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
Susceptibility weighted imaging
Susceptibility weighted imaging (SWI) is an MRI sequence that is particularly sensitive to compounds which distort the local magnetic field and as such make it useful in detecting blood products, calcium, etc.
Physics
SWI is a 3D high-spatial-resolution fully velocity corrected gradient-echo M...
Article
CT lumbar spine (protocol)
The CT lumbar spine or L-spine protocol serves as an examination for the assessment of the lumbar spine. As a separate examination, it is most often performed as a non-contrast study. It might be combined or simultaneously acquired with a CT abdomen. It also forms a part of a polytrauma CT or mi...
Article
MRI in patients with pacemaker systems
MRI in patients with cardiac implantable electronic devices (CIED) has increasingly become a requirement in radiological departments 1-8. Especially in the setting of patients with MR conditional pacemaker systems, where all the manufacturer's instructions are followed and a standardized institu...
Article
Image intensifier
Image intensifiers are used to convert low-energy x-rays into visible light images. Image intensifiers are several thousand times more sensitive compared to standard 400-speed screen-film combinations, and in practice can produce images using several thousand times less radiation 3,4.
The bigge...
Article
B-Flow
B-Flow is a type of ultrasound imaging that allows visualization of blood flow by selectively enhancing the signal from moving blood cells while simultaneously suppressing tissue signal 1. Unlike color Doppler, it does not show flow direction or amplitude.
B-flow is used clinically to image the...
Article
Noise power spectrum
The noise power spectrum (NPS), also known as the power spectral density, of a signal, is the Fourier transform of the noise autocorrelation. It gives the intensity of noise as a function of spatial frequency. It is used in all the main radiological modalities, most commonly x-ray-based, i.e. ra...
Article
Cardiac strain imaging
Strain imaging is a cardiac imaging technique that detects ventricular deformation patterns and functional abnormalities before they become obvious as regional wall motion abnormalities on conventional cine imaging or echo. It has become more popular lately due to several technological improveme...
Article
Dark-field computed tomography
Dark-field computed tomography is an emerging medical imaging technology. While conventional CT measures differential attenuation properties of the various tissues, dark-field CT utilizes its small-angle scattering (dark field) characteristics.
Clinical applications
To date, dark-field radiogr...
Article
Ultrasound (introduction)
Ultrasound (US) is an imaging technology that uses high-frequency sound waves to characterize tissue. It is a useful and flexible modality in medical imaging and often provides an additional or unique characterization of tissues when compared to other modalities such as conventional radiography ...
Article
Echo planar imaging
Echo planar imaging (EPI) is an MRI acquisition methodology with an excellent temporal resolution that is required in specific clinical settings e.g. cardiac imaging.
There are single-shot and multi-shot echo-planar sequences.
Clinical applications
Echo planar imaging is used under the follo...
Article
Doppler angle correction
Doppler angle correction refers to an imaging post-processing method used to adjust for the effects of insonation angle on the Doppler shift.
Technique
Measurement of flow velocity with Doppler imaging is dependent on the angle between the ultrasound beam and the target (insonation angle), wit...
Article
Extended reality
Extended reality, sometimes referred to as XR, is a term for technologies, such as those that include augmented reality, virtual reality and mixed reality, that allow visualization of three-dimensional virtual imaging.
Terminology
Virtual reality refers to technologies which allow complete imm...
Article
Amide proton transfer imaging
Amide proton transfer (APT) imaging is the most common type of chemical exchange saturation transfer technique that generates image contrast due to proton exchange between labeled protons in solute and free water protons1. APT imaging does not require exogenous gadolinium-based contrast and thus...
Article
Step-and-shoot tomosynthesis (breast)
Step-and-shoot is a technology of image acquisition in digital breast tomosynthesis characterized by stopping scanning at every single angle during image acquisition.
Step-and-shoot technology displays advantages in microcalcifications conspicuity, spatial resolution, signal-to-noise ratio impr...
Article
Flying focus tomosynthesis
Flying focus is a technology of image acquisition in digital breast tomosynthesis characterized by a continuous sweep during shooting.
Sharpness in digital systems is determined by the modulation transfer function (MTF), which determines contrast transfer as a function of spatial frequency.
Si...
Article
Zero echo time imaging
Zero echo time (ZTE) imaging is a development in MR technology, to better visualize tissues such as bone with the shortest T2 values.
Technique
Physical principles
In zero echo time imaging, the signal is acquired immediately after applying the radiofrequency pulse resulting in near-zero echo...
Article
Augmented reality
Augmented reality (AR) is a technology that uses computer-generated virtual content e.g. image rendering that is superimposed onto the user’s real environment 1. This is in contrast to virtual reality (VR) whereby the user is immersed into a completely virtual setting 1.
Clinical applications
...
Article
Pulsatile portal venous flow
A pulsatile portal venous flow pattern is an abnormal form of portal venous flow and can result from both physiological and pathological causes.
In well subjects, mild to marked pulsatility has been described. This is especially so in thin subjects, with a venous pulsatility index of >0.5, inve...
Article
Blooming artifact (MRI)
Blooming artifact is a susceptibility artifact encountered on some MRI sequences in the presence of paramagnetic substances that affect the local magnetic milieux. Although it is an artifact, it may be deliberately exploited to improve detection of certain small lesions, much as the T1 shortenin...
Article
Gadolinium contrast agents
Gadolinium-based contrast media (GBCM), gadolinium-based contrast agents (GBCAs), or simply gadolinium contrast agents, are molecular complexes containing the rare earth metal gadolinium, chelated to a carrier ligand. They are a type of paramagnetic contrast agent, which are the primary class of...
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