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.
More than 200 results
Article
Pulmonary emphysema
Pulmonary emphysema is defined as the "abnormal permanent enlargement of the airspaces distal to the terminal bronchioles accompanied by destruction of the alveolar wall 1. The criteria "absence of obvious fibrosis" may not be necessary because interstitial fibrosis may be present in cigarette s...
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Pylephlebitis
Pylephlebitis, also known as ascending septic thrombophlebitis, is a thrombotic occlusion of the portal vein or its branches secondary to infection in regions that drain to the portal venous system.
Clinical presentation
Clinical presentation is often vague. Patients may initially present with...
Article
Cases
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Anomalous course of coronary arteries
Anomalous course of a coronary artery is a type of congenital coronary artery anomaly. It may represent a benign and incidental finding, but rarely it is a malignant course predisposing patients to life-threatening myocardial ischemia or arrhythmias, depending on where the artery runs.
Clinica...
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Interarterial course of the right coronary artery
Interarterial course of the right coronary artery may occur if the right coronary artery (RCA) has an aberrant origin from the left coronary sinus. The interarterial course occurs because the artery passes between the ascending aorta and the pulmonary trunk 1-3.
It is an uncommon anatomic varia...
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Chiari malformations
Chiari malformations are a group of structural conditions characterized by congenital caudal 'displacement' of the cerebellar tonsils below the foramen magnum, often with associated caudal displacement of brainstem.
Terminology
The description of 'malformation' may not be accurate for Chiari 0...
Article
Tarlov cyst
Tarlov cysts, also called perineural cysts, are CSF-filled dilatations of the nerve root sheath at the dorsal root ganglion (posterior nerve root sheath). These are type II spinal meningeal cysts that are, by definition, extradural but contain neural tissue.
Most Tarlov cysts are asymptomatic, ...
Article
Pleural effusion
Pleural effusions are abnormal accumulations of fluid within the pleural space. They may result from a variety of pathological processes which overwhelm the pleura's ability to reabsorb fluid.
Terminology
"Pleural effusion" is commonly used as a catch-all term to describe any abnormal accumula...
Article
Effective dose
The effective dose (E) is a hypothetical equivalent dose uniformly applied to the whole body, which would result in the same health detriment through stochastic effects as the partial-body exposition being considered. It is calculated by summating the equivalent doses (HT) delivered to the irrad...
Article
Iliotibial band
The iliotibial band (ITB) or tract is a thick band of fascia along the lateral aspect of the thigh.
Gross anatomy
The ITB is a thickening in the fascia lata. Superiorly, it splits to enclose and anchor the aponeurosis of tensor fasciae latae and posteriorly most of the tendon of gluteus maximu...
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Müllerian duct anomalies
Müllerian duct anomalies (MDAs) are congenital abnormalities that occur when the Müllerian ducts (paramesonephric ducts) do not develop correctly. This may be due to complete agenesis, defective vertical or lateral fusion, or resorption failure.
Epidemiology
MDAs are estimated to occur in 1-5%...
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AFS classification of Müllerian anomalies
The American Fertility Society (AFS) classification of Müllerian anomalies is a seven-class system published in 1988, which is used to describe several embryonic Müllerian duct anomalies.
The American Fertility Society is now known as the American Society of Reproductive Medicine (ASRM), and th...
Article
WHO classification of breast tumors (5th ed.)
The WHO classification of breast tumors is the most widely used pathologic classification system for such disorders. This classification was last revised in 2019 with the publication of the 5th edition 1.
Classification
Epithelial tumors of the breast
benign epithelial proliferation and prec...
Article
CT stair-step artifact
The CT stair-step artifact is found in straight structures which are oriented obliquely with respect to movement of the table and appear around the edges of sagittal and coronal reformatted images when wide collimations and non-overlapping reconstruction intervals are used.
It is also seen in c...
Article
Accessory iliotibial band-meniscal ligament
Accessory iliotibial band-meniscal ligament (AIML) is a fibrous connection between the iliotibial band and anterolateral aspect of the lateral meniscus 1.
At least five distal insertions of the iliotibial tract about the knee have been described 2-4, but the accessory iliotibial band-meniscal l...
Article
Tissue weighting factor
The tissue weighting factor (WT) is a measure of relative contribution of an organ or tissue to the total health detriment due to stochastic effects resulting from a uniform irradiation of the entire body 1. It accounts for the variable sensitivity to ionizing radiation and size of a given organ...
Article
Gray (SI unit)
The gray (symbol Gy) is the SI unit of absorbed dose. It is defined as the absorption of one joule of energy originating from ionizing radiation per kilogram of matter 1,2, i.e. Gy = 1 J/kg.
Terminology
One gray is a large unit and is usually used with a prefix, e.g. milligray (mGy), microgray...
Article
Rem (unit)
The rem (an acronym for roentgen equivalent man) was the cgs unit of effective dose and was officially replaced by the sievert many years ago (1 Sv = 100 rem) 1.
One rem was a large quantity of radiation, and therefore for practical day to day use the millirem (mrem), representing one-thousand...
Article
Sievert (SI unit)
The sievert (symbol Sv) is the SI unit of equivalent dose and effective dose. It is dimensionally equivalent to one joule per kilogram 1.
Although sievert and gray (Gy) are dimensionally equivalent SI units of dose, they cannot be used interchangeably. Sievert is applicable only in context of r...
Article
Impending testicular infarction
Impending testicular infarction is a rare complication of epididymo-orchitis which can be diagnosed by absence or reversal of diastolic flow in intra-testicular arteries 1,2.
Clinical presentation
Patients may present with worsening of symptoms of epididymo-orchitis despite proper treatment.
...
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