The anterior to posterior fibular gap illustrates the displacement of the proximal and distal fibular fragments in trans-syndesmotic lateral malleolar fractures on the lateral view of the ankle and might indicate a medial injury.
The anterior to posterior fibular gap can be used in the s...
The tibiotalar angle is between the anatomic axis of the tibia and the superior articular surface of the talar dome. Differently from the talar tilt, the tibiotalar angle uses the tibial longitudinal axis instead of the distal articular surface as a tibial reference point.
The first to second metatarsal distance or M1-M2 distance is the length between the bases of the first and second metatarsal bone and a measurement for the evaluation of midfoot instability.
The first to second metatarsal distance is used for the evaluation and classification of midfoot ...
The hallux interphalangeal angle is between the proximal and distal phalanx of the great toe and serves for the evaluation of toe deformity at the level of the first interphalangeal joint.
The hallux interphalangeal angle is used in the setting of hallux valgus or hallux varus to assess ...
The distal metatarsal articular angle (DMAA) evaluates the relationship between the longitudinal axis and the articular surface of the first metatarsophalangeal joint and thus metatarsophalangeal coverage or joint congruity on a weight-bearing dorsoplantar radiograph of the foot.
Autoimmune hemolytic anemia is a group of hemolytic anemias characterized by an antibody response to red blood cells. It can present as acute or chronic anemia. It can be idiopathic or can occur with other disorders.
Several types have been described:
warm-antibody type anemia (WAIHA)
A mnemonic to remember the radiographic signs of pulmonary edema is:
A: alveolar opacification
D: diffuse interstitial thickening (septal lines) and diversion (vascular upper zone diversion, cephalisation)
E: effusions (pleural)
Medial cuneiform-fifth metatarsal height is the distance between the most inferior part of the medial cuneiform and the most inferior part of the base of the 5th metatarsal and is used to evaluate the height and integrity of the medial vertical arch 1.
Medial cuneiform-fifth metatarsal h...
The ADNEX (Assessment of Different NEoplasias in the adneXa) model is a risk model developed by the IOTA (International Ovarian Tumor Analysis) group to differentiate benign and malignant neoplasms of the ovary and, among them, four different subgroups (borderline, stage I cancer, stage II-IV ca...
"Bow-tie sign" refers to the appearance of rotated facets in unilateral facet joint dislocation. Facet joint displacement coupled with a rotational deformity gives a bow-like like appearance on a lateral view radiograph of spine 1.
Talar shift is a concept, sign and/or measurement describing a displacement of the talus in relation to the articular surface of the distal tibia and the malleolar end segment. The direction of the talar shift is further described in the medical literature and lateral talar shift receives the mo...
Talar tilt is a measurement of the angle between the talus and the distal tibia, used in the assessment of ankle instability and ankle osteoarthritis (OA).
Talar tilt is an important measurement in the assessment of ankle osteoarthritis. It is measured as part of the Kellgren and Lawrenc...
The Landells (and van Peteghem) classification of fractures of the atlas is one of the commonly used systems to describe C1 vertebral injuries.
Fractures are classified by their involvement of the C1 anterior arch, posterior arch, and/or lateral mass 1:
type I: confined to eith...
The term lead pipe fracture is the term for a radiographic appearance given to a simultaneous greenstick fracture of one side of the bone (usually metaphysis) with a buckle fracture of the opposing cortex of the same bone.
There are differing opinions in texts as to whether this term should be...
Age-related macular degeneration (AMD) is an eye disease that affects central vision. It occurs when aging causes damage to the macula. The macula is responsible for fine detailed vision also known as central vision.
Nerve compression syndromes of the shoulder is a term used to include diseases of the shoulder that cause weakness, discomfort or numbness of the upper extremity. These include quadrilateral space syndrome, suprascapular neuropathy, long thoracic nerve palsy and multiple others 1. They are usual...
The Greek alphabet has been used in science and mathematics for millennia. The alphabet has 24 letters with an order similar to the Latin alphabet (used for English and many European languages).
In the list, the name of the letter is given first, followed by the upper and lower case symbols 1....
Calcinosis of chronic renal failure is a rare cause of soft tissue calcifications in hemodialysis patients with chronic renal failure. This condition is characterized by the deposition of calcium phosphate crystals in the periarticular soft tissues, resulting in large calcified masses.
Lobular capillary hemangioma of the nasal cavity, also known as nasal pyogenic granuloma, is an uncommon benign, rapidly growing vascular neoplasm of the nasal cavity.
The term “pyogenic granuloma” is a misnomer due to its lack of infectious origin according to histological and mic...
Posterior ligamentous complex injury refers to tears/ruptures of the spinal posterior ligamentous complex, which consists of the ligamentum flavum, interspinous ligaments, supraspinous ligament, and facet joint capsules. Posterior ligamentous complex disruption is a central part of the currently...
Post traumatic arterio-venous vascular malformations are an uncommon acquired form arteriovenous malformations which occur following a traumatic to that site.
As with other vascular malformations, they comprise multiple communicating channels between arterial and venous channels at t...
Dural venous sinus cysts are rare, usually congenital lesions, most commonly observed as fluid-filled intraluminal lesions on cross-sectional imaging.
Dural venous sinus cysts are very rare, and are mostly congenital 1.
Most dural venous sinus cysts are true fluid-fi...
Ovarian agenesis refers to a situation where there is a congenital absence of the ovary.
Unilateral ovary agenesis affects approximately 1 in one in 11,240 women while bilateral agenesis is even rarer 1.
Most patients with agenesis of the ovary are asympt...
Ventricular arrhythmias are potentially very dangerous cardiac arrhythmias arising from the cardiac ventricles that require immediate attention and medical care and include the following rhythms:
premature ventricular complexes
torsades de pointes
Acute encephalopathy is a general term that describes the clinical presentation of a patient with acute cerebral dysfunction. It is usually caused by viral infections, metabolic disorders, dysfunction of the liver or kidneys, or hypertension.
Acute encephalopathy may occur in adults and childre...
Acute leukoencephalopathy with restricted diffusion (ALERD) is a clinicoradiological spectrum of disease with clinical features of leukoencephalopathy and associated imaging findings where diffusion restriction is the dominant finding.
The dominant radiological feature is...
Atrioventricular block, AV block or heart block is a conduction disturbance and a type of arrhythmia where the impulse transmission between the cardiac atria and ventricles is either transiently or permanently delayed or completely blocked 1.
Atrioventricular block can be found in...
Medical devices in the limbs are regularly observed by radiologists on plain film, CT and MRI reporting. Most commonly they include orthopedic hardware.
joint replacement hardware (arthroplasty)
joint fusion hardware (arthrodesis)
internal fixation hardware (ORIF)
The flame sign refers to a gradual tapering of contrast opacification in the mid-cervical internal carotid artery, sparing the carotid bulb. The sign can be observed on angiography (digital subtraction angiography 1, CT angiography 1, or contrast-enhanced MR angiography 2) in either of two scena...
The quadruple screening test, also known as the quad screen, AFP Plus quad test or multiple marker screening test, is a maternal antenatal screening blood test that can be used in conjunction with other investigations e.g. ultrasound soft markers, to estimate the risk of aneuploidy 1.
This is ...
The nasal septal cartilage, also known as quadrangular cartilage, forms most of the anterior portion of the nasal septum, and is one of five named nasal cartilaginous components supporting the external nose.
Most of the anterior one-third of the nasal septum is formed by the sept...
The characteristic shape of the crescent has been given to many radiological signs over the years.
crescent sign (disambiguation)
crescent sign (arterial dissection)
crescent sign (inguinal hernia)
crescent sign (intravenous pyelogram)
crescent sign (lung hydatid)
crescent sign (osteonecro...
The doughnut sign, also known as the bull's-eye, halo or ring sign, is the name of a distinctive appearance of a missed testicular torsion on scrotal scintigraphy.
In a missed torsion (i.e. established testicular infarction), there is a reactive hyperperfusion of the ipsilateral dartos muscle ...
Subependymal cysts may either be postnatally acquired post-hemorrhagic cysts or may be congenital (germinolytic). The congenital cysts may result from infection, ischemic injury, or hemorrhage.
Subependymal cysts are most frequently seen in preterm infants, likely related to their...
This is a basic article for medical students and other non-radiologists
Intussusception occurs when a loop of bowel is pulled into the lumen of a distal bowel loop, and is an important cause of acute abdominal pain, particularly in young children.
This is a summary article; ...
Peripheral T cell lymphoma is an uncommon, heterogeneous group of lymphoma. It can account for around 5-15% of non-Hodgkin lymphoma (NHL).
The word "peripheral" does not mean involvement in the extremities but refers to tumor cells that arise from lymphoid tissue outside of the bon...
Iodinated oil pulmonary embolism is a form of particulate material pulmonary embolism which in turn falls under non-thrombolic pulmonary emboli. Iodinated oil pulmonary embolism occurs in the setting of:
oily chemoembolisation of tumors
hepatocellular carcinoma 1,3
Presentation refers to the clinical details that need to be included as part of Radiopaedia cases and can include symptoms, signs, physical examination findings, relevant past history and/or laboratory studies. Complications, if part of the initial disease process (e.g. hemorrhage as a complicat...
A joint mouse (plural: joint mice) is a historical synonym for an intra-articular loose body. This evocative term predates the discovery of x-rays and originated in orthopedics. It derives from the way in which some intra-articular osteochondral fragments appeared to move rapidly around the insi...
A corkscrew esophagus, also known as a rosary bead esophagus, is a classic appearance of distal esophageal spasm on a barium swallow. It is actually quite a rare appearance which is seen in <5% cases of distal esophageal spasm. The finding is caused by multiple tertiary (non-propulsive) contract...
Pathology reports are encouraged to be uploaded as substantiation of the diagnosis of the case where appropriate.
text reports are preferred over scanned or photographed reports
no identifiable information should be included (see: patient confidentiality)
ideally, permission from the...
The Heidelberg bleeding classification categorizes intracranial hemorrhages occurring after ischemic stroke and reperfusion therapy.
Class 1: hemorrhagic transformation of infarcted brain tissue
1a: HI1: scattered small petechiae, no mass effect
1b: HI2: confluent petech...
The superficial epigastric vein (TA: vena epigastrica superficialis) is an important tributary of the great saphenous vein that drains the anterior abdominal wall inferior to the level of the umbilicus.
The superficial epigastric vein drains into the great saphenous vein at the saphenous openin...
The lateral thoracic vein (TA: vena thoracica lateralis) is a tributary of the axillary vein. It provides venous drainage for the axilla, anterolateral chest wall, including serratus anterior and pectoralis muscles and breast, and the supraumbilical abdominal wall.
In some texts, t...
The World Health Organizatiοn classification of skin tumors is the most widely used pathologic classification system for skin tumors. The most recent edition is the 4th, which was published in 2018 1. The radiologically relevant and common entities are reflected below.
Diverticula of the anal canal are very rare with only a few cases reported in the global literature.
Patients have presented with anorectal bleeding and/or pain.
The few cases have either not been characterized on imaging or only imaged on barium s...
Submandibular gland enlargement refers to an increase in the volume of the submandibular gland, exceeding "normal" values of 7.4 ± 1.8 mL 1.
submandibular duct stenosis (e.g. tumor, granulomatous disease)
acute sialadenitis: following ...
Syndesmotic screw fixation is a rigid fixation technique for stabilization of distal tibiofibular syndesmosis injury. Depending on the injury and the surgeon's preference it can involve the placement of one or two syndesmotic screws and can be combined with an antiglide plate.
The acromioclavicular (AC) distance or joint space is an important measurement in the evaluation of acromioclavicular joint injury.
The AC distance is assessed on the frontal radiograph of the shoulder as the distance between the medial cortex of the acromion and the lateral cortex...
An ulnar nerve neuropathy can refer to pathology and associated symptoms pertaining to the ulnar nerve anywhere along its course (i.e. from C8/T1 roots to the hand). It can occur at any site along its course and commonly occurs due to pathology at the elbow/cubital tunnel region or in the Guyon ...
Intramural pseudocysts are a rare form of pancreatic pseudocysts that occur within the wall of the upper gastrointestinal tract. They may result in gastric outlet obstruction.
They can considerably vary in size with one study reporting a range of 8 mm to 8 cm 1.
Unicentric Castleman disease (UCD) is considered the more common form of Castleman disease and involves one or more enlarged lymph nodes in a single region of the body that demonstrates histopathologic features that have features of Castleman disease. A subset of patients can have systemic symp...
Reduced leaflet motion refers to an abnormally decreased mobility of one or more valvular leaflets and is a phenomenon that has been observed after (transcatheter) implantation of prosthetic heart valves and gained clinical significance for the diagnosis of subclinical leaflet thrombosis.
The bowler hat sign refers to an appearance on a GI contrast study, which may be seen with both polyps and diverticula of the bowel. The filling defect produced by the pathology mimics the outline of a bowler hat. It was originally described for colonic lesions, but can be seen with lesions thro...
Diffuse low-grade glioma, MAPK pathway-altered is a novel tumor type included in the 5th Edition (2021) of the WHO brain tumor classification 1.
Several genetic mutations were recognized in low-grade IDH-wt/H3-wt brain diffuse gliomas occurring in children and adolescents, such as ...
Finger pathology is wide and includes all lesions involving the tendons, ligaments, muscles, bone, and articulations of the hand and foot digits.
brachydactyly - short digits
brachymetatarsia - short metatarsal
arachnodactyly - elongated, thin "spider-like" digits 1
Two different radiological signs are named for their similarity in size and shape to grains of rice.
rice bodies (intra-articular)
rice grain calcification (cysticercosis)
Hypovascular retroperitoneal lesions are those which do not enhance in the late arterial and portal venous phases on CT. Some of these lesions may show progressive enhancement in the delayed phase due to their fibrous or myxoid matrix components.
Hypervascular retroperitoneal lesions are findings that enhance avidly in the late arterial phase with or without washout in the portal venous and delayed phases, on contrast-enhanced CT or MRI.
Early enhancement with slow washout
Due to its distinctive morphology and its layered internal structure the onion has given rise to a number of signs in imaging:
onion bulb nerves: Charcot-Marie-Tooth type 1A and chronic inflammatory demyelinating polyneuropathies (CIDP)
onion peel sign: pulmonary hydatid cyst
onion skin peri...
Achard-Thiers syndrome is a rare condition in elderly postmenopausal females, which is illustrated by androgen excess and insulin resistance secondary to type 2 diabetes mellitus.
hirsutism in older females
high serum glucose levels
The long head of the biceps tendon (LHBT) is the proximal tendon of the long head of the biceps muscle and encircles the humeral head on its course. It has an intraarticular extrasynovial and an extraarticular portion.
insertion: supraglenoid tubercle of the scapula...
Salt and pepper noise, also known as impulse noise, has been used to describe the characteristic appearance of a certain artifact seen on MRI.
The artifact looks like innumerable black and white pixels throughout the image. Smoothing filters are algorithms designed to diminish the noise whilst ...
The salt and pepper sign has been given to the heterogeneous echotexture of the enlarged kidneys on ultrasound in children with autosomal recessive polycystic kidney disease (ARPCKD).
The salt and pepper sign has been used to describe the MRI appearance of the parotid gland in Sjögren syndrome. This pertains to a combination of punctate regions of calcification (pepper) and fatty replacement (salt) 1.
The salt and pepper sign is used to describe a typical MRI appearance of some highly vascular tumors which contain foci of hemorrhage, typically a paraganglioma 1-3. The appearance is on T1-weighted sequences, and is made up of:
punctate regions of hyperintensity = salt
small flow voids = pepp...
Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is an epileptogenic tumor of children and young adults.
First described in 2016 1, polymorphous low-grade neuroepithelial tumor of the young has been recently included in the new family of "pediatric-type" low-grade ...
The autonomic nervous system (ANS) is a subdivision of the peripheral nervous system. The autonomic system provides innervation of the involuntary muscles, i.e. myocardium and smooth muscle, and glands, through which fine control of homeostasis is maintained.
The afferent innervation of the aut...
Arrhythmia is depicted as an irregular heartbeat. When it is too fast, it is called tachycardia i.e. more than 100 beats per minute. On the other hand, too slow of a heartbeat is called bradycardia, with less than 60 beats per minute being recorded.
Prosthetic valve thrombosis, valve thrombosis or leaflet thrombosis refers to thrombus formation of any component of a prosthetic heart valve and is a cause of prosthetic valve dysfunction and a potentially reversible complication of valvular surgery 1,2.
Subclinical leaflet thrombosis is an en...
The peripheral nervous system (PNS) consists of the nerves (cranial nerves III-XII and spinal) and their related ganglia outside the central nervous system (CNS). The latter comprising the brain and spinal cord. The central nervous system and peripheral nervous system together form the nervous s...
The neurocranium (plural: neurocrania) is the name given to the portion of the skull that encloses the brain. It comprises the skull base and the skull vault. The neurocranium and facial bones (viscerocranium) together form the skull.
Hypervascular head and neck lesions are findings that enhance avidly after biphasic injection, on contrast-enhanced CT or MRI of the neck.
ectopic thyroid gland
hyperdense soft tissue mass on non contrast-CT
intense homogeneous enhancement after contrast injection
The nasolacrimal canal is the short bony passage along which the nasolacrimal duct courses in the face.
lacrimal groove of the medial maxilla
lacrimal hook of the lacrimal bone
superiorly: lacrimal bone
inferiorly: lacrimal process of the inferior n...
Pincer or split fractures are coronally oriented vertebral body fractures that involve the superior and inferior vertebral body endplates but do not involve the anterior or posterior cortices.
Pincer fractures may present in the setting of trauma, with an axial loading m...
A dependent contrast level within the inferior vena cava is a situation that can be observed in some cases with inferior vena caval contrast reflux. Its presence is usually associated with very poor cardiac output and can be accompanied by dependent layering of venous refluxed contrast within th...
Reflux of contrast into inferior vena cava can be common findings seen on CT. It is considered a specific but insensitive sign of right-sided heart disease / right heart dysfunction at low contrast injection rates although the usefulness decreases with high injection rates.
Distal biceps tendon injuries refer to strains, partial and complete tears of the distal biceps tendon complex.
Distal biceps tendon injuries are far less common than injuries to the proximal biceps tendon with an incidence of approximately 1.2/100000 1,2. They typically occur in ...
Chronic otitis media is a form of otitis media where there is a prolonged phase of inflammation in the middle ear with resultant tympanic membrane perforation.
There are a few types of chronic otitis media 1-5:
benign/inactive chronic otitis media: dry tympanic membrane perforation
Penile calcifications are a relatively rare finding. The commonest cause is Peyronie disease.
penile calciphylaxis (considered by some to be a form of calcinosis cutis)
penile urethral calculus
calcinosis cutis of the penis
idiopathic calcinosis cutis o...
Diffuse astrocytoma MYB or MYBL1 altered is a newly recognized pediatric brain tumor type included in the 5th Edition (2021) WHO brain tumor classification 1.
This tumor has been identified as a distinct pediatric entity from "adult-type" IDH-wt/H3-wt diffuse gliomas based on MYB o...
Delayed posthypoxic leukoencephalopathy (DPHL) is a demyelinating syndrome presenting as an acute neurological deterioration shortly after apparent recovery from a hypoxic-ischemic episode.
Given its low frequency, there are no large numbers regarding the prevalence and incidence ...
The carotid cistern is one of the basal (subarachnoid) cisterns that surrounds the supraclinoid internal carotid artery.
Relations and/or Boundaries
The carotid cistern lies between these brain structures:
medially: the optic chiasm and nerve
laterally: the mesial temporal lob...
Percutaneous mitral commissurotomy (PMC) also known as percutaneous mitral balloon commissurotomy (PMBC), percutaneous mitral valvotomy (PMV) or percutaneous mitral balloon valvuloplasty (PMBV) is a transcatheter procedure for the management of mitral stenosis.
History and etymology
Cachexia is a syndrome of metabolic dysfunction secondary to an underlying disease in which there is depleted skeletal muscle (sarcopenia) which may or may not be accompanied by an absolute loss of body fat.
Cancer cachexia is specifically used to refer to the cachexia associated ...
A tuberculous pleural effusion is one of the manifestations of pleural tuberculosis. It can have variable presentation ranging from a largely benign pleural effusion, with potential to completely resolve to a complicated effusion with loculations, pleural thickening and potentially progressing t...
Pleural tuberculosis refers to various manifestations of involvement of the pleura by Mycobacterium tuberculosis.
It manifests in various forms which include
tuberculous pleural effusion 3
Desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant is a rare and recently described type of pineal parenchymal tumor encountered in adults.
Desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant occurs in adolescents and young adults (mean age of diagnosis 40 yea...
Cameron lesions refer to linear ulcers or erosions that occur on the mucosal folds at the diaphragmatic impression of a hiatus hernia. They are usually radiographically occult and diagnosed endoscopically (although still useful for a radiologist to know).
Their prevalence has been...
Ablepharon macrostomia syndrome is a very rare genetic disorder characterized by macrostomia, wide mouth and microblepharon.
A few of the clinical features of this syndrome are:
The central nervous system (CNS) is the part of the nervous system that includes the brain and spinal cord.
The main components of the CNS are the brain and spinal cord. In addition, the CNS includes the optic nerves (cranial nerve II), retinas, olfactory nerves (cranial nerve I)...
Pannus describes an abnormal layer of granulation tissue. It is usually seen overlying joint surfaces (usually in the setting of rheumatoid arthritis, though pannus can be a feature of other inflammatory arthropathies), prosthetic heart valves, or overlying the cornea 1.
A key step in the path...
Diffuse glioneuronal tumor with oligodendroglial features and nuclear clusters is a novel glioneuronal tumor entity recently identified by a characteristic methylation profile 1.
The exact nature of diffuse glioneuronal tumors with oligodendroglial features and nuclear clusters has...