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.
16,680 results found
Article
Splenic cyst
Splenic epithelial cysts, also known as splenic epidermoid cysts or primary splenic cysts, are unilocular fluid lesions with thin and smooth walls and no enhancement. They represent ~20% of cysts found in the spleen, and are usually an innocuous incidental imaging finding.
Note that most (~80%)...
Article
Splenic pseudocyst
Splenic pseudocysts, also known as secondary splenic cysts, are acquired cystic lesions not delineated by a true epithelial wall. They represent the majority of the splenic cystic lesions, corresponding to approximately 80% of them (cf. splenic epithelial cysts). The main causes are:
splenic t...
Article
Doppler shift
Doppler shift or Doppler effect is defined as the change in frequency of sound wave due to a reflector moving towards or away from an object, which in the case of ultrasound is the transducer.
Terminology
When sound of a given frequency is discharged and subsequently reflected from a source th...
Article
Modified Choi classification of common bile duct duplication
Modified Choi classification of common bile duct duplication is a widely used system for classifying the rare duplication of the extrahepatic biliary tree. 1-3:
type I: distal septum splitting the bile duct lumen
type II: bifurcation of the distal bile duct with each lumen draining independent...
Article
Musculoskeletal imaging (dual-energy CT)
Dual-energy CT has a number of clinical applications in the assessment of the musculoskeletal system particularly in the realm of artefact reduction and material composition.
Detection of bone marrow edema
Similar to the concept of using virtual non-contrast imaging, virtual non-calcium images...
Article
Attenuation (ultrasound)
The amplitude and intensity of ultrasound waves decrease as they travel through tissue, a phenomenon known as attenuation. Given a fixed propagation distance, attenuation affects high frequency ultrasound waves to a greater degree than lower frequency waves. This dictates the use of lower freque...
Article
Refraction
Refraction of a sound wave occurs if it travels between tissues with different propagation speeds. As the incident pulse or returning echo strikes an interface of different density or elasticity and therefore a different propagation speed, the direction of the wave changes according to Snell’s l...
Article
Optical density
Optical density is a measure of the degree of radiographic film darkening, and is related to the proportion of incident x-ray photons that are transmitted through the tissue and strike the film 1.
Usage
Optical density is used to describe the level of film exposure in film-screen radiography. ...
Article
Fat containing thoracic lesions
There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall.
Differential diagnosis includes:
intrapulmonary: fat containing pulmonary lesions
pulmonary hamartoma
endobronchial lipoma
intrapulmonary lipoma
lipoid pneumonia
myeloli...
Article
Reverse rugger jersey spine
Reverse rugger jersey spine describes the low endplate densities at multiple contiguous vertebral levels producing an alternating lucent-sclerotic-lucent appearance. It's the reverse counterpart of the Rugger jersey spine and also mimics the horizontal stripes of a rugby jersey.
Pathology
This...
Article
Major and minor edits
The terms major edit and minor edit are used to describe article edits and are used in a variety of ways on the site.
Minor edits
Minor edits are changes that do not significantly alter the substance or meaning of the content. They are typically superficial in nature and focus on improving rea...
Article
Elastofibroma dorsi
Elastofibroma dorsi, a benign soft-tissue tumor, is distinctly situated in the infrascapular or subscapular region, being bilateral close to a third of cases. On imaging, it presents as a poorly defined soft-tissue mass with CT attenuation closely resembling adjacent skeletal muscle.
Epidemiol...
Article
Normal genitourinary tract imaging examples
This article lists examples of normal imaging of the genitourinary tract and surrounding structures, divided by modality.
Kidneys
Plain radiograph
KUB: example 1
abdominal x-ray: example 1
Intravenous Urogram (IVU) and Intravenous Pyelogram (IVP)
IVU: example 1, example 2
Ultrasound
rena...
Article
Cracking thyroid
Cracking thyroid is a term given to a very rare complication of thyroid fine needle aspiration (FNA) biopsy where there is acute pain and transient but marked thyroid swelling characterized by hypoechoic avascular septations on ultrasound 1,2. Onset is within a few minutes to a few hours post pr...
Article
Connective tissue disease-related interstitial lung disease (CTD-ILD)
Connective tissue disease-interstitial lung disease (CTD-ILD) has various manifestations however the most frequent patterns seen on CT are NSIP or UIP. CTD-ILD should be suspected in younger patients especially women and never-smokers and particulary if there is involvement of pleura, airways or...
Article
Esophageal lipomatosis
Esophageal lipomatosis describes fatty infiltration in the wall of the esophagus. It has been associated with oral and inhaled steroid use, but appears to be an asymptomatic incidental finding. 1
Associations
oral and inhaled steroid use
Radiographic features
CT
Esophageal lipomatosis ca...
Article
Carpal instability
Carpal instability refers to the inability of the wrist to maintain its structural stability under physiologic movements and loading forces ultimately leading to derangement of the carpal bones with associated malalignment.
Epidemiology
Associations
Clinical conditions associated with carpal ...
Article
Ring artifact
Ring artifacts are a CT phenomenon that occurs due to the miscalibration or failure of one or more detector elements in a CT scanner. Less often, it can be caused by insufficient radiation dose or contrast material contamination of the detector cover 2.
Features
This artifact usually occurs i...
Article
Straight-edge sign (usual interstitial pneumonia)
Straight-edge sign is an HRCT finding usually seen in the setting of usual interstitial pneumonia. It represents fibrosis isolated to the lung bases characterized by a clear demarcation in the craniocaudal plane on coronal images without significant extension along the lateral margins of the lun...
Article
Exuberant honeycombing sign (usual interstitial pneumonia)
The exuberant honeycombing sign is an HRCT finding typically observed in the context of usual interstitial pneumonia. This sign is characterized by the presence of extensive honeycomb-like cyst formation within the lungs, comprising more than 70% of the fibrotic portions of the lungs. In other w...