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 (you guessed it) toddlers. It is a potentially difficult diagnosis to establish on account of both the symptoms and imaging findings being subtle.
The term has sometimes a...
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...
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.
Torticollis can be acute (<1 week) or chronic ...
Torus ethmoidalis, also known as torus lateralis, is the term given when there is no air cell in the ethmoid bulla (failure of pneumatisation). It is encountered in 8% of subjects.
Torus fractures, also known as buckle fractures, are incomplete fractures of the shaft of a long bone that is characterised by bulging of the cortex. They result from trabecular compression from an axial loading force along the long axis of the bone. They are usually seen in children, frequently...
Torus tubarius or cushion of the auditory canal is a mucosal elevation in the 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 the torus tobarius. Immediately posterio...
Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart anomaly with an abnormal drainage anatomy of the entire pulmonary venous system. This contrasts with partial anomalous pulmonary venous return (PAPVR) where only part of the pulmonary venous anatomy is abnormal.
Total hip arthroplasty (THA) or total hip replacement (THR) is an orthopaedic procedure which involves the surgical excision of the femoral head and cartilage of the acetabulum and replacement of the joint with articulating femoral and acetabular components. It is a commonly performed procedure ...
Total knee arthroplasty (TKA), or total knee replacement (TKR), is an orthopaedic procedure whereby the three articular surfaces of the knee (femoral, tibial, and patellar) are replaced by prosthetic components.
TKA is the most common joint arthroplasty performed in the United States, with an e...
Total repair of tetralogy of Fallot is a corrective surgical procedure that involves closure of the ventricular septal defect (VSD) and relief of right ventricular outflow tract (RVOT) obstruction.
Most patients with tetralogy of Fallot (TOF) undergo elective surgical repair between ...
Total talar dislocation, also known as extrusion of the talus, is a tri-articular dislocation of talus at the tibiotalar, talonavicular and subtalar joints. Most injuries are compound.
Mechanism of injury
Total talar dislocation is a rare injury caused by the combination of tibiotal...
Tower vertebrae a rare manifestation of sickle cell disease, in which short infarcted vertebrae are seen adjacent to other abnormally grown in height vertebrae.
codfish or h-shaped vertebrae
anterior vertebral vascular notches
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...
Townes-Brocks syndrome (Renal-Ear-Anal-Radial (REAR) syndrome) is a rare autosomal dominant disease characterised by renal, anal, ear, and thumb abnormalities.
The major manifestations of this syndrome include:
renal: displaced or rotated kidneys, horseshoe kidney, p...
Toxic leukoencephalopathy is an encephalopathy predominantly affecting white matter as a result of a toxic substance. The presentation can either be chronic or acute. In the acute phase, acute toxic leukoencephalopathy can have a characteristic and profound MR imaging appearance that is potentia...
Toxic megacolon is a complication that can be seen in both types of inflammatory bowel disease, and less commonly in infectious colitis, as well as in some other types of colitis.
Toxic colitis is preferred by many now as the colon is not always dilated.
Toxoplasmosis is a common worldwide parasitic disease caused by the protozoan Toxoplasma gondii. It is usually an asymptomatic infection, but it is related with several sequelae when acquired in-utero or related with cerebral abscesses due to its reactivation in immunocompromised patients (e.g. ...
It is common for radiologists to be asked to distinguish between cerebral toxoplasmosis and primary CNS lymphoma (PCNSL) in patients with HIV/AIDS. Treatment is clearly different and thus accurate interpretation of CT and MRI is essential.
In many instances, the imaging appearance is classic an...
The TP53 gene, located on chromosome 17, is a tumour suppressor gene, responsible for the production of the p53 protein, a transcription regulatory protein which works in concert with a number of other proteins, together forming the p53 pathway 1,2.
Inherited mutations in this gene result in th...
Trabecular pattern of proximal femur refers to the five groups of trabeculae that are demonstrable within the femoral head and neck.
Trabecula is a supportive and connective tissue element which form in cancellous bone. Trabeculae develop in a normal bone and also in a healing bo...
The trachea, known colloquially as the windpipe, connects the upper respiratory tract to the lungs via the tracheobronchial tree, enabling gas exchange.
The trachea is a tube-shaped structure consisting of 15-to-20 D-shaped cartilage rings anterolaterally bridged by annular ligam...
Primary tracheal and endobronchial lesions are generally rare and can be either malignant or benign. The majority of these lesions are malignant.
primary malignant endobronchial lesions
squamous cell carcinoma: commonest malignant lesion in tr...
Tracheal atresia (TA) is an extremely rare anomaly and refers to a congenital absence of the trachea.
There may be a greater male predilection 5.
Tracheal atresia falls under the spectrum of laryngeal-tracheo-bronchial atresia which in turn results either from an obstr...
A tracheal bronchus (with some variations also known as a pig bronchus) is an anatomical variant where an accessory bronchus originates directly from the supracarinal trachea. The latter term (pig bronchus or bronchus suis) is often given when the entire upper lobe (usually right side) is suppli...
Tracheal buckling is a normal finding in young infants when it is more flexible. There is typically deviation of the trachea anteriorly and to the right (up to 90°) and any other configuration (i.e. to the left or posteriorly) should raise the possibility of underlying pathology.
Tracheal calcification, or tracheobronchial calcification, is a benign radiological finding of the middle aged and elderly and is usually of no clinical significance.
Patients are generally asymptomatic.
Long-term warfarin therapy may be associated with trache...
A tracheal diverticulum is usually an incidental finding. Occasionally it may mimic pneumomediastinum, so called pseudopneumomediastinum.
It may be congenital or acquired. The acquired form is thought to be due to prolonged increased intraluminal pressure, e.g. due to a chronic cough...
The differential for tracheal masses can be rather wide.
For a single mass consider:
direct invasion from adjacent organ (lung, thryoid,esophagus)
distant metastsis ( such as melanoma)
squamous cell carcinoma: commonest primary tracheal malignancy 2 ~50 %
Tracheal stenosis is usually acquired following intubation or tracheostomy. Inflammation and pressure necrosis of the tracheal mucosa most commonly occur at either the tracheostomy stoma or at the level of the tube balloon. Acute post-intubation stenosis results from mucosal oedema or granulatio...
Tracheal wall thickening may have several causes. For diagnostic purposes, tracheal thickening may be categorized by length of airway involvement in order to narrow the differential diagnoses. Note that some etiologies may be associated with either focal or diffuse pattern of involvement.
Tracheal webs occur as a thin layer of tissue that narrows the tracheal lumen. They do not completely obstruct the trachea.
The incidence of congenital tracheal is 1:10,000 births.
Some patients will be asymptomatic. Symptomatic patients can present with a ...
Trachelectomy (sometimes known as a cervicectomy) refers to removal of uterine cervix.
It is sometimes performed as a uterine sparing surgery for certain cases with cervical malignancy 2-3. When it is performed with curative intent it is often termed a radical trachelectomy and is often accomp...
Tracheobronchial amyloidosis refers to tracheal and/or bronchial involvement in amyloidosis. It is sometimes classified as a subtype of pulmonary amyloidosis.
It is a rare manifestation with some reports suggesting less than 100 published cases around the time of writing 5.
Tracheobronchial branching anomalies can be seen as an isolated finding or accompanying heterotaxy syndromes, pulmonary sling, and conditions associated with pulmonary underdevelopment (agenesis and aplasia), including the scimitar syndrome.
Abnormal branching patterns include:
right sided iso...
Tracheobronchial injury is a serious but uncommon manifestation of chest trauma. It is usually a fatal injury with only a small percentage of patients making it to hospital. Given the magnitude of force required to injure the major airways, there are often multiple chest injuries and other body ...
Tracheobronchial papillomatosis refers to the occurrence of multiple squamous cell papillomas involving trachea and bronchi. It is an unusual manifestation of recurrent respiratory papillomatosis (RRP), itself a rare condition where HPV-associated papilloma form along the aerodigestive tract 8.
A tracheo-bronchial stent is a device used in the treatment of symptomatic airway compression.
This device is inserted under bronchoscopic guidance in patients with external compression from mediastinal based malignancy, for example lung or oesophageal cancers. It may also be used in the treat...
The tracheobronchial tree is the branching tree of airways beginning at the larynx and extending inferiorly and peripherally into the lungs as bronchioles. The luminal diameter decreases as the branching increases more peripherally into the lungs. The walls of the airway down to the level of the...
Tracheobronchopathia osteochondroplastica (TO) is a very rare idiopathic non-neoplastic tracheobronchial abnormality.
The estimated prevalence on routine bronchoscopy can be up to 0.7%. It typically affects those in the 5th to 6th decades and there may be a male predilection 4.
Tracheomalacia, or sometimes described as tracheobronchomalacia, is a common incidental finding on imaging of the chest of older patients and manifests as an increase in tracheal diameter as well as a tendency to collapse on expiration. Generally, more than 70% collapse of the trachea during exp...
A dilated trachea has numerous causes, and in almost all cases represents tracheomalacia (increased size and increased compliance).
As is almost always the case, various diameters have been used. Typical figures include >26 mm in men, >23 mm in women or >3 cm for both genders.
Although many of...
Tracheo-oesophageal fistula is a pathological communication between the trachea and oesophagus.
It can be broadly classified into two types:
congenital tracheo-oesophageal fistula
acquired tracheo-oesophageal fistula: from malignancy/tuberculosis
Traction bronchiectasis refers to an aetiological sub type of bronchiectasis where there is irreversible dilatation of bronchi and bronchioles within areas of pulmonary fibrosis or distorted lung parenchymal architecture.
It can arise from a number of underlying causes which result i...
Trade-offs exist when changing imaging parameters to obtain the best images possible. The SNR, resolution, and acquisition time, are all interrelated. Changing one effects the others. An important job of the radiologist and MR radiographer is to decide what factors are more important for an exam...
Trampoline fractures are transverse fractures of the proximal tibial metaphysis that occur in children while jumping on a trampoline (or inflatable castle).
The fracture is thought to occur when a second, usually heavier individual causes the jumping surface to recoil upwards as the unsuspectin...
Tramp-stamp oedema is a colloquial term used by some radiologists to denote posterior lumbar subcutaneous oedema. The term is used to describe oedema in the distribution seen with lower back tattoos, usually in young women, which are known pejoratively as tramp-stamps.
This oedema is thought t...
Tram-track sign in the brain refers to the parallel calcification of the cortex in patients with Sturge-Weber syndrome 1.
It should not be confused with other tram-track signs elsewhere in the body.
Tram-track sign may be used in chest radiography or CT to denote the thickened non-tapering (parallel) walls of cylindrical bronchiectasis.
It should not be confused with other tram-track signs elsewhere in the body.
Tram-track sign may refer to a variety of appearances characterised by near-parallel lines in a number of contexts and regions including:
tram-track sign (brain): cortical calcification in Sturge-Weber syndrome
tram-track sign (orbit): e.g. optic nerve meningioma
tram-track sign (chest): thic...
Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may however also be seen in 1:
Transalar (transsphenoidal) herniation describes herniation of brain matter in and around the middle cranial fossa across the greater sphenoid wing and can be ascending or descending. Compression of structures against the sphenoid bone results in symptoms.
Transalar herniation is not...
Interhemispheric transcallosal approach is a common access route for surgery on the bodies of the lateral ventricles, and third ventricle, which does not lead to serious neurological deficits. It is therefore used for resection of intraventricular tumours such as:
Transcatheter aortic valve implantation or replacement (TAVI/TAVR) is a technique to replace the aortic valve through a transvascular or transapical approach. Compared to traditional open aortic valve replacement with sternotomy and a heart-lung bypass machine, the TAVI technique is less invasiv...
Transarterial chemoembolisation therapy (TACE) is a localised method of administrating chemotherapy directly to a liver tumour via a catheter study.
Transarterial embolisation (TAE) (i.e. without a chemotherapy agent added) is also used, and there is evidence that this may be just as effective ...
Transcoelomic spread describes the spread of a malignancy into body cavities that occurs via penetrating the surface of the peritoneal, pleural, pericardial, or subarachnoid spaces. For example, ovarian tumours can spread transperitoneally to the surface of the liver.
The transcriptome represents the portion of the genetic code of a cell which is transcribed into RNA (mRNA, tRNA, rRNA and non-coding RNA). It can be used to understand gene expression and signaling pathways.
Transependymal oedema, also known as interstitial cerebral oedema, is a type of cerebral oedema that occurs with increased pressure within the cerebral ventricles. FLAIR MRI sequence is the most sensitive MRI sequence to detect this type of oedema.
The ventricular ependymal lining is...
Transforaminal lumbar interbody fusion (TLIF) is a spinal fusion procedure performed as an alternative to posterior lumbar interbody fusion (PLIF) when posterior decompression of the spinal canal is not required 1.
A facetectomy is usually performed followed by a discectomy and insertion of in...
Transforaminal nerve root injfection is performed for radicular pain treatment and diagnosis.
See spinal interventional procedures for complications and equipment.
The desired needle tip position is just lateral to the pedicle immediately below the...
Transfusion related acute lung injury (TRALI) is defined as non-cardiogenic pulmonary oedema temporally related to transfusion therapy.
It tends to occur within 6 hours after a blood transfusion and requires exclusion of other alternative diagnoses such as sepsis, volume overload.
Transhiatal oesophagectomy is a type of oesophagectomy, a surgery that removes the distal oesophagus, usually for oesophageal carcinoma.
Removal of the oesophagus can be performed through the chest wall (a transthoracic oesophagectomy), but the thoracotomy is a major component of patient pain a...
Transient abnormal myelopoiesis (TAM) is a phenomenon that can happen in the fetuses or neonates with trisomy 21. The condition can mimic leukaemia.
The estimated incidence is at ~10% of newborns with trisomy 21 3.
In the context of kn...
Transient elastography most often refers to a type of elastography which relies on a mechanical pulse generated by an external probe.
The principle is similar to shear wave elastography, in that the elastic modulus is generated from shear wave velocity, but the application of the pulse from an ...
Transient global amnesia (TGA) is a clinical syndrome with no clear aetiology identified. Most symptoms are transient and resolve within a few hours.
Most common in patients of older age (50-70 years old).
Anterograde and partial retrograde amnesia lasting...
Transient hepatic attenuation differences (THAD) lesions refer to areas of parenchymal enhancement visible during the hepatic artery phase on helical CT. They are thought to be a physiological phenomenon caused by the dual hepatic blood supply. Occasionally they may be associated with hepatic tu...
Transient hepatic intensity differences (THIDs) are a phenomenon observed on MRI imaging of the liver. They are considered a direct equivalent to transient hepatic attenuation differences (THADs) noted on CT. They may be focal or nonfocal.
A focal THID lesion can arise...
Transient (non-obstructing) intussusception without a lead point is known to occur in both adults and children and occurs more frequently than was previously reported.
Transient intussusception of the small bowel has been reported in adults with coeliac disease and Crohn disease but is most fre...
Transient ischaemic attack (TIA), in the most recent definition, corresponds to a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction.
In the past, TIA was arbitrarily distinguished from stroke by the dur...
Transient ischaemic dilatation (TID) is a paradoxical phenomenon seen in myocardial perfusion SPECT imaging.
With severe balanced coronary artery disease, myocardial ischaemia may result in apparent enlargement of the left ventricular cavity during stress. The cause of this is not entirely cl...