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.

1,371 results found
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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. Generaly more than 70% of collapse of the trachea during th...
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Tracheomalacia (differential)

A dilated trachea has numerous causes, and in almost all cases represents tracheomalacia (increased size and increased compliance). As is almost always the case various diameters have been used. Typical figures include >26 mm (in men), >23 mm in women or >3 cm for both genders. Although many o...
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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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Tram-track sign (chest)

Tram-track sign may be used in chest radiography to denote the thickened non-tapering (parallel) walls of cylindrical bronchiectasis. It should not be confused with other tram-track signs elsewhere in the body. 
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Transfusion related acute lung injury

Transfusion related acute lung injury (TRALI) is defined as non-cardiogenic pulmonary oedema temporally related to transfusion therapy.  It tends to occur within 6 hours after a blood transfusion and requires exclusion of other alternative diagnoses such as sepsis, volume overload.  Radiograph...
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Transient tachypnoea of the newborn

Transient tachypnoea of the newborn (TTN), also known as retained fetal fluid or wet lung disease, presents in the neonate as tachypnoea for the first few hours of life, lasting up to one day. The tachypnoea resolves by two days.  Pathology amniotic fluid is expressed from the lungs during vag...
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Transudate

A transudate is a collection of fluid that has a relatively low specific gravity and protein concentration. They occur secondary to increased hydrostatic pressure or reduced colloid oncotic pressure: left ventricular failure (increased hydrostatic pressure) hypoalbuminaemia (decreased colloid ...
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Transverse cervical artery

The transverse cervical artery, also known as the cervicodorsal trunk, is 1 of the 4 branches of the thyrocervical trunk (off the first part of the subclavian artery). It is a short artery that bifurcates into the superficial and deep branches, both which course superficially and laterally acro...
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Trapped lung

Trapped lung, also known as unexpandable/unexpanded lung, is a term used where there is non-expandable lung post 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 rathe...
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Trauma CT thorax review areas (mnemonic)

Trauma CT thorax review areas are useful to reduce the potential for error, which is higher than usual given the larger number of images requiring review, and the often present time pressures and the potential presence of numerous concurrent injuries (see CT polytrauma).  Using some standard re...
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Tree-in-bud sign (lung)

Tree-in-bud sign or pattern describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern. Although initially described in patients with endobronchial tuberculosis, it is now recognised in a large number of conditions. Pathology Pathogenesis The tree-i...
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Triangle of safety

The triangle of safety is an anatomical region in the axilla that forms a guide as to the safe position for intercostal catheter (ICC) placement. With the arm abducted, the apex is the axilla, and the triangle is formed by the: lateral border of the pectoralis major anteriorly lateral border o...
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Triple-rule-out CT

Triple-rule-out CT (TRO CT) angiography may be ordered in the setting of acute chest pain to examine the thoracic aorta and the coronary and pulmonary arteries. The protocol helps exclude life-threatening causes of acute chest pain, especially if atypical, or if alternative causes to acute coron...
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Tuberculoma

Tuberculomas or tuberculous granulomas are well defined focal masses that result from Mycobacterium tuberculosis infection and are one of the more severe morphological forms of tuberculosis. Tuberculomas most commonly occur in the brain (see: CNS tuberculosis) and the lung (see: pulmonary tuberc...
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Tuberculosis (pulmonary manifestations)

Pulmonary manifestations of tuberculosis are varied and depend in part whether the infection is primary or post-primary. The lungs are the most common site of primary infection by tuberculosis and are a major source of spread of the disease and of individual morbidity and mortality. A general d...
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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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Tuberculous empyema

Tuberculous empyema is a chronic, active infection of the pleural space characterized by thick rind of pleura with thick and irregular calcification of both parietal and visceral pleura usually surrounding a loculated pleural fluid which contains a large number of tubercle bacilli 1. It is diff...
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Tuberous sclerosis

Tuberous sclerosis (TS), also known as tuberous sclerosis complex or Bourneville disease, is a neurocutaneous disorder (phakomatosis) characterised by the development of multiple benign tumours of the embryonic ectoderm (e.g. skin, eyes, and nervous system). Epidemiology Tuberous sclerosis has...
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Tulip bulb sign

Tulip bulb sign refers to characteristic appearance due to dilatation of sinuses of Valsalva slightly extending into the ascending aorta as seen on CT scan of chest.  It is seen especially in Marfan's syndrome. On CT angiography, aneurysm of the aortic root with effacement of sinotubular junct...
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Tumour like conditions of the pleura

There are many tumour-like conditions of the pleura. These are non-malignant entities that on imaging may mimic a pleural tumour. focal pleural origin pleural plaques thoracic splenosis thoracic endometriosis pleural pseudotumour extrapleural origin extrapleural haematoma diffuse diffu...
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Tumour-to-tumour metastasis

A tumour-to-tumour metastasis, also known as a collision tumour, is a rare metastatic process in which a primary malignant tumour ('donor') metastasises to another tumour ('recipient'), most commonly a benign tumour such as a meningioma. Epidemiology Tumour-to-tumour metastasis is considered v...
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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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Twelfth rib

The twelfth rib is an atypical rib. It is the shortest rib, and one of two floating ribs. Gross anatomy Osteology The 12th rib has a single facet on its head for articulation with the T12 vertebra. It has a short neck and no tubercle. It also lacks a costal groove and angle. internal surface ...
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Typical ribs

Typical ribs are those numbered 2 to 10 with ribs 1, 11 and 12 considered atypical. Gross anatomy A typical rib is long and flat. They contain a: head neck tubercle shaft angle Ribs have a rounded, smooth superior border. The inferior border is thin and sharp.  Osteology Head The head...
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Unfolded aorta

The term unfolded aorta refers to the widened and 'opened up' appearance of the aortic arch on a frontal chest radiograph. It is one of the more common causes for apparent mediastinal widening and is seen with increasing age. It occurs due to the discrepancy in the growth of the ascending aorta...
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Unifocalisation procedure

A unifocalisation procedure is a corrective surgical technique used in patients with complete pulmonary artery atresia with major aortopulmonary collateral arteries (MAPCAs). In this technique, the collateral vessels supplying blood from the aorta directly to the lungs are brought into continuit...
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Unilateral hyperlucent hemithorax (mnemonic)

Mnemonics for a unilateral hyperlucent hemithorax include: CRAWLS SAFE POEM ACROSSS Mnemonics CRAWLS C: contralateral lung increased density, e.g. supine pleural effusion R: rotation A: air, e.g. pneumothorax W: wall, e.g. chest wall mass, mastectomy, polio, Poland syndrome, surgical re...
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Unilateral hypertranslucent hemithorax

Unilateral hypertranslucent hemithorax has many potential causes. It may be the result of rotation away from an optimal position or because of pathology. Rotation A unilateral hypertranslucent hemithorax may be caused by the positioning of the patient. Rotation away from the radiation beam alt...
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Unilateral pulmonary artery atresia

Unilateral pulmonary artery atresia (UPAA) or unilateral absence of the pulmonary artery (UAPA) is a variant of pulmonary artery atresia.  Epidemiology The estimated prevalence is around 1 in 200,000 young adults. The reported frequency on the right side is slightly greater for some reason 10....
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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 pulmonary vein atresia

Unilateral pulmonary vein atresia is a type of pulmonary vein atresia. Pathology It results from failure of incorporation of the common pulmonary vein into the left atrium. There is no recognised right or left predilection. Clinical presentation The condition usually present in infancy or ch...
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Upper and lower lobe distribution of bilateral pulmonary pathologies (mnemonic)

Many pulmonary disease are described as upper or lower lobe predominant. The following mnemonics can aid recall of these differential diagnosis.  upper lobe or apical predominance: SET CAP  lower lobe or bibasilar predominance: BAD RASH Mnemonics SET CAP S: silicosis/sarcoidosis E: EG/extr...
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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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Upper lobe pulmonary fibrosis

Upper lobe predominant pulmonary fibrosis can be associated with a number of pathologies. These include cystic fibrosis - see pulmonary manifestations of cystic fibrosis pulmonary sarcoidosis Langerhans cell histiocytosis pulmonary tuberculosis pneumoconioses silicosis certain drug-induce...
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Upper lobe pulmonary venous diversion

Upper lobe pulmonary venous diversion (cephalisation) reflects elevation of left atrial pressure and can occur with pulmonary oedema. It produces Stag-antler's sign on frontal chest x-ray. The normal left atrial pressure is 5-10 mmHg. An elevation of left atrial pressure to 10-15 mmHg will resu...
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Upper zone

The upper zone is one of the four chest radiograph zones. Sometimes the upper zone includes the apical zone.  Radiographic appearance Plain radiograph on frontal chest radiographs, the upper zone extends from the inferior margin of the clavicles to the superior aspect of the hilum Related pa...
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Urinothorax

Urinothorax is a rare cause of pleural effusion due to the accumulation of urine within the pleural space. Pathology The aetiology of urinothorax can be dichotomised as either due to obstructive uropathy or due to trauma (including iatrogenic post-surgical trauma) to the urinary system 1-3. Ur...
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USB flash drive

The ubiquitous USB flash drive (or USB stick) may be an odd article on a radiology website, but those who report a lot of chest radiographs will be aware that it can be often be confused for an implantable loop recorder device.  Radiographic features Whilst USB drives come in a variety of shap...
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Usual interstitial pneumonia

Usual interstitial pneumonia (UIP) is one of the morphological and pathological patterns of interstitial lung disease. On imaging, it usually presents with a patchy craniocaudal gradient of peripheral septal thickening, bronchiectasis, and honeycombing.  Terminology In the past, the term UIP ...
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Usual interstitial pneumonia (American thoracic society criteria for histopathological diagnosis)

American Thoracic Society (ATS) criteria for histopathological diagnosis of usual interstitial pneumonia​ (UIP) are as follows:  advanced subpleural or paraseptal fibrosis +/- honeycombing  patchy temporally heterogeneous fibrosis fibroblastic foci absence of features against UIP inflammato...
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V/Q scan

V/Q (ventilation/perfusion) scan is a scintigraphic examination of the lung that evaluates pulmonary vasculature perfusion and segmental bronchoalveolar tree ventilation. Indications diagnosis of suspected pulmonary embolism (PE) monitor pulmonary function following lung transplant provide p...
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Varicella pneumonia

Varicella pneumonia is a type of viral pneumonia. It is a common cause of multiple small round calcific lung lesions. Varicella-zoster virus (VZV) most commonly causes self-limited benign disease (chickenpox) in children. However, in adults it tends to cause significant complications such as VZV...
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Varicose bronchiectasis

Varicose bronchiectasis refers to a morphological sub type of bronchiectasis. According to one study, this type as a pure form accounted for ~10% of all bronchiectasis 1. In this form there are intermittent narrowed and dilated segment to the affected bronchus when viewed in long axis and can gi...
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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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Vena caval foramen

The vena caval foramen is one of the three major apertures in the diaphragm. It is the highest of the three and situated at the level of T8-9. It is quadrilateral and placed at the junction of the right and middle leaflets of the central tendon. It transmits several structures between the thora...
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Venous drainage of the thoracic wall

The venous drainage of the thoracic wall drains deoxygenated venous blood from the peripheries of the thoracic cage back into systemic circulation. Gross anatomy Anterior thoracic wall Anterior intercostal veins The anterior intercostal veins originate from the intercostal space just inferio...
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Ventilator associated pneumonia

Ventilator-associated pneumonia (VAP) is a form of hospital acquired pneumonia (considered the commonest form 3). It is sometimes defined as as a pneumonia occurring more than 48 hours after patients have been intubated and received mechanical ventilation 5. It is usually suspected when the pa...
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Ventriculopleural shunt

Ventriculopleural shunting is an alternative option for the diversion of CSF and relief of hydrocephalus. In this technique, the distal catheter is placed in the pleural space. It is an alternative to a ventriculoperitoneal shunt (often considered a next most used alternative). Complications s...
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Vertical fissure line in the lung

The vertical fissure line commences in or near the costodiaphragmatic recess and heads superomedially towards the hilum and terminates before or at the horizontal fissure. More commonly occurs on the right and may indicate partial volume loss of the lower lobe 1.
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Viral bronchiolitis

Viral bronchiolitis refers to a bronchiolitis secondary to viral aetiology. Pathology Viral infection of airways resulting in inflammation and peribronchial oedema. Can then result in small airways occlusion which is the basis of hyperinflation and subsegmental atelectasis. Children more susce...
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Viral respiratory tract infection

Viral respiratory tract infection is a broad term given to pulmonary infection from various viral agents. Pathology They can be caused by any of a large number of viral agents, including but not limited to: RNA viruses orthomyxoviridae influenza pneumonia H1N1 pneumonia (swine influenza) ...
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Visceral pleural invasion

Visceral pleural invasion is a feature that can be seen in lung cancers. It is defined as tumour extension beyond the elastic layer of the visceral pleura. It is considered an aggressive sign and one of the most important adverse prognostic factors in non-small cell lung cancers 1. Pathology G...
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Water bottle sign (heart)

The water bottle sign or configuration refers to the shape of the cardiac silhouette on erect frontal chest x-rays in patients who have a very large pericardial effusion. Typically the effusion has accumulated over many weeks to months (e.g. in patients with malignancy) and the pericardium has g...
Article

Water-lily sign (liver)

The water-lily sign is seen in hydatid infections when there is detachment of the endocyst membrane which results in floating membranes within the pericyst that mimic the appearance of a water lily. It is classically described on plain radiographs (mainly chest X-ray) when the collapsed membran...
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Wave sign

The wave sign refers to the indentation of the normal thymus in young children by the ribs, resulting in a wavy border.
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Wells criteria for pulmonary embolism

The Wells criteria for pulmonary embolism is a risk stratification score and clinical decision rule to estimate the probability for acute pulmonary embolism (PE) in patients in which history and examination suggests acute PE is a diagnostic possibility. It provides a pre-test probability which, ...
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Westermark sign (lungs)

Westermark sign is a sign of pulmonary embolus (PE) seen on chest radiographs. Along with Fleishner sign and Hampton hump, it makes one of the three described signs of pulmonary embolus on chest radiographs. Pathology In one study (PIOPED) this sign was present on ~10% of chest x-rays of pati...
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Whipple disease (thoracic manifestations)

Thoraco-pulmonary manifestations of Whipple disease are uncommon and may result in later course of disease. Epidemiology Lung involvement is seen in 35-60% of patients with gastrointestinal whipple disease. Males are affected eight times than of females. Pathology Grossly there are areas of ...
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WHO classification scheme for thymic epithelial tumours

The WHO classification scheme for thymic epithelial tumours is one of many classifications systems for thymoma and related tumours, and classifies them according to histology: type a medullary thymoma spindle cell thymoma type ab: mixed thymoma type b1: lymphocyte rich predominantly cortic...
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Williams syndrome

Williams syndrome (WS) is characterised by some or all or the following features: craniofacial dysmorphism (e.g. elfin facies) oral abnormalities short stature (50% of cases) mild to moderate mental retardation supravalvular aortic stenosis 2 pulmonary artery stenosis 3 renal insufficienc...
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Williams-Campbell syndrome

Williams-Campbell syndrome (WCS) is a rare form of congenital cystic bronchiectasis, in which distal bronchial cartilage is defective. Pathology It is thought to result from a deficiency of cartilage formation in the 4th to 6th order segmental bronchi. Radiographic features HRCT shows cysti...
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Wilson Mikity syndrome

Wilson Mikity syndrome (WMS) refers to chronic lung disease in premature infants, characterized by early development of cystic interstitial emphysema (PIE). This is now sometimes considered as part of the spectrum of bronchopulmonary dysplasia. See also chronic pulmonary insufficiency of prema...
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Wound dehiscence

Wound dehiscence is a surgical complication whereby there is rupture of a wound along the surgical scar (dehiscence, refers to "splitting open"). This may occur on the skin surface, or along a deeper suture line. Clinical presentation Presentation may be with pain (e.g. sternal dehiscence), or...
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Xenon-127

Xenon-127 is a radiopharmaceutical principally used when a performing VQ scan. It is an not widely used alternative to xenon-133 with the main advantage being a higher proton energy allowing for post perfusion scanning.  photon energy: 203 KeV physical half life: 36.3 days
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Xenon-133

Xenon-133 is a radiopharmaceutical principally used when a performing VQ scan. Inhalation of this gas can also be used to assess cerebral blood flow. photon energy: 81 KeV physical half-life: 5.27 days biological half-life: 30 seconds normal distribution: lungs <15% of inhaled gas is absorb...
Article

Xiphisternum

The xiphisternum (also known as the xiphoid process or simply the xiphoid) is the smallest of the three parts of the sternum (manubrium, body or gladiolus and xiphisternum). It arises from the inferior and posterior margin of the sternal body and projects inferiorly. It is a small cartilaginous ...
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Yellow nail syndrome

The yellow nail syndrome (YNS) is rare disorder principally affecting lymphatic system It is characterised by  nail discolouration: yellow slow growing dystrophic nails peripheral / primary lymphoedema pulmonary manifestations exudative pleural effusions (least common manifestation) bronch...
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Young syndrome

Young syndrome shares similar clinical and radiological findings to primary ciliary dyskinesia and cystic fibrosis, however the underlying pathogenesis yet to be fully elucidated. Obstructive azoopsermia at the level of the epididymis is thought to be the cause of infertility. The commonly refer...

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