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.
716 results found
Article
Myocardial mapping
Myocardial mapping or parametric mapping of the heart is one of various magnetic resonance imaging techniques, which has evolved and been increasingly used in the last decade for non-invasive tissue characterization of the myocardium 1-5. Unlike normal T1-, T2- or T2*- images, parametric mapping...
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Dark-field radiography
Dark-field radiography is an emerging medical imaging technology. While conventional x-ray imaging is based on the differential attenuation of various organs and tissues, dark-field radiography utilizes ultra-small angle x-ray scattering similar to dark-field computed tomography.
Clinical appli...
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Citrate peak
Citrate is a compound examined in MR spectroscopy in the setting of possible prostate carcinoma. Citrate resonates at 2.6 ppm and is decreased in prostate cancer.
For more information go to: MR spectroscopy in prostate cancer
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Black boundary artifact
Black boundary artifact, also known as India ink artifact or type 2 chemical shift artifact, is an artificially-created black line located at fat-water interfaces such as those between muscle and fat. This results in a sharp delineation of the muscle-fat boundary lending the image an appearance ...
Article
Renal intraparenchymal acceleration time
Renal intraparenchymal acceleration time is a parameter used in assessing renal arterial stenosis on Doppler ultrasound. It is the time taken from the start of systole to peak systole.
normal range: a value of usually <0.07 seconds (<70 ms) is taken as being within normal limits 1
See also
a...
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Abdominal ultrasound
Abdominal ultrasound is a diagnostic imaging technique that evaluates the organs and structures in the abdomen, including the liver, gallbladder, pancreas, spleen, adrenal glands, kidneys, and abdominal aorta.
Normal ultrasound anatomy
On an ultrasound, the normal anatomy of the liver appears ...
Article
Tungsten
Tungsten (chemical symbol, W) is a hard refractory metallic element with remarkable resilience which forms the basis for its industrial uses. It is the metal of choice in the filaments and targets of x-ray tubes. There is no evidence that tungsten is required by the human body, although some mic...
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Grid cutoff
Grid cutoff is an unwanted absorption of x-rays via an x-ray grid, observed when a grid is employed incorrectly, most often seen with parallel grids. The term cutoff stems from the phenomenon in which the primary x-ray beam is 'cut off' by grid lines, leading to an overall decrease in optical de...
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Multipath artifact
A multipath artefact is an ultrasound beam artefact in which the primary beam reflects off anatomy at an angle, resulting in a portion of the beam returning to the transducer, whilst another portion takes a longer duration as it reflects a second structure. This phenomenon results in a propagati...
Article
Tube shielding
Tube shielding refers to the use of a material within the X-ray tube housing to limit leakage of scattered radiation, to protect both patients and staff from unnecessary exposure.
Lead (Pb) is an ideal material for this purpose due to its high atomic density (Z = 82). Due to these properties, i...
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Milliampere-seconds (mAs)
Milliampere-seconds, also more commonly known as mAs, is a measure of radiation produced (milliamperage) over a set amount of time (seconds) via an x-ray tube. It directly influences the radiographic density, when all other factors are constant.
An increase in tube current (mA) results in a hig...
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Sievert (SI unit)
The sievert (symbol Sv) is the SI unit of dose equivalent and is dimensionally-equivalent to one joule per kilogram. The sievert represents the stochastic effects of ionizing radiation as adjusted by a tissue weighting factor to account for differing responses of different human tissues to ioniz...
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Fourier transformation
The Fourier transform is a mathematical formula that converts a signal in time (or spatial) domain t to one in the frequency domain ω.
A frequency domain signal F(ω) is obtained by modulating the time domain signal f(t) to a special sinusoidal wave e-jωt across all time (from negative infinity ...
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CT pelvis (protocol)
The CT pelvis protocol serves as an outline for the acquisition of a pelvic CT. As a separate examination, it might be performed as a non-contrast or contrast study or might be combined with a CT hip or rarely with a CT cystogram. A pelvic CT might be also conducted as a part of other scans such...
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Cross-excitation artifact (MRI)
Cross-excitation artifact is a type of MRI artifact and refers to the loss of signal within a slice due to pre-excitation from RF pulse meant for an adjacent slice.
The frequency profile of the RF pulse is imperfect; this means that during slice selection there is some degree of excitation of t...
Article
Spontaneous echocardiographic contrast (SEC)
Spontaneous echocardiographic contrast (SEC), also known as “echocardiographic smoke” is an echogenic swirling pattern of blood flow created by enhanced ultrasonic back-scatter from clumping of the cellular components of blood in instances of stagnating or low-velocity (low-flow states) 1. It di...
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Radicals
Radicals (formerly called free radicals) are uncharged atoms or molecules in which an electron orbit has a single unpaired electron.
Terminology
Historically the International Union of Pure and Applied Chemistry (IUPAC) also used the term radical for any joined up group of atoms forming a side...
Article
Octreotide scintigraphy
Octreotide scintigraphy uses 111In-labeled octreotide, which is a somatostatin analog; it is also known as Octreoscan, a brand name for 111In-labeled pentetreotide. Pentetreotide is a DTPA-conjugated form of octreotide, originally manufactured by Mallinckrodt Nuclear Medicine LLC, which now form...
Article
Standard triangle language
Standard triangle language (STL), is one of many file formats used for 3D printing. For biomedical 3D printing from DICOM files, DICOM files must undergo image post-processing including segmentation and then be turned into an appropriate file format for printing. Currently (2019) STL is the most...
Article
Photocathode
A photocathode is a negatively charged electrode in a light detection device such as the input screen in an image intensifier (II) that is coated with a photosensitive compound. When this is struck by light photons, the absorbed energy causes electron emission due to the photoelectric (PE) effec...
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