onto the should...
Article

Acromioclavicular joint

The acromioclavicular (AC) joint is a plane synovial joint of the pectoral girdle. Gross anatomy The acromioclavicular joint is between the small facets of the convex distal clavicle and flat medial acromion. The articular surfaces are lined with hyaline cartilage 4. A fibrocartilaginous wedge...
Article

Acromioclavicular joint (AP view)

The acromioclavicular AP view is single projection assessing the patency of the acromioclavicular joint. See also, acromioclavicular joint injuries. Patient position patient is erect midcoronal plane of the patient is parallel to the image receptor, in other words, the patient's back is agai...
Article

Acromioclavicular joint (AP weight-bearing view)

The acromioclavicular AP weight-bearing view is and additional interjection often performed to rule out displacement when it is suspected yet not confirmed on the AP view See also, acromioclavicular joint injuries. Patient position the patient is erect holding a weight in the affected sides h...
Article

Acromioclavicular joint configuration

There is much variation in acromioclavicular (AC) joint configuration which may be confused with pathology.  The relationship of the acromion to the distal clavicle at the AC joint can be described in the coronal plane as 1, 2, 3: horizontal: normal low lying: associated with shoulder impinge...
Article

Acromioclavicular joint series

The acromioclavicular (AC) joint radiographic series is a used to evaluate the acromioclavicular joint and the distal clavicle. Indications AC radiographs are performed for a variety of indications including:  shoulder trauma direct blows to the should region following a fall onto adducted ...
Article

Acromiohumeral interval

Acromiohumeral interval is a useful and reliable measurement on AP shoulder radiographs and when narrowed is indicative of rotator cuff tear or tendinopathy.  Pathology Measurements of the acromiohumeral interval in the following intervals are suggestive of pathology 1-2: >12 mm: shoulder dis...
Article

Acromion

The acromion, also known as the acromial process, is a small section of the scapula that extends anteriorly from the spine of the scapula.  Gross anatomy It forms the acromioclavicular joint with the lateral third of the clavicle, and also connects with the coracoid process via the coraco-acro...
Article

Acro-osteolysis

Acro-osteolysis refers to resorption of the distal phalanx. The terminal tuft is most commonly affected but the shaft of the distal phalanx can also be affected in a few conditions. It is associated with a heterogeneous group of pathological entities and, some of which can be remembered by using...
Article

Acro-osteolysis (mnemonic)

The causes of acro-osteolysis can be remembered using the mnemonic: PINCH FO Mnemonic P: psoriasis/pyknodysostosis I: injury, e.g. thermal burn, frost bite N: neuropathy, e.g. diabetes, leprosy C: collagen vascular disease, e.g. scleroderma, Raynaud disease H: hyperparathyroidism F: fami...
Article

Acroparesthesia

Acroparesthesia refers to tingling, pins-and-needles, burning or numbness or stiffness in the hands and feet, particularly the fingers and toes 1. Occasionally episodic pain is also present, which can be very severe 1.  Is one of the more common manifestations of Fabry disease (more common than...
Article

ACR Thyroid Imaging Reporting and Data System (ACR TI-RADS)

ACR TI-RADS is a reporting system for thyroid nodules on ultrasound proposed by the American College of Radiology (ACR) 1. This uses a standardised scoring system for reports providing users with recommendations for when to use fine needle aspiration (FNA) or ultrasound follow-up of suspicious ...
Article

Acute abdominal series

The acute abdominal series is a common set of abdominal radiographs obtained to evaluate bowel gas.  Indications The acute series is used for a variety of indications including:  determine the amount of bowel gas, with possible bowel distention assess air-fluid levels query pneumoperitoneum...
Article

Acute acalculous cholecystitis

Acute acalculous cholecystitis refers to the development of cholecystitis in a gallbladder either without gallstones or with gallstones where they are not the contributory factor. It is thought to occur most often due to biliary stasis and/or gallbladder ischaemia. Epidemiology Acute acalculou...
Article

Acute airspace opacification with lymphadenopathy (differential)

Acute airspace opacification with lymphadenopathy is a subset of the differential diagnosis for generalised airspace opacification and includes: post-obstructive causes (usually chronic, but 'new' changes can occur) primary lung cancer pulmonary metastases lymphoma/leukaemia infection pri...
Article

Acute aortic syndrome

Acute aortic syndrome (AAS) describes the presentation of patients with one of a number of life threatening aortic pathologies that give rise to aortic symptoms. The spectrum of these aortic emergencies include: aortic dissection aortic intramural haematoma penetrating atherosclerotic ulcer ...
Article

Acute aspiration pneumonitis

Acute aspiration pneumonitis refer to a form aspiration pneumonia where the time of onset is rapid. Radiographic features Plain radiograph / CT Features can be variable and can range from a pulmonary oedema pattern to areas of consolidation. These changes may have a gravity dependant distribu...
Article

Acute bacterial meningitis complications (mnemonic)

The complications of acute bacterial meningitis can be remembered using the mnemonic: HACTIVE Mnemonic H: hydrocephalus A: abscess C: cerebritis / cranial nerve lesion T: thrombosis I: infarct V: ventriculitis/vasculopathy E: extra-axial collection: empyema and hygroma Related articles...

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.