The ankle teardrop sign is one of the radiological signs of an ankle joint effusion. It represents the presence of excess fluid in the inferior part of the anterior compartment of the ankle.
The teardrop sign indicates an uncollapsed intracapsular breast implant rupture and is seen as a small focal invagination of the implant shell caused by a minimal concealed leak of droplets of silicone outside the shell where the two membranes contact each other. It is best appreciated by MRI.
The teardrop sign of the superior mesenteric vein is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer.
Technetium 99m-methyl diphosphonate (99mTc MDP) is a radioisotope used in nuclear medicine especially for bone scans. Any disease process which results in extracellular fluid expansion will lead to accumulation of this isotope.
photon energy: 140 keV
physical half life: 6...
Technetium agents based on the technetium-99m (Tc-99m) radioisotope are frequently used agents in medical imaging. The radioactive technetium radiotracer can be chelated to a number of different compounds to create specific radiopharmaceuticals and optimise the functional imaging of various stru...
Masking is very important when viewing mammograms, especially with high-density breasts. It helps the adaptation of the eye to the luminance of the mammograms on the viewbox.
The technique of masking allows the comparative study of small areas of both breasts and is a featur...
Tectal beaking refers to the fusion of the midbrain colliculi into a single beak pointing posteriorly and invaginating into the cerebellum. It is seen with a Chiari type II malformation.
The term bird beak sign is used in a number of other contexts: see bird beak sign (disambiguati...
Tectal gliomas fall under the grouping of childhood brainstem gliomas and unlike the other tumours in that group they are typically low grade astrocytomas with good prognosis.
Tectal plate gliomas are encountered in children and adolescents 4. A male predilection has sometimes be...
The tectorial membrane is the thin superior continuation of the posterior longitudinal ligament from the body of the axis. It joins the axis body to the clivus on the anterior half of the foramen magnum, and ascends as high as the spheno-occipital synchondrosis and laterally extends to the hypog...
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.
There are twenty deciduous (primary) teeth in young children, with ten per jaw and five in each quadrant, which consist of (distal to mesial):...
The tegmentovermian angle is an important measurable parameter in the assessment of posterior fossa abnormalities in the fetus. The angle is constructed on midsagittal images of the fetal brain, ideally on MRI.
The angle is formed by the intersection of the following two lines 1:
line 1: along...
The tegmentum is one of the areas of the brainstem. It is a phylogenetically old part of the brainstem and, in adults, is the location of the brainstem nuclei.
In the midbrain, it sits between the quadrigeminal plate and cerebral peduncles. In the pons, it is posterior to the basilar part of t...
The tela choroidea is the thin, highly vascularised, loose connective tissue portion of pia mater that gives rise to the choroid plexus. Thus, it is basically the lamina propria of the ependyma and lies directly adherent to it, without any tissue in between the two 6.
Being part ...
A telangiectasia commonly refers to a group of abnormally prominent capillaries that occur close a mucosal surface. Rarely they are also referred to denote vascular malformations at other non mucosal sites (e.g capillary telangiectasiae of the brain 1)
There are numerous condition...
Telangiectatic osteosarcomas (TOS) are an uncommon variant of osteosarcoma that represent 2.5-12% of all osteosarcomas.
TOS have similar demographics to that of conventional osteosarcoma and typically presents in adolescents and young adults (reported age range of 3-67 years with...
Telecanthus represents increased intercanthal distance. It is often used interchangeably with hypertelorism, referring to increased distance between the eyes.
Causes and associations
trauma: naso-orbito-ethmoidal (NOE) fractures
sinus and orbital tumours
A telephone receiver deformity is a characteristic bowing of the shaft of the long bones, usually the humeri or femora, seen in thanatophoric dysplasia.
The telltale triangle sign, also known as the triangle sign or telltale triangle, is a radiographic sign seen on plain abdominal radiograph that signifies presence of pneumoperitoneum 1. It describes the appearance of a radiolucent triangle of gas formed between three loops of bowel or between t...
The temporal bone is situated on the sides and the base of the cranium and lateral to the temporal lobe of the 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:
Destructive lesions of the temporal bone (petrous pyramid, middle ear and antrum) have a relatively broad differential including 1:
lesions affecting petrous pyramid
neuroma of trigeminal and facial nerve
glomus jugulare tumour
Temporal bone fracture is usually a sequela of significant blunt head injury. In addition to potentially damage to hearing and the facial nerve, associated intracranial injuries, such as extra-axial haemorrhage, diffuse axonal injury and cerebral contusions are common. Early identification of te...
A helpful mnemonic for remembering the complications of temporal bone fractures that may require early intervention is:
C: carotid artery injury
L: leakage of CSF
O: other intracranial complications, e.g. hematoma
N: nerve injury leading to complete facial paralysis
Temporal encephaloceles are usually small encephaloceles often asymptomatic but increasingly recognised as potential causes of refractory epilepsy and as a sequela of idiopathic intracranial hypertension.
Temporal encephaloceles can be congenital or secondary to trauma, idiopathic...
The temporal fossa is located in the temporal region and communicates inferiorly with infratemporal fossa deep to the zygomatic arch.
The temporal fossa is bounded by a few anatomical landmarks, anteriorly the frontal process of the zygomatic bone, superiorly and posteriorly the...
The temporalis muscle is one of the muscles of mastication. It is responsible for both closing the mouth and retraction (posterior fibres).
origin: temporal fossa between the infratemporal crest and inferior temporal line
insertion: coronoid process and ramus of mandible
The temporal lobe is one of the four lobes of the brain (along with the frontal lobe, parietal lobe, and occipital lobe), and largely occupies the middle cranial fossa.
The temporal lobe is the second largest lobe, after the larger frontal lobe, accounting 22% of the total neocor...
Temporal lobe epilepsy (TLE) is the most common type of partial epilepsy, with often characteristic imaging and clinical findings. It is divided into two broad groups:
involves the mesial temporal lobe structures
most frequently due to mesial temporal sclerosis
The temporal pole is an anatomical landmark that corresponds to the anterior end of the temporal lobe, lying in the middle cranial fossa.
It corresponds to Brodmann area 38 and has strong connections with the amygdala and orbital prefrontal cortex, and is sometimes recognised as a component of...
Temporal resolution relates to the duration of time for acquisition of a single frame of a dynamic process, i.e., cine imaging.
The concept of temporal resolution is fundamental to cardiac CT and MRI, in which a rapidly beating heart is imaged over the order of milliseconds into mul...
Temporal tap manoeuvre consists in tapping over the ipsilateral superficial temporal artery while assessing the carotid bifurcation on Doppler ultrasound aiming to produce a reflected flow in the external carotid artery (ECA) and thus helping to distinguish which vessel is being assessed: extern...
Temporary ventricular assist devices (or temporary VADs) are temporary percutaneous devices used in supporting a failing heart in cardiogenic shock or perioperatively.
Temporary VADs consist of an inlet, outlet and impeller pump all housed within a catheter. Temporary VADs are insert...
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 a superior discotemporal space and inferior discomandibular space by the TMJ disc (or meni...
The axiolateral temporomandibular view allows for visualisation of the articular tubercle, mandibular condyle and fossa and is thus useful to identify structural changes and displaced fractures, as well as assess excursion and joint spaces.
Clinical indications include trauma, the presence of ...
The temporomandibular joint (TMJ) disc (or meniscus) is made of fibrocartilage and divides the joint into two compartments.
The disc is composed of fibrocartilage, with crimped collagen, thought to better absorb impacts. It has a biconcave shape with a thicker periphery attached...
Temporomandibular joint dislocation represents the condyle of the mandible being abnormally displaced, with a loss of the normal articulation with the glenoid fossa.
Dislocations of the temporomandibular joint (TMJ) are common and occur in as many as 7% of the entire population, a...
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).
TMJ dysfunction is far more common in women (F:M 8:1).
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:
rheumatoid arthritis (RA)
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
Temporomandibular joint (TMJ) pathology encompasses three main entities:
temporomandibular joint dysfunction: relating to abnormal TMJ disc relationship to condyle and temporal bone, which can lead to osteoarthritis.
temporomandibular joint inflammation
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
The temporopolar artery is usually a dorsolateral branch from the M1 segment of the middle cerebral artery (MCA) and supplies the polar and anterolateral portions of the temporal lobe.
This artery may arise as a branch from the anterior temporal artery 1.
The temporozygomatic suture (or zygomaticotemporal suture) is between the zygomatic process of the temporal bone and the temporal process of the zygomatic bone.
It can mimic a zygoma fracture.
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)
Tendon and ligamentous ossification has a relatively narrow differential, including:
diffuse idiopathic skeletal hyperostosis
ossification posterior longitudinal ligament (OPLL)
Idiopathic Achilles tendon ossification - isolated finding
post-traumatic - rand...
A number of processes can affect tendons.
Literally means a disease or disorder of a tendon and typically used to describe any problem involving a tendon. While many define tendinopathy as an umbrella term to describe all tendon pathology, others may use it to descr...
Mnemonics for remembering the three conjoined tendons that make up the pes anserinus include:
Say Grace before Tea
From anterior to posterior, the tendons are:
Say Grace before Tea
Tennis leg represents a myofascial or tendinous injury of the lower limb and, not surprisingly, is seen most frequently in tennis players.
Although classically seen in people who play tennis, it can also be induced by playing squash, skiing, and athletics. Therefore, it typically ...
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 ...
Tenosynovitis is a term describing the inflammation of the synovial membrane surrounding a tendon. The synovial membrane is part of a fluid-filled sheath that surrounds a tendon.
pain in the affected area and pain moving a joint
reddening along the length...
The tensile gallbladder fundus sign is positive when the gallbladder fundus is seen to bulge into, and distort, the anterior abdominal wall and is a feature of acute cholecystitis.
It is particularly useful as an early sign of the condition on CT as it has around a 75% sensitivity and 95% speci...
Tension gastrothorax describes a rare life-threatening condition caused by mediastinal shift due to a distended stomach herniating into the thorax through a diaphragmatic defect.
Presentation is generally with acute and severe respiratory failure, with clinical features ...
Tension pneumocephalus is a neurosurgical emergency that occurs when subdural air causes a mass-effect over the underlying brain parenchyma, often from a ball-valve mechanism causing one-way entry of air into the subdural space 1.
Tension pneumocephalus has a varied clinical ...
Tension pneumoperitoneum is a special and rare type of pneumoperitoneum, in which the free intra-abdominal peritoneal gas is under pressure.
The mechanism is thought to be a ball-valve effect allowing the one-way accumulation of gas. This results in:
elevation and splinting of the d...
Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exert positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest.
This is a basic article for medical students and other non-radiologists
Tension pneumothoraces are pneumothoraces under pressure. If the pressure gets high enough, the pneumothorax can compress the heart and great vessels, and even cause cardiac arrest.
Presentation is u...
The tensor fasciae latae muscle is the most anterior of the superficial group of muscles in the gluteal region and overlies the gluteus minimus and the anterior part of the gluteus medius.
origin: lateral aspect of crest of ilium between anterior superior iliac spine and tubercle of cr...
The tensor fasciae suralis muscle is an uncommon accessory muscle in the popliteal fossa. It can be an unusual cause of a popliteal fossa soft-tissue swelling or mass.
origin: may arise from the distal aspect of any of the hamstring muscles, in the majority of reported cases it origin...
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...
The tensor veli palatini is one of the 5 paired muscles of the soft palate. It is triangular in shape and it's tendon wraps around the pulley of pterygoid hamulus to alter the shape of the soft palate.
origin: it has 3 sites of origin:
scaphoid fossa of the medial pterygoid plate
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°.
Abnormalities of the posterior fossa / base of skull can alter this. For example this angle is elevated in ach...
The tentorial nerve is the first branch of the ophthalmic division of the trigeminal nerve (CN Va) which is the dominate dural nerve supplying most of the supratentorial dura. It specifically supplies the falx, calvarial dura and superior surface of the tentorium.
The tentorium cerebelli is the second largest dural fold after the falx cerebri. It lies in the axial plane attached perpendicularly to the falx cerebri and divides the cranial cavity into supratentorial and infratentorial compartments 1. It contains free and attached margins 2.
The tent sign is a term referring to a characteristic appearance of the posterior edge of the breast parenchyma when a mass (usually an infiltrating lesion) causes its retraction and forms an inverted "V" that resembles the tip of a circus tent.
The detection of a "tent sign" is facilitated by ...
Teratomas are germ cell tumours that arise from ectopic pluripotent stem cells that fail to migrate from yolk sac endoderm to the urogenital ridge during embryogenesis. By definition, they contain elements from all three embryological layers: endoderm, mesoderm and ectoderm although frequently, ...
Teres major is one of the seven scapulohumeral muscles that act around the glenohumeral joint to facilitate shoulder movement.
origin: caudal two thirds of lateral border and inferior angle of scapula
insertion: medial border of the intertubercular groove, which is the crest of lesser...
Teres minor is one of the four muscles that make up the rotator cuff, the others being: supraspinatus, infraspinatus, and subscapularis.
origin: lateral border of the scapula
insertion: greater tuberosity of the humerus
innervation: axillary nerve (C5-6)
arterial supply: circumflex ...
The terminal bronchioles are a continuation of the bronchi and are the last divisions of the conducting airways.
Terminal bronchioles, are confusingly named, as they not the final branches but rather the distal bronchioles that do not bear alveoli. The first 19 divisions from ...
Each breast lobe is drained by a collecting duct terminating in the nipple. The collecting duct has several branches, which ends in a terminal ductal-lobular unit (TDLU), the basic functional and histopathological unit of the breast. The TDLU is composed of a small segment of the terminal duct a...
The differential diagnosis for a terminal ileitis is quite extensive, and includes:
inflammatory bowel disease
Crohn disease (most common)
backwash ileitis due to ulcerative colitis
The terminal ileum is the most distal segment of small bowel. It immediately precedes the small bowel's connection with the colon through the ileocaecal valve. It is of particular interest since a number of infectious and inflammatory processes preferentially involve the segment.
location: the ...
Terminal myelocystoceles are an uncommon form of spinal dysraphism representing marked dilatation of the central canal of the spinal cord, herniating posteriorly through a dorsal spinal defect. The result is a skin-covered mass in the lower lumbar region, consisting of an ependyma-lined sac.
The terminal tuft is the most distal part of a distal phalanx, and comprises of the flared bone distal to the shaft.
spade phalanx sign
terminal tuft masses
as it is close to the nail, pathology or injuries of one can affect the other
There is only a short list of terminal tuft masses, which can arise from the adjacent soft tissues and erode the terminal tuft as well as arising from the terminal tuft itself:
epidermal inclusion cyst: history of penetrating trauma
giant cell tumour of the tendon sheath: occur laterally
The terminal zones of myelination are located at the posterior aspect of the lateral ventricles (the peritrigonal regions) and are the only part of the cerebral white matter that may exhibit high T2 signal in a normal brain at 2 years of age, when myelination of cerebral white matter normally be...
The Terminologia Anatomica (TA) is the global standard for correct gross anatomical nomenclature in humans 1. The second edition was published in 2011 4.
The standard anatomical terms are from Latin and Ancient Greek roots. The English edition of the Terminologia Anatomica provides the accepte...
The terminology section of a standard article does not appear in all articles and is only required where clarification about terminology is required.
The terminology section is located immediately after the introduction, and before epidemiology.
This section will usually b...
There are numerous terms used in radiology that are worth knowing and this is list of some of them.
The terrible triad of the elbow is a severe elbow fracture-dislocation pattern and is so-called because it has poor medium-to-long term outcome.
Most commonly due to a fall onto an outstretched hand, not necessarily high-energy, with the arm in semi-flexion and supination...
The Terry Thomas sign refers to an increase in the scapholunate space on an AP radiograph of the wrist (or coronal CT). The increased distance indicates scapholunate dissociation (often with rotary subluxation of the scaphoid) due to ligamentous injury. There is no consensus as to what measureme...
Terson syndrome refers to vitreous haemorrhage associated with subarachnoid haemorrhage, however some authors include retinal haemorrhage as well. The syndrome is a poor prognostic marker in patients with subarachnoid haemorrhage.
Terson syndrome has been reported to occur in 13-5...
TERT promoter mutations affect the TERT promoter (located on the short arm of chromosome 5) which encodes for the hTERT component of telomerase, an enzyme which maintains and lengthens telomeres 1. Mutations that result in enhanced activity of telomerase, and therefore longer telomeres, can be i...
The tesla (symbol T) is the derived SI unit of magnetic flux density, which represents the strength of a magnetic field. One tesla represents one weber per square metre. The equivalent, and superseded, cgs unit is the gauss (G); one tesla equals 10,000 gauss.
As for all eponymous ...
Testicular abscess is usually a complication of severe epididymo-orchitis and needs to be distinguished from other testicular pathology that may present with similar clinical or imaging features.
The majority of patients develop a testicular abscess as a result of untreated or se...
Testicular adrenal rests are a rare cause of a testicular mass.
Testicular adrenal rests can be known by a variety of terms 2:
testicular adrenal rest tumour (TART)
testicular adrenal rest tissue
testicular tumour of the adrenogenital syndrome
testicular adrenal-like tissue
Testicular and scrotal ultrasound is the primary modality for imaging most of the male reproductive system. It is relatively quick, relatively inexpensive, can be correlated quickly with the patient's signs and symptoms, and, most importantly, does not employ ionising radiation.
MRI is occasion...
Testicular and epididymal appendages are remnants of embryonic ducts and are quite common, with one or more being present in ~70% of patients 1.
Four such appendages have been described:
testicular appendix (hydatid of Morgagni)
it is a Müllerian duct remnant (paramesonephric d...
A testicular appendix (alternatively called appendix of testis or appendix testis) represents a developmental remnant of the paramesonephric duct (Müllerian duct) which is situated in the upper pole of the testis inside a groove between the testicle and the head of epididymis 1.
The testicular arteries (also known as the spermatic arteries) are the long, small-diameter gonadal arteries in the male that supply the testis alongside the cremasteric artery and the artery to the ductus deferens.
As paired structures they arise symmetrically, slightly...
Testicular cancers are the most common neoplasm in men between the ages of 20 and 34.
Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2.
The demographics of affected individuals depends on the age of the histology of the tumour. Over ...
The staging for testicular tumours is performed according to the TNM system with staging groupings. It can be remembered in its abbreviated form as:
stage I: confined to testis, epididymis, spermatic cord, scrotum
stage II: lymph nodes involved but no distant metastases and serum tumour marke...
Testicular choriocarcinoma is a type of non-seminomatous germ cell tumour.
Incidence peaks at around 20-30 years of age.
Can be variable with some patients initially presenting with metastates.
It is most commonly detected as a component of a m...
Simple testicular cysts are usually nonpalpable and thus are detected incidentally.
Testicular cysts require no treatment when discovered.
well-marginated with an imperceptible wall
anechoic with enhanced through transmission
no flow on color Doppler
Testicular descent occurs after the fourth month of fetal life. The testes are derived from the gonadal ridge medial to the mesonephric ridge of the intermediate cell mass. An elongated diverticulum of the peritoneal cavity, the processus vaginalis precedes the testis through the inguinal canal ...