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
Shading sign (endometrioma)
Shading sign is an MRI finding typically seen in an endometrioma. It may also be seen with some endometrioid tumors (e.g. endometrioid carcinoma of the ovary) and uncommonly other blood-containing lesions (e.g. hemorrhagic corpus luteum cysts).
The sign describes lesions that are hyperintense o...
Article
T2 dark spot sign (endometrioma)
T2 dark spot sign is an MRI appearance of endometriomas as a result of chronic hemorrhage. The sign is useful in differentiating a solitary endometrioma from a functional hemorrhagic ovarian cyst, as both might show high T1 signal with T2 shading.
The sign describes a focal T2 hypointense nodu...
Article
Mushroom cap sign (endometriosis)
The mushroom cap sign is one of the important signs of deep rectosigmoid endometriosis on T2-weighted MRI sequences. It is highly specific for submucosal involvement of the rectosigmoid colon and can be useful for differentiating endometriosis from other infiltrating lesions, such as malignancie...
Article
Obturator externus muscle
The obturator externus is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis.
Summary
Origin: external surface of obturator membrane and adjacent bone (inferior pubic ramus and the ramus of the ischium)
Insertion: trochanteric fossa of femur
Blood su...
Article
Mesothelioma
Mesothelioma is an aggressive malignant tumor of mesothelium and 90% of tumors arise from the pleura.
This article is about the pleural form of the disease, other locations include 17:
peritoneal mesothelioma (~10%)
pericardial mesothelioma (<1%)
cystic/multicystic mesothelioma
tunica vagi...
Article
Cryptogenic organizing pneumonia
Cryptogenic organizing pneumonia (COP) is a disease of unknown etiology characterized on imaging by multifocal ground glass opacifications and/or consolidation. A wide variety of infectious as well as noninfectious causes may result in a similar histologic pattern.
Terminology
Organizing pneum...
Article
CNS embryonal tumor with PLAGL amplification
CNS embryonal tumor with PLAGL amplification is a recently identified pediatric brain tumor found in both the supratentorial and infratentorial brain defined by amplification of the PLAGL1 or PLAGL2 genes. Given its histological overlap with other embryonal CNS tumors, it was previously misclass...
Article
Myometrial cysts
Myometrial cysts are cysts seen in the myometrium and these can be differentiated appropriately based on location and sonological or Doppler features. Most commonly they are benign 2.
Pathology
Etiology
They can arise from variable etiology and include 1,2:
adenomyosis
most often seen at t...
Article
Enchondromatosis
Enchondromatosis, also known as Ollier disease (see Terminology section), is a non-hereditary, sporadic, skeletal disorder characterized by multiple enchondromas principally located in the metaphyseal regions.
Terminology
Some authors make a distinction between Ollier disease and enchondromato...
Article
Coronoid process fracture
Fractures of the coronoid process of the ulna are uncommon and often occur in association with elbow dislocation.
Pathology
Mechanism
Fracture of the coronoid process is thought to result from elbow hyperextension with either avulsion of the brachialis tendon insertion or shearing off by the...
Article
Hyoid bone
The hyoid bone is a midline "U or horseshoe-shaped" bone that serves as a structural anchor in the mid-neck. It is the only bone in the human body that does not directly articulate with another bone (other than sesamoids). It is a place of convergence of multiple small neck muscles that permit t...
Article
Muscular attachments of the hyoid bone (mnemonic)
A handy mnemonic to recall the muscle attachments of the hyoid bone. The first sentence is for six muscles attaching superiorly, the second sentence is for three muscles attaching inferiorly. Both sentences are in order from lateral to medial:
Christopher, He Didn't See Girls Much. That's Obvio...
Article
Renal artery aneurysm
Renal artery aneurysms (RAA) are the second most common visceral aneurysms (15-22%), the most common being splenic artery aneurysms (60%).
Epidemiology
Renal artery aneurysms occur in ~0.1% of the population 6,8,10. They are more common in females 6. The median age at diagnosis is 50 years 8....
Article
Lung cancer (staging - IASLC 9th edition)
The IASLC (International Association for the Study of Lung Cancer) 9th edition lung cancer staging system was introduced in 2025 and supersedes the IASLC 8th edition. It is a TNM staging system.
There are only minor differences from the 8th edition.
no changes to the T staging.
subdivision of...
Article
Encapsulating peritoneal sclerosis
Encapsulating peritoneal sclerosis is a rare non-malignant cause of acute or subacute small bowel obstruction. It is characterized by total or partial encasement of the small bowel within a thick fibrocollagenous membrane.
Terminology
The condition was originally termed abdominal cocoon. The c...
Article
Hepatic adenoma
Hepatic adenomas, or hepatocellular adenomas (HCA), are benign, generally hormone-induced liver tumors. They are usually solitary but can be multiple. Most adenomas have a predilection for hemorrhage, and they must be differentiated from other focal liver lesions due to the risk of HCC transform...
Article
Hirschsprung disease
Hirschsprung disease, a neurocristopathy, is the most common cause of neonatal colonic obstruction (15-20%). It is commonly characterized by a short segment of colonic aganglionosis affecting term neonates, especially boys.
Epidemiology
Hirschsprung disease affects approximately 1:5000-8000 l...
Article
Odontogenic sinusitis
Odontogenic sinusitis describes inflammation of the maxillary sinus secondary to dental pathology or dental procedures.
Epidemiology
Odontogenic sinusitis accounts for 5-70% of cases of chronic maxillary sinusitis. It is the most common cause of unilateral maxillary sinusitis 5.
Clinical pres...
Article
Vasitis
Vasitis (plural: vasitides), also known as deferentitis (plural: deferentitides) refers to inflammation of the ductus deferens. Funiculitis or corditis refers to inflammation of the spermatic cord 7. They are uncommon inflammatory disorders generally classified as either asymptomatic vasitis nod...
Article
Quadriceps tendon rupture
Quadriceps tendon rupture is usually associated with forced flexion of the knee or a direct blow, although spontaneous ruptures are reported.
Pathology
Predisposing illnesses include:
connective tissue disorders
systemic lupus erythematosus
rheumatoid arthritis
gout
renal impairment
c...
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