Articles
Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.
782 results found
Article
Unilateral testicular lesions
The differential diagnosis for unilateral testicular lesions is wide-ranging.
Neoplastic
Common
seminoma (40-50% of testicular malignancies)
non-seminomatous germ cell tumors:
testicular teratoma
testicular epidermoid (teratoma with ectodermal elements only)
testicular choriocarcinoma
t...
Article
Upper gastrointestinal bleeding (differential)
An upper gastrointestinal bleed usually refers to bleeding proximal to the ligament of Treitz.
Pathology
Causes
peptic ulcer
gastritis
esophagitis
duodenitis
Mallory-Weiss tear
varices
tumor
vascular abnormality
vascular ectasia
angiodysplasia
Dieulafoy lesion
vascular malformation...
Article
Upper lobe bronchiectasis
Distribution of bronchiectasis can help in narrowing the differential diagnosis. Upper lobe bronchiectasis is typically seen in:
cystic fibrosis
tuberculosis
Rarely it may be seen with non-tuberculous mycobacterial infection (e.g. MAC infection 2). Traction bronchiectasis in the upper lobes c...
Article
Ureteral calcification
Ureteral calcification refers to the presence of calcium concretions within the ureteral lumen or wall.
Common
ureteric calculi
Uncommon
neoplastic 3
transitional cell carcinoma
hemangioma
papilloma
infections
tuberculosis 1
schistosomiasis of the urinary tract
iatrogenic
radiation u...
Article
Urinary bladder diverticula (causes)
There are numerous causes of urinary bladder diverticula:
Primary (congenital or idiopathic)
Hutch diverticulum (in paraureteral region)
Secondary
bladder outlet obstruction
bladder neck stenosis
neurogenic bladder
posterior urethral valve
prostatic enlargement (hypertrophy; carcinoma)
...
Article
Urinary bladder diverticulum
A urinary bladder diverticulum (plural: diverticula) is an outpouching from the bladder wall, whereby mucosa herniates through the bladder wall. It may be solitary or multiple in nature and can vary considerably in size.
Epidemiology
There are two peaks; one at 10 years and the other at 60-70 ...
Article
Urinary bladder wall or lumen calcification (differential)
Causes of urinary bladder wall or lumen calcification include:
Common
bladder calculus
schistosomiasis of the urinary tract
tuberculosis
Uncommon
neuroblastoma; pheochromocytoma
radiation reaction
alkaptonuria (ochronosis)
amyloidosis
calculus in a urachal cyst or in a bladder divertic...
Article
Urinary diversion
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")
th...
Article
Uterine enlargement (differential)
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
hormonal causes
exogenous h...
Article
Vacuum phenomenon
Vacuum phenomena describe aseptic gas collections (e.g. nitrogen and traces of oxygen and or carbon dioxide) within different specific tissues 1-3. Usually, they are seen within the intervertebral discs, the bones and within different joints, but can also be seen in other usually adjacent locati...
Article
Valgus vs varus
The terms valgus and varus refer to angulation (or bowing) within the shaft of a bone or at a joint in the coronal plane.
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 i...
Article
Valsalva maneuver
The Valsalva maneuver 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...
Article
Valvular heart disease
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...
Article
Vascular pedicle
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...
Article
Vascular rings and slings
Vascular rings and slings refer to the congenital vascular encirclement of the esophagus and/or trachea by anomalous/aberrant vessels.
Epidemiology
Vascular rings are rare, occurring in <1% of patients 1. No gender or ethnic predispositions have been identified 3.
Clinical presentation
Man...
Article
Venous thromboembolism
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
Lemierre syndrome
tumor thrombus
Article
Ventriculomegaly
Ventriculomegaly is defined as enlargement of the ventricles. Simply, there are two causes:
hydrocephalus
communicating
non-communicating
parenchymal atrophy
Refer to the article on hydrocephalus vs atrophy for more details on how to differentiate both entities.
Article
Ventriculoperitoneal shunt
Ventriculoperitoneal (VP) shunts are a device used to shunt cerebrospinal fluid in the treatment of hydrocephalus.
As the name suggests, a catheter is placed with its tip in the ventricle. The external portion of the catheter is connected to a valve that regulates the flow of CSF based on a pre...
Article
Vertebral body mass
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 tumor.
Classification
Broadly, these lesions can be separated into:
non-neoplastic lesions
primary bone tumors
secondary metast...
Article
Vertebral scalloping
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).
Posterior scalloping
Causes of...
Article
Vertebra plana
Vertebra plana (plural: vertebrae planae), also known as the pancake or silver dollar or 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.
Pathology
It can occur in a v...
Article
Vertical-banded gastroplasty
Vertical-banded gastroplasty (VBG) is an older, purely restrictive procedure used to treat morbid obesity.
Procedure
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...
Article
Very bizarre generalized lesions of bone (differential)
Very bizarre generalized 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
Paget disease
fibrous dysplasia
phakomatose...
Article
Vestibular line of Lapayowker
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...
Article
Viral encephalitides
Viral encephalitides are the result of brain parenchymal 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 meningiti...
Article
Visceral artery aneurysm
Visceral artery aneurysms are abnormal focal dilatations of arteries supplying abdominal organs. Visceral artery aneurysms include both true aneurysms and pseudoaneurysms.
Owing to different clinical manifestations and a unique, specific, pathology, renal artery aneurysms are discussed separate...
Article
Vulval neoplasms
Vulval neoplasms are rare and mostly seen in elderly female patients. Squamous cell carcinoma (SCC) is the most common malignancy of the vulva and only 30% of them are associated with oncogenic human papillomaviruses (HPVs).
Pathology
Squamous neoplastic lesions
Premalignant
classic vulvar...
Article
Wackenheims line
Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal.
Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
Article
Wartenberg syndrome
Wartenberg syndrome also known as cheiralgia paresthetica is due to compression of the superficial branch of the radial nerve in the distal forearm. It can be secondary to tight watch band or handcuffs, compression from distal radius fracture or idiopathic.
Clinical presentation
Patients pres...
Article
Weight loss
A clinical presentation of weight loss is extremely common and often a source of marked anxiety for the patient. The commonest cause of unintentional weight loss (UWI) is gastrointestinal tract disease, and not malignancy.
Terminology
The published literature lacks a consistent definition of w...
Article
Well-defined breast cancers (differential)
Certain well-defined breast cancers tend to lack the characteristic spiculation and can give false reassurance of more benign entities on both ultrasound and mammography. These include:
certain high grade invasive ductal carcinomas: not enough time for a desmoplastic reaction to form spiculatio...
Article
White coat hypertension
White coat hypertension (abbreviated alternatively as WCH or WCHT), not to be confused with the white coat effect (WCE), is commonly defined as typical in-clinic blood pressure (BP) measurements of 140/90 mm Hg or more in the presence of multiple daytime out-of-clinic home or ambulatory BP readi...
Article
White matter changes in HIV
White matter changes in HIV have overlapping appearances and varied in etiology. These can be divided into:
primary effects of HIV
opportunistic infection
neoplasms
vascular disease
metabolic and nutritional disorders
Primary effects of HIV
HIV encephalitis
Opportunistic infection
cytom...
Article
WHO classification of tumors of soft tissue
The World Health Organization (WHO) classification of soft tissue tumors is the most widely used pathologic classification system for such disorders. The current revision, part of the 5th edition of the WHO series, was published in 2020 and is reflected in the article below 1.
Classification
A...
Article
Widening of interpedicular distance
The interpedicular distance, which is the distance measured between the pedicles on frontal/coronal imaging, can be widened in a number of situations.
Pathology
Etiology
diastematomyelia
syringomyelia
conditions that can cause dural ectasia (can potentially cause widening)
Marfan syndrome
...
Article
Widening of the presacral space (differential)
Widening of the presacral space is one of the diagnostic indicators of the diseases involving pelvic pathology and rectal involvement. It is ideally measured on barium studies at the level of S3/4 disc level on lateral radiographs and the normal value of the presacral space is <15 mm in adults....
Article
Winking owl sign (spine)
The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent 5.
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to...
Article
X-ray artifacts
X-ray artifacts can present in a variety of ways including abnormal shadows noted on a radiograph or degraded image quality, and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.
There are common and distinct artifacts for fi...