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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
16,873 results found
Article
Ascites
Ascites (hydroperitoneum is a rare synonym) is defined as an abnormal amount of intraperitoneal fluid.
Terminology
Ascites (plural is the same word) tends to be reserved for relatively sizable amounts of peritoneal fluid. The amount has not been defined formally. It is noted physiologically, h...
Article
Focal fatty deposits in bone marrow
Focal fatty deposits, also known as marrow islands or replacements in the bone marrow, are well-defined focal fat islands within the bone marrow of the spine or other parts of the axial skeleton 1,2.
Epidemiology
Common in older individuals, related to age but not to sex.
Associations
Focal ...
Article
Posterior tibial line
The posterior tibial line is drawn along the posterior aspect of the distal tibial shaft on a lateral ankle x-ray and can be used to assess the sagittal alignment of the talus when comparing side-to-side and/or calculate the posterior tibial line-talar ratio 1,2.
Article
Contrast phases
Contrast phases are terms used to describe different stages of contrast enhancement to blood vessels, following the introduction of a pressure injected intravenous (IV) contrast agent such as iodine in CT.
Typical phases (time from injection) include:
early arterial phase
15-25 seco...
Article
Light chain deposition disease (pulmonary manifestations)
Pulmonary light chain deposition disease is a rare manifestation of systemic light chain deposition disease (LCDD).
Pathology
Fragments of immunoglobulin light chains secreted by a plasma clone are deposited as amorphous eosinophilic material in the alveolar walls, small airways, and vessels 2...
Article
Tuberous sclerosis (mnemonic)
The findings of tuberous sclerosis can be remembered with the help of the following mnemonic:
HAMARTOMAS
Mnemonic
H: hamartomas (CNS, retinal and skin)
A: angiofibroma (facial) or adenoma sebaceum
M: mitral regurgitation
A: ash-leaf spots
R: rhabdomyoma (cardiac)
T: tubers (cortical, sub...
Article
Crohn disease
Crohn disease, also known as regional enteritis, is an idiopathic inflammatory bowel disease characterized by widespread discontinuous gastrointestinal tract inflammation. The terminal ileum and proximal colon are most often affected. Extraintestinal disease is common.
Epidemiology
The diagnos...
Article
Echogenic fetal bowel
Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
Article
External auditory canal atresia
External auditory canal atresia, also known as congenital aural atresia, is characterized by complete or incomplete bony atresia of the external auditory canal (EAC), often in association with a dysplastic auricle and an abnormal middle ear cavity or ossicles.
Epidemiology
The incidence is 1 i...
Article
Hemimegalencephaly
Hemimegalencephaly is a rare congenital disorder of cortical formation with hamartomatous overgrowth of all or part of a cerebral hemisphere. This results from either increased proliferation or decreased apoptosis (or both) of developing neurons 2.
Epidemiology
Hemimegalencephaly is a cryptoge...
Article
Early pregnancy
Early pregnancy roughly spans the first ten weeks of the first trimester.
Radiographic features
Antenatal ultrasound
0-4.3 weeks: no ultrasound findings
4.3-5.0 weeks:
possible small gestational sac
possible double decidual sac sign (DDSS)
possible intradecidual sac s...
Article
External ear
The external ear (or outer ear) comprises the auricle (or pinna), the external auditory meatus, and the tympanic membrane ("eardrum"). The auricle concentrates and amplifies sound waves and funnels them through the outer acoustic pore into the external auditory meatus to the tympanic membrane.
...
Article
Hirschsprung disease
Hirschsprung disease is the most common cause of neonatal colonic obstruction (15-20%). It is commonly characterized by a short segment of colonic aganglionosis affecting term neonates, especially boys.
Epidemiology
Hirschsprung disease affects approximately 1:5000-8000 live births. In short-...
Article
Facet joint injection
Facet (zygapophyseal) joint injections are performed primarily for the diagnosis and differentiation of facet syndrome and radicular pain syndrome, and are one of the spinal interventional procedures. They can be performed under fluoroscopic, or CT image guidance, and cervical, thoracic or most ...
Article
Superior vermian vein
The superior vermian vein is formed in the midline over the superior aspect of the cerebellar vermis (over the anterior lobe) by multiple tributaries draining not just the subjacent vermis but also the adjacent cerebellar hemispheres. These tributaries most often coalesce into a single trunk ove...
Article
Hypermetropia
Hypermetropia, also known as long-sightedness or hyperopia, is a refractive disorder. Though it can happen in any age group, it usually starts from mid-late adulthood.
Clinical presentation
In this condition, distant objects are seen better than close objects.
Pathology
The blurriness of nea...
Article
Ciliopathies
Ciliopathies refer to diseases due to malfunctioning cilia (singular: cilium). Cilia are organelles that are external extensions of the cell membrane. Cilia fall into two main types: primary (or immotile) cilia and motile cilia.
Clinical presentation
Primary cilia are found in virtually every...
Article
Shoulder (supine lateral scapula view)
The supine lateral scapula view (anterior oblique AP) is a modified lateral shoulder projection often utilized in trauma imaging. Orthogonal to the AP shoulder (note so is an axillary view); It is a pertinent projection to assess suspected dislocations, scapula fractures and degenerative changes...
Article
Periosteal chondrosarcoma
Periosteal chondrosarcomas, previously also known as juxta-cortical chondrosarcomas, are cartilagineous or chondroid matrix-generating neoplasms originating in close association with the periosteum from the bony surface 1-3.
Terminology
The term ‘juxta-cortical chondrosarcoma’ is no longer rec...
Article
Subdural hygroma
Subdural hygromas (alternative plural: hygromata 9) refer to the accumulation of fluid in the subdural space. In many cases, it is considered an epiphenomenon of head injury when it is called a traumatic subdural hygroma.
Epidemiology
Subdural hygromas are encountered in all age-groups but ar...
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