V/Q (ventilation/perfusion) scan is a scintigraphic examination of the lung that evaluates pulmonary vasculature perfusion and segmental bronchoalveolar tree ventilation.
diagnosis of suspected pulmonary embolism (PE)
monitor pulmonary function following lung transplant
VACTERL is an acronym that describes a non-random constellation of congenital anomalies. It is not a true syndrome as such and is equivalent to the VATER anomaly.
The estimated incidence is 1 in 10,000-40,000 births 3.
The acronym VACTERL derives from:
V: vertebral an...
The VACTERL-H association is a rare non-random association which bears the features of the standard VACTERL association with added fetal hydrocephalus.
Unlike the standard VACTERL association which is sporadic, the VACTERL-H is hereditory with both X linked 3 and autosomal recessive 2 inheritan...
Vacuum phenomenon in the shoulder refers to the presence of intra-articular gas in the shoulder joint. It is a very common occurrence, particularly in external rotation. This can cause circular or linear areas of low signal intensity on GRE MR images of the shoulder obtained with external rotati...
The vagina is a midline fibromuscular tubular structure positioned in the female perineum extending superiorly to the cervix and uterus in the pelvis.
Gross morphology and relations
The vagina is 8-10cm in length, extending posterosuperiorly from the vestibule through the urogential diaphragm...
The vaginal artery is a branch of the anterior division of the internal iliac artery, and should not to be mistaken with the vaginal branch of the uterine artery. It is often considered to be a homolog of the inferior vesical artery, which is present only in males.
origin: anterior div...
Vaginal atresia refers to a spectrum of anomalies comprising of failure to form a part or all of the vagina.
It is considered the second most common cause of primary amenorrhea. The estimated
Incidence is at ~ 2 in 10000 women.
The most common sym...
The staging of primary vaginal cancer covers for all histological sub types and is as follows
FIGO staging system
stage 0: carcinoma in situ
stage I: tumour confined to vagina
stage II: invasion of paravaginal tissues but no extension beyond pelvic side walls
stage III: extension to pelvic ...
A vaginal leiomyoma is an extremely rare entity and falls under extra uterine pelvic leiomyomas.
They are extremely rare with only ~ 300 cases reported in literature 3.
It may occur anywhere along the vaginal canal and is usually localized, mobile, non-tender, and cir...
Vaginal lymphoma can refer to:
secondary involvement of the vagina (secondary vaginal lymphoma) from widespread generalised lymphoma
usually comprises of diffuse large cell B non-Hodgkin's lymphoma (DLBCL) 2
primary vaginal lymphoma
A vaginal pessary is a device inserted into the vagina which can either be mechanical or pharmaceutical.
A mechanical pessary is most commonly used to treat uterine prolapse. It is also used to treat stress urinary incontinence, a retroverted uterus, cystocele and rectocele. A bewildering array...
Vaginal stenosis refers to a narrowing of the vagina, it can be congenital or acquired.
Acquired causes include
scarring from prior pelvic irradiation - brachytherapy
Depending on the site of stenosis and state of menstruation there can be a...
Vagoglossopharyngeal neuralgia is an uncommon presentation of glossopharyngeal neuralgia where the typical symptoms of pain are associated with cardiac symptoms including arrhythmias, asystole, and syncope.
It is believed to be due to complex interconnections between the nervus intermedius, the...
The vagus nerve is the tenth cranial nerve and provides the bulk of the parasympathetic input to the gastrointestinal system and to the heart. It is a mixed sensory/motor/parasympathetic nerve.
The vagus nerve arises as multiple rootlets at the posterolatera...
The valence shell of an atom is the outermost shell of the electron cloud. It plays a large part in determining the chemical, thermal, optical and
electrical properties of the element. This occurs because it often not
full and movement of electrons may occur between it and a) electrons...
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 pressures. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling.
It is commonly ...
The valvulae conniventes, also known as Kerckring folds or plicae circulares, are the mucosal folds of the small intestine, starting from the second part of the duodenum, they are large and thick at the jejunum and considerably decrease in size distally in the ileum to disappear entirely in the ...
Van Buchem disease (VBD) is an extremely rare hereditary sclerosing bone dysplasia, also known as hyperostosis corticalis generalisata. This disease is characterised most notably by mandibular enlargement and thickening of the skull.
Less than 30 cases have been reported in the li...
van der Woude syndrome (VWS) is characterized by the association of congenital lower lip fistulae / pits with cleft lip and / or palate.
It is the one of the most common clefting syndromes in humans 1. VWS individuals have a high prevalence of hypodontia.
It carries anau...
Vanishing vertebrae is a rare ischaemic manifestation of sickle cell disease, in which a completely infarcted vertebral body literally disappears or vanishes, as a result of infarction. In the few reported cases, the posterior elements remain intact.
codfish or h-shaped vertebrae
Vanishing white matter disease (VWM), also known as childhood ataxia with central hypomyelination (CACH), is an exceedingly rare entity only fully described in 1997, but due to its name sometimes over-represented in differentials for white matter disease.
Most cases are encountere...
Variant anatomy of the aortic arch occurs when there is failure of normal aortic development. It results in a number of heterogenous anomalies of the aorta and its branch vessels.
Normally, the aorta ascends in the superior mediastinum to the level of the sternal notch before ar...
Variation in hepatic arterial anatomy is seen in 40-45% of people. Classic branching of the common hepatic artery from the coeliac artery, and the proper hepatic artery into right and left hepatic arteries to supply the entire liver, is seen in 55-60% of the population.
In general, the common ...
There can be several variations with cord insertion into the placenta:
central insertion (~90%): normal situation
eccentric cord insertion: lateral insertion of the umbilical cord at > 2 cm of the placental margin
sometimes used synonymous with marginal cord insertion
marginal cord insert...
There can be many variations in fetal presentation which is determined by which part of the fetus is projecting towards the internal cervical os. This includes:
cephalic presentation: fetal head presenting towards the internal cervical os, considered normal and occurs in the vast majority of b...
There can be several variations in placental morphology. These include:
single lobed discoid placenta (single disc): most common scenario
bilobed placenta: two near equal size lobes
succenturiate lobe(s): one of more smaller accessory lobes
circumvallate placenta: rolled placental edges with...
Varicella pneumonia is a type of viral pneumonia. It is a common cause of multiple small round calcific lung lesions. Varicella-zoster virus (VZV) most commonly causes self-limited benign disease (chickenpox) in children. However, in adults it tends to cause significant complications such as VZV...
Varicella zoster virus (VZV) encephalitis can be due to either an immune reaction to primary infection or reactivation of latent infection in cranial nerve or dorsal root ganglia following childhood chickenpox.
Manifestations following primary infection include:
Varicocele grading can be done variably. The most elaborate and accepted grading was given by Sarteschi, which is briefed below.
For a general discussion of this condition refer to the article: varicocele.
first do a baseline grey scale study in supine position and measure the dia...
Varicocoele is the dilatation of pampiniform plexus of veins, a network of many small veins found in the male spermatic cord. It is the most frequently encountered mass of the spermatic cord and is characterised by abnormal dilatation of the pampiniform plexus.
The estimated incid...
Varicocoele embolisation is a method treating varicocoeles by embolising the testicular vein.
failed surgical ligation
Relative contraindications include:
intravenous contrast allergy
Varicose bronchiectasis refers to a morphological sub type of bronchiectasis. According to one study, this type as a pure form accounted for ~10% of all bronchiectasis 1. In this form there are intermittent narrowed and dilated segment to the affected bronchus when viewed in long axis and can gi...
Varicose veins are dilated tortuous superficially located venous channels that accompany the superficial veins of the upper or lower limbs.
Varicose veins are more common in men than women, and are more common in the lower limb than in the upper limb. Risk factors include:
Vasa previa is a term given when there are abnormal fetal vessels within the amniotic membranes that either cross or run in extreme close proximity to the internal cervical os.
Vasa previa can be of two types
type I (present in ~ 90% of cases with vasa previa 3): abnormal fetal vess...
The VASARI MRI feature set is a system designed to enable consistent description of gliomas using a set of defined visual features and controlled vocabulary. It is the result of work by The Cancer Imaging Archive (TCIA) who publish relevant guides to use, and additional resources 1,2. The system...
Aorta - variants
SVC & IVC - variants
Intracranial arteries - variants
Vascular calcifications in the breast are calcifications associated with blood vessels.
They are most often seen in post menopausal women with arteriosclerotic heart disease.
Results due to calcified atherosclerotic plaques in the arterial walls.
Vascular compression disorders are numerous and can be divided into those cases where a vascular structure is the "compress-er" or the "compress-ee" . Some conditions fall into both categories, where one vessel compresses another.
Compression of a vascular structure
Vascular dementia, also known as vascular cognitive impairment, is the second most common cause of dementia after the far more common Alzheimer's disease. It is primarily seen in patients with atherosclerosis and chronic hypertension and results from the accumulation of multiple white matter or ...
Vascular Ehlers-Danlos syndrome (VEDS) or type IV Ehlers-Danlos syndrome (EDS 4) is the most malignant form of Ehlers-Danlos syndrome. This form is often accompanied by neuro-vascular complications secondary to vessel dissections and/or aneurysms.
This results from a mutation in the ...
Vascular malformations and tumours are a heterogeneous group of lesions that may affect the arterial, capillary, venous or lymphatic system or any combination thereof. They encompass a bewildering range of lesions, syndromes, and masses ranging from the relatively common (e.g. infantile hemangi...
Venous pathology is common and includes:
disorders of vessel wall
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.
coeliac artery compression syndrome
hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
hypothenar hammer syndrome
thoracic aortic injury
renal pedicle injury
Vasculitis describes generalised inflammation of vessels. Vasculidities carry a broad range of clinical presentations and as a whole can involve almost any organ system.
Some vasculitides are due to direct vessel injury from an infectious agent. However a large proportion show eviden...
Vasculopathies caused by varicella zoster virus (VZV) represent a group of illness involving both small and large CNS arteries caused by a inflammatory process involving the media and the vascular endothelium, usually in immunocompromised individuals due the viral reactivation and spread thought...
Vasogenic cerebral oedema refers to a type of cerebral oedema in which the blood brain barrier (BBB) is disrupted (cf. cytotoxic cerebral oedema, where BBB is intact). It is an extracellular oedema which mainly affects the white matter via leakage of fluid from capillaries.
It is most frequentl...
The vastus intermedius muscle is one of the four quadriceps muscle. The others are the vastus medialis, the lateralis, and the rectus femoris.
upper two thirds of anterior and lateral surfaces
lateral margin of patella
lateral condyle of...
The vastus lateralis is the largest of the quadriceps muscles. The others are the vastus medialis, the vastus intermedius, and the rectus femoris.
lateral part of intertrochanteric line
margin of greater trochanter
lateral margin of gluteal tuberosity
lateral lip of...
The vastus medialis muscle is one of the four quadriceps muscle. The others are the vastus intermedius, the vastus lateralis, and the rectus femoris.
medial part of intertrochanteric line
medial lip of the linea aspera
medial supracondylar line
VATER (equivalent to VACTERL) is the non-random constellation of a number of congenital anomalies.
V : vertebral anomalies
A : anal atresia
TE : tracheo-oesophageal fistulas
R : radial ray hypoplasia, polydactyly and renal agenesis
The prevalence of at least 3/5 anomalies oc...
There are many signs in radiology which are vegetable and plant inspired, they include
celery stalk metaphysis: osteopathia striata and congenital rubella infection
celery stalk anterior cruciate ligament: ACL mucoid degeneration
Christmas tree intestinal atresia
The vein of Galen, also known as the great cerebral vein or great vein of Galen, is a short trunk formed by the union of the two internal cerebral veins and basal veins of Rosenthal. It lies in the quadrigeminal cistern. It curves backward and upward around the posterior border of the splenium o...
Vein of Galen aneurysmal malformations (VGAM's), probably better termed as median prosencephalic arteriovenous fistula, are uncommon intracranial anomalies that tend to present dramatically during early childhood with features of a left-to-right shunt and high-output cardiac failure.
The vein of Labbé, also known as inferior anastomotic vein, is part of the superficial venous system of the brain.
The vein of Labbé is the largest channel that crosses the temporal lobe between the Sylvian fissure and the transverse sinus and connects the superficial middle cerebral vein and ...
Veins of Sappey are small veins around the falciform ligament that drain the venous blood from the anterior part of the abdominal wall directly into the liver. This flow dilutes the portal perfusion at these sites, causing hepatic pseudolesions.
The superior vein of Sappey drains...
Velamentous cord insertion is one of the types of abnormal umbilical cord insertion into the placenta.
The estimated incidence is ~1% in singleton and ~9% in twin pregnancies respectively. It is also more common in placenta previa than in normally located placentas. The prevalence...
The velum interpositum is a small membrane containing a potential space just above and anterior to the pineal gland which can become enlarged to form a cavum velum interpositum.
The velum interpositum is formed by an invagination of pia matter forming a triangular membrane the a...
Vena cava filter is an endovascular device which is typically placed in the infrarenal inferior vena cava (IVC) to prevent pulmonary embolism in selected patients. This procedure is most often performed by interventional radiologists under fluoroscopic guidance.
The vena caval foramen is one of the three major apertures in the diaphragm. It is the highest of the three and situated at the level of T8-9. It is quadrilateral and placed at the junction of the right and middle leaflets of the central tendon.
It transmits several structures between the thora...
The venous distension sign is a finding that may be identified on sagittal imaging of the dural venous sinuses which is said to have a diagnostic sensitivity and specificity of 94% for intracranial hypotension. The sign is positive when there is a convex inferior margin of the midportion of the ...
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
Venous vascular malformations of the facial nerve, previously known as facial nerve haemangiomas, are rare benign vascular malformations of the facial nerve usually presenting as a facial nerve palsy, which can be rapid onset mimicking a Bell palsy.
As they do not appear to have c...
Ventilator-associated pneumonia (VAP) is a form of hospital acquired pneumonia (considered the commonest form 3).
It is sometimes defined as as a pneumonia occurring more than 48 hours after patients have been intubated and received mechanical ventilation 5.
It is usually suspected when the pa...
Ventral cord herniation, also known by a variety of other terms such as spontaneous thoracic cord herniation or idiopathic spinal cord herniation, is a rare cause of focal myelopathy due to herniation of the thoracic cord through a dural defect.
Post surgical cord herniation can occur at any l...
Ventricular septal defects (VSD) represent defects in the interventricular septum that allow a haemodynamic communication between the right and left ventricles. It typically results in a left-to-right shunt.
They represent one of the most common congenital cardiac anomalies and ma...
The ventricular system in the brain is composed of CSF-filled ventricles and their connecting foraminae. They are continuous with the central spinal canal.
two lateral ventricles
The interconnections between the ventricles occurs through the following:
Ventriculitis refers to inflammation, usually due to infection, of the ependymal lining of the cerebral ventricles. It is most often due to intraventricular rupture of brain abscess.
Its epidemiology is varied and depends on the underlying cause.
meningitis (both pyogenic and vi...
Ventriculoatrial shunting is an alternative option for the diversion of CSF and relief of hydrocephalus. In this technique, the distal catheter is placed in the right atrium or even in the superior vena cava 1-2.
It is not the only alternative for the traditional ventriculoperitoneal shunt, an...
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...
Ventriculopleural shunting is an alternative option for the diversion of CSF and relief of hydrocephalus. In this technique, the distal catheter is placed in the pleural space. It is an alternative to a ventriculoperitoneal shunt (often considered a next most used alternative).
The ventriculus terminalis, also known as the 5th ventricle, is an ependymal-lined, anatomical remnant, positioned at the transition from the tip of the conus medullaris to the origin of the filum terminale.
It represents the canalization and retrogressive differentiation of the caudal end of ...
A Venus necklace is a term almost never used, but for the sake of completeness is included here. It is used by some authors 1 to describe a series of T2 hyperintense lesions on the inferior surface of the corpus callosum in the midline (callososeptal interface), most frequently seen in multiple ...
Vernet syndrome (also known as the jugular foramen syndrome) is a constellation of cranial nerve palsies due to compression from a jugular foramen lesion such as a glomus jugulare tumour or schwannoma. It consists of motor paralysis of:
glossopharyngeal nerve (CN IX)
vagus nerve (CN X)
Vertebra plana or pancake vertebra is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced crush fracture. It can occur with a variety of settings, including:
Langerhans cell histiocytosis (LCH)
Mnemonics to remember the causes of vertebra plana include:
E: eosinophilic granuloma
T: trauma; tuberculosis
F: fracture (trauma)
E: eosinophilic granuloma
T: tumor (e.g. metastases, myelom...
C7, also called vertebra prominens, is the seventh cervical vertebra and looks like vertebrae C3-C6, but has some distinct features making it an atypical vertebrae. The name vertebra prominens arises from its long spinous process, which is easily palpable.
C7 possesses the stand...
The vertebral column is affected by a range of anatomical variants of the body and/or neural arch as well as accessory ossicles.
The vertebral artery (VA) arises from the subclavian artery, ascends in the neck to supply the posterior fossa and occipital lobes as well as provides segmental vertebral and spinal column blood supply.
origin: branch of the 1st part of the subclavian artery
course: ascends posterior ...
Vertebral artery dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima. It is potentially lethal and can be difficult to diagnose clinically and radiologically.
Vertebral artery dissections have an incidence of 1-5 per...
Vertebral artery ectasia refers to an abnormal dilatation of the vertebral artery. It is also known as a Dolicoarterial loop (of Danziger).
Vertebral arterial wall thinning and elongation (usually age-related); majority are unilateral.
Occlusion of the carotid arteries (bilaterally)...
Vertebral artery thrombosis results in complete or partial occlusion of the vertebral artery and alteration of blood flow to the posterior cerebral circulation. Ischaemia or infarction to structures supplied by these arteries may result in a range of symptoms.
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 body squaring refers to loss of normal concavity of the anterior border. It is seen in a variety of conditions.
Ankylosing spondylitis is the most common cause of vertebral body squaring. It usually involves multiple levels and typically...
Vertebral haemangiomas are the most common benign vertebral neoplasms. They are usually asymptomatic and incidentally detected due to their characteristic features on imaging for other reasons.
Please refer on the article on primary intraosseous haemangioma for a general discussion in this enti...
Vertebral metastases represent the secondary involvement of the vertebral spine by haematogenous spread metastatic cells. They must be included in any differential diagnosis of a bone lesion in a patient older than the age of 40.
This article will focus only in the metastasis involving the bone...
Vertebral pneumatocysts refer to the presence of air filled cavity within the vertebrae, more prevalent on the cervical spine. Intraosseous pneumatocysts are more common adjacent to the sacroiliac joint while it is rare in the vertebral column. Other causes of vertebral air e.g. Kummel disease, ...
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).
Vertebral vascular foramina are normal findings seen on cross sectional imaging and should not be mistaken for a fracture, especially in the setting of trauma.
basivertebral veins (forms Hahn's canal): foramen seen on the posterior surface of vertebral body in midline