A surgical sieve is an approach to differential diagnosis that helps, especially when under the pressure of the exam situation. Differentials from the sections of the sieve can be considered in turn, helping to extend the list in a structured way. They include:
Suspicious breast calcifications are calcifications within the breast that are not benign. These calcification need further work up and biopsy. These can be divided as
suspicious calcification of intermediate concern
suspicious calcification raising high probability of malignancy
Swan neck deformity is a deformity of the digits that consists of:
hyperextension of the proximal interphalangeal (PIP) joints
compensatory flexion of the distal interphalangeal (DIP) joints
Swan neck deformity is seen in 3,4:
rheumatoid arthritis (classical association)
There are a large number of causes for a symmetrical periosteal reaction 1,2:
chronic venous insufficiency
physiologic periosteal reaction of the newborn (Caffey disease), most common cause before 6 months old
juvenile idiopathic arthritis
Synchronous primary lung carcinoma (SPLC) is a term given to the occurrence of two or more primary lung carcinomas within different portions of the lung in the same time period.
They are thought to the carry the same pathophysiological mechanism as metachronous lung carcinoma (i.e. two or more ...
Syndactyly refers to a congenital fusion of two or more digits. It may be confined to soft tissue (soft tissue syndactyly / simple syndactyly) or may involve bone (bony syndactyly / complex syndactyly).
The overall estimated incidence is at ~1 per 2500 to 5000 live births 6,8. The...
Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus. They are seen in only a limited number of conditions including:
Appearance on plain radiographs comprises v...
Syringobulbia is a rare entity and refers to a syrinx that extends into the medulla oblongata 1.
Some authors use syringobulbia to refer to a syrinx present in any portion of the brainstem rather than specifically involving the medulla oblongata, and therefore encompassing syringop...
Syrinx is the collective name given to hydromyelia, syringomyelia, syringobulbia, syringopontia, syringomesencephaly, and syringocephalus.
The use of the general term 'syrinx' has grown out of the difficulty in distinguishing between hydromyelia and syringomyelia using current imag...
Thoracic manifestations of systemic lupus erythematosus can be variable.
For a general discussion, and for links to other system specific manifestations, please refer to the article on systemic lupus erythematosus.
pleuritis: considered one of the c...
There are many types of talar dislocation given its multiple articulations:
total talar dislocation
Talar fractures are an uncommon injury, accounting for <5% of all foot fractures. Recognition of the unique talar anatomy is important for correct diagnosis.
talar head fractures
talar neck fractures
talar body fractures
talar dome osteochondral fracture
Tauopathies are a heterogeneous group of neurodegenerative diseases characterised by abnormal metabolism of tau proteins leading to intracellular accumulation and formation of neurofibrillary tangles (NFT). These neurofibrillary tangles are deposited in the cytosol of neurons and glial cells.
Tear drop sign of the superior mesenteric vein (SMV) 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.
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
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
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)
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 diaphragm red...
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 rapid recognition and treatment is required if a cardiorespiratory arrest is to be a...
The differential diagnosis for a terminal ileitis is quite extensive, and includes:
inflammatory bowel disease
Crohn's disease (most common)
backwash ileitis due to ulcerative colitis
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...
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 ...
Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In t...
Testicular trauma is the third most-common cause of acute scrotal pain and may result in various degree of damage to the testes.
Testicular rupture and testicular ischaemia/infarct are two severe complications which need to be ruled out. Other injuries that can occur include 1:
The four "Ds" of radiology reporting are the basic sequential tasks that a radiologist performs when reporting/reading a case, whether it be in training, the exam environment or in day-to-day clinical practice.
The 4 "Ds"
Diagnosis or differential diagnoses
There are a number of causes and mimics of thoracic aortic dilatation.
post-stenotic dilatation, e.g. bicuspid aortic valve
thoracic aortic aneurysm
atherosclerosis (usually descending thoracic aorta)
The differential for thoracic aortic stenosis includes:
aortitis (especially Takayasu arteritis)
Williams syndrome: supravalvular aortic stenosis
congenital rubella syndrome: supravalvular aortic stenosis
Thoracoliths are rare, calcified pleural-based nodules that are almost always incidental findings. They are usually considered mobile, and more common on the left.
The exact aetiology is unknown and theories include 1,2:
calcified fibrin body
degenerated pleural lipoma
Thorotrast is a radioactive radiographic contrast agent containing thorium dioxide first produced in Germany in 1928 and was in use until the 1950s. It was used primarily for cerebral angiography, and 90% of the estimated 50,000-100,000 patients who received it were studied for this purpose.
Threatened miscarriage (or threatened abortion) is mainly a clinical term, used when a pregnant woman in first 20 weeks of gestation presents with spotting, mild abdominal pain and contractions, with a closed cervical os.
It occurs in 20-25% of pregnancies and is associated with ...
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 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
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 nor synonymised with hyperthyroidism, the latter of which is a g...
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...
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...
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 ...
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 ...
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 a relatively common occurrence 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 appearances a...
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 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 is a benign radiological finding of the middle aged and elderly and is usually of no clinical significance.
The appearance is often striking as individual tracheal rings become radio-opaque and stand out from the soft tissue mediastinum.
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 %
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% of collapse of the trachea during ...
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...
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...
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...
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 lesions of the splenium of the corpus callosum, also known as mild encephalitis/encephalopathy with a reversible isolated SCC lesion (MERS), are occasionally encountered on MRI studies and may be due to a number of underlying aetiologies.
Unlike other causes of ...
Transtentorial herniation is a type of cerebral herniation. There are two types:
descending transtentorial herniation, more frequently known as uncal herniation
ascending transtentorial herniation, which is less common than uncal herniation
Trapped lung, also known as unexpandable/unexpanded lung, is a term used where there is non-expandable lung after fluid removal, often thoracentesis. It is similar to but not entirely synonymous with the term lung entrapment, which is a similar condition but caused by active pleural disease rath...
Trauma is a leading cause of mortality in pregnancy. Pregnancy increases the incidence and severity of abdominal trauma in females.
Trauma affects up to 7% of pregnancies, and the incidence of pregnancy in level 1 trauma patients is estimated to be ~2% 1.
Traumatic spinal cord injury can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal stenos...
The triangle of Guillain and Mollaret, also known as dentatorubro-olivary pathway, has three corners 1:
inferior olivary nucleus
contralateral dentate nucleus
Connecting fibres are only identified between the red nucleus and inferior olivary nucleus (central tegmental tract) and ...
Triphalangeal thumb is considered a form of pre-axial polydactyly.
Triphalangeal thumbs have an incidence of 1 in 25,000 7.
A triphalangeal thumb, as the name implies, has three phalanges instead of the usual two. There is an autosomal dominant genetic transmission 8....
Troponin elevation can occur from a number causes although there is no imaging involved, it is useful for the radiologist to have a basic understanding of their causes (especially when interpreting imaging findings associated with troponin elevation). The cardiac troponin complex consists of thr...
Tuberculosis of the central nervous system can result from either haematogenous spread from distant systemic infection (e.g. pulmonary tuberculosis) or direct extension from local infection (e.g. tuberculous otomastoiditis).
Intracranial manifestations of tuberculosis are protean and can affect...
Tuberculous adrenalitis is the result of adrenal mycobacterium tuberculosis (TB) infection. Its incidence has decreased in the western world with the declining incidence of tuberculosis.
As the tuberculous infection causes destruction of the adrenal cortex, primary adrenal insufficie...
Tumours of the chest wall are varied, some of which are found most often in this region. They can be divided into benign and malignant tumours and into those which arise in the ribcage and those of soft tissue density.
Benign tumours include 1,3-4:
Tumours of the male urethra are uncommon. They can be categorised both on the grounds of histology and location.
squamous cell carcinoma of the urethra: 80%
urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra)
adenocarcinoma of the urethra: 5...
The small intestine is rarely the site of malignant tumours, although it accounts for ~75% of the entire length of the GI tract and more than 90% of the mucosal surface. Approximately 40 different histologic tumour types have been described.
In this article, an overview will be given of the mo...
Tumours that metastasise to bone may be remembered using the mnemonic "lead kettle" spelled PBKTL (lead is Pb on the Periodic Table).
For females, breast and lung are the most common primary sites; nearly 80% of cancers t...
Twin pregnancies are the most common multifetal pregnancies.
Multifetal pregnancies account for ~ 1% of all pregnancies, but are seen in much higher numbers in populations where in vitro fertilisation (IVF) is a common practice, most of which are twin pregnancies.
Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna.
Ulnar variance may be:
neutral (both the ulnar and radial articular surfaces at the same level)
positive (ulna projects more distally)
negative (ulna projec...
Ultrasound appearance of liver metastases can have bewildering variation.Caveat: Presence of hepatic steatosis can affect the sonographic appearance of liver lesions.
Patterns do exist between ultrasound appearance of the liver metastases and the likely primary, which is sometimes helpful in di...
Umbilical cord cysts can refer to any cystic lesion associated with the umbilical cord. They can be single (commoner) or multiple.
They may be seen in ~3% of pregnancies in the first trimester 8.
Umbilical cord cysts can represent either true or false cysts:
Unilateral axillary lymphadenopathy while being more concerning than bilateral axillary lymphadenopathy can still arise from a various benign as well as malignant causes.
other regional infective causes
ipsilateral arm infection, e.g. cellulitis
Unilateral facet dislocation is a relatively stable type of facet dislocation.
Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
Unilateral pulmonary oedema represents only 2% of cardiogenic pulmonary oedema with predilection for the right upper lobe and is strongly associated with severe mitral regurgitation 1, 2. It is hypothesised that the regurgitation jet is directed towards the right superior pulmonary vein thus pre...
An upper gastrointestinal bleed usually refers to bleeding proximal to the ligament of Treitz.
Distribution of bronchiectasis can help in narrowing the differential diagnosis. Upper lobe bronchiectasis is typically seen in:
Rarely it may be seen with non tuberculous mycobacterial infection (e.g. MAC infection 2)
When in mid-upper lobes also consid...
There are numerous causes of urinary bladder diverticula:
Primary (congenital or idiopathic)
Hutch diverticulum (in paraureteral region)
Bladder outlet obstruction
bladder neck stenosis
posterior urethral valve
prostatic enlargement (hypertrophy; carcinoma)
Bladder diverticulum are outpouchings from the bladder wall, whereby mucosa herniates through the bladder wall. They may be solitary or multiple in nature and can vary considerably in size.
There are two peaks - one at 10 years and the other at 60-70 years 2.
Causes of urinary bladder wall or lumen calcification include:
schistosomiasis of the urinary tract
calculus in a urachal cyst or in a bladder divertic...
Urinary diversion is created after the removal of the urinary bladder (radical cystectomy or cystoprostatectomy, usually done to treat invasive bladder cancer).
There are three main varieties:
neobladder formed from a segment of ileum (i.e. ileal conduit, also known as a "Bricker conduit")
Uterine enlargement can occur in a number of situations from both diffuse and focal processes. These include:
gestation related events
normal intrauterine pregnancy
molar pregnancy - gestational trophoblastic disease
postpartum uterus - still larger than usual
The terms valgus and varus refer to angulation (or bowing) within the shaft of a bone or at a joint.
It is determined by the distal part being more medial or lateral than it should be. Whenever the distal part is more lateral, it is called valgus. Whenever the distal part is more medial, it is ...
The Valsalva manoeuvre is the forced expiration of air against a closed airway, resulting in increased intra-abdominal, intrathoracic and pharyngeal pressure. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling.
It is commonly u...
Valvular heart diseases, or cardiac valvulopathies, describe any acquired or congenital disease affecting one or more of the four cardiac valves.
This is a general index article that classifies cardiac valvulopathies depending on which valve(s) is affected 1. See individual articles for in-dept...
Vascular pedicle is bordered on the right by venous structures (right brachiocephalic vein above and superior vena cava) and on the left by an arterial structure (the left subclavian artery origin). The azygos vein (black oval) is seen en face above the right main bronchus.
The vascular pedicle...
Vascular rings and slings refer to the congenital vascular encirclement of the oesophagus and/or trachea by anomalous/aberrant vessels.
Vascular rings are rare, occurring in <1% of patients 1. No gender or ethnic predispositions have been identified 3.
Venous thromboembolism covers a wide spectrum of diseases. Individual conditions and complicating condition include:
deep vein thrombosis (DVT)
pulmonary embolism (PE)
dural venous sinus thrombosis
Ventriculomegaly is defined as enlargement of the ventricles. Simply, there are two causes:
Refer to the article on hydrocephalus vs. atrophy for more details on how to differentiate both entities.
Ventriculoperitoneal (VP) shunts are a device used in the treatment of non-obstructive hydrocephalus.
As the name suggests, a catheter is placed in the ventricle, and another catheter travels under the skin to opens into the peritoneal cavity, both the catheters being connected to each other th...
The differential diagnosis for a vertebral body mass is broad and may range from a completely benign, sclerotic enostosis (bone island) to a malignant primary bone tumour.
Broadly, these lesions can be separated into:
primary bone tumours
Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring).
Vertebra plana (a.k.a. pancake / silver dollar / coin-on-edge vertebra) is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Plural is vertebrae planae. It can occur in a variety of settings, incl...
Vertical-banded gastroplasty (VBG) is an older, purely restrictive procedure used to treat morbid obesity.
It involves creating a small gastric pouch, based on the lesser curvature of the stomach (which is thicker and less resistant to stretching than the greater curvature), by using...
Very bizarre generalised lesions of bone tend to make you exclaim "Oh my! What is going here?" Although there are numerous potential causes, in this situation it is worth thinking of a number of entities:
skeletal dysplasias and metabolic diseases
The vestibular line of Lapayowker refers to a vertical line passing down the most lateral aspect of vestibular apparatus. The petrous part of internal carotid artery lies medial to this line but lies lateral to it in the case of an aberrant internal carotid artery which is the characteristic ang...
Viral encephalitides are the result of the brain parenchyma infection by a number of different viruses, many of which have similar presentations and imaging features. Specific diagnosis often requires PCR.
For viral infection of the meninges, please refer to the general article on viral mening...