Coronary Artery Calcium Data and Reporting System (CAC-DRS) is a structured reporting scheme for all non-contrast CT scans in the evaluation of coronary artery disease, which can help in communication between clinicians and radiologists. These guidelines have been recommended by the Society of C...
Cor pulmonale is defined as a failure of the structure and function of the right ventricle in the absence of left ventricular dysfunction. It is caused by an underlying primary disorder of the respiratory system. It has a generally chronic and slowly progressive course, although acute onset or w...
Correct chest radiograph terminology is very helpful when describing pathology. It is especially important when describing findings to colleagues (radiologist or not), who may not be able to see the image in front of them, e.g. over the phone, or when describing an image in a radiology exam.
The costal cartilages form part of the thoracic cage and anterior chest wall. There are ten costal cartilages bilaterally, one for each of the corresponding 1st to 10th ribs, and each of the first seven ribs forms one of the seven costochondral joints.
Costal cartilages 1-7 articulate with the ...
Costal cartilage fractures are fractures of the cartilage connecting the ribs anteriorly to the sternum.
There is little published data on costal cartilage fractures. Most reported cases are in males and resulted from blunt trauma or a fall 1,2.
In young ch...
The costal hook sign is a chest x-ray feature seen in some cases of flail chest. It represents the rotation of a fractured rib along its long axis, something that is only possible if a second fracture is present along its length, even if the second fracture is not visible 1.
The costocervical trunk is one of the branches of the second part of the subclavian artery. It arises from the posterior wall of the subclavian artery, posterior or medial to the anterior scalene muscle and courses posterosuperiorly across the suprapleural membrane where it divides into 2 branc...
The costochondral joints are the joints between each rib and its costal cartilage. They are primary cartilaginous joints. These joints represent the demarcation of the unossified and ossified part of the rib 1. The joint is held together by periosteum, with the lateral aspect of the costal ca...
Costochondritis (rare plural: costochondritides) is a common self-limiting painful inflammation of multiple costochondral junctions and/or the costosternal articulation. There is usually a distinct absence of swelling and chest wall palpation usually reproduces the pain.
It is important to not...
The costoclavicular ligament or rhomboid ligament is the major stabilizing factor of the sternoclavicular joint and is the axis of movement of the joint.
The costoclavicular ligament binds the inferior medial clavicle (via the rhomboid fossa) to the first costal cartilage and adj...
The costoclavicular space is the anterior portion of the superior thoracic aperture, between the clavicle and first rib. The subclavian vessels and brachial plexus pass though the space related to the scalene muscles. Proximally, the plexus passes through the interscalene space, and distally thr...
The costovertebral joint is an articulation between the ribs and the vertebral column.
The ribs articulate with the thoracic vertebrae via two distinctly different joints:
costovertebral joint - articulation between the head of the rib and the vertebral body
The costoxiphoid ligaments, also known as the chondroxiphoid ligaments, are inconstant fibrous structures joining the anterior and posterior surfaces of the xiphoid to the respective surfaces of the adjacent seventh and, occasionally, sixth costal cartilages.
COVID-19 is a zoonotic illness caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus was previously known as 2019 novel coronavirus. The first cases were seen in the city of Wuhan, China in December 2019, and have been linked to the Huanan Seafood Wholesale Market...
Crack lung is a term used to describe an acute pulmonary injury related to smoked crack cocaine.
On imaging, it is characterized by interstitial and alveolar lung opacities with a diffuse distribution and commonly involving the perihilar regions.
Patients present with s...
Crazy paving refers to the appearance of ground-glass opacity with superimposed interlobular septal thickening and intralobular septal thickening, seen on chest HRCT. It is a non-specific finding that can be seen in a number of conditions.
The crescent sign is described in hydatid disease. When the hydatid cyst erodes the adjacent bronchus or bronchiole, the trapped air between the pericyst and the laminated membrane of the endocyst give a crescent-shaped rim of air around the cyst, thus is termed the crescent sign 1, 2. It can b...
Croup, also known as acute laryngotracheobronchitis, is due to viral infection of the upper airway by parainfluenza virus or respiratory syncytial virus (RSV).
Although imaging findings are not required for the diagnosis, classic findings of narrowing of the subglottic airway and dilatation of ...
Crow feet sign is a characteristic, but uncommon, feature seen in round atelectasis.
On CT, this is seen as linear bands radiating from a mass into adjacent lung tissue resembling the feet of a crow. This sign should not be confused with fibrotic changes occurring in the lung.
A crus (plural: crura) is an anatomical term used for a structure which resembles a leg.
crus (internal capsule)
crus (semicircular duct)
Cryptococcomas are a rare complication of infection by the Cryptococcus genus of invasive fungi, where a discreet, encapsulated lesion of immune infiltrates and pathogen forms. Cryptococcus gattii is most often isolated but Cryptococcus neoformans may also form cryptococcomas.
Cryptococcosis is a fungal infection caused by Cryptococcus neoformans, a globally distributed fungus that is commonly found in soil, especially that containing pigeon and avian droppings. Infection is acquired by inhaling spores of fungus.
Occurs worldwide without any defined en...
Cryptogenic fibrosing alveolitis (CFA) is a fibrosing lung disease that is characterized by inflammation and fibrosis of the alveoli and interstitium of the lungs, favoring the subpleural and basal regions.
There is some overlap in definition with the term idiopathic pulmonary fibrosis 1.
Cryptogenic organizing pneumonia (COP) is a disease of unknown etiology characterized on imaging by multifocal ground glass opacifications and/or consolidation. A wide variety of infectious as well as noninfectious causes may result in a similar histologic pattern.
The CT angiogram sign refers to vessels appearing prominent during a contrast enhanced CT as they traverse an airless low attenuation portion of consolidated lung. Although initially thought to be specific for bronchoalveolar carcinoma, it has now been recognized as a generic appearance provided...
This is a basic article for medical students and other non-radiologists
Chest CT is a computed tomography examination of the thoracic cavity performed for a variety of reasons, from suspected cancer to penetrating chest trauma.
A CT chest can be performed with or without IV contrast and when I...
CT guided thoracic biopsy is usually performed for the diagnosis of suspicious lung, pleural or mediastinal lesions. It can be performed as an outpatient procedure where patient monitoring and complications support are available. A small percentage of lung and pleural biopsies may be performed ...
CT polytrauma/multitrauma, also called trauma CT, whole body CT (WBCT) or panscan, is an increasingly used investigation in patients with multiple injuries sustained after significant trauma.
Clinical assessment and mechanism of injury may underestimate injury severity by 30% 8. There is some e...
The computed tomography pulmonary angiogram (CTPA/CTPE) is a commonly performed diagnostic examination to exclude pulmonary emboli. Each radiology department will have a slightly different method for achieving the same outcome, i.e. adequate enhancement of the pulmonary trunk and its branches.
Currarino-Silverman syndrome, also known as pectus carinatum type 2 deformity, is a rare disorder.
Patients present with a high carinate chest deformity due to a premature fusion of the manubriosternal joint and sternal ossification centers. Congenital heart diseases have...
This is a basic article for medical students and other non-radiologists
Chest x-ray CVC (central venous catheter) position should be assessed following initial placement and on subsequent radiographs.
This is a summary article; for a more in-depth reference article see centr...
A number of entities can present as cyanotic congenital heart disease. These can be divided into those with increased (pulmonary plethora) or decreased pulmonary vascularity :
increased pulmonary vascularity
total anomalous pulmonary venous return (TAPVR) (types I and II)
transposition of the...
Cylindrical bronchiectasis, also known as tubular bronchiectasis, is the most commonly identified morphologic type of bronchiectasis where there is smooth uniform enlargement of bronchi with loss of the normal distal tapering of the airways but without focal outpouchings or tortuosity.
For a ge...
Cyriax syndrome, also known as slipping rib syndrome, occurs when hypermobility of the rib cartilage of the lower ribs slips and moves, leading to pain in lower chest or upper abdomen 1.
This condition may occur at any age, but is reportedly more common in middle-aged adults, and ...
A cyst is an abnormal fluid-filled structure which is lined by epithelium; with one exception: lung cysts may contain gas or fluid. By contradistinction, a pseudocyst lacks an epithelial lining and instead has a vascular and fibrotic capsule.
Cysts are extremely common and found in most organs....
Cystic bronchiectasis is one of the less common morphological forms of bronchiectasis. It may be present on its own or may be occur in combination with other forms of bronchiectasis.
For a general discussion, please refer to the article on bronchiectasis.
It is character...
Cystic fibrosis (CF) is an autosomal recessive genetic disease that affects the exocrine function of the lungs, liver, pancreas, and small bowel resulting in progressive disability and multisystem failure. This article is a general discussion of the disease. Each organ system will be discussed s...
The head and neck manifestations of cystic fibrosis are common compared to the well-known respiratory manifestations.
For general discussion of cystic fibrosis, and a discussion of its other manifestations, please refer to:
cystic fibrosis (parent article)
pulmonary manifestations of cystic ...
Pulmonary manifestations of cystic fibrosis are some of the best known in cystic fibrosis (CF). This is partly because the lungs are often severely affected and the cause of significant morbidity and mortality.
For general discussion of cystic fibrosis, and a discussion of its other manifestat...
Cystic hygroma, also known as cystic or nuchal lymphangioma, refers to the cystic variety of congenital lymphangioma which, most commonly, occur in the cervicofacial regions, particularly at the posterior cervical triangle.
They usually occur in the fetal/infantile and pediatric...
Cystic lung disease is an umbrella term used to group the conditions coursing with multiple lung cysts.
The clinical presentation is an important clue to the differential diagnosis of cystic lung diseases 12.
Diseases that present with insidious dyspnea or spontaneous p...
Cystic lesions in pediatric patients are usually congenital lesions and, as such, can be seen antenatally and following delivery.
These congenital lesions are predominantly covered by the overarching diagnosis of bronchopulmonary foregut malformation. This is a ...
The differential diagnosis for cystic masses of the mediastinum include:
esophageal duplication cyst
cystic teratoma of mediastinum
cystic degeneration of an intrathoracic tumor
Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions:
squamous cell carcinoma metastases
plasmacytoid T-cell leukemia
acute myeloid leukemia
herpes simplex lymphadenit...
Cystic pulmonary metastases are atypical morphological form on pulmonary metastases where lesions manifest as distinct cystic lesions. It is slightly different from the term cavitating pulmonary metastases in that the lesions are extremely thin walled.
It has been reported with many ...
Cystic retroperitoneal lesions can carry a relatively broad differential, which includes:
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
perianal mucinous c...
Cytomegalovirus (CMV) pneumonia is a type of viral pneumonitis and occurs due to infection with cytomegalovirus (CMV), which is a member of the Herpetoviridae family.
CMV infection is particularly important in those who are immunocompromised (e.g. those with AIDS / allogenic bone ...
The dark bronchus sign is the appearance of a relatively darker bronchus as compared to adjacent ground glass opacity. If the ground glass opacity progresses to consolidation, air bronchograms will be visualized.
This sign is useful to identify diffuse ground glass opacity on HRCT chest in cas...
The DeBakey classification, along with the Stanford classification, is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management.
The DeBakey classification divides dissections into 1-5:
type I: involves asc...
A mnemonic used to remember the DeBakey classification 1 is:
B: both ascending and descending aorta (type I)
A: ascending aorta (type II)
D: descending aorta (type III)
Decompression illness (DCI) results from a reduction in the pressure surrounding a body. It can occur in divers, compressed air workers, aviators and astronauts.
Diving-related decompression illness is classified into two main categories:
arterial gas embolism (AGE) secondary to pulmonary deco...
The deep sulcus sign on a supine chest radiograph raises suspicion of a pneumothorax.
On a supine plain chest film (common in intensive care units or as part of a trauma radiograph series), it may be the only suggestion of a pneumothorax because air collects anteriorly and basally, within the n...
The deep sulcus sign can refer to two different radiographic signs but is best known in the chest:
deep sulcus sign (chest): of pneumothorax on supine CXR:
deep sulcus sign (knee): better known as the lateral femoral notch sign of ACL injury
Dehiscence is a general term referring to 'splitting open' and is used in a variety of contexts in medicine generally and radiology more specifically.
The two most common usages are:
splitting open of a wound (e.g. sternal dehiscence)
loss of bone separating one structure from another (e.g. ...
Dendriform (or dendritic) pulmonary ossification is a rare morphological subtype of pulmonary ossification whereby the thin branching calcified lines on CT resemble a dendrite (however a dendritic pattern may not always be present on CT).
They may also be seen as small nodules in the peripheral...
The dense hilum sign suggests a pathological process at the hilum or in the lung anterior or posterior to the hilum. Malignancy, especially lung cancer, should be suspected.
On a well-centered chest posteroanterior (PA) radiograph the density of the hilum is comparable on...
The dependent viscera sign is one of the signs of diaphragmatic rupture on axial CT or MR images, where herniated viscera lie against the posterior thoracic wall in a dependent position, as they are no longer supported by the diaphragm.
collar sign (or hourglass sign)
Descending necrotizing mediastinitis is a severe form of mediastinitis and refers to an acute, polymicrobial infection of the mediastinum that usually spreads downwards from oropharyngeal, cervical, and odontogenic infection.
diabetes: more than one-third of patients...
Desquamative interstitial pneumonia (DIP) is an interstitial pneumonia closely related to and thought to represent the end stage of respiratory bronchiolitis interstitial lung disease (RB-ILD). It is associated with heavy smoking.
It is considered one of the rarest of idiopathic i...
Dextrocardia is a congenital cardiac malrotation in which the heart is situated on the right side of the body (dextroversion) with the apex pointing to the right.
Dextrocardia merely refers to the laterality of the heart, it says nothing about the orientation of the patient's other...
As a part of international evidence-based guidelines adopted by a collaborative effort of the American Thoracic Society (ATS), the European Respiratory Society (ERS), the Japanese Respiratory Society (JRS), and the Latin American Thoracic Association (ALAT), specific diagnostic HRCT criteria for...
In 2018, the Fleischner Society provided updated diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern based on literature review and the expert opinion of members. As a part of this white paper, diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern were updat...
The diaphragm is the dome-shaped muscle that separates the thoracic cavity from the abdominal cavity, enclosing the inferior thoracic aperture.
The muscular fibers of the diaphragm originate around the circumference of the inferior thorax and converge to a common insertion point ...
The diaphragmatic apertures are a series of apertures that permit the passage of structures between the thoracic and abdominal cavities. There are three main apertures:
aortic hiatus (T12) (not a true aperture)
esophageal hiatus (T10)
vena caval foramen (T8)
The vertebral levels of these ape...
A useful mnemonic to remember the thoracic spinal levels at which the three major structures pass through the diaphragmatic apertures is:
I 8 10 eggs at 12 - where 8 is a homophone for 'ate' and the 'e' in eggs is for the US spelling of esophagus
I 8: inferior vena cava at T8
Diaphragmatic dysfunction is a rather broad descriptive term which can include
diaphragmatic paralysis (can range from complete to partial)
Other conditions which which can be variably associated with dysfunction include
diaphragmatic elevation / hemigraphragmatic elevati...
Diaphragmatic eventration refers to an abnormal contour of the diaphragmatic dome. It typically affects only a segment of the hemidiaphragm, compared to paralysis/weakness where the entire hemidiaphragm is typically affected.
Diaphragmatic eventration is congenital in nature and due...
Diaphragmatic hernias are defined as either congenital or acquired defects in the diaphragm.
Demographics and etiology
There are two main types of congenital diaphragmatic hernia (CDH)s which are uncommon yet distinct entities that usually occur on the left side (80%) of the diaphr...
Diaphragmatic mesothelial cysts are rare benign congenital lesions involving the diaphragm. They are thought to derive from from coelomic remnants.
They typically present in the pediatric population.
Typically right sided and seen as a cystic mass betw...
Diaphragmatic paralysis (also considered very similar to the term diaphragmatic palsy) can be unilateral or bilateral.
Clinical features are highly variable according to underlying etiological factor:
unilateral paralysis: asymptomatic in most of the patients as the othe...
Diaphragmatic rupture often results from blunt abdominal trauma. The mechanism of injury is typically a motor-vehicle collision.
Given that the most common mechanism is motor vehicle collisions, it is perhaps unsurprising that young men are most frequently affected. The estimated ...
A small cardiothoracic ratio (CTR) is defined as <42%/0.42 when assessed on a PA chest radiograph, and is often called small heart syndrome. A pathologically-small heart is also known as microcardia.It can be due to/associated with a number of entities:
adrenal insufficiency, e.g. Addison disea...
An anterosuperior mediastinal mass can be caused by neoplastic and non-neoplastic pathology. As their name suggests, they are confined to the anterior mediastinum, that portion of the mediastinum anterior to the pericardium and below the level of the clavicles.
The differential diagnosis for a...
Diffuse airway narrowing can occur from a number of pathologies. These include
granulomatosis with polyangiitis
various infections including
Diffuse alveolar damage (DAD) is a common manifestation of drug-induced lung injury that results from necrosis of type II pneumocytes and alveolar endothelial cells.
Affected patients present with dyspnea, cough, and occasionally fever. Diffusion capacity of the lung for ...
Diffuse alveolar hemorrhage (DAH) is a subset of diffuse pulmonary hemorrhage when bleeding is diffuse and directly into the alveolar spaces. It can occur in a vast number of clinical situations and can be life-threatening.
Blood tends to fill alveolar spaces at multiple sites.
Diffuse ground-glass nodules can arise from many causes. These include:
atypical infections (especially in immunosuppressed patients) 1,3
pneumocystis jirovecii pneumonia
pulmonary herpes simplex infection
pulmonary respiratory syncytial viral infection
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an extremely rare pulmonary disorder at the benign end of the neuroendocrine cells proliferation spectrum. It is mainly seen in non-smoker middle-age females with a history of chronic cough or asthma. On imaging, it is cha...
Diffuse panbronchiolitis (DPB) or Asian panbronchiolitis is an idiopathic progressive inflammatory small airway obstructive lung disease.
There is a striking predilection in patient from East Asia (e.g. Japan, Korea, China). It tends to present around the 3rd to 6th decade and oft...
Diffuse pleural thickening refers to a morphological type of pleural thickening. It can occur from malignant as well as nonmalignant causes, which include:
diffuse pleural fibrosis / fibrothorax 6
asbestos related pleural disease: typically seen a continuous sheet of pleural thickening often i...
Diffuse pulmonary hemorrhage (DPH) is a subtype of pulmonary hemorrhage where bleeding into the lung is diffuse. If the bleeding is into the alveolar spaces this can be further subclassified as diffuse alveolar hemorrhage (DAH).
While the exact presentation can vary is ha...
Diffuse pulmonary lymphangiomatosis (DPL) is a rare condition characterized by diffuse proliferation of anastomosing lymphatic channels (lymphangiomas).
There is no recognized gender predilection. It typically manifests in children and young adults.
Diffuse pulmonary meningotheliomatosis is a rare condition manifested by multiple minute pulmonary meningothelial nodules (MPMNs) scattered throughout the lungs.
There may be an increased female predilection and they tend to peak around the 5th to 7th decades of life at the time o...
Diffuse pulmonary nodules are usually seen as multiple pulmonary nodular opacifications on a HRCT chest scan. They can signify disease processes affecting either the interstitium or the airspace. They can range from a few millimeters to up to 1 cm and when very small and numerous there can be so...
A number of differentials must be kept in mind while approaching diffuse pulmonary nodules. Interpretation is easier if nodules are the only abnormality.
These differentials can be narrowed down based on the several criteria:
Based on appearance
Diffuse pulmonary parenchymal amyloidosis is considered the least common form of pulmonary amyloidosis 6.
Unlike the nodular form, patients tend to be more symptomatic and often have symptoms of cough and shortness of breath. The most common presentation in this form ten...
Conditions associated with diffuse tracheal narrowing or collapse include (in alphabetical order):
chronic obstructive pulmonary disease (COPD): saber sheath trachea
granulomatosis with polyangiitis
tracheobronchial tuberculosis 3
tracheomalacia/tracheobronchomalacia (due to col...
Diffusing capacity of the lungs for carbon monoxide (often abbreviated as DLCO) is a measure that determines how much oxygen travels from the alveoli of the lungs to the bloodstream. It is an index of the surface area available for gas exchange.
It becomes decreased in situations such as
A ditzel is an informal term widely used by radiologists to refer to indeterminate small pulmonary nodules 1.
History and etymology
The etymology of the term ditzel is disputed. It might be derived from the American term 'ditzy' meaning silly or inane, but there is a lack of good evidence for...
Diverticula are outpouchings of a hollow viscus and can be either true or false.
Occasionally a diverticulum is used in a more general sense to mean the outpouching of other anatomical structures, e.g. frontal intersinus septal cells are hypothesized to form as diverticula from the frontal sinu...
Doege-Potter syndrome is a non-islet cell tumor hypoglycemia, secondary to a solitary fibrous tumor (SFT). It is rare, and more associated with malignant SFTs.
Domestically acquired particulate lung disease (DAPLD) or hut lung is a pneumoconiosis due to exposure from smoke from biomass fuel used in cooking in an enclosed space.
Typically women who present with symptoms of a pneumoconiosis without the history of occupational exposure 2,3...
A "dot in box" appearance is a pattern that has been described with pulmonary lymphangitis carcinomatosis. The interlobular septal thickening from lymphangitis forms polygonal arcades accounting for the box while the prominence of the centrilobular bronchovascular bundle is thought to represent...