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.

1,113 results found
Article

Systemic lupus erythematosus (thoracic manifestations)

Thoracic manifestations of systemic lupus erythematosus can be variable.  For a general discussion, and for links to other system specific manifestations, please refer to the article on systemic lupus erythematosus.  Pathology Pleuropulmonary manifestations pleuritis: considered one of the c...
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Talar dislocation

There are many types of talar dislocation given its multiple articulations: tibiotalar dislocation subtalar dislocation total talar dislocation talonavicular dislocation ​Chopart fracture-dislocation
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Talar fractures

Talar fractures are an uncommon injury, accounting for <5% of all foot fractures. Recognition of the unique talar anatomy is important for correct diagnosis. Pathology Location talar head fractures talar neck fractures talar body fractures talar dome osteochondral fracture posterior talar...
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Tauopathy

Tauopathies are a heterogeneous group of neurodegenerative diseases characterised by abnormal metabolism of tau proteins leading to intracellular accumulation and formation of neurofibrillary tangles (NFT). These neurofibrillary tangles are deposited in the cytosol of neurons and glial cells.  ...
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Telecanthus

Telecanthus represents increased intercanthal distance. It is often used interchangeably with hypertelorism, referring to increased distance between the eyes. Causes and associations trauma: naso-orbito-ethmoidal (NOE) fractures ethnic variation acquired sinus and orbital tumours sinus pol...
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Temporal bone destructive lesions (differential)

Destructive lesions of the temporal bone (petrous pyramid, middle ear and antrum) have a relatively broad differential including 1: lesions affecting petrous pyramid acoustic schwannoma meningioma glioma neuroma of trigeminal and facial nerve chordoma glomus jugulare tumour epidermoid of...
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Temporomandibular joint effusion

Temporomandibular joint (TMJ) effusions are unusual in asymptomatic patients, and thus should trigger a careful search for underlying pathology. It usually precedes osteoarthritis of the TMJ. Effusions are seen in: TMJ dysfunction septic arthritis rheumatoid arthritis (RA) Radiographic featu...
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Tension pneumothorax

Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exert positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest. Fo...
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Terminal ileitis (differential)

The differential diagnosis for a terminal ileitis is quite extensive, and includes: inflammatory bowel disease Crohn disease (most common) backwash ileitis due to ulcerative colitis infectious colitis Yersinia spp.  Yersinia enterocolitica Yersinia pseudotuberculosis Salmonella spp. Clo...
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Terminal tuft mass

There is only a short list of terminal tuft masses, which can arise from the adjacent soft tissues and erode the terminal tuft as well as arising from the terminal tuft itself: epidermal inclusion cyst: history of penetrating trauma tenosynovial giant cell tumour: occur laterally subungual gl...
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Terminal zones of myelination

The terminal zones of myelination are located at the posterior aspect of the lateral ventricles (the peritrigonal regions) and are the only part of the cerebral white matter that may exhibit high T2 signal in a normal brain at 2 years of age, when myelination of cerebral white matter normally be...
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Testicular cancer

Testicular cancers are the most common neoplasm in men between the ages of 20 and 34 years. Epidemiology Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2. The demographics of affected individuals depends on the age of the histology of the tumour....
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Testicular microlithiasis

Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.  The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In t...
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Testicular trauma

Testicular trauma is the third most-common cause of acute scrotal pain and may result in various degree of damage to the testes. Pathology Testicular rupture and testicular ischaemia/infarct are two severe complications which need to be ruled out. Other injuries that can occur include 1: test...
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The four "Ds" of radiology reporting

The four "Ds" of radiology reporting are the basic sequential tasks that a radiologist performs when reporting/reading a case, whether it be in training, the exam environment or in day-to-day clinical practice.  The 4 "Ds" Detect Describe Diagnosis or differential diagnoses Decision By sti...
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Thoracic aortic dilatation (differential)

There are a number of causes and mimics of thoracic aortic dilatation. Differential diagnosis senile ectasia hypertension post-stenotic dilatation, e.g. bicuspid aortic valve thoracic aortic aneurysm atherosclerosis (usually descending thoracic aorta) collagen disorders Marfan syndrome ...
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Thoracic aortic stenosis (differential)

The differential for thoracic aortic stenosis includes: atherosclerosis aortitis (especially Takayasu arteritis) radiation coarctation pseudocoarctation Williams syndrome: supravalvular aortic stenosis congenital rubella syndrome: supravalvular aortic stenosis
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Thoracolith

Thoracoliths are rare, calcified pleural-based nodules that are almost always incidental findings. They are usually considered mobile, and more common on the left. Pathology The exact aetiology is unknown and theories include 1,2: calcified fibrin body degenerated pleural lipoma old tubercu...
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Threatened miscarriage

Threatened miscarriage (or threatened abortion) is mainly a clinical term, used when a pregnant woman in first 20 weeks of gestation presents with spotting, mild abdominal pain and contractions, with a closed cervical os.  Epidemiology It occurs in 20-25% of pregnancies and is associated with ...
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Thyroid inflammatory conditions

A number of inflammatory conditions can affect the thyroid gland, which are commonly described as thyroiditides: acute thyroiditis acute suppurative thyroiditis (AST)  autoimmune thyroiditis​ subacute lymphocytic thyroiditis: silent thyroiditis or painless subacute thyroiditis  postpartum t...
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Thyroid malignancies

Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits. Pathology Classification Thyroid malignancies can be categorised into the following key subtypes: primary thyroid cancers ​papillary thyroid carcinoma: 60-80% of carcinomas follicular thyr...
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Tibiotalar slant

Tibiotalar slant is the superolateral inclination of the tibial plafond, and results in an ankle valgus deformity. There are a number of causes 1: trauma, i.e. distal tibial fractures osteomyelitis and/or septic arthritis juvenile idiopathic arthritis haemophilic arthropathy sickle cell dis...
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Tonsillar herniation

Tonsillar herniation is a type of cerebral herniation characterised by the inferior descent of the cerebellar tonsils below the foramen magnum. The terminology of caudally displaced tonsils is discussed in the article on cerebellar tonsillar ectopia. Pathology It is a secondary sign of signif...
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Tonsillitis

Tonsillitis refers to inflammation of any of the tonsils and is one of the most common head and neck infections in adolescents and young adults. Clinical presentation Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervica...
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Torticollis

Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the paediatric age group.  Pathology Torticollis can be acute (<1 week) or chronic ...
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Total hip arthroplasty

Total hip arthroplasty (THA) or total hip replacement (THR) is an orthopaedic procedure which involves the surgical excision of the femoral head and cartilage of the acetabulum and replacement of the joint with articulating femoral and acetabular components. It is a commonly performed procedure ...
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Toxoplasmosis vs lymphoma

Toxoplasmosis and lymphoma are frequently differential diagnoses in patients with HIV/AIDS and as treatment is substantially different distinguishing the two is important.  In many instances, the imaging appearance is classic and differentiation is not problematic; however, in 50-80% of cases, ...
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Tracheal and endobronchial lesions

Primary tracheal and endobronchial lesions are generally rare and can be either malignant or benign. The majority of these lesions are malignant. Pathology Malignant primary malignant endobronchial lesions bronchogenic adenocarcinoma squamous cell carcinoma: commonest malignant lesion in tr...
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Tracheal buckling

Tracheal buckling is a normal finding in young infants when it is more flexible. There is typically deviation of the trachea anteriorly and to the right (up to 90°) and any other configuration (i.e. to the left or posteriorly) should raise the possibility of underlying pathology.  Practical poi...
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Tracheal masses

The differential for tracheal masses can be rather wide. For a single mass consider: metastasis  direct invasion from adjacent organ (lung, thyroid, oesophagus and larynx) distant metastasis (e.g. melanoma, breast, renal and colon cancer)  primary neoplasms: squamous cell carcinoma: common...
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Tracheal wall thickening

Tracheal wall thickening may have several causes. For diagnostic purposes, tracheal thickening may be categorized by length of airway involvement in order to narrow the differential diagnoses. Note that some etiologies may be associated with either focal or diffuse pattern of involvement. Focal...
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Tracheomalacia

Tracheomalacia, or sometimes described as tracheobronchomalacia, is a common incidental finding on imaging of the chest of older patients and manifests as an increase in tracheal diameter as well as a tendency to collapse on expiration. Generally, more than 70% collapse of the trachea during exp...
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Traction bronchiectasis

Traction bronchiectasis refers to an aetiological sub type of bronchiectasis where there is irreversible dilatation of bronchi and bronchioles within areas of pulmonary fibrosis or distorted lung parenchymal architecture. Pathology It can arise from a number of underlying causes which result i...
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Transalar herniation

Transalar (transsphenoidal) herniation describes herniation of brain matter in and around the middle cranial fossa across the greater sphenoid wing and can be ascending or descending. Compression of structures against the sphenoid bone results in symptoms. Pathology Transalar herniation is not...
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Transependymal oedema

Transependymal oedema, also known as interstitial cerebral oedema, is a type of cerebral oedema that occurs with increased pressure within the cerebral ventricles. FLAIR is the most sensitive MRI sequence for detection. Pathology The ventricular ependymal lining is eventually disrupted, allowi...
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Transient hepatic attenuation differences

Transient hepatic attenuation differences (THAD) lesions refer to areas of parenchymal enhancement visible during the hepatic artery phase on helical CT. They are thought to be a physiological phenomenon caused by the dual hepatic blood supply. Occasionally they may be associated with hepatic tu...
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Transtentorial herniation

Transtentorial herniation is a type of cerebral herniation. There are two types: descending transtentorial herniation, more frequently known as uncal herniation ascending transtentorial herniation, which is less common than uncal herniation
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Trapped lung

Trapped lung, also known as unexpandable/unexpanded lung, is a term used where there is non-expandable lung after fluid removal, often thoracentesis. It is similar to but not entirely synonymous with the term lung entrapment, which is a similar condition but caused by active pleural disease rath...
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Trauma in pregnancy

Trauma is a leading cause of mortality in pregnancy. Pregnancy increases the incidence and severity of abdominal trauma in females.  Epidemiology Trauma affects up to 7% of pregnancies, and the incidence of pregnancy in level 1 trauma patients is estimated to be ~2% 1.  Pathology Aetiology ...
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Traumatic spinal cord injury

Traumatic spinal cord injury can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal stenos...
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Triphalangeal thumb

Triphalangeal thumb is considered a form of pre-axial polydactyly. Epidemiology Triphalangeal thumbs have an incidence of 1 in 25,000 7.  Pathology A triphalangeal thumb, as the name implies, has three phalanges instead of the usual two. There is an autosomal dominant genetic transmission 8....
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Troponin

Troponin is a protein of key importance in the functioning of skeletal and cardiac muscle. It forms part of the contractile mechanism, and comprises three main subunits: troponin C, troponin I, and troponin T.  Troponin elevation Elevation of serum troponin can occur from a number of causes an...
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Tuberculosis (intracranial manifestations)

Tuberculosis of the central nervous system can result from either haematogenous spread from distant systemic infection (e.g. pulmonary tuberculosis) or direct extension from local infection (e.g. tuberculous otomastoiditis). Intracranial manifestations of tuberculosis are protean and can affect...
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Tuberculous adrenalitis

Tuberculous adrenalitis is the result of adrenal mycobacterium tuberculosis (TB) infection. Its incidence has decreased in the western world with the declining incidence of tuberculosis. Pathology As the tuberculous infection causes destruction of the adrenal cortex, primary adrenal insufficie...
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Tubulinopathy

Tubulinopathy refers to a wide spectrum of cortical malformations that result from defects in genes encoding the tubulin protein that regulates neuronal migration during brain development. Clinical presentation Some series report a high prevalence of seizures during infancy which may the initi...
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Tumours of the chest wall (differentials)

Tumours of the chest wall are varied, some of which are found most often in this region. They can be divided into benign and malignant tumours and into those which arise in the ribcage and those of soft tissue density. Benign Benign tumours include 1,3,4: soft tissue haemangioma: common lym...
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Tumours of the male urethra

Tumours of the male urethra are uncommon. They can be categorised both on the grounds of histology and location. Histology squamous cell carcinoma of the urethra: 80% urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra) adenocarcinoma of the urethra: 5...
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Tumours of the small intestine

The small intestine is rarely the site of malignant tumours, although it accounts for ~75% of the entire length of the GI tract and more than 90% of the mucosal surface. Approximately 40 different histologic tumour types have been described.  In this article, an overview will be given of the mo...
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Tumours that metastasise to bone (mnemonic)

Tumours that metastasise to bone may be remembered using the mnemonic "lead kettle" spelled PBKTL (lead is Pb on the Periodic Table). PB-KTL Mnemonic P: prostate B: breast K: kidney T: thyroid L: lung For females, breast and lung are the most common primary sites; nearly 80% of cancers t...
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Twin pregnancy

Twin pregnancies are the most common multifetal pregnancies.  Epidemiology Multifetal pregnancies account for ~ 1% of all pregnancies but are seen in much higher numbers in populations where in vitro fertilisation (IVF) is a common practice, most of which are twin pregnancies. Classification ...
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Ulnar variance

Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna.  Ulnar variance may be: neutral (both the ulnar and radial articular surfaces at the same level) positive (ulna projects more distally) negative (ulna projec...
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Ultrasound appearances of liver metastases

Ultrasound appearance of liver metastases can have bewildering variation, and the presence of hepatic steatosis can affect the sonographic appearance of liver lesions. Radiographic features Ultrasound Patterns do exist between ultrasound appearance of the liver metastases and the likely prima...
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Umbilical cord cyst

Umbilical cord cysts can refer to any cystic lesion associated with the umbilical cord. They can be single (commoner) or multiple. Epidemiology They may be seen in ~3% of pregnancies in the first trimester 8. Pathology Umbilical cord cysts can represent either true or false cysts: true cyst...
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Unilateral axillary lymphadenopathy (differential)

Unilateral axillary lymphadenopathy while being more concerning than bilateral axillary lymphadenopathy can still arise from a various benign as well as malignant causes. Benign mastitis other regional infective causes tuberculosis ipsilateral arm infection, e.g. cellulitis silicone induce...
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Unilateral facet dislocation

Unilateral facet dislocation is a relatively stable type of facet dislocation. Pathology Mechanism Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
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Unilateral pulmonary oedema

Unilateral pulmonary oedema represents only 2% of cardiogenic pulmonary oedema with predilection for the right upper lobe and is strongly associated with severe mitral regurgitation 1, 2. It is hypothesised that the regurgitation jet is directed towards the right superior pulmonary vein thus pre...
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Unilateral testicular lesions

The differential diagnosis for unilateral testicular lesions is wide-ranging.  Neoplastic Common seminoma (40-50% of testicular malignancies) non-seminomatous germ cell tumours: testicular teratoma testicular epidermoid (teratoma with ectodermal elements only) testicular choriocarcinoma ...
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Upper gastrointestinal bleeding (differential)

An upper gastrointestinal bleed usually refers to bleeding proximal to the ligament of Treitz. Pathology Causes peptic ulcer gastritis oesophagitis duodenitis Mallory-Weiss tear varices tumour vascular abnormality vascular ectasia angiodysplasia Dieulafoy lesion vascular malformati...
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Upper lobe bronchiectasis

Distribution of bronchiectasis can help in narrowing the differential diagnosis. Upper lobe bronchiectasis is typically seen in: cystic fibrosis tuberculosis Rarely it may be seen with non tuberculous mycobacterial infection (e.g. MAC infection 2) When in mid-upper lobes also consid...
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Urinary bladder diverticula (causes)

There are numerous causes of urinary bladder diverticula:  Primary (congenital or idiopathic) Hutch diverticulum (in paraureteral region) Secondary bladder outlet obstruction bladder neck stenosis neurogenic bladder posterior urethral valve prostatic enlargement (hypertrophy; carcinoma) ...
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Urinary bladder diverticulum

Bladder diverticulum are outpouchings from the bladder wall, whereby mucosa herniates through the bladder wall. They may be solitary or multiple in nature and can vary considerably in size. Epidemiology There are two peaks - one at 10 years and the other at 60-70 years 2. Pathology Diverticu...
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Urinary bladder wall or lumen calcification (differential)

Causes of urinary bladder wall or lumen calcification include: Common bladder calculus schistosomiasis of the urinary tract tuberculosis Uncommon neuroblastoma; pheochromocytoma radiation reaction alkaptonuria (ochronosis) amyloidosis calculus in a urachal cyst or in a bladder divertic...
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Urinary diversion

Urinary diversion is created after the removal of the urinary bladder (radical cystectomy or cystoprostatectomy, usually done to treat invasive bladder cancer). There are three main varieties: neobladder formed from a segment of ileum (i.e. ileal conduit, also known as a "Bricker conduit") th...
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Uterine enlargement (differential)

Uterine enlargement can occur in a number of situations from both diffuse and focal processes. These include:  gestation related events normal intrauterine pregnancy molar pregnancy - gestational trophoblastic disease  postpartum uterus - still larger than usual hormonal causes exogenous h...
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Valgus vs varus

The terms valgus and varus refer to angulation (or bowing) within the shaft of a bone or at a joint. It is determined by the distal part being more medial or lateral than it should be. Whenever the distal part is more lateral, it is called valgus. Whenever the distal part is more medial, it is ...
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Valsalva manoeuvre

The Valsalva manoeuvre is the forced expiration of air against a closed airway, resulting in increased intra-abdominal, intrathoracic and pharyngeal pressure. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling. It is commonly u...
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Valvular heart disease

Valvular heart diseases, or cardiac valvulopathies, describe any acquired or congenital disease affecting one or more of the four cardiac valves. This is a general index article that classifies cardiac valvulopathies depending on which valve(s) is affected 1. See individual articles for in-dept...
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Vascular pedicle

Vascular pedicle is bordered on the right by venous structures (right brachiocephalic vein above and superior vena cava) and on the left by an arterial structure (the left subclavian artery origin). The azygos vein (black oval) is seen en face above the right main bronchus. The vascular pedicle...
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Vascular rings and slings

Vascular rings and slings refer to the congenital vascular encirclement of the oesophagus and/or trachea by anomalous/aberrant vessels.  Epidemiology Vascular rings are rare, occurring in <1% of patients 1. No gender or ethnic predispositions have been identified 3.  Clinical presentation Ma...
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Venous thromboembolism

Venous thromboembolism covers a wide spectrum of diseases. Individual conditions and complicating condition include: deep vein thrombosis (DVT) pulmonary embolism (PE) dural venous sinus thrombosis Lemierre's syndrome tumour thrombus
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Ventriculomegaly

Ventriculomegaly is defined as enlargement of the ventricles. Simply, there are two causes: hydrocephalus communicating non-communicating parenchymal atrophy Refer to the article on hydrocephalus vs atrophy for more details on how to differentiate both entities. 
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Ventriculoperitoneal shunt

Ventriculoperitoneal (VP) shunts are a device used to shunt cerebrospinal fluid in the treatment of hydrocephalus. As the name suggests, a catheter is placed with its tip in the ventricle. The external portion of the catheter is connected to a valve that regulates the flow of CSF based on a pre...
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Vertebral body mass

The differential diagnosis for a vertebral body mass is broad and may range from a completely benign, sclerotic enostosis (bone island) to a malignant primary bone tumour. Classification Broadly, these lesions can be separated into: non-neoplastic lesions primary bone tumours secondary meta...
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Vertebral scalloping

Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring). Posterior scalloping Causes of...
Article

Vertebra plana

Vertebra plana (a.k.a. pancake / silver dollar / coin-on-edge vertebra) is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Plural is vertebrae planae. It can occur in a variety of settings, incl...
Article

Vertical-banded gastroplasty

Vertical-banded gastroplasty (VBG) is an older, purely restrictive procedure used to treat morbid obesity. Procedure It involves creating a small gastric pouch, based on the lesser curvature of the stomach (which is thicker and less resistant to stretching than the greater curvature), by using...
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Very bizarre generalised lesions of bone (differential)

Very bizarre generalised lesions of bone tend to make you exclaim "Oh my! What is going here?"  Although there are numerous potential causes, in this situation it is worth thinking of a number of entities: skeletal dysplasias and metabolic diseases Paget disease fibrous dysplasia phakomatose...
Article

Vestibular line of Lapayowker

The vestibular line of Lapayowker refers to a vertical line passing down the most lateral aspect of vestibular apparatus. The petrous part of internal carotid artery lies medial to this line but lies lateral to it in the case of an aberrant internal carotid artery which is the characteristic ang...
Article

Viral encephalitides

Viral encephalitides are the result of brain parenchymal infection by a number of different viruses, many of which have similar presentations and imaging features. Specific diagnosis often requires PCR.  For viral infection of the meninges, please refer to the general article on viral meningiti...
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Visceral artery aneurysm

Visceral artery aneurysms are abnormal focal dilatations of arteries supplying abdominal organs. Visceral artery aneurysms include both true aneurysms and pseudoaneurysms. Owing to different clinical manifestations and a unique, specific, pathology, renal artery aneurysms are discussed separate...
Article

Vulval neoplasms

Vulval neoplasms are rare and mostly seen in an elderly female patients. Squamous cell carcinoma is most common malignancy of the vulva which only 30% of them are associated with oncogenic HPV viruses. Pathology Squamous neoplastic lesions  Premalignant  classic vulvar intraepithelial neopla...
Article

Wackenheims line

Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal. Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
Article

Wartenberg syndrome

Wartenberg syndrome also known as cheiralgia paresthetica is due to compression of superficial branch of the radial nerve in the distal forearm. It can be secondary to tight watch band or handcuffs, compression from distal radius fracture or idiopathic.  Clinical presentation Patients present ...
Article

Well-defined breast cancers (differential)

Certain well-defined breast cancers tend lack the characteristic spiculation and can give false reassurance of more benign entities on both ultrasound and mammography. These include: certain high grade invasive ductal carcinomas: not enough time for a desmoplastic reaction to form spiculation ...
Article

White coat hypertension

White coat hypertension (abbreviated alternatively as WCH or WCHT), not to be confused with the white coat effect (WCE), is commonly defined as typical in-clinic blood pressure (BP) measurements of 140/90 mm Hg or more in the presence of multiple daytime out-of-clinic home or ambulatory BP readi...
Article

White matter changes in HIV

White matter changes in HIV have overlapping appearances and varied in aetiology. These can be divided into: primary effects of HIV opportunistic infection neoplasms vascular disease metabolic and nutritional disorders Primary effects of HIV HIV encephalitis Opportunistic infection cyto...
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Widening of interpedicular distance

The interpedicular (IP) distance, which is the distance measured between the pedicles on frontal/coronal imaging, can be widened in a number of situations. Pathology Causes include: diastematomyelia syringomyelia conditions that can cause dural ectasia (can potentially cause widening) Marf...
Article

Widening of the presacral space (differential)

Widening of the presacral space is one of the diagnostic indicators of the diseases involving pelvic pathology and rectal involvement. It is ideally measured on barium studies at the level of S3/4 disc level on lateral radiographs and the normal value of the presacral space is <15 mm in adults.​...
Article

Winking owl sign (spine)

The (absent) pedicle sign, also called the winking owl sign, occurs on plain film when a pedicle is absent. The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other open eye, and the spinous process to the beak of the animal on ...
Article

X-ray artifacts

Artifacts can present in a variety of ways including abnormal shadow noted on a radiograph or degraded image quality and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.  There are common and distinct artifacts for film, comp...

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