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.
717 results found
Article
CT neck (protocol)
The CT neck protocol serves as a radiological examination of the head and neck. This protocol is usually performed as a contrast study and might be acquired separately or combined with a CT chest or CT chest-abdomen-pelvis. On rare occasions, it will be performed as a non-contrast study. Dependi...
Article
Air gap technique (general radiography)
The utilization of the air gap technique in general radiography is limited due to the need for equipment facilitation to create the air gap when it is not inherent in the standard technique.
Horizontal-beam lateral hip
There are many different methods of performing the horizontal beam lateral ...
Article
CT chest abdomen-pelvis (protocol)
The CT chest-abdomen-pelvis protocol serves as an outline for an examination of the trunk covering the chest, abdomen and pelvis. It is one of the most common CT examinations conducted in routine and emergencies. It can be combined with a CT angiogram.
Note: This article aims to frame a genera...
Article
MRI
MRI (an abbreviation of magnetic resonance imaging) is an imaging modality that uses non-ionizing radiation to create useful diagnostic images.
In simple terms, an MRI scanner consists of a large, powerful magnet in which the patient lies. A radio wave antenna is used to send signals to the bod...
Article
Magnetic resonance neurography
Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral nerves.
It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions.
Dedicated high-resolution...
Article
Spatial resolution
Spatial resolution refers to the ability of an imaging modality to differentiate two adjacent structures as being distinct from one another. Other related terms include definition or visibility of detail.
Spatial resolution is expressed in line pairs per mm (lp mm).
The absence of spatial reso...
Article
Nuclide
A nuclide is a nuclear-centric term describing an atomic species by its nuclear composition and nuclear energy state.
A nuclide has a specific number of protons and neutrons and will additionally have a specific energy state of its nucleus.
Radionuclides are unstable nuclides that undergo radi...
Article
X-rays
X-rays (or much more rarely, and usually historically, x-radiation or Roentgen rays) represent a form of ionizing electromagnetic radiation. They are produced by an x-ray tube, using a high voltage to accelerate the electrons produced by its cathode. The produced electrons interact with the anod...
Article
RadLex
RadLex is a lexicon of radiological information that has been produced by the Radiological Society of North America (RSNA). It is an ontological system whose principle aim is to develop a useful vocabulary for radiologists.
In the words of the RSNA
"As images, imaging reports, and medical re...
Article
Ultrasound artifacts
Ultrasound artifacts are commonly encountered and familiarity is necessary to avoid false diagnoses. In some cases, specific artifacts can even offer valuable diagnostic information. For instance, some artifacts may be indicative of certain pathologies. They are not to be confused with ultrasou...
Article
Reverse Bernheim phenomenon
Reverse Bernheim phenomenon, also known as reverse Bernheim syndrome or reverse Bernheim effect, describes the compromise of left ventricular filling caused by the interventricular septum bulging into the left ventricle. When there is right ventricular pressure and volume overload, the intervent...
Article
Doppler waveforms
Doppler waveforms refer to the morphology of pulsatile blood flow velocity tracings on spectral Doppler ultrasound. Waveforms differ by the vascular bed (peripheral, cerebrovascular, and visceral circulations) and the presence of disease.
Radiographic features
Ultrasound
Doppler
Most authori...
Article
Tissue weighting factor
The tissue weighting factor (WT) is a relative measure of the risk of stochastic effects that might result from irradiation of that specific tissue. It accounts for the variable radiosensitivities of organs and tissues in the body to ionizing radiation.
To calculate the effective dose, the indi...
Article
Radiofrequency shielding
Radiofrequency or RF shielding is a technique for creating electromagnetic (EM) isolation, which is critical during the acquisition of MR images. RF shielding serves to both prevent external EM interference from contaminating the target tissue signal, and to ensure that signals generated by MR i...
Article
Gadopiclenol
Gadopiclenol (also known by its brand names Elucirem or Vueway) is a new (late 2022) extracellular intravenous gadolinium-based contrast agent (GBCA) used in magnetic resonance imaging.
macrocyclic, non-ionic molecule
100% renally excreted
T1 relaxivity: 12.8 mM·s at 1.5 T and 11.6 mM·s at 3 ...
Article
MRI contrast agents
MRI contrast agents have become an indispensable part of contemporary magnetic resonance imaging. Although MRI was initially hoped to provide a means of making definitive diagnoses without administering contrast media, it has been found that the addition of contrast agents in many cases improves...
Article
Beta decay
Beta decay represents radioactive decay in which a beta particle is emitted. Beta particles may be either electrons or positrons (β- or β+), having negative or positive charge respectively. The kinetic energy of beta particles has a continuous spectrum.
Beta minus decay
If the number of neutro...
Article
Radiofrequency transmitter
The radiofrequency (RF) transmitter is the generator of the radiofrequency current which is delivered to the transmitting coil. This creates a signal which is used to excite protons in the imaging field. Radiofrequency coils can be both transmitters and receivers of the radiofrequency signal or ...
Article
Compression in mammography
In mammography, compression of the breast is performed to reduce its thickness. By doing so, the following benefits are achieved:
improved subject contrast (by reducing scattered radiation)
improved density uniformity
improved visualization of breast tissue near chest wall (by spreading out s...
Article
Temporal resolution
Temporal resolution relates to the duration of time for acquisition of a single frame of a dynamic process, i.e., cine imaging.
Discussion
The concept of temporal resolution is fundamental to cardiac CT and MRI, in which a rapidly beating heart is imaged over the order of milliseconds into mul...
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