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.
More than 200 results
Article
Chevron sign (achondroplasia)
The chevron sign refers to an inverted-V, or caret (^) shaped physis due to central depression of the metaphysis with focal protrusion of the adjacent epiphysis noted in children with achondroplasia. It is most commonly seen in the epiphysis of the distal femur and proximal tibia. It tends to di...
Article
Lymph node enlargement
Lymph node enlargement (rarely lymphadenomegaly) is often used synonymously with lymphadenopathy, which is not strictly correct.
Terminology
Lymphadenopathy (or adenopathy) is, if anything, a broader term than lymph node enlargement, referring to any pathology of lymph nodes, not necessarily r...
Article
Dead pixel artifact
Dead pixel artifact is an artifact seen in direct digital radiography systems where a detector element fails to receive a proper signal and therefore appears as a bright white dot in an x-ray image.
A defective pixel on the display monitor can also lead to a white dot appearance (termed stuck p...
Article
Photon-counting computed tomography
Photon-counting computed tomography uses energy-resolving detectors, thereby enabling scanning at multiple energies.
Technique
Physical principles
Clinical CT systems rely on energy-integrating detectors, which measure the total x-ray energy reaching the detector during the measurement period...
Article
Supracondylar humeral fracture
Supracondylar humeral fractures, often simply referred to as supracondylar fractures, are a classic pediatric injury which requires vigilance as imaging findings can be subtle.
Epidemiology
Simple supracondylar fractures are typically seen in younger children, and are uncommon in adults; 90% a...
Article
Electron
Electrons are fundamental subatomic particles involved in various atomic processes, including those relevant to X-ray production and interactions with matter.
Properties
Subatomic particle with a mass of 9.109 × 10⁻³¹ kg (~0.0005 relative mass to proton).
Carries a -1 charge (-1.6 × 10⁻19 C)....
Article
Inferior mesenteric vein
The inferior mesenteric vein (IMV) drains blood from the distal portion of the colon as well as the rectum (i.e. the hindgut).
Gross anatomy
Origin and course
The inferior mesenteric vein drains the mesenteric arcade of the hindgut (comprising of distal transverse, descending, and sigmoid co...
Article
Diverticulitis (summary)
This is a basic article for medical students and other non-radiologists
Diverticulitis is one of the presentations of diverticular disease and is most often a complication of colonic diverticulosis. Differentiating one from the other is critical since uncomplicated diverticulosis is mostly asym...
Article
Selective internal radiation therapy
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE) or hepatic radioembolization, is a treatment for non-resectable liver tumors. The procedure consists of a transcatheter injection of radioactive particles via the hepatic artery.
It is technically...
Article
DNA
DNA (deoxyribonucleic acid) is a nucleic acid that encodes the genetic information (genome) necessary for RNA (ribonucleic acid) transcription (transcriptome) and protein synthesis (proteome) 1. It is contained in the nucleus of eukaryotic cells in the form of chromatin or chromosomes 7,8. Human...
Article
Mass attenuation coefficient
The mass attenuation coefficient (MAC) is a quantity used in calculations involving the penetration and energy deposition of photons (such as X-rays and gamma rays) in various materials, including biological tissues and shielding substances.
Definition
The MAC is defined as the linear attenuat...
Article
Technetium-99m agents
Technetium agents based on the technetium-99m (Tc-99m) radioisotope are frequently used agents in medical imaging. A radiopharmaceutical labeled with Tc-99m constitutes a co-ordination complex in which ligands bond to a central atom of Tc-99m by co-ordinate covalent bonds 4 .
The radioactive te...
Article
Photoluminescence
Photoluminescence is a type of luminescence in which energy source for material to absorb, store and convert to light are electromagnetic radiation. Photoluminescent materials have important applications in radiology.
Types
Fluorescence refers to the near instantaneous emission of light follow...
Article
Half-value layer
Half-value layer (HVL) is the thickness of a material required to reduce the air kerma of an X-ray or gamma-ray beam to half its original value. HVL is most accurately measured under narrow-beam geometry, as broad-beam setups allow scatter to reach the detector, leading to an underestimation of ...
Article
Linear attenuation coefficient
Linear attenuation coefficient (µ) is a constant that describes the fraction of attenuated incident photons in a monoenergetic beam per unit thickness of a material 1. It includes all possible interactions including coherent scatter, Compton scatter and photoelectric effect 1. Its complement is ...
Article
Incisural line
The incisural line is a midsagittal line connecting the Galenic venous confluence point (which includes the internal cerebral veins, the mesencephalic veins, and the basal veins of Rosenthal) with the base of the dorsum sella 1.
It is a fixed anatomically-based line of reference at the tentoria...
Article
Tuberculum-venous confluence line
The tuberculum-venous confluence line is a midsagittal line formed by the interconnection between the Galenic venous confluence (which includes the internal cerebral veins, the mesencephalic veins, and the basal veins of Rosenthal) and the tuberculum sella 1.
This is an artificial reference lin...
Article
Heterozygous HTRA1-related cerebral small vessel disease
Heterozygous HTRA1-related cerebral small vessel disease, also known as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy type 2 (CADASIL2), is a very rare monogenic cerebral small vessel disease.
Heterozygous HTRA1-related cerebral small vessel disease ...
Article
Pseudo-Meigs syndrome
Pseudo-Meigs syndrome refers to a clinical syndrome of pleural effusion and ascites associated with an ovarian tumor that is not a fibroma or a fibroma-like tumor.
Pathology
Entities that have been reported to result in pseudo Meigs syndrome include
Krukenberg tumors
colon carcinoma metastas...
Article
Jejunoileal diverticulitis
Jejunoileal diverticulitis (plural diverticulitides), an acute inflammation of diverticula of the jejunum or ileum, is much rarer than colonic diverticulitis.
Epidemiology
The jejunum is a more common site of acquired diverticula of the small bowel than the ileum 1.
Clinical presentation
Div...
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