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.
16,879 results found
Article
Cord presentation
A cord presentation (also known as a funic presentation or obligate cord presentation) is a variation in the fetal presentation where the umbilical cord points towards the internal cervical os or lower uterine segment.
It may be a transient phenomenon and is usually considered insignificant un...
Article
Chemical shift ratio
Calculating the chemical shift ratio (CSR) is one way of differentiating benign thymic tissue from thymic neoplasms 1:
CSR = (tSIopp / mSIopp) / (tSIin / mSIin)
in = in phase, m = muscle, opp = opposed phase, SI = signal intensity, and t = thymus
Using a cut-off if 0.849, CSR is 100% specific...
Article
Left ventricular diverticulum
True diverticula of the left ventricle refer to congenital anomalies affecting the left ventricle.
Epidemiology
The condition typically occurs in children and is thought to occur in around 0.4% of cases based on autopsy studies.
Clinical presentation
In isolated cases, they are often asympto...
Article
Kerley lines in the exam
Getting a film with Kerley lines in the exam is one of the many exam set-pieces that can be prepared for.
Radiographic features
Plain radiograph
There are bilateral basal interstitial lines that extend to the pleural surface - these are septal (Kerley B) lines. There is slight asymmetry of th...
Article
T1 vertebra
T1 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a complete facet for the 1st rib and a demifacet for the 2nd rib. It contains lips on the upper surface of the body. T1 also has a spinous process more horizontal than other thoracic vertebrae.
Article
CSF cleft sign
The CSF cleft sign in neuroimaging can be used to distinguish an extra-axial lesion from an intra-axial lesion and is typically used in the description of a meningioma.
Classically, the cleft was regarded as representing a thin rim of CSF between a tumor and brain parenchyma. However, it often ...
Article
Renal milk of calcium cysts
Renal milk of calcium cysts refer to the appearance of a calcium precipitate found either within a calyceal diverticulum, that has lost communication with the collecting system, or within a simple renal cyst.
Clinical presentation
Renal milk of calcium cysts are typically asymptomatic.
Radio...
Article
Chronic lung allograft dysfunction
Chronic lung allograft dysfunction (CLAD) is one of the late-stage post lung transplant complications. It is the most common cause of mortality in lung transplant recipients after the 1st year of transplantation 4.
Pathology
It is a clinical spirometric diagnosis characterized by an irreversib...
Article
Physical principles of ultrasound
Medical ultrasound is based on the use of high-frequency sound to aid in the diagnosis and treatment of patients. Ultrasound frequencies range from 2 to approximately 15 MHz, although even higher frequencies may be used in some situations.
The ultrasound beam originates from mechanical oscillat...
Article
Pulmonary opacification
Pulmonary opacification represents the result of a decrease in the ratio of gas to soft tissue (blood, lung parenchyma and stroma) in the lung. When reviewing an area of increased attenuation (opacification) on a chest radiograph or CT it is vital to determine where the opacification is. The pat...
Article
Kuwada classification of Achilles tendon tear
The Kuwada classification of Achilles tendon tear was proposed in 1990 4 and remains the most widely used system for describing Achilles tendon rupture.
Classification
Achilles tendon tears may be grouped (according to severity of the tear and degree of retraction) into four types:
type...
Article
Accessory sutures
The parietal and occipital bones in particular are common regions for accessory sutures because of their multiple ossification centers.
It is important to know these anatomic variations, mainly on the head trauma image studies in children, where it could be difficult to differentiate non-depres...
Article
Pyramidal lobe of thyroid
The pyramidal lobe of thyroid (also known as Lalouette pyramid 5) is a normal anatomic variant representing a superior sliver of thyroid tissue arising from the thyroid isthmus. It is seen as a third thyroid lobe and is present in 10-30% of the population.
It represents a persistent remnant of ...
Article
Gallbladder cancer
Gallbladder cancer is relatively uncommon compared to other hepatobiliary malignancies.
Pathology
Primary
gallbladder carcinoma
gallbladder adenocarcinoma: most common 1
gallbladder squamous cell carcinoma
gallbladder neuroendocrine carcinoma
gallbladder sarcoma: very rare 2
gallbladder ...
Article
iOS case packs
In 2008 the first version of Radiopaedia Teaching Cases became available on the Apple AppStore. Ten years later the app was retired and was no longer available for download.
To make these curated cases available once more we are creating these public playlists. Be patient, they will be gradual...
Article
Mercury embolism
Mercury embolism is a rare condition caused by the embolism of elemental mercury secondary to suicidal or accidental intravenous injection 1,4.
Pathology
Etiology
Mercury embolism is primarily from intravenous injection of elemental mercury although it has rarely been seen secondary to inges...
Article
Isotone
Isotones are atomic species that share the same number of neutrons and differ in the number of protons.
Examples of isotones include carbon-12, nitrogen-13 and oxygen-14. These atoms all have six neutrons and six, seven and eight protons respectively.
A mnemonic that can be used to differentia...
Article
Baumann angle
Baumann angle, also known as the humeral-capitellar angle, is used for the evaluation of the displacement of pediatric supracondylar humeral fractures. It is measured on a frontal radiograph, with elbow in extension.
This angle is formed by the humeral axis and a straight line through the epiph...
Article
Pulmonary edema (summary)
This is a basic article for medical students and other non-radiologists
Pulmonary edema refers to the abnormal accumulation of fluid in the extravascular compartments of the lung. This initially results in interstitial edema and perihilar airspace opacification.
Reference article
This is a su...
Article
Sigmoid shaped interventricular septum
A sigmoid-shaped interventricular septum is considered an anatomical variant that gives the interventricular septum a sigmoid or S like contour. It may be more common in elderly patients. It has occasionally been associated with syncope 1 and mild ventricular obstruction 2.
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