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.

1,844 results found
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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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Trichoptysis

Trichoptysis (rare plural: trichoptyses) is an extremely rare symptom, whereby patients cough up hair. It is highly specific for rupture of a mediastinal teratoma into the tracheobronchial tree, however it is not pathognomonic as several articles claim (see below) 1,2. Nevertheless it remains a ...
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Trigonum parietale (azygos lobe)

The trigonum parietale refers to a triangular opacity seen on chest radiograph that correlates with a small piece of extrapleural areolar tissue that lies between the layers of pleura in the fissure of an azygos lobe 1-4. It may be seen at the most superior portion of the azygos fissure and shou...
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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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True thymic hyperplasia

True thymic hyperplasia is a form of thymic hyperplasia where there is enlargement of the thymus but with its normal structure being retained.  Pathology The underlying pathogenesis of true thymic hyperplasia is largely unknown.  There is an increase of both size and weight of the gland but w...
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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

Tuberculosis (commonly abbreviated to TB, short for tubercle bacillus) encompasses an enormously wide disease spectrum affecting multiple organs and body systems predominantly caused by the organism Mycobacterium tuberculosis. A small proportion can also be caused by Mycobacterium bovis.  Epide...
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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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Tuberculosis (summary)

This is a basic article for medical students and other non-radiologists Tuberculosis (TB) is a non-bacterial multisystem infection that often affects the lungs. It may be a primary tuberculous infection, secondary infection or appear as chronic scarring. TB may also be seen on a chest x-ray as ...
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Tuberculous empyema

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

Tuberculous pleuritis refers to inflammation of the pleura due to infection by Mycobacterium tuberculosis. It is considered the second most common form of extra-pulmonary tuberculosis 1. It may progress into a tuberculous empyema. Epidemiology It may be commoner in young males and afflicted pa...
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Tuberous sclerosis

Tuberous sclerosis (TS), also known as tuberous sclerosis complex (TSC) or Bourneville disease, is a phakomatosis (neurocutaneous disorder) characterized by the development of multiple benign tumors of the embryonic ectoderm (e.g. skin, eyes, and nervous system). Epidemiology Tuberous sclerosi...
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Tularemia

Tularemia is a rare and highly virulent febrile zoonotic bacterial infection caused by Francisella tularensis, which has been developed as a bioweapon by several countries. It can infect the skin and mucous membranes, lungs and intestine and cause systemic disease and death. Epidemiology The m...
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Tulip bulb sign

Tulip bulb sign refers to the characteristic appearance of annuloaortic ectasia as seen on CT angiography. There is symmetric dilatation of the three sinuses of Valsalva, with extension into the ascending aorta and effacement of the sinotubular junction.  It is seen especially in Marfan syndro...
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Tumor like conditions of the pleura

There are many tumor-like conditions of the pleura. These are non-malignant entities that on imaging may mimic a pleural tumor. focal pleural origin pleural plaques thoracic splenosis thoracic endometriosis pleural pseudotumor extrapleural origin extrapleural hematoma diffuse diffuse p...
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Tumors of the chest wall (differentials)

Tumors of the chest wall are varied, some of which are found most often in this region. They can be divided into benign and malignant tumors and into those which arise in the ribcage and those of soft tissue density. Benign Benign tumors include 1,3,4: soft tissue hemangioma: common lymphan...
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Tumor spread through air spaces

Tumor spread through air spaces (STAS) is a relatively recently recognized pattern of invasion in lung adenocarcinoma. According to the 2015 WHO classification, STAS is defined as “micropapillary clusters, solid nests, or single cells spreading within air spaces beyond the edge of the main tumor...
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Tumor-to-tumor metastasis

A tumor-to-tumor metastasis, also known as a collision tumor, is a rare metastatic process in which a primary malignant tumor ('donor') metastasizes to another tumor ('recipient'), most commonly a benign tumor such as a meningioma. Epidemiology Tumor-to-tumor metastasis is considered very rare...
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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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Type IV endoleak

Type IV endoleaks are a type of endoleak which usually occurs secondary to graft porosity and are typically seen in the immediate post operative angiogram following an endovascular aneurysm repair. Epidemiology Type IV endoleaks are extremely rare and studies report a prevalence of 0.3%. This ...
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Typical pulmonary carcinoid tumors

Typical pulmonary carcinoid tumors are considered the more common and more benign low grade form of peripheral pulmonary carcinoid tumors. There is little or no known association between typical carcinoid tumors and tobacco use or exposure to other carcinogens which contrasts to atypical carcino...
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Typical ribs

Typical ribs are those numbered 2 to 10 with ribs 1, 11 and 12 considered atypical. Some authors however include ribs 2 and 10 also 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 infe...
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Unfolded aorta

The term unfolded aorta refers to the widened and decreased curvature of the aortic arch on a frontal chest radiograph giving an ‘opened up’ appearance. It is one of the more common causes for apparent mediastinal widening and is seen with increasing age, usually associated with aortic calcifica...
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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), also known as unilateral absence of the pulmonary artery (UAPA) or proximal interruption of the pulmonary artery, is a variant of pulmonary artery atresia.  Terminology The term interruption is preferred by some to absence or atresia because the anom...
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Unilateral pulmonary edema

Unilateral pulmonary edema represents only 2% of cardiogenic pulmonary edema with predilection for the right upper lobe and is strongly associated with severe mitral regurgitation 1, 2. It is hypothesized that the regurgitation jet is directed towards the right superior pulmonary vein thus prefe...
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Unilateral pulmonary vein atresia

Unilateral pulmonary vein atresia is a type of pulmonary vein atresia. Clinical presentation The condition usually present in infancy or childhood with recurrent episodes of pneumonia and/or hemoptysis. Presentation in adulthood does occur but is uncommon. Pathology It results from failure o...
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Upper and lower lobe distribution of bilateral pulmonary pathologies (mnemonic)

The upper and lower lobe distribution of certain bilateral pulmonary pathologies can be recalled using the following mnemonics: upper lobe or apical predominance: CASSET HPP or SET CAP lower lobe or bibasilar predominance: BAD RASH Mnemonics CASSET HPP C: cystic fibrosis A: ankylosing spo...
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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). Traction bronchiectasis in the upper lobes c...
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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 allergic bronchopulm...
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Upper lobe pulmonary venous diversion

Upper lobe pulmonary venous diversion (also described as cephalisation of the pulmonary veins) reflects elevation of left atrial pressure and is an early sign of pulmonary edema. Clinical presentation The normal left atrial pressure is 5-10 mmHg. An elevation of left atrial pressure to 10-15 m...
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Upper zone

The upper zone is one of four arbitrary chest radiograph zones useful for describing the location of findings on a chest radiograph. Some radiologists consider the upper zone to include the apical zone.  Radiographic appearance Plain radiograph on frontal chest radiographs, the upper zone ext...
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Urinothorax

Urinothorax (plural: urinothoraces), also known as urothorax, is a rare cause of pleural effusion due to the accumulation of urine within the pleural space. Clinical presentation Patients present with varying degrees of respiratory distress depending on the amount of fluid that has accumulated...
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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 or leadless pacemaker.  Radiographic features Whilst USB drives com...
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Usual interstitial pneumonia

Usual interstitial pneumonia (UIP) is a histopathologic and radiologic pattern of interstitial lung disease, which is the hallmark pattern for idiopathic pulmonary fibrosis (IPF).  On imaging, usual interstitial pneumonia usually presents with a lung volume loss and a craniocaudal gradient of p...
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Usual interstitial pneumonia (American thoracic society criteria for histopathological diagnosis)

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

The Valsalva maneuver 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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Vaping-associated lung disease

Vaping-associated lung disease, or EVALI (E-cigarette or vaping product use-associated lung injury), consists of patterns of inhalational pulmonary injury induced by electronic cigarettes (also known as e-cigarettes, e-vaporizers, e-hookahs, vapes, vape pens). These products heat up a liquid con...
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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 most commonly causes self-limited benign disease (chickenpox) in children. However, in adults it tends to cause significant complications including varicel...
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Varicose bronchiectasis

Varicose bronchiectasis refers to an uncommon morphological subtype of bronchiectasis. According to one study, this type as a pure form accounted for ~10% of all bronchiectasis 1. For a general discussion, please refer to the article on bronchiectasis. Radiographic features There are intermit...
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Vascular invasion in lung cancer

Vascular invasion in lung cancer is one of the invasive patterns that can occur in lung cancer. Dependent on the publication, this could mean: intratumoral vascular invasion (IVI)  microscopic vascular invasion (MVI) lymphovascular invasion (LVI) lymphatic permeation arterial invasion veno...
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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 esophagus 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 Man...
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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 periphery of the thoracic cage back into the systemic circulation. Gross anatomy Anterior thoracic wall Anterior intercostal veins The anterior intercostal veins originate from the intercostal space just infer...
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Venous thoracic outlet syndrome

The venous thoracic outlet syndrome is the second commonest form of thoracic outlet syndrome (with neurogenic thoracic outlet syndrome being the commonest and the arterial thoracic outlet syndrome being the least common). Clinical presentation It may develop suddenly, often after unusual and t...
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Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a form of hospital-acquired pneumonia (considered the commonest form 3). Terminology Ventilator-associated pneumonia is defined as pneumonia occurring more than 48 hours after patients have been intubated and started on mechanical ventilation 5. Epidem...
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Ventilator induced lung injury

Ventilator-induced lung injury (VILI) is a type of acute lung injury usually inflicted or aggravated by mechanical ventilation. It may during invasive or non-invasive ventilation. Pathology The predominant mechanisms include: alveolar overdistention (volutrauma) / regional lung overdistension...
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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 (plural: bronchiolitides) refers to a bronchiolitis secondary to viral etiology. Pathology Viral bronchiolitis is due to viral infection of airways which results in inflammation and peribronchial edema. This can then result in occlusion of the small airways leading to hyper...
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Viral respiratory tract infection

Viral respiratory tract infection is a broad term given to pulmonary infection caused by viruses. 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) H5N1 pne...
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Viscera

The viscera (singular: viscus) refers to all the internal organs within the major cavities of the thorax, abdomen and pelvis. Therefore it does not include organs of the CNS, head and neck or musculoskeletal compartments nor does it encompass non-internal organs (e.g. the skin) 1. Splanchnology...
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Visceral pleural invasion

Visceral pleural invasion is a feature that can be seen in lung cancers. It is defined as tumor 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 Gr...
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Vital capacity

Vital capacity (commonly termed VC) is a spirometric parameter defined as the maximum amount of air that can be expelled from the lungs after a maximum inhalation. It is equal to the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. Vital capacity increases with: ...
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Vitamin E

Vitamin E (the tocopherols) are a group of fat-soluble vitamins that act as antioxidants. Vitamin E are also hematinics. hypovitaminosis E is rarely seen outside premature infants hypervitaminosis E is extremely rare as the toxicity of vitamin E is low except in chronic (usually >1 year) high ...
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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 monitor pulmonary function following lung transplant provide preope...
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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...
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Water-lily sign (hydatid cyst)

The water-lily sign, also known as the camalote 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...
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Well differentiated fetal adenocarcinoma of lung

A well-differentiated fetal adenocarcinoma (WDFA) of lung is a rare low grade lung tumor. Some consider this as a variant of adenocarcinoma with others considering this under the group of pulmonary blastomas 5.  According to classification by the World Health Organization in 1999, it was remove...
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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

Westermark sign is a sign of pulmonary embolus seen on chest radiographs. It is one of several described signs of pulmonary embolus on chest radiographs. Pathology The theory behind the sign is either obstruction of the pulmonary artery or distal vasoconstriction in hypoxic lung 3. In one stu...
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Whipple disease (thoracic manifestations)

Thoraco-pulmonary manifestations of Whipple disease are uncommon and present in the late stages of the disease. Epidemiology Lung involvement is seen in 35-60% of patients with gastrointestinal whipple disease. Clinical presentation Majority of patients present with non-specific pulmonary an...
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WHO classification scheme for thymic epithelial tumors

The WHO classification scheme for thymic epithelial tumors is one of many classifications systems for thymoma and related tumors, and classifies them according to histology: type a medullary thymoma spindle cell thymoma type ab: mixed thymoma type b1: lymphocyte rich predominantly cortical...
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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. Clinical presentation Williams-Campbell syndrome may present with recurrent pneumonia, wheezing, barrel-chest deformity, and Harrison sulcus 8. Pathology It ...
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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. History and etymology Almost 51 years ago, Wilson...
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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 not a 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. Mode of decay: Beta decay photon energy: 81 KeV physical half-life: 5.27 days biological half-life: 30 seconds normal distribution: lungs <1...
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Xiphisternal joint

The xiphisternal joint (or more rarely, the sternoxiphoid joint) is a symphysis between the inferior margin of the body of the sternum and the superior margin of the xiphoid process. In most people it ossifies with age, usually becoming fully fused by the age of 40 years, forming a synostosis.  ...
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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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Years criteria for pulmonary embolism

The YEARS criteria is a diagnostic algorithm that determines the risk of pulmonary embolism (PE) derived from three items in the Wells score that are most predictive of PE1. Unlike the Wells score, it uses a variable D-dimer threshold based off clinical pre-test probability. The YEARS criteria i...
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Yellow nail syndrome

The yellow nail syndrome (YNS) is a rare disorder principally affecting the lymphatic system. It is characterized by a clinical triad: nail discolouration (chromonychia): yellow to dark green slow-growing dystrophic nails (scleronychia) 9 lymphedema (peripheral/primary) pulmonary disease: se...
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Yellow nail syndrome (pulmonary manifestations)

Pulmonary manifestations of yellow nail syndrome are principally centered around chronic cough effects for recurrent lung infections (bronchiectasis) and pleural effusions. The role of proposed lymphatic impairment could account for the development of pleural effusions and smooth interlobula...
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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 is yet to be fully elucidated. Obstructive azoospermia at the level of the epididymis is thought to be the cause of infertility. The commonly r...

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