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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First rib

The first rib is the most superior of the twelve ribs. It is an atypical rib and is an important anatomical landmark and is one of the borders of the superior thoracic aperture. Gross anatomy Osteology Compared to a typical rib, the first rib is short and thick and it has a single articular f...
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Fistula

A fistula (plural: fistulae) is an abnormal connection between two epithelial surfaces such as between hollow organs, skin or vessels. Conventionally, the name of a specific fistula type is a combination of the two organs For discussions of specific fistulae please refer to individual articles....
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Flail chest

Flail chest or flail thoracic segment occurs when three or more contiguous ribs are fractured in two or more places. Clinically, a segment of only one or two ribs can act as a flail segment, hence there is some controversy between the clinical and radiological definitions. Clinical presentation...
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Flattening of the diaphragm

Flattening of the diaphragm is the most sensitive sign on chest radiographs for the presence of hyperinflation of the lungs, usually due to emphysema 1-2. The normal dome of each hemidiaphragm should rise at least 1.5 cm above a line connecting the costophrenic angle posteriorly and sternophren...
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Flat waist sign

The flat waist sign refers to flattening of the left heart border, specifically the contours of the aortic arch and adjacent pulmonary trunk. It is seen in severe left lower lobe collapse and is caused by leftward displacement and rotation of the heart. It is different to the straight left hear...
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Fleischner sign (disambiguation)

Fleischner sign can refer to two distinctly separate signs: Fleischner sign (enlarged pulmonary artery) Fleischner sign (tuberculosis of ileocecal junction)
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Fleischner sign (enlarged pulmonary artery)

The Fleischner sign refers to a prominent central pulmonary artery that can be commonly caused either by pulmonary hypertension or by distension of the vessel by a large pulmonary embolus. It can be seen on chest radiographs, CT pulmonary angiography (CTPA), and MR pulmonary angiography (MRPA). ...
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Fleischner Society

The Fleischner Society is a interdisciplinary learned society with the key aim to advance the study of pathologies of the chest by the use of thoracic imaging. History Eight radiologists congregated in November 1969 to found a new society to advance the knowledge of diseases of the chest, pred...
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Fleischner Society pulmonary nodule recommendations

The Fleischner Society pulmonary nodule recommendations pertain to the follow-up and management of indeterminate pulmonary nodules detected incidentally on CT. The guideline does not apply to lung cancer screening, patients younger than 35 years, or patients with a history of primary cancer or i...
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Fluid bronchogram sign

The fluid bronchogram sign can be seen on chest CT or ultrasound as the presence of fluid attenuation material within respiratory bronchioles with surrounding collapsed or consolidated lung. The presence of this sign suggests endobronchial obstruction as a precipitating cause for consolidation/...
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Fluid color sign

The fluid color sign is a diagnostic sign to differentiate a pleural effusion from pleural thickening by means of color Doppler ultrasound. In the case of pleural effusion a color signal is seen in the pleural fluid during respiratory and cardiac movement, whereas this color signal is not seen i...
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Fluoroscopic evaluation of esophagectomy

Fluoroscopic evaluation of esophagectomy is an important study, given the high rate of complication following esophagectomy (~10-20% rate of leak). Although the approach will differ slightly depending on the type of esophagectomy performed, the principles are similar. Procedure Preprocedural e...
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Fluoroscopy

Fluoroscopy is an imaging modality that allows real-time x-ray viewing of a patient with high temporal resolution. It is based on an x-ray image intensifier coupled to a still/video camera. In recent years flat panel detectors (which are similar to the digital radiography used in projection radi...
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Focal interstitial pulmonary fibrosis

Focal interstitial pulmonary fibrosis refers to a manifestation of pulmonary fibrosis where changes are confined and localized to a small region of the lung, they can arise of range of etiologies with one rather common example being osteophyte induced adjacent pulmonary atelectasis and fibrosis....
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Focal lymphoid hyperplasia of the lung

Focal lymphoid hyperplasia of the lung refers to an abnormal accumulation of non-malignant lymphocytic aggregates within the lung.  Terminology Previously known as pulmonary pseudolymphoma. Clinical presentation Clinical features can vary from being asymptomatic to various symptoms such as w...
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Focal pulmonary opacity (mnemonic)

Causes of focal pulmonary opacities on a chest radiograph can be remembered using the rather crude mnemonic: 4 Fs Mnemonic F: 'fection (pulmonary infection) F: 'farction (pulmonary infarction) F: fluid (pulmonary edema) F: f***ed (lung cancer)
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Follicular bronchiolitis

Follicular bronchiolitis (FB) is a nonneoplastic primary polyclonal B cell hyperplasia of the bronchus-associated lymphoid tissue (BALT) due to chronic exposure to antigens in those with underlying collagen vascular or immune deficiency diseases which usually manifested as small centrilobular gr...
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Foramen of Morgagni

The foramina of Morgagni, also known as the sternocostal triangles, are small defects in the posterior aspect of the anterior thoracic wall between the sternal and costal attachments of the diaphragm. The internal thoracic vessels descend through these foramina to become the superior epigastric ...
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Foregut duplication cyst

Foregut duplication cysts are a type of congenital duplication cyst. They are sometimes classified under bronchopulmonary foregut malformations. Entities classified as foregut duplication cysts include: bronchogenic cysts neurenteric cysts other enteric cysts esophageal duplication cysts l...
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Funnel trachea

Funnel trachea is a colloquialism for a congenital long-segment intrathoracic tracheal stenosis.  The diameter of the trachea immediately below the cricoid is normal, and becomes progressively more stenotic caudally. The posterior, membranous portion of the trachea may be partially or completel...
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Galaxy sign (lungs)

The so-called galaxy sign, initially described as the sarcoid galaxy, represents a coalescent granuloma seen in a minority of patients with pulmonary sarcoidosis 1. The same appearance can be seen in tuberculosis 2,3. In other words, it represents a mass-like region composed of numerous smaller ...
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Ganglioneuroma

Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along the peripheral autonomic ganglion sites.  On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, they ar...
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Garland triad

Garland triad, also known as the 1-2-3 sign or pawnbroker's sign, is a lymph node enlargement pattern on chest radiographs which has been described in sarcoidosis: right paratracheal nodes right hilar nodes left hilar nodes Hilar lymphadenopathy is symmetrical and usually massive. These so-c...
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Gastro-pleural fistula

A gastro-pleural fistula is a very rare situation characterized by a pathological communication between the stomach and the pleural cavity. They can occur in number of situations: trauma (stab injuries 3) iatrogenic (following bariatric, pulmonary or esophageal surgery 1) malignancy (ovarian...
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GATA2 deficiency

GATA2 deficiency is a germ-line disease expressed as a wide spectrum of phenotypes, including monocytopenia, myelodysplasia, myeloid leukaemias, and lymphedema. It is a rare cause of pulmonary alveolar proteinosis. Clinical presentation GATA2 deficiency has considerably variable clinical manif...
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Geneva score

The Geneva score, similarly to the Wells score, is a clinical stratifying system to estimate the probability of pulmonary embolism (PE) in patients in which this diagnosis was considered. The criteria were originally published by the clinical team of the Geneva University Hospital in 2001 1, and...
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Ghon lesion

Ghon lesion, sometimes called Ghon focus, represents a tuberculous caseating granuloma (tuberculoma) and represents the sequelae of primary pulmonary tuberculosis infection. Terminology Radiologically, this term is used quite loosely to refer to a calcified granuloma; technically, the Ghon les...
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Giant cell interstitial pneumonia

Giant cell interstitial pneumonia is a rare form of pulmonary fibrosis. It is currently considered form of pneumoconiosis and in many situations is caused by exposure to metal compounds such as cobalt or tungsten carbide. While some authors consider this term to be synonymous with or being almo...
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Ginkgo leaf sign (disambiguation)

The ginkgo leaf sign can refer to: ginkgo leaf sign (chest) of chest wall surgical emphysema ginkgo leaf sign (spine) of spinal meningioma
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Ginkgo leaf sign (subcutaneous emphysema)

The ginkgo leaf sign of the chest, also referred as the ginkgo leaf sign of subcutaneous emphysema, is a radiographic appearance seen with extensive subcutaneous emphysema of the chest wall. Gas outlines the fibers of the pectoralis major muscle and creates a branching pattern that resembles the...
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Golden S-sign (lung lobe collapse)

The Golden S-sign is seen on both PA chest radiographs and on CT scans. It is named because this sign resembles a reverse S shape, and is therefore sometimes referred to as the reverse S-sign of Golden. Although typically seen with right upper lobe collapse, the S-sign can also be seen with the...
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Goodpasture syndrome

Goodpasture syndrome, also referred as antiglomerular basement membrane (anti-GBM) antibody disease, is an autoimmune disease characterized by damage to the alveolar and renal glomerular basement membranes by a cytotoxic antibody. It is a type of pulmonary-renal syndrome. Goodpasture syndrome i...
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Good syndrome

Good syndrome is a rare paraneoplastic syndrome in which a thymoma causes hypogammaglobulinemia and humoral immunodeficiency. It has been estimated to occur in 0.2%–2% of thymomas 2. thymoma low to absent B-cells T-cell mediated defects CD4 T-cell lymphopenia inverted CD4/CD8+ T-cell ratio ...
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Graft versus host disease (pulmonary manifestations)

Pulmonary graft versus host disease (GvHD) is one of the thoracic manifestations that can complicate hematopoietic stem cell transplantation. Pulmonary GvHD can be broadly divided into acute and chronic disease 1-4: acute pulmonary GvHD pulmonary involvement is rare the median time of onset o...
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Granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA), previously known as Wegener granulomatosis, is a multisystem necrotizing non-caseating granulomatous c-ANCA positive vasculitis affecting small to medium sized arteries, capillaries and veins, with a predilection for the respiratory system and kidneys 3. ...
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Granulomatosis with polyangiitis (pulmonary manifestations)

This article discusses the pulmonary manifestations of granulomatosis with polyangiitis (previously known as Wegener granulomatosis). It is classified as a type of pulmonary angiitis and granulomatosis. For a general discussion of the condition, please refer to the main article on granulomatosi...
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Granulomatous bronchiolitis

Granulomatous bronchiolitis is a pathological type of bronchiolitis (not an imaging classification) characterized by an underling granulomatous reaction involving the small airways (bronchioles).  Pathology It is grouped as form of cellular bronchiolitis 1 Causes It can be associated with a ...
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Granulomatous lung disease

Granulomatous lung disease refers to a broad group of infectious and non-infections conditions characterized by the formation of granulomas. The spectrum includes infectious mycobacterial pulmonary tuberculosis pulmonary non-tuberculous mycobacterial infection fungal pulmonary coccidioido...
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Granulomatous lymphocytic interstitial lung disease

Granulomatous-lymphocytic interstitial lung disease (GLILD) is a relatively recent term given to describe non-infectious, diffuse lung disease complications that have been reported to traditionally develop in common variable immunodeficiency (CVID) patients. Some papers also report the occurrenc...
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Gravity dependent atelectasis

Gravity dependent atelectasis refers to a form of lung atelectasis which occurs in the dependent portions of the lungs due to a combination of reduced alveolar volume and increased perfusion. Being due to gravity, it usually has a dependent and subpleural distribution. It is very commonly seen i...
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Ground-glass opacification

Ground-glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide etiology including infection, chronic interstitial disease an...
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H1N1 influenza

H1N1 influenza is a strain of influenza that notably resulted in a pandemic in 2009. It was referred to as 'swine flu' due to the origin of the virus. Clinical presentation There can be a wide spectrum of clinical syndromes ranging from being asymptomatic to fulminant viral pneumonia, respirat...
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Hemopneumothorax

A hemopneumothorax (plural: hemopneumothoraces) (or, less commonly, haematopneumothorax or pneumohemothorax) is a term given when there is concurrent presence of a hemothorax and pneumothorax. It is a variant of a hydropneumothorax.  Epidemiology Approximately 5% of patients with pneumothorax ...
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Hemoptysis

Hemoptysis (plural: hemoptyses) refers to coughing up of blood. Generally, it appears bright red in color as opposed to blood from the gastrointestinal tract which appears dark red. It is considered an alarming sign of a serious underlying etiology. Terminology Massive hemoptysis is referred t...
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Hemorrhagic intracranial metastases (mnemonic)

A mnemonic for primary malignancies responsible for hemorrhagic intracranial metastases is: MR CT BB Mnemonic M: melanoma R: renal cell carcinoma C: choriocarcinoma T: thyroid carcinoma, teratoma B: bronchogenic carcinoma B: breast carcinoma
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Hemorrhagic pneumonia

Hemorrhagic pneumonia refers to a descriptive term for pneumonia (infective - inflammatory consolidation of the lung) when is complicated by pulmonary hemorrhage. It can be localized or diffuse to varying degrees dependent on the extent of involvement +/- etiological agent. Pathology The preci...
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Hemorrhagic pulmonary metastases

Hemorrhagic pulmonary metastases are those which tend to be complicated by pulmonary hemorrhage within them, resulting in characteristic imaging appearances.  Metastases of some tumor histologies are more likely to hemorrhage -- knowledge of this can help refine the differential diagnoses. Path...
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Hemothorax

A hemothorax (plural: hemothoraces), or rarely hematothorax, literally means blood within the chest, is a term usually used to describe a pleural effusion due to accumulation of blood. If a hemothorax occurs concurrently with a pneumothorax it is then termed a hemopneumothorax.  A tension hemot...
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Hair artifact

Hair artifact and hair-product artifacts are artifacts produced by the presence of the patient's hair across the field of view during acquisition of an image, which can affect all modalities to varying degrees. For example, in mammography, hair may appear as curvilinear white lines or may simula...
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Hairy pleural plaque

Hairy pleural plaques are a manifestation of asbestos-related disease. They arise from the visceral pleura, typically from an interlobar fissure. The hairiness stems from short radially-oriented linear regions of fibrosis extending from the plaque into the adjacent lung parenchyma. Compared to ...
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Haller index

The Haller index (HI), also known as the pectus index, is a simple mathematical way to assess and describe the chest cage on CT of the thorax and is used in the detection of pectus excavatum, as well as preoperative and postoperative assessment 1,5. Technique The Haller index is calculated by ...
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Halo sign (chest)

The halo sign in chest imaging is a feature seen on lung window settings (typically HRCT), ground glass opacity surrounding a pulmonary nodule or mass and represents hemorrhage. It is typically seen in angioinvasive aspergillosis. Pathology Histopathologically, it represents a focus of pulmona...
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Hamman syndrome

Hamman syndrome, also known as Macklin syndrome, refers to spontaneous pneumomediastinum along with subcutaneous emphysema. Epidemiology It is a rare entity most often encountered in young adults. It is a known entity peri- and postpartum 3. Clinical presentation The condition is most common...
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Hampton hump

Hampton hump refers to a dome-shaped, pleural-based opacification in the lung most commonly due to pulmonary embolism and lung infarction (it can also result from other causes of pulmonary infarction (e.g. vascular occlusion due to angioinvasive aspergillosis). While a pulmonary embolism is expe...
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Hard metal pneumoconiosis

A hard metal pneumoconiosis is usually classified as a type of fibrotic pneumoconiosis where the precipitating agent consists of a fine particulate form of hard metal such as: cobalt/cobalt-tungsten alloys 10 tungsten/tungsten carbide alloys implicated alloys often contain small amounts of ot...
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Haystack sign (pneumomediastinum)

The haystack sign on chest radiographs in pediatric patients is indicative of pneumomediastinum. The pediatric heart is surrounded above and below with gas, giving it an appearance of a haystack from Monet's paintings. 
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Head cheese sign (lungs)

The head cheese sign refers to a juxtaposition of regions with three (or sometimes more) different densities/regions of different attenuation within the lungs: ground glass opacities (high attenuation) mosaic attenuation pattern (low attenuation) normal lung tissue (normal attenuation) A mix...
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Heart

The heart is a hollow, muscular organ of the middle mediastinum, designed to pump oxygenated blood around the systemic circulation and de-oxygenated blood around the pulmonary circulation. Gross anatomy The heart has a somewhat conical form and is enclosed by pericardium. It is positioned post...
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Heart chambers

There are four heart chambers, the right atrium, left atrium, right ventricle and left ventricle. These receive blood from the body and lungs and contract to transmit blood to the lungs for oxygenation and to the body for use in metabolism. It is best to list the four chambers in order of the s...
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Heart failure (summary)

This is a basic article for medical students and other non-radiologists Heart failure is a syndrome of cardiac ventricular dysfunction, where the heart is unable to pump sufficiently to meet the body's blood flow requirements. Clinical presentation Although it is useful to divide the signs an...
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Heimlich valve

The Heimlich valve, also known as the flutter valve, is a unidirectional valve to ensure that gas/fluid drained from the pleural space cannot flow back in.  The Heimlich valve is cheap, easy to use, and does not require clamping unlike 'traditional' thoracostomy drainage tubes. Suction can stil...
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Heiner syndrome

The Heiner syndrome is a rare form of primary pulmonary hemosiderosis associated with an allergy to cow's milk. The syndrome includes: rectal blood loss with hypochromic microcytic anemia pulmonary infiltrates (often recurrent) hypoproteinemia See also pulmonary hemosiderosis
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Hematopoietic stem cell transplantation (thoracic complications)

There are many thoracic complications that can occur following hematopoietic stem cell transplantation. These can precipitate during various stages following transplantation and can be either infectious or noninfectious. Complications Early pulmonary edema engraftment syndrome diffuse alveo...
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Hemiazygos vein

The hemiazygos vein is the asymmetric counterpart to the azygos vein and forms part of the azygos venous system.  Terminology Spelling it "hemiazygous" when referring to the vein is incorrect, regardless of whether British or American English 7. In the context of anatomy, see Terminologia Anat...
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Hemithorax white-out (differential)

Complete white-out of a hemithorax on the chest x-ray has a limited number of causes. The differential diagnosis can be shortened further with one simple observation: the position of the trachea. Is it central, pulled or pushed from the side of opacification? Is there pulmonary volume loss or vo...
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Hepatic hydrothorax

Hepatic hydrothorax (HH) is an uncommon manifestation of cirrhosis with ascites. It is one of the pulmonary complications of cirrhosis with portal hypertension.  It is characterized by formation of pleural effusions usually greater than 500 mL, in patients with portal hypertension without any o...
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Hepatisation of the lung

Pulmonary hepatisation refers to the pathologic alteration of lung tissue such that it resembles liver tissue. The term originates as a classic descriptor in surgical pathology, used to describe intermediate stages of lobar pneumonic consolidation. In imaging, the term is similarly used to desc...
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Hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) refers to the combination of hepatic dysfunction (cirrhosis) hypoxemia (alveolar-arterial O2 gradient of >15 mmHg; >20 mmHg in >64 years old patients) peripheral pulmonary arterial dilatation (due to right to left micro-shunts) Epidemiology It is estimated to ...
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HER-2 mutations in lung cancer

Human epidermal growth factor receptor 2 (HER-2) mutations may be detected in approximately 3% of lung adenocarcinomas 1. Radiographic features CT Early studies have suggested HER2-mutant tumors exhibit more aggressive features in general and tend to: exhibit a locally-invasive behavior comp...
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Hereditary connective tissue disease

Hereditary connective tissue diseases are a group of connective tissue disease that have a degree of inheritance risk. They include:  Marfan syndrome: genetic disease causing abnormal fibrillin Ehlers-Danlos syndrome: progressive deterioration of collagen and affects joints, heart valves, orga...
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Hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterized by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system. Epidemiology Worldwide prevalen...
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Hermansky-Pudlak syndrome

Hermansky-Pudlak syndrome (HPS) is a rare syndrome which consists of: oculocutaneous hypopigmentation (albinism) platelet dysfunction  abnormal storage of autofluorescent pigment (ceroid or lipofuscin)  typically occurs within lysosomal organelles of the cells of multiple organs and the reti...
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Hernia (general)

Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening. The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...
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Heroin induced pulmonary edema

Heroin-induced pulmonary edema is an etiological subtype of non-cardiogenic pulmonary edema. It may be prevalent in up to 40% of patients admitted with a heroin overdose 2. It is defined by some authors as a syndrome in which a patient develops significant hypoxia (room air saturation< 90% with...
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Hiatus hernia

Hiatus hernias occur when there is herniation of abdominal contents through the esophageal hiatus of the diaphragm into the thoracic cavity. Epidemiology The prevalence of hiatus hernia increases with age, with a slight female predilection. Clinical presentation Many patients with hiatus her...
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High altitude pulmonary edema

High altitude pulmonary edema is a subtype of pulmonary edema and is caused by prolonged exposure to an environment with a lower partial oxygen atmospheric pressure. Epidemiology It occurs most frequently in young males and ~24-48 hours after they have made a rapid ascent to heights greater th...
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High attenuation lymphadenopathy

High attenuation lymphadenopathy (or adenopathy) variably refers to abnormal lymph nodes with attenuation on CT usually higher compared to muscle, either on a noncontrast exam or following contrast administration (i.e., hyperenhancement) 5. High attenuation nodes may be due to calcifications or...
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Hilar point

The hilar point on chest radiographs is formed by the outer margins of the superior pulmonary vein and the descending pulmonary artery as they cross past each other. 
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Hilum convergence sign

The hilum convergence sign is a useful chest radiograph sign to help distinguish a bulky hilum due to pulmonary artery dilatation from a juxtahilar mass/nodal enlargement.  If pulmonary artery branches are visible through the opacity and converge towards the waist of the heart (positive hilum c...
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Hilum overlay sign

The hilum overlay sign is useful in differentiating cardiac enlargement from a mediastinal mass. It refers to an abnormally dense hilum on frontal chest radiograph with preserved visualization of the hilar vessels.   If a mass arises from the hilum, the normal pulmonary vessels (interlobar arte...
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Histoplasmoma

Histoplasmoma is the name for a specific kind of nodule secondary to granulomatous reaction to histoplasmosis infection often described as having a pathognomic target lesion appearance. Histoplasmomas can appear in the lungs or central nervous system. Although classically conceived as a solitar...
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Histoplasmosis

Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum.  Pulmonary histoplasmosis is the most common manifestation of this infectious disease. Disseminated or extra-pulmonary (pericardial, articular) histoplasmosis is often seen in immunosuppressed patients. As such, these are in...
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HIV/AIDS

Acquired immunodeficiency syndrome (AIDS) is an immunosuppressed state, caused by infection with the human immunodeficiency virus (HIV). It is characterized by opportunistic infections, neoplasms, and neurological manifestations. Epidemiology According to the United Nations programme on HIV/AI...
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HIV/AIDS (pulmonary and thoracic manifestations)

Pulmonary manifestations of HIV/AIDS are a major contributor to morbidity and mortality related to the disease. The differential in an HIV patient with a chest complaint is broad. Infectious causes are the most common, however, neoplasms, lymphoma and interstitial pneumonias also play a signific...
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HIV associated follicular bronchiolitis

HIV associated follicular bronchiolitis is a form of bronchiolitis that occurs in those with HIV. Epidemiology It has been described in both HIV-positive children and adults. Pathology It is manifested by bronchial-associated lymphoid tissue hyperplasia thought to be due to repetitive antige...
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HIV associated neoplasms

HIV-associated neoplasms are numerous and can be broadly divided into two groups: AIDS-defining malignancies associated but not AIDS defining malignancies AIDS-defining malignancies The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4: Ka...
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Hodgkin lymphoma (pulmonary manifestations)

Pulmonary manifestations of Hodgkin lymphoma are relatively rare, present in  5-12% of patients at the time of diagnosis. It is relatively more common with the nodular sclerosing subtype. Pulmonary involvement usually indicates stage IV disease.  Radiographic features Bilateral involvement is ...
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Hoffman-Rigler sign (heart)

The Hoffman-Rigler sign is a sign of left ventricular enlargement inferred from the distance between the inferior vena cava (IVC) and left ventricle (LV).​ Radiographic features On a lateral chest radiograph, if the distance between the left ventricular border and the posterior border of IVC e...
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Holly leaf sign

The holly leaf sign refers to the appearance of pleural plaques on chest radiographs. Their irregular thickened nodular edges are likened to the appearance of a holly leaf.
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Holt-Oram syndrome

Holt-Oram syndrome (HOS) is an autosomal dominant syndrome that results in congenital heart defects and upper limb anomalies:  congenital heart defects  atrial septal defect (ASD) (commonest cardiac defect 4) ventricular septal defect (VSD) aortic coarctation upper limb abnormalities radia...
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Honeycombing (lungs)

Honeycombing is a CT imaging descriptor referring to clustered cystic air spaces (between 3-10 mm in diameter, but occasionally as large as 2.5 cm) that are usually subpleural and basal in distribution. They can be subdivided into: microcystic honeycombing macrocystic honeycombing The walls o...
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Horizontal fissure

The horizontal fissure (also called the minor fissure) is a unilateral structure in the right lung that separates the right middle lobe from the right upper lobe. Gross anatomy The horizontal fissure arises from the right oblique fissure and follows the 4th intercostal space from the sternum u...
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Horseshoe lung

Horseshoe lung is one of the rare congenital anomalies of the lung. A band of pulmonary parenchyma is formed extending between the right and left lungs. The pulmonary tissue can be seen either anterior to the aorta or posterior to the pericardium at the caudal end. Pathology Associations card...

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