The thumb AP (anteroposterior) view is one of the standard views for assessment of the thumb. The PA (posteroanterior) view can be utilised when the patient is unable to achieve the position required for the AP view. They are one part of the three view thumb series.
There will be some magnific...
The thumb lateral view is an orthogonal projection of AP/PA view and helps in the localisation of a foreign body in the thenar eminence, as well as providing valuable information of suspected dislocations.
patient is seated alongside the table
the forearm is placed on table
The thumb oblique view is a part of the thumb series and is particularly useful in cases with traumatic indications.
patient is seated alongside the table
forearm is placed on table
the wrist is kept in ulnar deviation and thumb abducted
fingers are kept in contact with the...
Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by oedema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen.
The thumb series is comprised of a posteroanterior and oblique, projection. The posteroanterior projection is interchangeably performed anterioposter or posteroanterior depending on mobility. It examines in detail the first metacarpal and its articulations. Thumbs have a vital impact in our day ...
This is a basic article for medical students and other non-radiologists
A thumb series (or thumb x-ray) is usually performed in the Emergency Department or Orthopaedic service following thumb trauma with suspected fracture or dislocation.
This is a summary article. For more ...
The thumb sign or thumbing of the pons is described in chordomas as is meant to be relatively specific. It is seen in midline sagittal projection as a projection of the tumour indenting the pons 1,2.
thumb sign (disambiguation)
The term thumb sign is used to refer to a number of separate radiological appearances, including:
thumb sign (Marfan disease) - a clinical sign
thumb sign (epiglottitis)
thumb sign (chordoma)
The thumb sign in epiglottitis 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.
Thumb sign is...
A thunderclap headache is a very sudden onset headache, and often described as being hit in the head with a baseball bat (cricket bat etc... presumably feel similar). Often it is described as the 'worst or first' headache.
Classically it has been seen as a symptom of subarachnoid haemorrhage, h...
The Thurstan Holland fragment also known as the Thurstan Holland sign is an eponymous radiological sign depicting a triangular portion of the metaphysis remaining with the epiphysis in a physeal fracture. This fragment is one of the tell-tale signs of a type 2 Salter-Harris fracture 1.
Thymic carcinoid tumour refers to a carcinoid tumour arising in the thymus. It is the most common histologic type for a neuroendocrine tumour of the thymus.
Affected patients are typically in the fourth or fifth decades of life. There is a recognised male predominance with M:F rat...
Thymic carcinoma is part of the malignant end of thymic epithelial tumours.
Patients are typically 50 to 70 years of age at presentation 9.
The incidence of paraneoplastic syndromes is thought to be low. At least 10 different histologic variants have been described 4. ...
Thymic cysts are cysts that occur within, or arise from, the thymus.
Thymic cysts are uncommon lesions and are estimated to account for approximately 1-3% of all anterior mediastinal masses 4. Approximately 50% of congenital thymic cysts are incidentally discovered during the firs...
Thymic epithelial tumours are rare tumours arising from thymus in anterior mediastinum of middle age patients. However, they are still the most common primary neoplasm of the thymus and anterosuperior mediastinum. This article discusses thymomas, invasive thymomas and thymic carcinoma.
Thymic hyperplasia is a disorder whereby there is hyperplasia of the thymus gland.
Thymus hyperplasia can be subdivided into two forms:
true thymic hyperplasia
Both true thymic hyperplasia and lymphoid hyperplasia manifest as diffuse symmetric enlargement of...
The thymic notch sign represents the normal thymus in a newborn on a frontal chest radiograph. Interruption of the cardiac silhouette forms a notch, which may be seen on either side, but more frequently is seen on the left side.
In periods of bodily stress the thymus may acutely shrink to 40% of its original volume (depending on the severity and duration of the stress). During the recovery phase it can grow back to its original size or even larger (up to 50% larger). This "rebound effect" is known as thymic rebound hype...
The thymic sail sign represents a triangular-shaped inferior margin of the normal thymus seen on a neonatal frontal chest radiograph. It is more commonly seen on the right side, but can also be bilateral. It is seen in 3-15% of all cases. This sign should not be confused with the spinnaker sail ...
Thymolipoma is a rare, benign anterior mediastinal mass of thymic origin, containing both thymic and mature adipose tissue.
Thymolipomas comprise ~5% (range 2-9%) of all thymic neoplasms, but are less common than a mediastinal lipoma of non-thymic origin. There is no recognised s...
The thymus is a T-cell producing lymphoid organ in the anterior mediastinum that plays a role in the development of the immune system, particular the maturation of T-cells. It typically has a retrosternal location and hence can mimic retrosternal pathology.
It is relatively large...
The thyrocervical trunk is one of the 3 branches of the first part of the subclavian artery and gives off numerous branches to supply viscera of the neck, the brachial plexus, neck muscles and the scapular anastomosis.
The trunk arises lateral to the vertebral artery from the anterosuperior wal...
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.
The thyroglossal duct arises from foramen caecum located at the junction of...
Thyroglossal duct cysts (TGDC's) are the most common type of congenital neck cysts and paediatric neck masses. 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, ...
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.
origin: oblique line ...
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.
The majority of pa...
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 bilateral and symmetrical enlargement of the extraocular muscle bellies. The typical distribution is: inferior rectus > ...
Successful treatment of thyroid cancer 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 nodules, h...
The thyroid cartilage is the largest of the cartilages of the larynx, with its superior pole sitting at the level of the C4 vertebrae.
The thyroid cartilage consists of two laminae that are fused anteriorly in the median plane to form the laryngeal prominence. Each laminae posses...
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:
right common carotid artery
internal thoracic artery
The thyroidea ...
The thyroid gland is an endocrine organ in the neck which is completely enveloped by pretracheal fascia (middle-layer of the deep cervical fascia) and lies in the visceral space.
The thyroid extends from C5 to T1 and lies anterior to the thyroid and cricoid cartilages of the lar...
TI-RADS is a risk stratification system for classifying thyroid lesions and was recently recognized in an American College of Radiology (ACR) white paper1. Its use is being advocated similar to BI-RADS category for breast lesions.
In 2017, a white paper2 was released by the ACR committee on th...
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...
A number of inflammatory conditions can affect the thyroid gland, which are commonly described as thyroiditides:
acute suppurative thyroiditis (AST)
subacute lymphocytic thyroiditis: silent thyroiditis or painless subacute thyroiditis
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.
Thyroid lymphoma accounts for <5% of thyr...
Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits.
Thyroid malignancies can be categorised into the following key subtypes:
primary thyroid cancers
papillary thyroid carcinoma: 60-80% of carcinomas
A mnemonic for thyroidal mass differential diagnosis is:
C: colloid cyst
H: hyperplasia (parathyroid gland)
Thyroid scan (thyroid scintigraphy) is a nuclear medicine examination used to evaluate thyroid tissue.
functional status of a thyroid nodule
thyrotoxicosis: differential diagnosis
whole body scan for distant metastases
estimation of local residual thyro...
Tc-99m pertechnetate thyroid scan is a functional nuclear medicine study used to assess the thyroid gland.
fast for 4 hours prior to exam
dose and route of administration
111-185 MBq (3-5 mCi) IV
time of imaging
Thyroseq® is an expanded gene classifier test designed for further evaluation of indeterminate thyroid nodules on fine needle aspiration (FNA). In particular, it is designed to further evaluate nodules that show atypia of undetermined significance / follicular lesion of undetermined significance...
Thyrotoxicosis is a hypermetabolic clinical syndrome caused by a pathological excess of circulating free T4 (thyroxine) and/or free T3 (tri-iodothyronine).
Although commonly done, thyrotoxicosis should not be confused with, nor is it synonymous with hyperthyroidism. The latter term...
This is a basic article for medical students and other non-radiologists
A tib/fib x-ray, also known as tib/fib series or tib/fib radiograph, is a set of two x-rays of the leg (knee to ankle). It is performed to look for evidence of injury (or pathology) affecting the leg, often after trauma.
The tibia (plural: tibiae) is the largest bone of the leg and contributes to the knee and ankle joints. (shin- or shank-bone are lay terms). It is medial to and much stronger than the fibula, exceeded in length only by the femur.
The tibia has a prismoid shaft, expande...
The tibia fibula AP view is part of a two view series of the entire tibia, fibula, and both the knee and ankle joint.
the patient may be supine or sitting upright with their leg straighten on the table
the foot is in dorsiflexion
the toes will be pointing directly toward th...
The tibia fibula lateral view is part of a two view series of the entire tibia, fibula, and both the knee and ankle joint.
the patient is in a lateral recumbent position on the table
the lateral aspect of the knee and ankle joint should be in contact with the table resulting...
The tibia/fibula is comprised of an anteroposterior (AP), and lateral radiograph. The series is often used in emergency departments to evaluate the entirety of the tibia and fibula after trauma.
The tibia/fibula radiographs are performed for a variety of indications including:
Tibial hemimelia or tibial deficiency is an uncommon abnormality which can range from isolated mild shortening to complete tibial absence 1.
Tibial hemimelia is extremely rare, occurring in only one out of one million live births 2.
The affected limb is sho...
The tibialis anterior muscle is one of the muscles of the anterior compartment of the leg involved in dorsiflexion and inversion of the foot.
origin: body of the tibia
insertion: medial cuneiform and first metatarsal
action: dorsiflexion and inversion of the foot
arterial supply: an...
The tibialis posterior muscle is one of the small muscles of the deep posterior compartment of the leg.
origin: inner posterior borders of the tibia and fibula
insertion: navicular and medial cuneiform
the tendon splits into two slips after passing inferior to plantar calcaneonavicu...
The tibial nerve is one of two terminal branches of the sciatic nerve and supplies the leg and foot with motor and sensory supply.
origin: the terminal branch of sciatic, at or above the popliteal fossa
course: courses straight down the popliteal fossa, passing deep to gastrocnemius t...
The tibial plateau is the proximal articular surface of the tibia.
The tibial plateau is composed of two parts:
concave articular surfaces of the oval-shaped medial and circular-shaped lateral tibial condyles (medial and lateral tibial plateaus)
the medial tibial plateau is lar...
Tibial plateau fractures were originally termed a bumper or fender fracture but only 25% of tibial plateau fractures result from impact with automobile bumpers.
The most common mechanism of injury involves axial loading, e.g. fall from a significant height. In younger patients, the m...
Tibial tuberosity avulsion fractures are uncommon and usually associated with sports activities that require jumping. Avulsion occurs with the violent active extension of the knee or passive flexion against contracted quadriceps muscles.
Although an acute injury, tibial tuberosity avulsion is m...
Tibial tuberosity transfer is surgical procedure performed for patella instability. Tibial tuberosity transfer can simultaneously correct a high-riding patella. The goal of the surgery is often to transfer the distal attachment of the patellar tendon, thereby shifting the force vector medially a...
Tibia vara (also known as genu varus and bow-leggedness) is a varus deformity with outward bowing at the knee and medial angulation (inward) of the lower leg in relation to the thigh's coronal axis.
The differential of bow-legging in children is long, with common causes including Blount disease...
The tibiofemoral joint is a modified hinge synovial joint between the distal femur and the proximal tibia.
articulation: modified hinge joint between the medial and lateral condyles of the femur and the tibial condyles
ligaments: transverse ligament of the knee, medial an...
The tibioperoneal or TP trunk, which occasionally referred to as the tibiofibular trunk is the direct continuation of the popliteal artery in the posterior upper leg after the anterior tibial artery origin. It is a short trunk that bifurcates into two terminal branches.
Tibiotalar slant is the superolateral inclination of the tibial plafond, and results in an ankle valgus deformity. There are a number of causes 1:
trauma, i.e. distal tibial fractures
osteomyelitis and/or septic arthritis
juvenile idiopathic arthritis
sickle cell dis...
Tietze syndrome refers to a benign costochondritis accompanied by hypertrophy of the costal cartilages.
The exact incidence of occurrence is not known. It is seen most commonly in the 2nd to 5th decades of life. Both sexes are affected equally.
It is characterised as a...
The tiger stripe appearance refers to the characteristic alternating hypo and hyperintense bands on MRI in Lhermitte-Duclos disease. This rare cerebellar tumour appears like the coat of a tiger.
tigroid pattern - in brain
Tight filum terminale syndrome is caused by incomplete involution of the distal spinal cord during embryogenesis. This leads to development of an abnormally thickened filum terminale, which may be associated with lipomas or cysts within the filum.
Tight filum terminale syndrome is always associ...
Tillaux fractures are Salter-Harris III fractures through the anterolateral aspect of the distal tibial epiphysis, with variable amounts of displacement.
It occurs in older children and adolescents when the medial aspect of the distal tibial growth plate has started to fuse.
A way to overcome ultrasound attenuation is time gain compensation (TGC), in which signal gain is increased as time passes from the emitted wave pulse. This correction makes equally echogenic tissues look the same even if they are located in different depths.
The basis of this is that of return...
Time of flight angiography (TOF) is an MRI technique to visualize flow within vessels, without the need to administer contrast. It is based on the phenomenon of flow-related enhancement of spins entering into an imaging slice. As a result of being unsaturated, these spins give more signal that s...
The Tinel sign refers to distal paresthesia which is induced by percussion over the affected portion of an entrapped nerve.
It is particularly useful in the diagnosis of entrapment syndromes:
carpal tunnel syndrome
tarsal tunnel syndrome
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.
It is thought that as many as 40 million people in the United States may have tinnitus. The repor...
Tip of the iceberg sign refers to one of the characteristic appearances of an ovarian dermoid cyst. If there are echogenic cyst contents of sebum and hair, they cause marked posterior acoustic attenuation so that only the superficial part of the cyst is seen. Just like an iceberg, you may only b...
TIPS evaluation is useful to ensure that the shunt is working properly and that no stenosis has occurred within the stent. Ultrasound is often used as a first-line modality.
The normal TIPS should show colour Doppler flow throughout its length. The in-stent ve...
Tissue tropism is a phenomenon by which certain host tissues preferentially support the growth and proliferation of pathogens. This concept is central to the radiological evaluation of infectious disease.
As infections that display tissue tropism will thrive in certain tissue locati...
The tissue weighting factor (WT) is a relative measure of the risk of stochastic effects that might result from irradiation of that specific tissue. It accounts for the variable radiosensitivities of organs and tissues in the body to ionising radiation.
To calculate the effective dose, the indi...
The TNM system has been widely adopted in many areas as a replacement for idiosyncratic disease specific systems. The precise details depend on the primary tumour site and/or histology but in general:
Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
The TOAST (trial of ORG 10172 in acute stroke treatment) classification denotes five sub types of ischaemic stroke.
large-artery atherosclerosis (embolus / thrombosis)*
cardioembolism (high-risk / medium-risk)*
small-vessel occlusion (lacune)*
stroke of other determined aetiology *
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...
The Todani classification of bile duct cysts divides choledochal cysts into five groups.
See: type I choledochal cyst
account for 80-90% of all bile duct cysts
characterised by fusiform dilation of the extrahepatic bile duct
a subclassification has been proposed
Toddler fractures are minimally or undisplaced spiral fractures usually of the tibia, typically encountered in toddlers. It is a potentially difficult diagnosis to establish on account of both the symptoms and imaging findings being subtle.
The term has sometimes also been used to ...
Todd paralysis, also known as Todd paresis or postictal paralysis, describes transient focal neurological deficits after an epileptic seizure. It is an important clinical and imaging differential diagnosis of ischaemic stroke presenting with a seizure.
The incidence of Todd para...
Toes AP view is part of a three view toe series and includes the phalanges and the toe(s) of interest and the distal half of the associated metacarpals.
the patient can be either supine or be sitting upright on the table
knee should be flexed so the plantar surface of the foo...
The toes medial oblique view is part of the toe series examining the phalange and metatarsals of the foot.
the patient may be supine or upright depending on comfort
the affected leg must be flexed enough that the plantar aspect of the foot is resting on the image receptor
The toes series is comprised of an AP, AP oblique, and a lateral projection. The series is often utilised in trauma situations. It examines the entirety of the proximal middle and distal phalanges of the foot.
Toe radiographs are performed for a variety of indications including 1:...
The sesamoid view of the toes is a specialed view examing the sesamoid bones of the first metatarsal.
the patient may be supine or sitting upright with their leg straighten on the table
the foot is in dorsiflexion
the toes pulled back toward the patient
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.
Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
Tombstone iliac wings, also referred to as Mickey Mouse ears pelvis 1, are an imaging descriptor for the iliac wings of individuals with achondroplasia. These are seen to be small and squared and have been likened to the appearance of tombstones or the ears of Mickey Mouse.
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.
The tongue has a tip, ventral surface, dorsal surface and root. The tongue is made of a midline lingual septum an...
Tonsillar herniation is a type of cerebral herniation characterised by the inferior descent of the cerebellar tonsils below the foramen magnum.
The terminology of caudally displaced tonsils is discussed in the article on cerebellar tonsillar ectopia.
It is a secondary sign of signif...
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.
Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervica...
Tonsilloliths, also known as tonsil (or tonsillar) stones or calculi, are clusters of calcifications that form in tonsillar crypts, within the tonsils or around them. Although they are uncommon and benign, they may be symptomatic (pain, halitosis, etc).
Small foci of calc...
Tooth-knuckle injuries are sustained when the clenched fist of a patient strikes the teeth of an opponent.
Tooth-knuckle injuries are also referred to as clenched fist injuries, closed fist injuries and fight bite injuries.
These injuries are most commonly found in y...
The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.
Tophi (plural of tophus) appear as lumps on affected joints due to deposits of monosodium urate (MSU) crystals in patients with longstanding high levels of serum uric acid (hyperuricaemia).
Tophi are a pathognomonic feature of gout.
History and etymology
Tophus means "stone" in Latin.
Top of the basilar syndrome, also known as rostral brainstem infarction, occurs when there is thromboembolic occlusion of the top of the basilar artery. This results in bilateral thalamic ischaemia due to occlusion of perforator vessels.
Clinically, top of the basilar syn...
Torg's classification of proximal fifth metatarsal fractures is based on the degree of sclerosis adjacent to the fracture on imaging at the time of presentation to determine the fracture age.
narrow fracture line with sharp margins and no widening
minimal cortical hyper...
Tornwaldt cyst (also spelled as a Thornwaldt cyst or Thornwald cyst) is a common incidental benign midline nasopharyngeal mucosal cyst.
The lesion is developmental and usually asymptomatic. In most cases it is found incidentally; as such, age of diagnosis typically represents age ...
Torsion of the appendix testis is the most common cause of an acute painful hemiscrotum in a child. The appendix testis is located at the upper pole of the testis (between the testis and the head of the epididymis).
The normal appendix testis is 1 to 4 mm in length, and it is oval or pedunculat...