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.

73 results found
Article

T staging for a tumour in the oral cavity

The T staging for a tumour in the oral cavity is as follows: Oral cavity The anterior border of the oral cavity is the junction of the skin and vermilionborder of the lip. The posterior border is formed by the junction of the hard and soft palates superiorly, the circumvallate papillae inferio...
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T staging of a hypopharygeal tumour

The T staging of a hypopharygeal tumour is as follows Definition The hypopharynx includes the pyriform sinuses, the lateraland posterior hypopharyngeal walls, and the postcricoid region. T1: tumour is limited to one subsite of the hypopharynx and 2 cm or less in greatest dimension T2: tumour...
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T staging of a tumour in the oropharynx

The T staging of a tumour in the oropharynx is as follows: Definition: The oropharynx includes the base of the tongue, the inferiorsurface of the soft palate and uvula, the anterior and posteriortonsillar pillars, the glossotonsillar sulci, the pharyngeal tonsils, and the lateral and posterior ...
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Tc-99m pertechnetate

Tc-99m pertechnetate is one of the technetium radiopharmaceuticals used in renal imaging. Characteristics photon energy: 140 keV physical half life biological half life: 6 hours normal distribution: stomach, thyroid, salivary glands, (testicles) excretion: renal, GI target organ: thyroid,...
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Tc-99m sestamibi

Tc-99m sestamibi is one of the technetium radiopharmaceuticals.  Characteristics photon energy: 140 KeV physical half life: 6 hours normal distribution: thyroid, parathyroid, heart excretion: hepatobiliary target organ: colon, kidneys, bladder, gallbladder Uses, doses and timings parathy...
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Teeth

Teeth can be both primary and secondary, with the eruption of permanent teeth occurring over a long period between the ages of 6 and 24.  Gross anatomy There are twenty deciduous (primary) teeth in young children, with ten per jaw and five in each quadrant, which consist of: two molars one c...
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Telecanthus

Telecanthus represents increased intercanthal distance. It is often used interchangeably with hypertelorism, referring to increased distance between the eye. Causes and associations trauma: naso-orbito-ethmoidal (NOE) fractures ethnic variation acquired sinus and orbital tumours sinus poly...
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Temporal bone

The temporal bone is situated on the sides and the base of the cranium and lateral to the temporal lobe of cerebrum. The temporal bone is one of the most important calvarial and skull base bones. The temporal bone is very complex and consists of five parts: squamous part mastoid part petrous ...
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Temporal bone fracture complications (mnemonic)

A helpful mnemonic for remembering the complications of temporal bone fractures that may require early intervention is:  CLONE Mnemonic C: carotid artery injury L: leakage of CSF O: other intracranial complications, e.g. hematoma N: nerve injury leading to complete facial paralysis E: ext...
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Temporal bone fractures

A temporal bone fracture is usually a sequela of blunt head injury, generally from severe trauma. Associated intracranial injuries, such as extra-axial haemorrhage, shear (or diffuse axonal) injury and brain contusion are common. Early identification of temporal bone trauma is essential to mana...
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Temporalis muscle

The temporalis muscle is a broad, radiating muscle, situated at the side of the head which arises from the whole of the temporal fossa (except that portion of it which is formed by the zygomatic bone) and from the deep surface of the temporal fascia. Its fibers converge as they descend, and end ...
Article

Temporomandibular joint

The temporomandibular joint (TMJ) is an atypical synovial joint located between the condylar process of the mandible and the mandibular fossa and articular eminence of the temporal bone. It is divided into superior discotemporal space and inferior discomandibular space by the TMJ disc (or menisc...
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Temporomandibular joint disc

The temporomandibular joint (TMJ) disc (or meniscus) is made of fibrocartilage and divides the joint into two compartments.  Gross anatomy The disc is composed of fibrocartilage, with crimped collagen, thought to better absorb impacts. It has a biconcave shape with a thicker periphery attached...
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Temporomandibular joint dysfunction

Temporomandibular joint (TMJ) dysfunction is characterised by an abnormal relationship between the disc and the adjacent articular surfaces (condyle below with mandibular fossa and articular eminence above).  Demographics and clinical presentation It is characterised by pain, clicking and func...
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Temporomandibular joint effusion

Temporomandibular joint (TMJ) effusions are unusual in asymptomatic patients, and thus should trigger a careful search for underlying pathology. It usually precedes osteoarthritis of the TMJ. Effusions are seen in: TMJ dysfunction septic arthritis rheumatoid arthritis (RA) Radiographic featu...
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Temporomandibular joint inflammation

Temporomandibular joint (TMJ) inflammation may occur as a result of an inflammatory arthropathy or secondary to TMJ dysfunction. Since the TMJ is a synovial joint, it is susceptible to inflammatory arthropathies that affect other joints.  rheumatoid arthritis (RA) : is by far the most common  ...
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Temporomandibular joint pathology

Temporomandibular joint (TMJ) pathology encompases three main entities: TMJ dysfunction : relating to abnormal TMJ disc relationship to condyle and temporal bone, which can lead to osteoarthritis. TMJ inflammation TMJ trauma See also TMJ anatomy
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Temporomandibular joint trauma

The temporomandibular joint (TMJ) can be affected by trauma in a number of ways: condylar process fractures temporomandibular joint dislocation fracture of the mandibular fossa  
Article

Temporozygomatic suture

The  temporozygomatic suture (or zygomaticotemporal suture) exists between the temporal process of the zygomatic bone and the zygomatic process of the temporal bone.  It can mimic a zygoma fracture.
Article

Tendinous ring

The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles). The tendinous ring straddles the superior orbital fissure and through it (from superior to inferior) pass: superior division of the oculomotor nerve (CN III) nasocilia...
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Tenon capsule

The tenon capsule also known as fascia bulbi or bulbar sheath functions as an extraocular muscle pulley. It also provides a socket which separates the globe from the surrounding fat and allows free movement. It merges posteriorly with the dural sheath of the optic nerve and extends anteriorly to...
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Tensor tympani

The tensor tympani is a short muscle in the middle ear that arises from the superior surface of the cartilaginous part of the Eustachian tube, the greater wing of the sphenoid, and the petrous part of the temporal bone. It passes across the tympanic cavity and inserts into the upper end of the h...
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Tentorial angle

The tentorial angle is measured between a line connecting the nasion with the tuberculum sellae and the the angle of the straight sinus. Normally it should measure between 27 and 52 degrees. Abnormalities of the posterior fossa / base of skull can alter this. For example this angle is elevated ...
Article

Terson syndrome

Terson syndrome refers to intraocular haemorrhage associated with subarachnoid haemorrhage. It is usually vitreous or retinal in location.  Diagnosis is usually made on fundoscopic evaluation. However, it may be overlooked in the setting of severe trauma and subarachnoid haemorrhage. The presen...
Article

Third branchial cleft cyst

Third branchial cleft cysts are a very rare type of branchial cleft cysts. Although they are extremely rare, they still remain the second most common congenital lesion of the posterior cervical region after cervical lymphatic malformations or cystic hygromas 3. Pathology Location By definitio...
Article

Thumb sign of epiglottitis

The thumb sign is a manifestation of an oedematous and enlarged epiglottis which is seen on lateral soft-tissue radiograph of the neck, and it suggests a diagnosis of acute infectious epiglottitis. This is the radiographic corollary of the omega sign 1-3.  Terminology Thumb sign is a term also...
Article

Thymic cyst

Thymic cyst is a cyst that occurs in relation to the thymus. They can be seen in a variety of settings: congenital: contains thymic tissue in wall, often unilocular acquired: often multi locular secondary to thoracotomy following chemotherapy or radiotherapy for mediastinal malignancy infl...
Article

Thyroglossal duct

The thyroglossal duct is an epithelium-lined connection between the foramen caecum and the thyroid that develops during the descent of the thyroid. It usually involutes in the 8th-10th week of gestation.  Gross anatomy The thyroglossal duct arises from foramen caecum located at the junction of...
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Thyroglossal duct cyst

Thyroglossal duct cysts (TGDC's) are the most common congenital neck cyst. They are typically located in the midline and are the most common midline neck mass in young patients. They can be diagnosed with multiple imaging modalities, including ultrasound, CT, and MRI. Epidemiology Thyroglossal...
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Thyrohyoid muscle

The thyrohyoid muscle is an infrahyoid muscle of the neck that is innervated by the ventral ramus of C1. The primary function of the thyrohyoid muscle is to depress and fix the hyoid bone and larynx though it may also raise the larynx when the hyoid bone is fixed. Summary origin: oblique line ...
Article

Thyroid acropachy

Thyroid acropachy is an unusual presentation of autoimmune thyroid disease, (~1% of patients with Graves disease). It can occur in hyperthyroid, euthyroid, hypothyroid, or even post-treatment patients. It is almost always associated with thyroid ophthalmopathy.  Epidemiology The majority of pa...
Article

Thyroid associated orbitopathy

Thyroid associated orbitopathy (TAO) is the most common cause of proptosis in adults and is most frequently associated with Graves disease. On imaging, it is characterised by extra-ocular muscles bellies enlargement (frequently: inferior rectus > medial rectus  > superior rectus) sparing ...
Article

Thyroid cancer staging

Successful treatment of thyroid malignancies highly depends on accurate preoperative staging. Ultrasound and ultrasound guided FNA or core biopsy remain the investigation of choice for diagnosing primary thyroid malignancies; CT and MRI are inferior to ultrasound for characterising thyroid nodu...
Article

Thyroid cartilage

The thyroid cartilage is the largest of the cartilages of the larynx, with its superior pole sitting at the level of the C4 vertebrae. Gross Anatomy The thyroid cartilage consists of two laminae that are fused anteriorly in the median plane to form the laryngeal prominence. Each laminae posses...
Article

Thyroid gland

The thyroid gland is an endocrine organ in the neck which is completely enveloped by the middle-layer of the deep cervical fascia and lies in the visceral space.  Gross anatomy The thyroid extends from C5 to T1 and lies anterior to the thyroid and cricoid cartilages of the larynx and the first...
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Thyroid image reporting and data system (TIRADS)

TIRADS is a risk stratification system for classifying thyroid lesions and was recently recognized in an ACR white paper 5. Its use is being advocated similar to BIRADS category for breast lesions.  Classification Classification system has been proposed by Horvath et al1, with a modified recom...
Article

Thyroid inferno

Thyroid inferno refers to the colour Doppler appearance of the thyroid gland in active Graves disease (inclusive of variants such as Marine Lenhart syndrome), and consists of multiple small areas of colour flow seen diffusely throughout the gland representing increased vascularity and arterioven...
Article

Thyroid inflammatory conditions

A number of inflammatory conditions can affect the thyroid gland, which are commonly described as thyroiditides: acute thyroiditis acute suppurative thyroiditis (AST)  autoimmune thyroiditis​ subacute lymphocytic thyroiditis: silent thyroiditis or painless subacute thyroiditis  postpartum t...
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Thyroid lymphoma

Thyroid lymphoma is rare, accounting for a minority of both thyroid malignancies and lymphoma in general.  The thyroid may be affected primarily or secondary to lymphoma elsewhere. This article is concerned with primary thyroid lymphoma.  Epidemiology Thyroid lymphoma accounts for <5% of t...
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Thyroid malignancies

Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits. Pathology Classification Thyroid malignancies can be categorised into the following key subtypes: primary thyroid cancers ​papillary thyroid carcinoma: 60-80% of carcinomas follicular thyr...
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Thyroid mass (mnemonic)

A mnemonic for thyroidal mass differential diagnosis is: CATCH Mnemonic C: carcinoma A: adenoma  T: thyroiditis C: colloid cyst H: hyperplasia (parathyroid gland)
Article

Thyroid scan (I-123)

Thyroid scan (thyroid scintigraphy) is a nuclear medicine examination used to evaluate thyroid tissue.  Clinical indications functional status of a thyroid nodule thyrotoxicosis: differential diagnosis thyroid cancer whole body scan for distant metastases estimation of local residual thyro...
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Thyroidea ima artery

The thyroidea ima artery is an uncommon variant of the blood supply to the inferior aspect of the thyroid gland. It is reported in ~7.5% (range 1.5-12.2%) of individuals and can arise from: brachiocephalic trunk right common carotid artery aortic arch internal thoracic artery The thyroidea ...
Article

Thyrotoxicosis

Thyrotoxicosis is a hypermetabolic clinical syndrome caused by a pathological excess of circulating free T4 (thyroxine) and/or free T3 (triiodothyronine). Terminology Although commonly done, thyrotoxicosis should not be confused nor synonymized with hyperthyroidism, the latter of which is a gr...
Article

Tinnitus

Tinnitus refers to a  sensation of “sound in one ear or both ears, such as buzzing, ringing, or whistling, occurring without an external stimulus” 1. It can be subjective or objective. Epidemiology It is thought that as many as 40 million people in the United States may have tinnitus. The repo...
Article

Tobey-Ayer-Queckenstedt sign

Tobey-Ayer-Queckenstedt sign is used in the diagnosis of unilateral and bilateral lateral sinus thrombophlebitis. In cases where the lateral sinus is obstructed on one side, compression of the jugular vein on the intact side causes a rise in CSF pressure, whereas compression of the obstructed si...
Article

Tolosa-Hunt syndrome

Tolosa-Hunt syndrome (THS) is an idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion. Clinical presentation Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
Article

Tongue

The tongue is a complex, principally muscular, structure that extends from the oral cavity to the oropharynx. It has important roles in speech, swallowing and taste.  Gross anatomy The tongue has a tip, ventral surface, dorsal surface and root. The tongue is made of a midline lingual septum an...
Article

Tonsillitis

Tonsillitis refers to inflammation of any of the tonsils and is one of the most common head and neck infections in adolescents and young adults. Clinical presentation Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervica...
Article

Tonsilloliths

Tonsilloliths, also known as tonsil stones or tonsils calculi, are clusters of calcifications that form into tonsillar crypts within the tonsils or around them. Although they are an uncommon benign finding, they may be symptomatic (pain, halithosis, etc.). Radiographic features Small foci of c...
Article

Tornwaldt cyst

Tornwaldt cyst (also spelled as a Thornwaldt cyst or Thornwald cyst) is a common incidental benign midline nasopharyngeal mucosal cyst. Epidemiology The lesion is developmental and usually asymptomatic. In most cases it is found incidentally and as such age of diagnosis represents age of imagi...
Article

Torticollis

Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the paediatric age group.  Pathology Torticollis can be acute (<1 week) or chron...
Article

Torus tubarius

Torus tubarius or cushion of the auditory canal is a mucosal elevation in lateral aspect of the nasopharynx, formed by the underlying pharyngeal end of the cartilaginous portion of the Eustachian tube. The opening of the Eustachian tube is anterior to torus tobarius. Immediately posterior to the...
Article

Towne projection

The Towne projection is an fronto-occipital projection with the central ray angle laying 40 degrees cranially in the midline to the  patient. The projection is used to visualize the petrous part of the pyramids, the dorsum sellae and the posterior clinoid processes, which are visible in the shad...
Article

Towne view (skull AP axial view)

The Towne view is an angled AP radiograph of the skull. Patient position the patient's nuchal ridge is placed against the image detector dorsum sella overlies the foramen magnum image size: 24 x 30 cm X-ray beam features the beam travels posterior to anterior (AP) direction, with ~30-40° o...
Article

Trachea

The trachea, known colloquially as the windpipe, connects the upper respiratory tract to the lungs via the bronchial tree, enabling gas exchange. Gross anatomy The trachea is a tube-shaped structure consisting of 15-to-20 D-shaped cartilage rings anterolaterally bridged by annular ligaments. T...
Article

Transverse cervical nerve

The transverse cervical nerve, also known as the superficial cervical nerve, cutaneous cervical nerve or anterior cutaneous cervical nerve of the neck, is a cutaneous branch of the cervical plexus that innervates the skin covering the anterior cervical region. Gross anatomy Origin The transve...
Article

Transverse temporal bone fractures

Transverse temporal bone fractures are orientated perpendicular to the long axis of the petrous temporal bone, with the line of force running roughly anterior to posterior. A more current classification of the extent of temporal bone fractures describes the integrity of the otic capsule rather t...
Article

Trapdoor fracture

A trapdoor fracture is a fracture of the orbital floor where the inferiorly displaced blowout fracture recoils back to its original position and potentially entraps contents of the orbit. It is seen in children and young adults due to the elasticity of the orbital floor. These fractures may be ...
Article

Trapezius muscle

The trapezius muscle is a large, broad superficial muscle of the posterior neck and back. It gains its name from its diamond shape. Along with sternocleidomastoid muscle, it is invested by the superficial layer of the deep cervical fascia, which splits around it.  Summary origin: superior nuch...
Article

Traumatic neck injury

Traumatic injury to the neck can be a potentially devastating injury due to the high density of crucial anatomical structures within the neck.  Epidemiology Young males are highly represented in patient with traumatic neck injury. In one study, 11:1 ratio of males to females were identified in...
Article

Treacher-Collins syndrome

Treacher Collins syndrome (TCS) (also called mandibulofacial dysostosis (MCD)) is a genetic abnormality due to bilateral malformation of 1st and 2nd branchial arches. It has an autosomal dominant mode of inheritance arising because due to mutation of TSC gene on chromosome 5. Epidemiology The ...
Article

Trigeminal nerve branches (mnemonic)

A mnemonic for remembering the names of skull foramen that the branches of the trigeminal nerve (CN V) pass through is: Standing Room Only Mnemonic standing: superior orbital fissure (frontal branch of trigeminal nerve) room: foramen rotundum (maxilary branch of trigeminal nerve) only: fora...
Article

Trigeminal neuralgia

Trigeminal neuralgia or tic douloureux corresponds to a clinical manifestation of sudden severe paroxysms of pain which usually lasts a few seconds to a few minutes, more often involving the maxillary branch of the trigeminal nerve. A vascular compression is the most prevalent cause. Other cause...
Article

Trochlear apparatus calcification

Trochlear apparatus calcification in the orbit is a common incidental finding on CT of the head, found in ~12.5% of patients. There is no association with diabetes mellitus but an association has been demonstrated with autoimmune disease and elevated ALP 1,2. 
Article

True vocal cords

The true vocal cords are the thickened, free edge of the cricovocal membrane, the cricovocal ligament, lined by mucous membrane. Together they form part of the glottis, the V-shaped aperture through which air passes. Their primary role is in phonation where vibration of the adducted vocal cords ...
Article

Trumpeted internal acoustic meatus sign

A trumpeted internal acoustic meatus (IAM) is an indirect sign of an acoustic schwannoma and is useful in helping differentiating between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus 1. It is characterized by widenin...
Article

Tuberculous cervical lymphadenitis

Tuberculous cervical lymphadenitis, also known as scrofula and King's evil, continues to be seen in endemic areas and in the industrialised world particularly among the immunocompromised. Epidemiology Tuberculous cervical lymphadenitis is the most common manifestation of extra-pulmonary tuberc...
Article

Tuberculous otomastoiditis

Tuberculous otomastoiditis is an uncommon form of acute otomastoiditis that occurs secondary to tuberculosis infection, although its frequency is increasing as a result of greater population of immunocompromised patients. Clinical presentation Classically it is described as presenting with pa...
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Tullio phenomenon

The Tullio phenomenon describes the precipitation of vertigo and nystagmus by a loud noise. Aetiology The tympanic membrane and ossicular chain must be intact with a mobile footplate. It can be present in may situations congenital syphilis, with a semicircular canal fistula post-fenestratio...
Article

Tympanic membrane

The tympanic membrane is a thin membrane that separates the external ear from the middle ear. It acts to transmit sound waves from air in the external auditory canal to the ossicles of the middle ear. The malleus is the first bone in the ossicular chain that eventually sees the sound wave trans...
Article

Tympanic membrane retraction

Tympanic membrane retraction usually occurs when a portion of the tympanic membrane becomes weakened and is pulled inwards by the negative pressure within the middle ear.  Pathology As the membrane is pulled inwards, it can be draped over the ossicles, resulting in a variety of symptoms. Clas...
Article

Tympanic part of temporal bone

The tympanic part of the temporal bone is situated inferiorly to the squamous part and anteriorly to the mastoid part. The tympanic part surrounds the external auditory meatus, forming the anterior wall, floor and some posterior wall of the bony external acoustic meatus. The lateral border of t...

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