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.

1,708 results found
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Hospital-acquired pneumonia

Hospital-acquired pneumonia (HAP) or nosocomial pneumonia is defined by the American Thoracic Society (ATS) guidelines as pneumonias that occur more than 48 hours after hospital administration but were not present at the time of admission. Epidemiology It can be a common cause of pneumonia in ...
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Hot tub lung

Hot tub lung refers to pulmonary disease in otherwise healthy patients that can occur by secondary exposure to aerosolized non-tuberculous mycobacteria in contaminated hot water-steam (classically described in hot tubs, hence the name).  Clinical presentation It can present as an acute pulmona...
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HRCT chest

High-resolution CT (HRCT) of the chest, also referred to as HRCT chest or HRCT of the lungs, refers to a CT technique in which thin-slice chest images are obtained and post-processed in a high-spatial-frequency reconstruction algorithm. This technique obtains images with exquisite lung detail, w...
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HRCT chest: expiration

Expiratory high-resolution CT (HRCT) imaging corresponds to an additional CT acquisition performed as part of the HRCT chest protocol. It represents a scan performed with the patient on supine and images obtained at the end-expiration.  It is a useful method for detecting small airways obstruct...
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HRCT chest: prone images

Prone high-resolution CT (HRCT) imaging corresponds to an additional CT acquisition performed as part of the HRCT chest protocol. It represents a scan performed with the patient on prone position and images obtained in full inspiration.  This additional imaging is particularly useful for detect...
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Human coronavirus

The human coronaviruses (hCoVs), members of the family Coronaviridae, are enveloped RNA viruses that affect humans, mammals and birds, causing both acute and chronic illnesses. Four of the seven known human coronaviruses usually cause a mild coryzal illness only, these are HKU1, NL63, OC43, and...
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Hybrid lesion (pediatric chest)

A hybrid lesion in pediatric chest radiology refers to a combination of a congenital pulmonary airways malformation (CPAM) and a pulmonary sequestration (most commonly extralobar). It falls under a type of bronchopulmonary foregut malformation. Due to more sophisticated imaging, they are increas...
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Hydatid cyst signs

There are several signs of hydatid cysts seen associated with hydatid disease: cumbo sign: air is seen between the pericyst and the laminated membrane of the cyst  serpent sign: internal rupture of the cyst with collapse of membranes of the parasite into the cyst water lily sign: endocyst flo...
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Hydatid disease

Hydatid cysts result from infection by the Echinococcus species, and can result in cyst formation anywhere in the body. Epidemiology Cystic echinococcosus has a world wide geographical distribution. The Mediterranean basin is an important endemic area 6,7. Pathology There are two main specie...
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Hydropneumothorax

A hydropneumothorax (plural: hydropneumothoraces) (or less commonly pneumohydrothorax (plural: pneumohydrothoraces)) is the term given to the concurrent presence of a pneumothorax and pleural effusion (i.e. hydrothorax) (i.e. gas and fluid) in the pleural space. Pathology It may arise in vario...
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Hyparterial bronchus

A hyparterial bronchus is any bronchus originating inferior to the level of the pulmonary artery. Conversely, the right superior lobar bronchus can be referred to by its anatomical relationship to the pulmonary arteries as being eparterial. The term may be encountered in the classification of ...
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Hyperacute lung transplant rejection

Hyperacute lung transplant rejection is a rare, rapid and often fatal form of early post lung transplant complications. Epidemiology Hyperacute rejection occurs in the first few hours after reperfusion of the allograft lungs.  Pathology Following recommencement of blood flow into the allogra...
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Hyperattenuating pulmonary abnormalities

Hyperattenuating pulmonary abnormalities refer to lung parenchymal opacities/lesions that are generally higher attenuation on CT than most soft tissues. An exact definition is usually not provided 1-3, while some authors focus on abnormalities that are as subjectively opaque as bony structures 4...
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Hyperattenuating pulmonary consolidation

Hyperattenuating pulmonary consolidation refers to a region of lung parenchyma with air space opacification that has higher attenuation on CT than muscle or than expected with typical causes of consolidation such as pneumonia (fluid attenuation) or cancer (soft tissue attenuation). The differen...
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Hypercontracting (nutcracker) esophagus

Hypercontracting (nutcracker) esophagus is a motility disorder of the esophagus. This condition is primarily diagnosed with manometry with high intra-esophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.  Hypercontracting esophagus ("nutcracker esophagus")...
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Hyperdense pulmonary mass

There are only a few causes of a pulmonary mass with internal calcification. They include:  granuloma: most common pulmonary hamartoma bronchogenic carcinoma carcinoid tumors pulmonary metastases mucoid calcification of mucinous adenocarcinoma breast carcinoma gastrointestinal tract aden...
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Hyperdense pulmonary nodules

Hyperdense pulmonary nodules are a subset of pulmonary nodules that have relatively increased attenuation, usually caused by calcification within the nodule. Here, we broadly refer to a nodule as a pulmonary opacity <30 mm. Differential diagnosis calcified pulmonary nodules are a specific grou...
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Hyperimmunoglobulin IgE syndrome

Hyperimmunoglobulin E (hyper IgE) syndrome (HIES), also known as Job syndrome, consists of a heterogeneous group of complex hereditary combined B- and T-cell immune deficiency diseases characterized by recurrent Staphylococcus aureus chest infections, characteristic coarse facial appearance and ...
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Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis (EAA), represents a group of pulmonary disorders mediated by an inflammatory reaction to inhalation of an allergen that can lead to lung fibrosis.  Its diagnosis relies on a constellation of findings: exposure to an ...
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Hypertension

Hypertension refers to an increase in blood pressure above the 'normal' for the age, sex and ethnicity of the patient. This can be specified according to the vascular system involved. Although generally when it is not specified it is assumed to refer to the systemic type. systemic hypertension ...
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Hypogammaglobulinaemia

Hypogammaglobulinaemia is an immune disorder characterized by a reduction in all types of gammaglobulins.  Terminology While hypogammaglobulinaemia means some of loss of gammaglobulins, a total loss is termed agammaglobulinaemia which can occur in as an x linked form - X-linked agammaglobuline...
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Ichikado CT scoring of acute respiratory distress syndrome

CT scoring systems have been proposed in patients with acute respiratory distress syndrome (ARDS) to predict clinical outcomes. This scoring system was established by Ichikado et al. in 2006 2 and at the time of writing (July 2016), this is the most widely used CT scoring system. Classification...
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Idiopathic dilatation of the pulmonary trunk

Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly comprising of pulmonary trunk enlargement with or without dilatation of the right and left pulmonary arteries. For this diagnosis, exclusion of pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and confirma...
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Idiopathic giant bullous emphysema

Idiopathic giant bullous emphysema, also known as vanishing lung syndrome (VLS), is characterized by giant emphysematous bullae, which commonly develop in the upper lobes and occupy at least one-third of a hemithorax. It is a progressive condition that is also associated with several forms of em...
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Idiopathic interstitial pneumonia (mnemonic)

Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. A useful mnemonic for the American Thoracic Society-European Respiratory Society (ATS-ERS) classification of IIPs is: All Idiopathic Chronic Lung Disease aRe Nonspecifically Patterned The mnemoni...
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Idiopathic interstitial pneumonias

The idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. They are characterized by cellular infiltration of the interstitial compartment of the lung with varying degrees of inflammation and fibrosis. Classification Over the years many attempts have...
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Idiopathic interstitial pneumonias: HRCT chest approach

The approach to HRCT chest in patients with suspected idiopathic interstitial pneumonia (IIP) is with the aim to: make sure an appropriate study requested i.e. HRCT chest with optimal individually adjusted protocol and ensure adequacy of the HRCT chest quality (see imaging protocol below) meti...
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Idiopathic pauci immune pulmonary capillaritis

Idiopathic pauci immune pulmonary capillaritis (IPIPC) is considered a rare type of pulmonary vasculitis. Some authors consider this due be an organ specific subset of microscopic polyangiitis 3. It can result in diffuse alveolar hemorrhage. Pathology It is an isolated small vessel vasculitis ...
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Idiopathic pneumonia syndrome

Idiopathic pneumonia syndrome (IPS) refers to diffuse lung injury which can occur following haematopeotic stem cell transplantation where neither an infectious nor non-infectious etiology can be found. Epidemiology The incidence of IPS is thought to be around 12% following haematopoetic stem c...
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Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome and considered the most common and the most lethal form of pulmonary fibrosis corresponding to the histologic and imaging pattern of UIP. It is more common in elderly men and diagnosed by:  histological or imaging pattern of usual inter...
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Idiopathic pulmonary hemosiderosis

Idiopathic pulmonary hemosiderosis (IPH) is an uncommon form of pulmonary hemosiderosis. It is characterized by the triad of hemoptysis iron deficiency anemia diffuse pulmonary infiltrates, usually represented by diffuse pulmonary hemorrhage The diagnosis is usually made by exclusion 1. Epi...
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IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs. Terminology This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
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IgG4-related lung disease

IgG4-related lung disease is a recently described condition. It may occur with or without systemic involvement. It is considered part of the spectrum of IgG4-related disease. Radiographic features CT On HRCT of the chest, it may be categorized into four major subtypes 5: solid nodular subtyp...
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Immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) is paradoxical deterioration of a pre-existing illness following abrupt improvement in an individual's immune function. It is classically seen in HIV/AIDS patients following initiation of highly active anti-retroviral therapy (HAART). Increasing...
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Incidental lung nodules

Incidental lung nodules are encountered commonly in normal clinical practice on CT. The risk of developing cancer in very small nodules (<5 mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result, it...
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Incomplete border sign (chest)

The incomplete border sign is useful to depict an extrapulmonary mass on chest radiograph. An extrapulmonary mass will often have an inner well-defined border and an ill-defined outer margin 1-3. This can be attributed to the inner margin being tangential to the x-ray beam and has good inherent...
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Incomplete double aortic arch

Incomplete double aortic arch is a rare vascular ring anomaly wherein a segment of the minor aortic arch, usually the left, is atretic.  Clinical presentation As in the case of other vascular rings, this anomaly can cause 1: stridor wheezing dysphagia Some patients may reach adulthood with...
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Increased cardiothoracic ratio (summary)

This is a basic article for medical students and other non-radiologists Increased cardiothoracic ratio describes widening of the cardiac silhouette on a chest radiograph. This is only of use when making an assessment of a PA chest x-ray since the AP chest x-ray causes the artefactual magnificat...
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Increased retrosternal airspace

Increased retrosternal airspace is an indicator of hyperinflation of the lungs and is usually due to emphysema. The thickness of the space between the ascending aorta and the posterior margin of the sternum (3 cm inferior to the sternomanubrial joint) and is normally no more than 2.5 cm 1 altho...
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Infantile fibrosarcoma of the lung

Infantile fibrosarcoma of the lung, also known as primary bronchopulmonary fibrosarcoma, is a very rare spindle-cell tumor. Epidemiology More than 80% of cases are reported to occur within the 1st year of life. There is a slight predominance in male infants 1,2. Clinical presentation Patient...
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Infectious bronchiolitis

Infectious bronchiolitis refers to subtype of bronchiolitis where there is an definite infective precipitant. It falls under the subgroup in inflammatory bronchiolitides and by some authors is considered a type of cellular bronchiolitis 3. It tends to be more clinically severe in children than a...
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Inferior accessory fissure of the lung

The inferior accessory fissure of the lung, also known as Twining's line, divides the medial basal bronchopulmonary segment from the rest of the lower lobe. This accessory fissure is present in around 12% of people when examined with CT and is visible on 5-8% of frontal chest x-rays. It is appr...
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Inferior cavoatrial junction

The inferior cavoatrial junction (ICAJ) is the term given to the point at which the inferior vena cava (IVC) enters the right atrium. It is less commonly used/seen, in contradistinction to the superior cavoatrial junction.  Accurate localization of the inferior cavoatrial junction is of practic...
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Inferior mediastinum

The inferior mediastinum is the box-shaped space in the mediastinum below the transthoracic plane of Ludwig between the wedge-shaped superior mediastinum above and the diaphragm and inferior thoracic aperture below. There are no physical structures that divide the superior and inferior mediastin...
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Inferior pulmonary ligament

The inferior pulmonary ligament (or just the pulmonary ligament) is a normal anatomical structure that is often seen on chest x-ray and CT chest.  Gross anatomy The inferior pulmonary ligament is a fused triangular-shaped sheet of parietal and visceral pleura that extends from the hilum to the...
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Inferior thoracic aperture

The inferior thoracic aperture connects the thorax with the abdomen. Gross anatomy The inferior thoracic aperture is irregular in shape and is more oblique and much larger than the superior thoracic aperture. The diaphragm occupies and closes the inferior thoracic aperture, thereby separating ...
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Inflammatory bowel disease (thoracic manifestations)

Thoracic manifestations of both ulcerative colitis and Crohn disease can be variable and cannot be used to differentiate between these entities. They can develop at any time with respect to the clinical onset of the underlying disease. Actually, they can also predate the colonic disease or deve...
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Inflammatory bronchiolitis

While the term bronchiolitis in itself implies "inflammation" of the bronchioles by definition, some authors group the term inflammatory bronchiolitis as a specific group in terms of imaging as distinct from the more fibrotic - constrictive type 1. Conditions that are described under this inclu...
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Inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumors (IMT), also known as plasma cell granulomas, are rare neoplasms that have a diverse spectrum of biological behavior.  Terminology These tumors were previously referred as inflammatory pseudotumor.   Epidemiology They can occur at any age and there is curre...
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Inflammatory myofibroblastic tumor of the lung

Inflammatory myofibroblastic tumors of the lungs are a location-specific type of inflammatory myofibroblastic tumors. Epidemiology They are very rare with their incidence reported at approximately 0.04-1% of all the pulmonary neoplasms 1. While it can affect any age group, around 25% of cases ...
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Infusothorax

Infusothorax (plural: infusothoraces), also known as a chemothorax, is a complication of central venous catheter malposition where the catheter tip is located in the pleural space and the infusion of the fluid collects inadvertently in the pleural space in the form of a pleural effusion. Longer ...
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Innermost intercostal muscles

The innermost intercostal muscles are muscles of respiration. They are the deepest intercostal muscles located in the intercostal spaces, and contract along with the internal intercostal muscles to reduce the transverse dimension of the thoracic cavity during expiration. Gross anatomy The inne...
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Innominate artery compression syndrome

Innominate artery compression syndrome, also known as brachiocephalic artery compression syndrome, is a rare cause of tracheal stenosis that occurs in the pediatric population. Radiographic features The brachiocephalic artery usually takes its origin to the left of the trachea. The artery subs...
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Inorganic dust

Inorganic dust types are derived from mineral rather than biological elements (organic compounds). Inhalation of these dusts may result in lung disease (pneumoconiosis), often after years of cumulative exposure. The commonest inhaled dusts that cause disease are asbestos, silica and coal dust. ...
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Interchondral joints

The interchondral joints are small articulations between the apposed costal cartilages of the ribs 7-10. On each side are three diminutive synovial joints between the surfaces of the 6th and 7th costal cartilages, 7th and 8th costal cartilages and 8th and 9th costal cartilages. The 9th and 10th...
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Intercostal catheter

The intercostal catheter (ICC or chest tube) is a tube inserted into the pleural space to drain gas or fluid. It is mainly inserted to treat pneumothorax. Indication The indications are wide and can include 1: pneumothorax chest trauma pleural effusion hemothorax chylothorax bronchopleur...
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Intercostal lung hernia

Intercostal lung hernias are defined as a protrusion of the lung beyond the confines of the thoracic cage. They are uncommon, mostly seen post trauma or thoracotomies.  Clinical presentation Hernias which are symptomatic may cause dyspnea, chest wall pain or a visible or palpable chest bulge (...
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Intercostal muscles

The intercostal muscles are an important group of muscles in the intercostal spaces (between the ribs) that contract during respiration. Three muscles are classically described, from superficial to deep: external intercostal muscles internal intercostal muscles innermost intercostal muscles ...
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Intercostal nerve

The intercostal nerves are the somatic nerves that arise from the anterior divisions of the thoracic spinal nerves from T1 to T11. These nerves in addition to supplying the thoracic wall also supply the pleura and peritoneum. Gross anatomy Intercostal nerves can be divided into atypical and ty...
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Intercostal nerve neurilemmoma

Intercostal nerve neurilemmomas, also known as intercostal nerve schwannoma or neurinoma, are nerve sheath encapsulated tumors affecting intercostal nerves.   Please refer to the article on schwannomas for a broad discussion about these tumors.  Epidemiology They account for <10% of primary n...
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Intercostal spaces

The intercostal spaces are the space between the ribs. There are 11 spaces on each side and they are numbered according to the rib which is the superior border of the space.  Gross anatomy The intercostal spaces contain three layers of muscle: the external, internal and innermost layers with t...
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Interface sign (HRCT chest)

The interface sign is a feature seen on HRCT chest imaging and refers to the presence of irregular interfaces at the margins of pulmonary parenchymal structures or the pleural surface of the lung. It suggests interstitial thickening.
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Interlobular septa

The interlobular septa (singular: interlobular septum) are located between the secondary pulmonary lobules and are continuous with both the subpleural interstitium (peripheral connective tissue) and the peribronchovascular interstitium (axial connective tissue) as well as the more delicate intra...
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Interlobular septal thickening

There are many causes of interlobular septal thickening, and this should be distinguished from intralobular septal thickening. Thickening of the interlobular septa can be smooth, nodular or irregular, with many entities able to cause more than one pattern. Pathology Causes of septal thickening...
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Internal intercostal muscle

The internal intercostal muscles are important muscles of respiration. They number eleven on each side and are located in the intercostal spaces, reducing the transverse dimension of the thoracic cavity during expiration. Gross anatomy The internal intercostal muscles are the middle muscle of ...
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Internal thoracic artery

The internal thoracic artery (previously called the internal mammary artery) supplies the anterior body wall and its associated structures from the clavicles to the umbilicus. Gross anatomy Origin The internal thoracic artery arises from the first part of the subclavian artery in the base of ...
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Interstitial lung abnormality

An interstitial lung abnormality (ILA) is an imaging descriptor often encapsulating several imaging patterns of increased lung density / attenuation detected on chest CT scans in patients with no prior or established history of interstitial lung disease. Terminology It is considered a relative...
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Interstitial lung disease

Interstitial lung disease (ILD) is an umbrella term that encompasses a large number of disorders that are characterized by diffuse cellular infiltrates in a periacinar location. The spectrum of conditions included is broad, ranging from occasional self-limited inflammatory processes to severe de...
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Interstitial lung disease without volume loss (mnemonic)

A useful mnemonic to remember the causes of interstitial lung diseases which do not cause volume loss is: LENT Mnemonic L: lymphangioleiomyomatosis E: eosinophilic granuloma (pulmonary Langerhans cell histiocytosis) N: neurofibromatosis type 1 T: tuberous sclerosis
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Interstitial lung pattern (radiograph)

An interstitial lung pattern is a regular descriptive term used when reporting a plain chest radiograph. It is the result of the age-old attempt to make the distinction between an interstitial and airspace (alveolar) process to narrow the differential diagnosis. A re-read of the timeless work o...
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Interstitial thickening (lung)

Interstitial thickening is pathological thickening of the pulmonary interstitium and can be divided into: interlobular septal thickening intralobular septal thickening See also interlobular septa secondary pulmonary lobules HRCT terminology
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Intralobular septa

The intralobular septa (sing: septum) are delicate strands of connective tissue separating adjacent pulmonary acini and primary pulmonary lobules. They are continuous with the interlobular septa which surround and define the secondary pulmonary lobules.  See also HRCT terminology
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Intralobular septal thickening

Intralobular septal thickening is a form of interstitial thickening and should be distinguished from interlobular septal thickening. It is often seen as fine linear or reticular thickening.  It has been described with any conditions of variable etiology which include sarcoidosis 2 asbestosis ...
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Intrapleural space

The intrapleural or pleural space is the fluid-filled space in between the parietal and visceral layers of the pleura. In normal conditions it contains only a small amount of serous pleural fluid. Variant anatomy Rarely there may be anomalous communication of the pleural spaces anteriorly.  R...
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Intrapulmonary lipoma

Intrapulmonary lipomas are rare fat containing benign lung lesions. Epidemiology They mostly occur in the adult population, with occurence in the pediatric population extremely rare. Pathology As with all lipomas they are composed of adipose tissue. The origin of the peripheral intrapulmonar...
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Intrapulmonary lymph nodes

Intrapulmonary lymph nodes, or pulmonary lymph nodes, are normal lymph nodes found within the lung parenchyma itself. They are commonly found during the assessment of CTs of the chest and are, sometimes, difficult to distinguish from pulmonary nodules. The pulmonary lymph nodes are divided into...
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Intrathoracic sarcoma

Sarcomatoid neoplasms involving the chest comprise of a broad group of tumors that occur in the lung, mediastinum, pleura, and chest wall. These tumors have mesenchymal component. They include primary sarcomatoid tumors of the chest usually arising from the chest wall Ewing sarcoma of the ch...
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Invasive aspergillosis

Invasive aspergillosis is a form of pulmonary aspergillosis seen in patients with decreased immunity. It comprises a number of entities that are discussed individually: subacute invasive pulmonary aspergillosis (previously known as chronic necrotizing aspergillosis (CNA) or semi-invasive asperg...
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Invasive mucinous adenocarcinoma of the lung

Invasive mucinous adenocarcinoma of the lung is a subtype of invasive adenocarcinoma of the lung formerly known as mucinous bronchoalveolar carcinoma (BAC). They are more likely to be multicentric and tend to have a worse prognosis than non-mucinous types.  Terminology In 2011, the Internation...
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Investigation of hemoptysis (summary)

This is a basic article for medical students and other non-radiologists. Hemoptysis is the coughing up of frank blood or blood-stained mucus/pus from the lungs and it is an important indicator of pathology. Careful assessment of history, clinical examination and investigations will help elicit ...
Article

Investigation of pleuritic chest pain (summary)

This is a basic article for medical students and other non-radiologists Pleuritic chest pain is chest pain that is precipitated by movement or forceful breathing and tends to be sharp in nature. It is often accompanied by a perception of dyspnea which may be secondary to suppression of respirat...
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Isolated unilateral absence of pulmonary artery

Isolated unilateral absence of the pulmonary artery (IUAPA) is the congenital absence of the left or right pulmonary artery.  When found in combination with other congenital vascular abnormalities it is known as unilateral absence of the pulmonary artery (UAPA). Epidemiology Unilateral absence...
Article

Isomerism

Isomerism is a term which in general means 'mirror-image'. It is used in the context of heterotaxy and is of two types: left isomerism right isomerism Left isomerism Mirror image of the structures on the left side of the chest along the left-right axis of the body, i.e. patients with isomeri...
Article

Jellyfish sign (ultrasound)

The jellyfish sign refers to the sonographic appearance of atelectatic lung "swimming" within a large pleural effusion. The mobility of the lung within pleural fluid implies an absence of lung consolidation and the absence of pleural adhesions 1. It is also suggestive of a transudative pleural e...
Article

Juxtaphrenic peak sign

The juxtaphrenic peak sign, also known as diaphragmatic tenting or Kattan sign, refers to the peaked or tented appearance of a hemidiaphragm which can occur in the setting of lobar collapse. It is caused by retraction of the lower end of diaphragm at an inferior accessory fissure (most common 1)...
Article

Kaposi sarcoma

Kaposi sarcoma is a low-to-intermediate grade mesenchymal tumor that involves the lymphovascular system. The tumor can involve the pulmonary, gastrointestinal, cutaneous and musculoskeletal systems. Pathology There are four recognized variants 1: classic (chronic): multiple distal lower extre...
Article

Kartagener syndrome

Kartagener syndrome is a subset of primary ciliary dyskinesia, an autosomal recessive condition characterized by an abnormal ciliary structure or function, leading to impaired mucociliary clearance.  Epidemiology The prevalence of primary ciliary dyskinesia is approximately 1 in 12,000-60,000 ...
Article

Kerley lines in the exam

Getting a film with Kerley lines in the exam is one of the many exam set-pieces that can be prepared for. The film goes up and after a couple of seconds pause, you need to start talking: CXR There are bilateral basal interstitial lines that extend to the pleural surface - these are septal (Ke...
Article

Kirklin sign

The Kirklin sign refers to a deformity of the normal gastric bubble on an upright chest radiograph due to a mass lesion of the gastric cardia or fundus. The Kirklin sign is different from the Kirklin complex, a gastric finding on upper GI fluoroscopy. History and etymology Byrl Raymond Kirkli...
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Klebsiella pneumonia

Klebsiella pneumonia, also known as Friedländer pneumonia, refers to pneumonia resulting from an infection from the organism Klebsiella pneumoniae.  Epidemiology There tends to be a higher prevalence in older patients with alcoholism and debilitated hospitalized patients 3. Pathology Klebsie...
Article

Knuckle sign (pulmonary embolism)

The knuckle sign refers to the abrupt tapering or cutoff of a pulmonary artery secondary to an embolus. It is better visualized on CT pulmonary angiography (CTPA) than chest x-ray. This is an important ancillary finding in pulmonary embolism (PE), and often associated with the Fleischner sign of...
Article

KRAS mutation

KRAS (shortened name for the gene Kirsten RAt Sarcoma viral oncogene homolog) mutations are associated in a number of malignancies including:  certain adenocarcinomas of the lung colorectal carcinoma 1 pancreatic ductal adenocarcinoma Several germline KRAS mutations have also been found to b...
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Kveim Stilzbach skin test

The Kveim Stilzbach skin test is a sensitive and specific test for sarcoidosis, requiring the intradermal injection of homogenized spleen or liver material from a patient with known sarcoidosis. In patients with sarcoidosis, a typical sarcoid granuloma will develop at the injection site within 4...

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