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.
16,872 results found
Article
Rule of Spence
The Rule of Spence is a radiologic method to evaluate the likelihood of injury to the transverse atlantal ligament (TAL) on an open mouth AP (“peg”) radiograph. As originally framed, if the combined projection of the lateral masses of the atlas is more than 6.9 mm beyond the lateral masses of th...
Article
Embryonic growth discordance
Embryonic growth discordance is a term given to a twin growth discordance occurring during the early embryonic period. It is principally manifested by a discrepancy in crown rump length. It is considered independent of the chorionicity of the twins 5.
Epidemiology
Embryonic growth discordance...
Article
Incisivus labii inferioris muscle
The incisivus labii inferioris muscle (TA: pars labialis musculi orbicularis oris) is one of the facial muscles. It acts as a supplementary muscle to the orbicularis oris muscle.
Terminology
The incisivus labii inferioris muscle is often omitted from major anatomical texts or articles on the f...
Article
Papillary intralymphatic angioendothelioma
Papillary intralymphatic angioendothelioma (PILA) (also known - especially historically - as a Dabska tumor) is a rare, low-grade soft tissue tumor 1. The lesion is borderline-malignant and metastasis is distinctly unusual.
Epidemiology
Less than 40 cases have been reported in the global liter...
Article
Spinal epidermoid cyst
Spinal epidermoid cysts are cystic tumors lined by squamous epithelium. Unlike dermoid cysts, they do not contain skin appendages (hair follicles, sweat glands, sebaceous glands). They are usually extramedullary but rarely can be intramedullary. They may be congenital or acquired.
This article ...
Article
Python (programming language)
Python is a high-level, general-purpose computer programming language. Initially, Python was created by Dutch computer programmer Guido van Rossum and was first released in 1991. The version 3.7.4 (which is the most stable release as of July 2019) Python language has objects and associated mach...
Article
Reticuloendothelial MRI contrast agents
Reticuloendothelial MRI contrast agents can best be discussed in terms of those used for liver and spleen imaging and those for lymph node imaging.
Liver and spleen
The use of Gd-DTPA with routine imaging sequences of the liver is unsatisfactory. Particulate contrast agents targeted to the ret...
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
Twin reversed arterial perfusion
Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic pregnancies. It develops when the following conditions are present:
1. lack of a well-formed heart in one of the twins (so-called acardiac twin)
2. a superficial artery-to-artery placental anastomosis prov...
Article
Twin anemia polycythemia sequence
Twin anemia polycythemia sequence (TAPS) is considered a variant of the twin to twin transfusion syndrome (TTTS) occurring in monochorionic twin pregnancies.
Epidemiology
TAPS may occur spontaneously in up to 5% of monochorionic twins and may also develop after incomplete laser treatment in tw...
Article
Twin-to-twin transfusion syndrome
Twin-to-twin transfusion syndrome (TTTS) is a potential complication that can occur in a monochorionic twin pregnancy (either MCDA or MCMA).
Epidemiology
This complication can occur in ~10% (range 15-25%) of monochorionic pregnancies, giving an estimated prevalence of ~1:2000 of all pregnanci...
Article
Braxton Hicks contractions
Braxton Hicks contractions, aka practice contractions or false labor, are physiological contractions of myometrium that occur in pregnancy. They are often sporadic and start by ~6 weeks.
Radiographic features
Antenatal ultrasound
It may be seen as a transient change myometrial thickness 2.
H...
Article
Stub
Stubs are short incomplete articles that are little more than a placeholder for a longer definitive article. The length of the article is less important than how long it is in contrast to how long it should be. In other words, some articles need only be a paragraph long to be considered complete...
Article
Primary hyperaldosteronism
Primary hyperaldosteronism is a condition of excess aldosterone production and occurs secondary to bilateral adrenal hyperplasia, adrenal cortical adenoma, or rarely, adrenal carcinoma. When primary hyperaldosteronism is due to aldosterone-producing adenoma it is called Conn syndrome 2,3,9. Diff...
Article
Brain arteriovenous malformation
Brain arteriovenous malformations are a type of intracranial high-flow vascular malformation composed of enlarged feeding arteries, a nidus of vessels closely associated with the brain parenchyma through which arteriovenous shunting occurs, and draining veins.
Terminology
This article correspo...
Article
Medulloblastoma
Medulloblastomas are the most common malignant brain tumors of childhood, most often presenting as midline masses in the roof of the 4th ventricle with associated mass-effect and hydrocephalus. Treatment typically consists of surgical resection, radiation therapy, and chemotherapy, with the prog...
Article
Thyroid malignancies
Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits.
Epidemiology
Risk factors
head and neck irradiation (see radiation-induced thyroid cancer)
family history of thyroid cancer
age <30 or >60 years
male
>2 cm
Pathology
Classification
Th...
Article
Hydrogen
Hydrogen (chemical symbol H) is one of the basic organic elements, and all organic compounds contain hydrogen. It is the commonest element in the visible universe comprising greater than 75% of all matter.
Chemistry
Physical chemistry
Hydrogen is an odorless, tasteless and colourless gas. It ...
Article
Eagle syndrome
Eagle syndrome refers to symptomatic elongation of the styloid process or calcified stylohyoid ligament 1,2. It is often bilateral. In most cases, the cause is unknown; however, the condition is sometimes associated with disorders causing heterotopic calcification such as abnormal calcium/phosph...
Article
Leadless cardiac pacemaker
Leadless cardiac pacemakers are a type of cardiac conduction device. These pacemakers are self-contained right ventricular single-chamber pacemakers that are implanted percutaneously via a femoral approach 1-3. There are currently two leadless cardiac pacemakers on the market: Nanostim™️ (Abbott...
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