The fallen lung sign (also known as CT fallen lung sign) describes the appearance of collapsed lung away from the mediastinum encountered with tracheobronchial injury (in particular those >2 cm away from the carina). It is helpful to look for this rare but specific sign, in cases of unexplained ...
Familial Mediterranean fever (FMF) (also known as recurrent polyserositis) is a genetic autoimmune condition that is notable for its spontaneous self-limiting acute episodes of fever and serositis, especially peritonitis and synovitis.
Familial Mediterranean fever tends to be ethn...
The differential of a fat containing solitary pulmonary nodule is very narrow.
In a well circumscribed smooth or lobulated mass (especially if it has been largely stable in size over time) presence of fat is essentially pathognomonic of a pulmonary hamartoma, and usually not further assessment ...
There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall.
Differential diagnosis includes:
intrapulmonary: fat containing pulmonary lesions
Fat embolism syndrome (FES) is a rare clinical condition caused by circulating fat emboli leading to a multisystemic dysfunction. The classical clinical triad consists of:
It occurs in ~2.5% (range 0.5-4%) of tho...
Fat stranding is a common sign seen on CT wherever fat can be found. It is most commonly seen in abdomen/pelvis, but can also be seen in retroperitoneum, thorax, neck and subcutaneous tissues. It can be helpful in localizing both acute and chronic pathology.
Fatty mediastinal masses are relatively uncommon, and the differential diagnosis is brief, including 1-4:
benign mature teratoma
extravasation of lipid-rich hyperalimentation fluid 3
fibrofatty replacement of the central portion of mediastinal l...
Feeding vessel sign consists of a distinct vessel leading directly to a nodule or a mass. This sign indicates either that the lesion has a hematogenous origin or that the disease process occurs near small pulmonary vessels.
A number of vessel-related non-neoplastic disorders of the lung produc...
Feingold syndrome is characterized by the combination of:
alimentary tract atresias especially esophageal atresia
Feline esophagus also known as esophageal shiver, refers to the transient transverse bands seen in the mid and lower esophagus on a double-contrast barium swallow.
The appearance is almost always associated with active gastro-esophageal reflux 2,3 and is thought to be due to contract...
Felix Fleischner (1893-1969) was a renowned chest radiologist who had two distinguished careers, first in Vienna, before the Second World War, and secondly in Boston, Massachusetts, after fleeing Europe in 1938. The Fleischner Society was named in dedication to him.
Felix George Fle...
A ferruginous body is a histological finding in interstitial lung disease that is a result of inorganic dust inhalation.
Macrophage ingestion of the inorganic fiber results in a fibrotic reaction with encasement of the fiber in iron-rich material that is derived from proteins such as ferritin a...
Fetal adenocarcinoma of the lung (FLAC) is a rare form of adenocarcinoma of lung (falls under invasive category).
Some reports suggest its occurence at ~0.1%-0.5% of all pulmonary neoplasms 1. Despite its "fetal" tissue morphology it typically presents in middle aged to elderly p...
The FEV1/FVC ratio (FEV1%), also known as the Tiffeneau-Pinelli index, is a spirometric parameter and refers to a calculated ratio which represents the proportion of a patients vital capacity that they are able to expire in the first second of forced expiration.
FEV1% is used in the diagnosis a...
Fibrinous pericarditis results from fine granular roughening of the pericardium.
Pericardial friction rub may be heard.
acute rheumatic fever
myocardial infarction: Dressler syndrome
chronic renal fail...
Fibrobullous disease is an observational finding where there are bullous spaces interspersed by areas of scarring (fibrosis). In general, there may be an apical predilection. This has been described in association with two arthritides:
ankylosing spondylitis 1
rheumatoid arthritis 2
Fibrosarcoma of the chest wall refers to a malignant tumor arising from the chest wall.
It typically presents in adults, although the age range of presentation is wide. It rarely occurs as a congenital form in infants and children 2.
In the thorax, fibrosarcomas usuall...
Fibrosing mediastinitis is a rare non-malignant acellular collagen and fibrous tissue proliferative condition occurring within the mediastinum. On imaging, the condition can sometimes mimic malignancy.
Although it can potentially present at any age, it typically presents in young ...
Fibrosing organizing pneumonia is a terms usually given in a situation to cases with previous organizing pneumonia which progresses with a fibrotic component. Many of these cases tend to be those of secondary organizing pneumonia.
Fibrothorax is defined as fibrosis within the pleural space and is sometimes referred to as pleural peel. It occurs secondary to the inflammatory response to one of the following events:
tuberculosis / tuberculous pleuritis / tuberculous empyema: mainly as a late sequela 3
The term fibrotic idiopathic interstitial pneumonia (FIIP) refers to a morphological subset of idiopathic interstitial pneumonia where there is greater than 5% of honeycombing present on HRCT 1.
fibrotic non specific interstitial pneumonitis
Fibrotic non-specific interstitial pneumonitis is a histological subtype of non-specific interstitial pneumonitis (NSIP). It is considered the more common form 1. This pattern manifests as chronic interstitial inflammation obscured by interstitial fibrosis (with dense collagen), a temporal homog...
The figure 3 sign is seen in aortic coarctation and is formed by prestenotic dilatation of the aortic arch and left subclavian artery, indentation at the coarctation site (also known as the "tuck"), and post-stenotic dilatation of the descending aorta.
On barium studies of the esophagus in pati...
A filling defect is a general term used to refer to any abnormality on an imaging study which disrupts the normal opacification (filling) of a cavity or lumen. The opacification maybe physiological, for example, bile in the gallbladder or blood in a dural venous sinus, or maybe due to the instal...
Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.
Finger clubbing presen...
The finger in glove sign can be seen on either a chest radiograph or CT chest and refers to the characteristic sign of a bronchocoele. The same appearance has also been referred to as:
rabbit ear appearance
mickey mouse appearance
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.
Compared to a typical rib, the first rib is short and thick and it has a single articular f...
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....
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.
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...
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...
Fleischner sign can refer to two distinctly separate signs:
Fleischner sign (enlarged pulmonary artery)
Fleischner sign (tuberculosis of ileocecal junction)
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).
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.
Eight radiologists congregated in November 1969 to found a new society to advance the knowledge of diseases of the chest, pred...
The Fleischner Society pulmonary nodule recommendations pertain to the follow-up and management of indeterminate pulmonary nodules detected incidentally on CT and are published by the Fleischner Society. The guideline does not apply to lung cancer screening, patients younger than 35 years, or pa...
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/...
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...
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.
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...
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....
Focal lymphoid hyperplasia of the lung refers to an abnormal accumulation of non-malignant lymphocytic aggregates within the lung.
Previously known as pulmonary pseudolymphoma.
Clinical features can vary from being asymptomatic to various symptoms such as w...
Causes of focal pulmonary opacities on a chest radiograph can be remembered using the rather crude mnemonic:
F: 'fection (pulmonary infection)
F: 'farction (pulmonary infarction)
F: fluid (pulmonary edema)
F: f***ed (lung cancer)
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...
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 ...
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:
other enteric cysts
esophageal duplication cysts
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...
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 ...
Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along with the peripheral autonomic ganglion sites.
On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, th...
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...
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)
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.
GATA2 deficiency has considerably variable clinical manif...
The Geneva score is a clinical decision rule used to estimate the pre-test 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 revised and simplifie...
A Ghon lesion, sometimes called a Ghon focus, represents a tuberculous caseating granuloma (tuberculoma) and represents a sequela of primary pulmonary tuberculosis infection.
Radiologically, this term is used quite loosely to refer to a calcified granuloma; technically, the Ghon le...
Giant cell carcinomas of the lung are a rare type of non-small cell lung carcinomas (NSCLC) classified under sarcomatoid carcinomas of the lungs.
They represent less than 0.5% of all NSCLC 2. There is a recognized association with smoking 1.
Symptoms are n...
Giant cell interstitial pneumonia is a rare form of pulmonary fibrosis. It is currently considered a 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 al...
The ginkgo leaf sign can refer to:
ginkgo leaf sign (chest) of chest wall surgical emphysema
ginkgo leaf sign (spine) of spinal meningioma
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...
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...
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...
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.
low to absent B-cells
T-cell mediated defects
CD4 T-cell lymphopenia
inverted CD4/CD8+ T-cell ratio
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...
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.
Thoracic manifestations of granulomatosis with polyangiitis (GPA), which is a type of pulmonary angiitis and granulomatosis, are common; with lung involvement seen in about 95% of cases.
For a general discussion of the condition, please refer to the main article on granulomatosis with polyangii...
Granulomatous bronchiolitis is a pathological type of bronchiolitis (not an imaging classification) characterized by an underling granulomatous reaction involving the small airways (bronchioles).
It is grouped as form of cellular bronchiolitis 1
It may be associated with ...
Granulomatous lung disease refers to a broad group of infectious and non-infectious conditions characterized by the formation of granulomas. The spectrum includes:
pulmonary non-tuberculous mycobacterial infection
Granulomatous-lymphocytic interstitial lung disease (GL-ILD) 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.
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...
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...
H1N1 influenza is a strain of influenza that notably resulted in a pandemic in 2009. It was referred to colloquially as 'swine flu' due to the origin of the virus, but it was also named H1N1/09 virus. A specific but different strain of H1N1 (called H1N1 influenza A) was the cause of the Spanish ...
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.
Approximately 5% of patients with pneumothorax ...
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.
Massive hemoptysis is referred t...
A mnemonic for primary malignancies responsible for hemorrhagic intracranial metastases is:
MR CT BB
MR CT HBO
MR CT BB
R: renal cell carcinoma
T: thyroid carcinoma, teratoma
B: bronchogenic carcinoma
B: breast carcinoma
MR CT HBO
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.
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.
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...
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 ...
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.
The Haller index is calculated by ...
The halo sign in chest imaging is a feature seen on lung window settings, ground glass opacity surrounding a pulmonary nodule or mass and represents hemorrhage. It is typically seen in angioinvasive aspergillosis.
Histopathologically, it represents a focus of pulmonary infarction sur...
Hamman syndrome, also known as Macklin syndrome, refers to spontaneous pneumomediastinum along with subcutaneous emphysema.
It is a rare entity most often encountered in young adults. It is a known entity peri- and postpartum 3.
The condition is most common...
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...
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...
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.
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)
The heart is a hollow, muscular organ of the middle mediastinum, designed to pump oxygenated blood around the systemic circulation and deoxygenated blood around the pulmonary circulation.
The heart has a somewhat conical form and is enclosed by the pericardium. It is positioned p...
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...
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.
This is a summary article; read more in our arti...
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...
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)
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.
The hemiazygos vein is the asymmetric counterpart to the azygos vein and forms part of the azygos venous system.
The spelling hemiazygous when referring to the vein is incorrect, regardless of whether British or American English is used 7. In the context of anatomy, hemiazygos vei...
Hemithoracic volume loss can occur from a number situations
pulmonary hypoplasia (unilateral)
isolated unilateral pulmonary artery agenesis
skeletal deformities - e.g. kyphosis,
Infection in childhood
Other infective - inflammat...
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...
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...