365 results found
Article
Noise (CT)
Noise in computed tomography is an unwanted change in pixel values in an otherwise homogeneous image. Often noise is defined loosely as the grainy appearance on cross-sectional imaging; more often than not, this is quantum mottle.
Noise in CT is measured via the signal to noise ratio (SNR); co...
Article
Automation bias
Automation bias is a form of cognitive bias occurring when humans overvalue information produced by an automated, usually computerized, system. Users of automated systems can fail to understand or ignore illogical or incorrect information produced by computer systems.
Computer programs may crea...
Article
SPECT vs PET
Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are nuclear medicine imaging techniques which provide metabolic and functional information unlike CT and MRI.
They have been combined with CT and MRI to provide detailed anatomical and metabolic informatio...
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
CT chest (summary)
This is a basic article for medical students and other non-radiologists
Chest CT is a computed tomography examination of the thoracic cavity performed for a variety of reasons, from suspected cancer to penetrating chest trauma.
A CT chest can be performed with or without IV contrast and when I...
Article
Patent foramen ovale
A patent foramen ovale (PFO) is a normal foetal interatrial connection which can persist into adult life. This can cause stroke due to paradoxical embolus.
Terminology
PFO is an anatomical variant due to persistence of a normal foetal structure rather than a malformation, in contradistinction ...
Article
Tomosynthesis
Tomosynthesis, also referred to as digital tomosynthesis, is an imaging modality similar to computed tomography (CT), but distinct in that it uses a more limited angle during image acquisition. Rather than 360-degree acquisition of a structure (as in CT), tomosynthesis involves an x-ray tube arc...
Article
Imaging data sets (artificial intelligence)
The aggregation of an imaging data set is a critical step in building artificial intelligence (AI) for radiology. Imaging data sets are used in various ways including training and/or testing algorithms. Many data sets for building convolutional neural networks for image identification involve at...
Article
CT pulmonary angiogram (protocol)
The computed tomography pulmonary angiogram (CTPA/CTPE) is a commonly performed diagnostic examination to exclude pulmonary emboli (PE). Each radiology department will have a slightly different method for achieving the same outcome, i.e. diagnostic density of the main pulmonary artery and its br...
Article
Fetal abdominal circumference
Abdominal circumference (AC) is one of the basic biometric parameters used to assess fetal size. AC together with biparietal diameter, head circumference, and femur length are computed to produce an estimate of fetal weight. In the second trimester, this may be extrapolated to an estimate of ges...
Article
Student t-test
The student t-test is an analysis of variance that is found in many radiology studies.
To use the test on the data, the data must:
be a comparison of only two groups
must not be "matched data" (e.g. before and after results for the same group)
must be from a normally distributed population
...
Article
Kernel (image processing)
Kernel is a term borrowed from linear algebra, that in applications for image processing specifically, implies a numerical matrix that defines a linear transformation on an image matrix.
Typically, kernels are small matrices, and if the desired specific effect of a kernel is known, many compute...
Article
Contrast-induced acute kidney injury
Contrast-induced acute kidney injury (CI-AKI), formerly termed contrast-induced nephropathy (CIN) 12, describes an association between intravenous or intra-arterial contrast administration and renal impairment, but increasingly the evidence shows that contrast is not the cause of the renal impai...
Article
Colon cut-off sign
The colon cut-off sign describes gaseous distension seen in the proximal colon associated with abrupt termination of gas within the colon usually at the level of the splenic flexure and decompression of the more distal part of the colon. Though originally described in abdominal radiographs, this...
Article
ABR core exam
The ABR core exam is set by the American Board of Radiology, and is the first of two exams necessary for certification in diagnostic and interventional radiology in the United States of America. It is taken at the end of PGY4 of radiology residency training.
The exam is computer-based and occur...
Article
Uploading DICOM images to Radiopaedia
Uploading DICOM images to Radiopaedia is possible through the case creation page with full client-side anonymisation.
Here is what occurs:
drag and drop: drag and drop the DICOM folder into the case upload area (this will not be uploaded at this stage)
anonymisation: the files will be proce...
Article
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...
Article
Diffuse alveolar damage
Diffuse alveolar damage (DAD) is a common manifestation of drug-induced lung injury that results from necrosis of type II pneumocytes and alveolar endothelial cells.
Clinical presentation
Affected patients present with dyspnea, cough, and occasionally fever. The diffusion capacity of the lung ...
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
ABR certifying exam
The ABR certifying exam is the second of two exams necessary for certification in diagnostic and interventional radiology in the United States of America (the first is the core exam). It is taken 15 months after the end of the PGY 5 year (or three months after a one year PGY 6 fellowship).
The ...
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