Articles

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%)...

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...

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...

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...

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...

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...

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...

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. ...

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...

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...

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...

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...

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...

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...

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...

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...

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 ...

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...

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...

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...