Calcific tendinitis of the longus colli muscle is an inflammatory/granulomatous response to deposition of calcium hydroxyapatite crystals in the tendons of the longus colli muscle.
Patients can present with debilitating symptoms that are unrelated to the degree of calcif...
Numerous causes of calcification of the globe are encountered, varying from the benign to malignant. When calcification is seen of the posterior half of the globe, it could relate to any of the layers (scleral, choroidal or retinal), as it is not possible to separate them out on CT.
Calcifying epithelial odontogenic tumour, also known as a Pindborg tumour, is typically located in the premolar and molar region of the mandible, although up to a third are found in the maxilla.
Usually they are seen in the 4th to 6th decades. They are rare tumours.
A simple mnemonic to recall a list of commonly calcifying metastases is:
B: breast cancer
T: papillary thyroid cancer
O: ovarian cancer (especially mucinous)
M: mucinous adenocarcinoma (especially colorectal carcinoma)
The Caldwell view is a caudally angled PA radiograph of the skull, designed to better visualize the paranasal sinuses, especially the frontal sinus.
the patient's forehead is placed against the image detector
petrous ridge is below orbits
image size: 24 x 30 cm
X-ray beam f...
Capillary haemangiomas of the orbit, also known as strawberry haemangiomas, on account of its colouring, or orbital infantile haemangiomas, are the most common orbital tumours of infancy, and unlike orbital cavernous haemangiomas, they are neoplasms rather than vascular malformations.
The Capp triad refers to the constellation of clinical and imaging findings in patients with spontaneous retropharyngeal haematomas, and consists of:
tracheal and oesophageal compression
anterior displacement of the trachea
subcutaneous bruising over the neck and anterior chest
Serum carcinoembryonic antigen (CEA) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumour markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue.
Normal range of CEA is...
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionising radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
Carcinoma ex pleomorphic adenoma is the most common of three malignant mixed tumours of salivary glands, and are thought to arise from pre-existing pleomorphic adenomas (or benign mixed tumours) 1.
These tumours usually occur in older patients (6th to 8th decade), who have had a p...
Carcinosarcomas are highly malignant biphasic tumours with both carcinomatous (epithelial) and sarcomatous (bone, cartilage, or skeletal muscle) components.
It can arise in many organs:
lung 5: pulmonary carcinosarcoma
oesophagus 1: oesophageal carcinosarcoma
genitourinary tract ...
The carina is part of the trachea and is an important reference point in chest imaging.
The carina is found at the base of the trachea and it is formed as the main bronchi divide into right and left branches.
The carina usually sits in the T4/T5 plane and is at the level of the ...
Caroticocavernous fistulas (CCF) represent abnormal communication between the carotid circulation and the cavernous sinus. They can be classified as direct or indirect which are separate conditions with different aetiologies.
Direct CCFs are often secondary to trauma, and as suc...
The caroticotympanic branch (tympanic branch) is a small branch from the C2 segment of the internal carotid artery. It is a vestigial remnant of the hyoid artery.
It passes posterolaterally into the middle ear cavity and anastomoses with the inferior tympanic artery (a branch of the external ca...
The carotid bifurcation is the point at which the common carotid artery terminates. As it does so, it forms the internal and external carotid arteries which go on to supply the head and neck.
It is closely related anatomically to the carotid body, a small group of chemoreceptors and supporting ...
The carotid body is located within the neck, and in close proximity to the carotid bifurcation. It is composed of a number of chemoreceptor cells and supporting matrix and detects changes in the composition of blood in the common carotid as it forms the internal and external carotid arteries.
Carotid body tumour, also known as a chemodectoma or carotid body paraganglioma, is a highly vascular glomus tumour that arises from the paraganglion cells of the carotid body. It is located at the carotid bifurcation with characteristic splaying of the ICA and ECA.
The carotid canal is a passage within the petrous temporal bone and transmits the internal carotid artery and sympathetic plexus. Its inferior opening is called the carotid foramen and is situated anteriorly to the jugular fossa and medially to the tympanic plate. The carotid canal is initially ...
The carotid space is one of the seven deep compartments of the head and neck.
The carotid space is a roughly cylindrical space that extends from the skull base through to the aortic arch. It is circumscribed by all three layers of the deep cervical fascia, forming the carotid sh...
Carotidynia or (Fay syndrome) is a rare syndrome characterised by neck pain in the region of the carotid bifurcation. There is confusion in the literature as to what this term actually refers to, with some authors suggesting that the term should be reserved for a pain syndrome with no structural...
Castleman disease (CD), also known as angiofollicular lymph node hyperplasia or giant lymph node hyperplasia, is an uncommon benign B-cell lymphoproliferative condition. It can affect several regions of the body although commonly described as a solitary mediastinal mass.
There are two distinct ...
Cataract is an opacification or thickening of the lens and is the leading cause of blindness in the world 2.
Visual deterioration occurs with increasing degrees of severity. The diagnosis is made clinically.
Common causes include:
old age (most co...
Cavernous sinus thrombosis (CST) is a rare condition, most commonly infectious in nature, and the diagnosis on imaging is not always straightforward. It has high mortality and morbidity rates.
CST is rare with ~4.5 cases per 1,000,000 per year 5. It is the least common dural venou...
Cebocephaly refers to a type of rare midline craniofacial anomaly where there is a single nostril (which usually ends blindly 6-7) with proboscis-like nose 8 and hypotelorism.
holoprosencephaly: particularly alobar holoprosencephaly
Cemento-ossifying fibroma (COF) is a rare benign neoplasm that usually arises from the mandible and maxilla. They most often arise from the tooth bearing areas of these bones.
In the 2005 WHO histological classification of odontogenic fibromas this tumour is referred as "ossif...
Cementoblastoma is one of many mandibular lesions is a rare tumour of the cementum, with only approximately 100 cases reported. Key to diagnosis both radiologically and histologically is attachment to the tooth root.
Cementoblastomas have been previously described in the literatur...
Cervical lymph node groups describe the anatomic position of the nodes. It differs from cervical lymph node levels, covering all lymph nodes not just those relevant to head and neck surgery.
Groups described in the literature include but are not limited to:
Cervical lymph node staging is important in a variety of tumours, especially squamous cell carcinoma of the head and neck.
TNM nodal staging
Nodal staging is the same for squamous cell carcinomas of most regions of the upper aerodigestive tract of the head and neck, including those of the of t...
The cervical plexus is formed by the ventral (anterior) rami of the C1 to C5 nerve roots and innervates the diaphragm, provides motor supply to some neck muscles and cutaneous sensation to the skin of the head, neck and chest.
anterior rami of C1 to C5 nerves
Chamberlain line is a line joining the back of hard palate with the opisthion on a lateral view of the craniocervical junction.
It helps to recognise basilar invagination which is said to be present if the tip of the dens is >3 mm above this line.
McGregor developed a modifica...
Charcot-Leyden crystals consist of collections of bipyramidal crystalloid made up of eosinophilic membrane proteins, which occur in:
other eosinophilic lung disease 2
certain cases of sinusitis (e.g. allergic fungal sinusitis)
They may be detected in the sputum or sinus secretions wi...
Cherubism has historically been considered a variant of fibrous dysplasia, but in reality is likely a distinct entity.
Cherubism is inherited as an autosomal dominant 2 disorder of variable penetrance, with onset in early childhood (typically in the 3-4 years of age). Interesting...
Choanal atresia refers to a lack of formation of the choanal openings. It can be unilateral or bilateral.
It frequently presents in neonates where it is one of the commonest causes of nasal obstruction in this age group. There is a recognised female predilection. The incidence is ...
Cholesteatoma is histologically equivalent to a epidermoid cyst and is composed of desquamated keratinizing stratified squamous epithelium forming a mass. They usually present with conductive hearing loss.
The mass is lined by epithelium (facing inwards) which continues to grow, ther...
Chondrosarcomas of the base of skull are rare compared with other base of skull tumours, but are an important differential diagnosis as surgical resection and management are affected by the preoperative diagnosis.
Chondrosarcomas of the base of skull make up only a small fraction ...
Chorda tympani is a nerve that arises from the mastoid segment of the facial nerve carrying afferent special sensation from the anterior two-thirds of tongue via the lingual nerve as well as efferent parasympathetic secretomotor innervation to the submandibular and sublingual glands.
Chorioretinal lacunae refer to punched out lesions in pigmented layer of retina, usually around the optic disc. It is a considered a consistent feature of Aicardi syndrome.
A choristoma is simply a collection of microscopically normal cells or tissues in an abnormal location. This is different to a hamartoma which is derived only from local tissues.
adrenal choristoma (myelolipoma)
facial nerve choristoma
Choroidal detachment is a detachment of the choroid from the underlying sclera due to increased intraocular pressure (IOP), and occurs in some settings:
exudative: fluid accumulating in the suprachoroidal space secondary to many causes, most commonly inflammation (e.g. uve...
A choroidal effusion is an accumulation of fluid in the supra-choroidal space (between the choroid and sclera). It differs from a retinal detachment in its clinical presentation and radiologic appearance.
Choroidal effusions can be associated with :
ocular hypotony : small globe with a charact...
Choroidal osteomas are rare benign calcific masses of the globe.
Choroidal osteomas are typically found in young Caucasian women 1. A number of familial cases have been reported 3.
These lesions are usually unilateral (75%), and result in painless and gra...
Chronic invasive fungal sinusitis (CIFS) is a form of invasive fungal sinusitis.
The condition has a more prolonged course than acute invasive fungal sinusitis, usually more than 12 weeks 5. Patients are usually immunocompetent or have a milder level of immunocompromise....
Chronic otomastoiditis (COM) should be considered a separate entity from acute otomastoiditis, and is thought to be primarily due to Eustachian tube dysfunction. Interestingly COM is not found in non-human primates. Upright posture and enlarged skull have been postulated as potential predisposin...
Chronic sinusitis refers to ongoing long term sinus infection-inflammation that often develops secondary to a prolonged/refractory acute sinus infection.
It most commonly affects young to middle-aged adults but can uncommonly affect children.
deviated nasal ...
Chvostek sign is the facial twitch obtained by tapping the distribution of the facial nerve in front of the tragus. It is caused by mechanical irritability of peripheral nerves. It is indicative of hypocalcemia and is the most reliable test for hypocalcemia.
Cirsoid aneurysms are rare arteriovenous malformations of the scalp and extremities.
Patients often present with a slow-growing pulsatile mass and may also experience bleeding, tinnitus and/or a headache 3.
Cirsoid aneurysms develop due to an abnormal arteri...
CT is the modality of choice for assessment of antrochoanal polyps. A classification system has been proposed:
Stage I : strictly an antronasal polyp
Stage II : if the polyp extends to the nasopharynx and the accessory ostium of the maxillary sinus is occluded fully by the neck of the ACP
Cleft palate is a type of facial cleft. It can occur in two main aetiologically different forms:
in association with a cleft lip: cleft lip +/- palate (much commoner)
on its own: isolated cleft palate (rarer)
The differential of a mass involving or arising from the clivus is a relatively narrow one and can be divided into whether the lesion arises from the skull base itself, from the intracranial compartment or from below the base of skull.
When evaluating the clivus it is important to compare the...
A cloverleaf skull (also known as kleeblattschädel) refers to type of severe craniosynostosis which gives the skull a cloverleaf shape. It typically results from intrauterine premature closure of sagittal, coronal and lambdoid sutures.
thanatophoric dysplasia: classical...
Coalescent mastoiditis is simply the term given to acute otomastoiditis when mucoperiosteal disease extends to involve the bone. The septae which normally separate one mastoid air cell from another are resorbed. This change is only easily appreciated on thin section bone-algorithm through the te...
The coca-cola bottle sign refers to the appearance of the muscles of the orbit in thyroid eye disease. The belly of the muscle enlarges with sparing of the tendinous insertion, giving the appearance of the traditional coca-cola bottle.
The enlargement of the muscles follows the I'M SLOW format...
The cochlea is part of the inner ear osseous labyrinth found in the petrous temporal bone.
The cochlea is a shell-shaped spiral that turns between two-and-a-half and two-and-three-quarters times around the modiolus (a central column of bone).
Cochlear anomalies are variety of congenital anomalies which, depending on the exact time at which an insult occurs during embryogenesis, may have different manifestations. Terminology is often used imprecisely leading to confusion not only among clinicians but also in the literature.
Cochlear implants (CI) are a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. Unlike conventional hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning audi...
The cochlear promontory is the name given to the bone that overlies the basal turn of the cochlea protruding into the middle ear cavity.
glomus tympanicum paragangliomas typically arise in the region of the cochlear promonotory
Cogan syndrome is a rare vasculitis of children and young adults which primarily characterized by 1,4,6:
inflammatory eye disease (ocular keratitis, uveitis, scleritis, optic neuritis) 6
audiovestibular symptoms (similar to Meniere disease) 6
However, it can potentially affect a multitude of ...
Collet-Sicard syndrome is a constellation of cranial nerve palsies due to a lesion at the jugular foramen such as a glomus jugulare tumour or schwannoma. It consists of :
Vernet syndrome, consisting of motor paralysis of
glossopharyngeal nerve (CN IX)
vagus nerve (CN X)
accessory nerve (CN X...
The colliscalene triangle is an important anatomical region of the neck, situated medial to the scalenus anterior muscle.
medial: lateral border of longus colli
lateral: medial border of scalenus anterior
inferior: first part of the subclavian artery
apex: carotid ...
Colloid nodules (CN) are non-neoplastic benign nodules occurring within the thyroid gland. They form the vast majority of nodular thyroid disease.
Colloid nodules are composed of irregularly enlarged follicles containing abundant colloid. Some colloid nodules can be cystic (cystic co...
Coloboma is collective term encompassing any focal discontinuity in the structure of the eye, and should not be confused with staphylomas, which are due to choroidal thinning.
Most commonly colobomas are due to failure of closure of the choroidal fissure posteriorly. Typically colob...
The common carotid artery is a paired structure that supplies blood to the head and neck.
origin: branch of the aorta (left) and brachiocephalic trunk (right)
course: posterior to sternoclavicular joint, lateral to thyroid and trachea
supply: head and neck
main branches: none (usua...
Common variable immunodeficiency (CVID) is a condition that is associated with an impaired immune system. It is considered the most common symptomatic primary immunodeficiency, and is characterised by recurrent respiratory tract infections.
The commonest presentation is t...
Concha bullosa (also known as a middle turbinate pneumatisation) is a common finding and although associated with deviation of the nasal septum, it is usually of little clinical importance.
Concha bullosa is a normal variant and is one of the most common variations of sinonasal an...
Conductive hearing loss is caused by a range of developmental, congenital or acquired pathology to the external, middle or inner ear.
Essentially any process that obstructs or disrupts the passage of sound waves through the outer or middle ear can cause conductive hearing loss and th...
The condylar canal (canalis condylaris) is located in the condylar fossa, posterior to the occipital condyles. It transmits the emissary veins which originate at the sigmoid sinus and drain into the occipital vein.
The condylar canaI has a variable presence and seen only in ~55% (range 50-60%) ...
Condylar process fractures are fractures of the condylar process of the mandible. The condylar process of the mandible is involved in around 30% of all mandibular fractures.
Condylar fractures are classified according to the location of the fracture and the direction displacement of the condyle...
Congenital absence of the internal carotid artery (ICA) is a rare anomaly that occurs in less than 0.01% of the population. It encompasses agenesis, aplasia, and hypoplasia 1.
The most common type of collateral flow is through the circle of Willis, through the anterior communicating artery (ACO...
Congenital cataracts are a major cause of blindness with early detection the most important factor in reducing impact on future vision.
Incidence is ~3 per 100,000 in the United Kingdom 1. Will be higher in areas with increased rates of congenital infection 5.
Congenital cervical teratoma refers to a teratoma arising in the cervical region. They are thought to account for ~3% of teratomas in childhood/infancy 3.
The estimated occurrence in neonates is ~1:20,000-40,000 live births 8.
Most tumours are diagnosed at ...
Congenital cholesteatomas are identical to epidermoid cysts, differing only in name and location.
They are intraosseous inclusions of ectoderm, and are therefore comprised of keratin debris and cholesterol. Characteristically, they are located at the petrous apex. In contrast middle...
A congenital granular cell myoblastoma (also known as congenital epulis) is a very rare benign tumour which classically presents in the fetal-neonatal population.
It occurs almost exclusively in females when it presents in the fetal neonatal population although no such predilectio...
The features of an infant with congenital hypopituitarism can be recalled with the following mnemonic:
5 P's of cretinism
P: pot belly
P: puffy face
P: protruding umbilicus
P: poked out tongue
Congenital hypothyroidism (CHT), previously known as cretinism, can be of thyroidal or central (hypothalamic/pituitary) origin and can have a widely diverse molecular aetiology.
Most children are asymptomatic birth, and are diagnosed after screening. In untreated CHT pati...
Congenital anomalies of the ossicles are most frequently associated with external ear abnormalities also, although they can occur in isolation.
They cause conductive hearing loss (CHL).
When bilateral they are most frequently genetic, with autosomal dominant inheritance, whereas unilater...
Convexal subarachnoid haemorrhages (SAH) are nontraumatic intracranial haemorrhages that occur within the surface sulci of the brain (c.f. basal cisternal distribution of aneurysmal SAH). There are various causes of convexal SAH, some of which include:
dural venous sinus thromboses
A convoluted cerebriform pattern is a term used to denote the appearance of an sinonasal inverted papilloma on MRI. The appearance is seen on both T2 and post contrast T1 images and appears as alternating roughly parallel lines of high and low signal intensity.
This sign has been reported as p...
The coronal suture is the cranial suture formed between the two parietal bones and the frontal bone. At the junction of coronal, sagittal and frontal sutures is the anterior fontanelle which is open at birth and usually fuses at around 18-24 months after birth.
Fusion of the coronal suture occu...
Cranial gun shot injuries are a form of penetrating traumatic brain injuries, which are much less common than blunt traumatic brain injuries.
Please see the main article "imaging of gun shot injuries" for a general description of imaging features.
Craniofacial fibrous dysplasia is one of four types of fibrous dysplasia and is characterised, as the name suggests, by involvement of the skull and facial bones.
For a general discussion of the underlying pathology, refer to the parent article fibrous dysplasia.
Craniotomy is a surgical procedure where a piece of calvarial bone is removed to allow intracranial exposure. The bone flap is replaced at the end of the procedure, usually secured with microplates and screws. If the bone flap is not replaced it is either a craniectomy or cranioplasty.
The cribriform plate is a sieve-like structure between the anterior cranial fossa and the nasal cavity. It is a part of ethmoid bone and supports the olfactory bulb. It is perforated by foramina for the passage of the olfactory nerves and the nerves to the upper part of the nasal septum, the lat...
The cricoid cartilage is a ring shaped structure that sits just below the thyroid cartilage. It is the only complete cartilaginous ring of the whole airway.
The anterior portion is called the arch and the posterior quadrangular shaped portion is the lamina. It articulates with th...
Cricopharyngeal muscle spasm is also known as cricopharyngeal achalasia, although some authors distinguish between these entities, and may present as a cause of dysphagia.
There is confusing use of the terms cricopharyngeal muscle spasm, cricopharyngeal achalasia and cricopharyngea...
The crista galli is a thick, midline, smooth triangular process arising from the superior surface of the ethmoid bone, projecting into the anterior cranial fossa. It separates the olfactory bulbs, which lie either side of it in the olfactory fossae of the cribriform plate. It serves as an anteri...
CSF otorrhoea is defined as leakage of CSF from subarachnoid space into the middle ear cavity or mastoid air cells.
There are a number of underlying causes, and thus no specific demographic is affected.
Patients typically present with conductive deafness a...
This is a basic article for medical students and other non-radiologists
CT investigations are performed for a variety of reasons. There are a number of ways to read and look at these scans, and these pages should give some help for what to look for.
There is a lot to take in, with scans includ...
CT polytrauma/multitrauma (also called trauma CT) is an increasingly used test in the patient with multiple injuries sustained after significant trauma.
There is some evidence that trauma patients who undergo whole body CT (WBCT) / panscan have better survival than patients who undergo selectiv...
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...
The differential diagnosis cystic mass adjacent to the angle of mandible includes:
branchial cleft cyst
from metastatic squamous cell carcinoma
from metastatic papillary thyroid cancer
Cystic hygroma (CH) refers to a type of congenital lymphangioma
They usually occur in the fetal/infantile and paediatric populations with most lesions presenting by the age of two. The estimated prevalence in the fetal population is 0.2-3%.
Patients in t...
The differential for cystic parotid lesions includes:
bilateral cystic parotid lesions
benign lymphoepithelial lesions of HIV
unilateral cystic parotid lesion(s)
first branchial cleft cyst: parotid lymphoepithelial cy...