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2005 WHO histological classification of odontogenic tumors

The 2005 WHO histological classification of odontogenic tumors lays out a classification system for neoplasms and other tumors related to the odontogenic apparatus. At the time of writing (2016), it is still the most widely used classification system although a new revision is due to come up in ...

Aberrant internal carotid artery

Aberrant internal carotid artery is a variant of the internal carotid artery and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the internal carotid artery 5. Gross anatomy There is consequent enlargement of the usually sma...

Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...

Accessory maxillary ostium

Accessory maxillary ostia are a common anatomic variant, and are usually found incidentally on CT scans of the paranasal sinuses. Accessory ostia of the maxillary sinus are common, occurring in up to 40% patients 1. No significant association has been found between the presence of accessory osti...

Accessory meningeal artery

The accessory meningeal artery is a branch of the maxillary artery but can also branch from the middle meningeal artery. The artery passes upwards through the foramen ovale to supply the trigeminal ganglion and the dura mater of Meckel cave and the middle cranial fossa. It also usually supplies...

Accessory parotid gland

Accessory parotid glands are a normal variant and represent ectopic salivary tissue separate from, but usually in close proximity to, the main parotid glands. Epidemiology Accessory parotid glands are commonly picked up incidentally on ultrasound; seen in ~20% of the general population 2. Gro...

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...

Achondroplastic base of skull abnormalities

Achondroplasia is the most common cause of short-limb dwarfism. (For a general discussion, see the generic article on achondroplasia.) As the skull base forms by endochondral ossification whereas the skull vault by membranous ossification, there is a marked discrepancy in relative size as the s...

Acinic cell carcinoma (salivary glands)

Acinic cell carcinomas of the salivary glands are rare malignant neoplasms that account for 1-3% of all salivary gland tumors. Pathology Pathology may superficially resemble normal serous (acinar) cells of the salivary glands. It is considered a low-grade, indolent malignancy, but with a tend...

Acquired cholesteatoma

Acquired cholesteatomas makeup 98% of all middle ear cholesteatomas and are almost always closely related to the tympanic membrane, from which most are thought to arise. Clinical presentation The vast majority of acquired cholesteatomas develop as a result of chronic middle ear infection and ...

Acrocephalopolysyndactyly

Acrocephalopolysyndactyly (ACPS) syndrome is comprised of a rare group of disorders collectively characterized by: calvarial anomalies: e.g. craniosynostoses digital anomalies: syndactyly and polydactyly While there can be some overlap in features, they can be primarily classified into the fo...

Acrocephalosyndactyly

Acrocephalosyndactyly syndromes (ACS) are a rare group of disorders collectively characterized by: calvarial anomalies, e.g. craniosynostoses digital anomalies, e.g. syndactyly Classification While there can be some overlap in features, they can be primarily classified into the following maj...

ACR Thyroid Imaging Reporting and Data System (ACR TI-RADS)

ACR TI-RADS is a reporting system for thyroid nodules on ultrasound proposed by the American College of Radiology (ACR) 1. This uses a standardized scoring system for reports providing users with recommendations for when to use fine needle aspiration (FNA) or ultrasound follow-up of suspicious ...

Acute invasive fungal sinusitis

Acute invasive fungal sinusitis is the most aggressive form of fungal sinusitis. It is seen particularly in immunocompromised patients and is the source of significant morbidity and mortality. It should be distinguished from the other two forms of invasive fungal sinusitis, chronic invasive fung...

Acute mastoiditis

Acute mastoiditis refers to a suppurative infection of the mastoid air cells. It is the most common complication of acute otitis media. Terminology In acute otitis media, an inflammatory middle ear effusion is present that can freely move into the mastoid air cells. Consequently, some authors ...

Acute otitis externa

Acute otitis externa (AOE), also known as "swimmer's ear", is inflammation of the external auditory canal (EAC) that can involve the pinna as well. Bacterial infection, most commonly with Pseudomonas aeruginosa, is responsible for the overwhelming majority of cases. It is a common condition. Ep...

Acute sinusitis

Acute sinusitis (rare plural: sinusitides) is an acute inflammation of the paranasal sinus mucosa that lasts less than four weeks and can occur in any of the paranasal sinuses. If the nasal cavity mucosa is also involved then the term rhinosinusitis may be used. Clinical presentation Fever, he...

Adenocarcinoma of the lacrimal glands

Adenocarcinoma of the lacrimal glands is rare, with few cases reported in the literature since it was first described in 1996 1. Primary adenocarcinoma of the lacrimal gland is extremely rare; only 9 cases have been reported in the literature 1,2. It can be classified into high- and low-grade ma...

Adenoidal hypertrophy (adults)

Adenoidal hypertrophy or enlargement in adults is much less commonly seen than in children. It is usually due to chronic infection or inflammation. HIV always needs to be excluded as a cause. Pathology In general, the adenoid tonsils enlarge after birth, maximizing by 6 years old. Thereafter, ...

Adenoidal hypertrophy (children)

Adenoidal hypertrophy or enlargement in children is common and due to an increase in the size of the adenoids. For adenoidal enlargement in adults, which is much rarer and usually pathological, please see the separate article, adenoidal hypertrophy (adults). Clinical presentation nasal congest...

Adenoid cystic carcinoma

Adenoid cystic carcinomas are a rare histological subtype of adenocarcinoma. Pathology Adenoid cystic carcinomas are generally considered low grade 4. The tumors have a notable tendency for perineural spread. Location They have a wide distribution and mainly occur in relation to the airways,...

Adenoid cystic carcinoma of lacrimal glands

Adenoid cystic carcinoma (ACC) of the lacrimal glands is an extraconal malignancy usually originating from the orbital lobe of the lacrimal gland. Clinical presentation It often presents with orbital pain and paresthesia, since this type of tumor is frequently associated with perineural spread...

Adenoid cystic carcinoma of the salivary glands

Adenoid cystic carcinoma (ACC) of the salivary glands is the second most common malignancy involving the minor salivary glands behind mucoepidermoid carcinoma and the second most common malignancy involving the parotid gland. Pathology Adenoid cystic carcinomas arise more commonly in the minor...

Adenoid facies

Adenoid facies, also known as the long face syndrome, refers to the long, open-mouthed face of children with adenoid hypertrophy. Hypertrophy of the nasopharyngeal pad of lymphoid tissues (adenoids) is the most common cause of nasal obstruction in children. The mouth is always open because upper...

Adenoid tonsil

The adenoid tonsils, or often just simply the adenoids (also known as the nasopharyngeal or pharyngeal tonsils), are paired foci of lymphatic tissue located on the superoposterior wall of the nasopharynx and form part of Waldeyer's ring.

Adenolipoma (thyroid gland)

Adenolipoma of the thyroid gland (also known as a thyrolipoma or a thyroid hamartoma) is a rare, benign fat-containing thyroid lesion. These lesions are usually well encapsulated and are composed of varying degrees of follicular thyroid tissue (thyroid adenoma) and mature adipose tissue; the amo...

Adenomatoid odontogenic tumor

Adenomatoid odontogenic tumors are rare and differ from most other dentition related lesions in that they more frequently occur in the maxilla. Epidemiology They are also seen more frequently in females, most frequently in the second decade of life. Radiographic features They present as an e...

Adhesive otitis media

Adhesive otitis media is a form of chronic otitis media where there is an adhesion of medial ear structures as a result of chronic inflammation. There are often complete or partial adhesions between the thin retracted and atrophic pars tensa and the medial wall of the middle ear. Soft tissue deb...

Adrenal vein sampling

Adrenal vein sampling (AVS) is a procedure where blood is collected from the adrenal veins via catheter to confirm autonomous hormone production, if it is unilateral or bilateral, and to guide further treatment. Indication Adrenal vein sampling is commonly performed in primary aldosteronism, b...

Adult cervical lymphadenopathy (differential)

Cervical lymphadenopathy in an adult can result from a vast number of conditions. They include: malignancy metastases from head and neck tumors lymphoma other neoplastic lesions Castleman disease Kaposi sarcoma infection bacterial infection viral infection Epstein-Barr virus herpes ...

Agger nasi cells

Agger nasi air cells are the most anterior ethmoidal air cells lying anterolateral and inferior to the frontal recess and anterior and above the attachment of the middle turbinate. They are located within the lacrimal bone and therefore have as lateral relations the orbit, the lacrimal sac and t...

AIDS-defining illness

AIDS-defining illnesses are conditions that in the setting of a HIV infection confirm the diagnosis of AIDS, and do not commonly occur in immunocompetent individuals 2. According to the CDC surveillance case definition 1, they are: Infectious bacterial infections: multiple or recurrent candid...

Alar fascia

The alar fascia is a thin fibroareolar membrane separating the (anterior) true retropharyngeal space from the (posterior) danger space. It is the ventral component of the deep layer of the deep cervical fascia. Notably, in the well patient, the alar fascia is not usually visible on cross-sectio...

Allergic fungal sinusitis

Allergic fungal sinusitis is the most common form of fungal sinusitis and is common in warm and humid climates. On imaging, it usually presents as opacification and expansion of multiple paranasal sinuses, unilaterally or bilaterally, with content that is centrally hyperdense on CT. MRI shows T2...

Allgrove syndrome

Allgrove syndrome (also known as triple A syndrome) is an autosomal recessive condition that consists of three main findings: achalasia alacrima ACTH insensitivity

Alphanumeric system of dental notation

The alphanumeric system of dental notation is a modification of Palmer notation for numbering and naming teeth made for electronic transcription. Its use is primarily in the United Kingdom 1,3,4. Permanent teeth First, the jaws are divided into four quadrants 1-5. Each quadrant is denoted by t...

Alport syndrome

Alport syndrome is an X-linked dominant disease characterized by progressive sensorineural hearing loss, renal disease and, at times, ocular lesions. Clinical presentation hematuria sensorineural hearing loss: typically high frequency 2 ocular abnormalities anterior lenticonus: most common ...

Amaurosis fugax

Amaurosis fugax is the transient monocular loss of vision, normally lasting a few seconds to a few minutes, secondary to vascular ischemia or insufficiency. Epidemiology It has an incidence of 50,000 per year in the United States. Clinical presentation Patients present with transient monoc...

Ameloblastic fibroma

Ameloblastic fibromas appear as unilocular lucent mandibular lesions, most frequently in the posterior mandible, and are usually associated with impacted teeth, centered on the unerupted crown. They, therefore, appear very similar to unilocular ameloblastomas. They are composed of enamel and emb...

Ameloblastic fibro-odontoma

Ameloblastic fibro-odontoma (AFO) is a rare benign mixed odontogenic tumor that usually arises in the maxilla and mandible. According to the 2005 WHO classification of odontogenic tumors, it is defined as a benign tumor that resembles ameloblastic fibroma but contains enamel and dentin. Epidemi...

Ameloblastoma

Ameloblastomas are locally aggressive benign tumors that arise from the mandible, or, less commonly, from the maxilla. Usually present as a slowly but continuously growing hard painless lesion near the angle of the mandible in the 3rd to 5th decades of life, which can be severely disfiguring if ...

American Dental Association Universal Numbering System

The American Dental Association Universal Numbering System is a tooth notation system primarily used in the United States. Teeth are numbered from the viewpoint of the dental practitioner looking into the open mouth, clockwise starting from the distalmost right maxillary teeth. Permanent teeth...

American Journal of Neuroradiology (AJNR)

American Journal of Neuroradiology (AJNR) is the premier publication of the American Society of Neuroradiology and was first published in 1980. Its founding editor was Juan M Taveras (1919-2002), the pioneering American neuroradiologist, who was a co-founder of the American Society of Neuroradio...

American Society of Neuroradiology

American Society of Neuroradiology (ASNR) was established in 1962 to ensure that neuroradiologists in the United States could freely exchange ideas and act with a common voice. It publishes the American Journal of Neuroradiology (AJNR). History At the VIth Symposium Neuroradiologicum held in R...

Ampulla (disambiguation)

Ampulla (plural: ampullae) is an anatomical term used for tubular structures with a short segmental bulbous dilatation: ampulla (fallopian tube) ampulla (lacrimal system) ampulla (esophagus) ampulla (rectum) ampulla (semicircular ducts) ampulla (spleen) ampulla of Vater ampulla (vas defe...

Anaplastic thyroid cancer (staging)

Anaplastic thyroid cancer staging refers to TNM staging of anaplastic thyroid carcinomas. Papillary, follicular, and medullary thyroid carcinomas are staged separately. The following article reflects the 8th edition manual published by the American Joint Committee on Cancer, which is used for st...

Anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma is a highly aggressive form of thyroid cancer and accounts for ~1-2% of primary thyroid malignancies. Of all the subtypes, this carries the worst prognosis. Epidemiology Typically occurs in the elderly (peak incidence in 6th to 7th decades). A significant proportio...

Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...

Angular artery (facial artery branch)

The angular artery is the terminal branch of the facial artery. It becomes the angular artery after the lateral nasal artery branch from the facial artery. It courses superiorly along the lateral border of the external nose to the medial canthus. It is accompanied by the angular vein which drai...

Angular vein

The angular vein drains the anterior region of the scalp 1. It is formed by the union of the supratrochlear and supraorbital veins and becomes the facial vein 1,2,3. Gross Anatomy The angular vein is formed at the medial canthus as the supratrochlear vein and supraorbital vein unite 1,2. The a...

Aniridia

Aniridia refers to either the clinical sign of a complete/partial absence of the iris, or more specifically to the disease entity classic aniridia. Rarely other genetic conditions may cause this sign. Epidemiology Classic aniridia is inherited as an autosomal dominant condition and is seen in ...

Anisocoria

Anisocoria is present when an individual's pupils differ in size. If a person's pupils are symmetric there is said to be isocoria. Epidemiology The prevalence of transient physiological anisocoria of >0.4 mm is found in up to 20% population. However persistent anisocoria seems to be rarer, in ...

Annular ligament (disambiguation)

The annular ligament can refer to: annular ligament of the stapes annular ligament of the proximal radio-ulnar joint

Annulus of Zinn contents (mnemonic)

A mnemonic to remember the contents of the tendinous ring (also known as the annulus of Zinn) from superior to inferior is: "One Canal, Several Orbital Nerves In One Annulus" Mnemonic: OC: optic canal SO: superior division of oculomotor nerve N: nasociliary nerve IO: inferior division of o...

Anorexia nervosa

Anorexia nervosa is a psychiatric disorder characterized by distorted self-perception of body weight leading to starvation, obsession with remaining underweight, and an excessive fear of gaining weight. One in five patients with anorexia dies due to complications of the disease. Epidemiology T...

Ansa cervicalis

The ansa cervicalis (or ansa hypoglossi, an archaic synonym) is a component of the cervical plexus which gives muscular branches to the geniohyoid muscle of the suprahyoid group and most of the infrahyoid (strap) muscles (excluding the thyrohyoid muscle). It lies within the carotid triangle, s...

Anterior cervical space

The anterior cervical space is a small infrahyoid compartment of the head and neck. It is a fat containing space and is not enclosed by fascia 1. Gross anatomy Contents areolar fat Relations posterior: carotid space medial: visceral space superior: submandibular space Related pathology ...

Anterior commissure of the larynx

The anterior commissure of the larynx is the anterior junction point of the true vocal cords. It is bounded anteriorly by the thyroid cartilage and is part of the laryngeal glottis.

Anterior cranial fossa

The anterior cranial fossa constitutes the floor of the cranial vault which houses the frontal lobes of the brain. Gross anatomy Structures present in the midline of the anterior cranial fossa from anterior to posterior are: groove for superior sagittal sinus groove for anterior meningeal v...

Anterior division of the mandibular nerve

The anterior division of the mandibular division of the trigeminal nerve has four branches, which are all motor branches except one. The four branches are: deep temporal nerves lateral pterygoid nerves masseteric nerve buccal nerve

Anterior epitympanic recess

The anterior epitympanic recess, also known as the supratubal recess, is a small discrete space in the epitympanum anterior to the malleus. It is separated from the epitympanum proper by the cog.

Anterior ethmoidal artery

The anterior ethmoid artery is a branch of the ophthalmic artery. It supplies the anterior and middle ethmoidal sinuses, frontal sinus, the lateral nasal wall and the nasal septum (see nasal cavity). Gross anatomy It traverses the anterior ethmoidal foramen with the anterior ethmoidal nerve (w...

Anterior ethmoidal nerve

The anterior ethmoidal nerve is an extraconal branch of the nasociliary nerve, a branch of the ophthalmic division of the trigeminal nerve. Some authors describe it as either the terminal branch or a direct continuation of the nasociliary nerve. It branches off distal to the infratrochlear nerv...

Anterior ethmoidal notch

The anterior ethmoidal notch contains the anterior ethmoidal artery and has significant rates of anatomic variation that put the artery during function endoscopic sinus surgery (FESS). Gross anatomy The anterior ethmoidal notch lies in the medial wall of the superomedial orbit, adjacent to the...

Anterior jugular vein

The anterior jugular vein is a paired tributary of the external jugular vein. Gross anatomy Location It arises beneath the chin in the region of the hyoid bone or suprahyoid neck. Origin and course The anterior jugular vein has its origin as the confluence of several small superficial subma...

Anterior lacrimal crest

The anterior lacrimal crest is a bony projection on the frontal process of the maxilla continuous with the orbital rim which creates the lateral margin of the lacrimal sac fossa. The medial palpebral ligament is attached to anterior lacrimal crest. Immediately anterior to the anterior lacrimal ...

Anterior lenticonus

Anterior lenticonus is present when the anterior surface of the ocular lens assumes a conical shape. Epidemiology It can be unilateral or bilateral. Bilateral anterior lenticonus is associated with Alport syndrome. Clinical presentation Decreased visual activity and irregular refraction that...

Anterior naris

The anterior (or external) nares (singular: naris) (or nostrils) form the entrance to the nose. Each naris is formed by a ring of structures: medially the columella (soft tissue anteroinferior portion of the nasal septum) laterally and superiorly the nasal ala inferiorly the nasal sill By vi...

Anterior superior alveolar canal

The anterior superior alveolar canal courses through the anterior wall of the maxillary sinus, and contains the anterior superior alveolar nerve, artery and vein. Usually, it shares a common channel with the infraorbital canal but when seen separately should not be confused for a fracture.

Anterior superior alveolar nerve

The anterior superior alveolar nerve, also known as the anterior superior dental nerve, is the third branch of the infra-orbital nerve, from the maxillary division of the trigeminal nerve. It is the largest of the superior alveolar nerves and contributes to the superior dental plexus. Gross an...

Anterior triangle

The anterior triangle forms the anterior compartment of the neck and is separated from the posterior triangle by the sternocleidomastoid muscle. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomi...

Anterior tympanic artery

The anterior tympanic artery is the second named branch of the first part of the maxillary artery. The vessel passes through the petrotympanic fissure to supply the lining of the middle ear and accompanies the chorda tympani in its course.

Antrochoanal polyp

Antrochoanal polyps (ACP) are solitary sinonasal polyps that arise within the maxillary sinus. They pass to the nasopharynx through the sinus ostium and posterior nasal cavity, enlarging the latter two. Similar, less common, polyps can arise in the sphenoid sinus extending into the nasopharynx:...

Antrolith

An antrolith is a calcified mass within the maxillary sinus. The origin of the nidus of calcification may be extrinsic (foreign body in sinus) or intrinsic (stagnant mucus, fungal ball). Most antroliths are small and asymptomatic. Larger ones may present as a chronic maxillary sinusitis with sy...

Aphakia

Aphakia (less commonly aphacia) is the absence of the lens from the ocular globe. Pathology Etiology surgical removal of a cataract (commonest cause) trauma congenital Treatment and prognosis Surgical insertion of an intraocular lens implant, in which case the aphakic appearance is calle...

Apical periodontitis

Apical periodontitis refers to a spectrum of diseases that occur around the tooth apex these can include 1: periapical granuloma periapical abscess periapical (radicular) cyst Complications Apical periodontal disease of the maxillary teeth can extend into the maxillary sinuses with resultan...

Ariboflavinosis

Ariboflavinosis is the term given to riboflavin (vitamin B2) deficiency. Epidemiology Ariboflavinosis has been seen in both developed and developing countries, and across the socioeconomic spectrum. It is usually present in the context of other hypovitaminoses. It has been found to more comm...

Arnold's nerve

Arnold's nerve is the auricular branch, also known as the mastoid branch, of the vagus nerve (CN X). Origin and course Arnold's nerve originates from the superior ganglion of the vagus nerve and also has a small contribution from the inferior ganglion of the glossopharyngeal nerve. It ascends ...

Arrested pneumatization of the skull base

Arrested pneumatization of the skull base is an anatomical variant that most commonly occurs in association with the sphenoid sinus. It is known that the sphenoid bones undergo early fatty marrow conversion antecedent to normal pneumatization. However, for unclear reasons, some individuals exper...

Arterial supply of the head and neck

The arteries of the head and neck are branches of the common carotid and subclavian arteries. common carotid artery carotid body carotid bifurcation internal carotid artery (segments) caroticotympanic artery persistent stapedial artery ophthalmic artery supraorbital artery lacrimal arte...

Artificial Intelligence (AI) TI-RADS

AI TI-RADS (Artificial Intelligence Thyroid Imaging Reporting and Data System) is a data-driven analysis and revision of the 2017 ACR TI-RADS 1. Published in May 2019 2, this had the intention of simplifying categorization and improving specificity while maintaining high sensitivity. This system...

Aryepiglottic folds

The aryepiglottic folds are two ligamentomuscular structures within the supraglottic larynx that function to protect the airway when swallowing. Gross anatomy Each aryepiglottic fold is comprised of the superior ligamentous edge of the quadrangular membrane and covering mucous membrane 1, the ...

Arytenoid cartilage

The arytenoid cartilages are paired hyaline cartilages that articulate with the sloping upper border of the lamina of the cricoid cartilage by the cricoarytenoid joint. This joint allows movement of the arytenoid cartilages, which is vital in approximating, tensing and relaxing the vocal folds. ...

Ascending cervical artery

The ascending cervical artery is 1 of the 4 branches of the thyrocervical trunk (off the first part of the subclavian artery). It is a small artery that ascends medial to the phrenic nerve on the prevertebral fascia. It contributes many small spinal branches into the intervertebral foramina of ...

Ascending pharyngeal artery

The ascending pharyngeal artery, the smallest branch of the external carotid artery, is a long, slender vessel, deeply seated in the neck, beneath the other branches of the external carotid and under the stylopharyngeus. Summary origin: a branch of the external carotid artery course: vertical...

Aspergillus flavus

Aspergillus flavus is a fungus and one of the species of Aspergillus that is common in the environment and responsible for pathology in humans. It is the second most common cause of pulmonary aspergillosis (after Aspergillus fumigatus) and can additionally cause corneal, otomycotic, and nasoorb...

Aspiration

Aspiration occurs if liquid or solid material enters the subglottic lower respiratory tract. Terminology The term aspiration is used if material passes below the level of the vocal folds, i.e. subglottic. If material enters the larynx but remains above the vocal folds this is called penetratio...

Assessment of thyroid lesions (general)

Assessment of thyroid lesions is commonly encountered in radiological practice. Thyroid mass hyperplastic/colloid nodule/nodular hyperplasia: 85% adenoma follicular: 5% others: rare carcinoma papillary: 60-80% of carcinomas follicular: 10-20% medullary: 5% anaplastic: 1-2% thyroid ly...

Assessment of thyroid lesions (ultrasound)

Ultrasound is the first line imaging modality for assessment of thyroid nodules found on clinical examination or incidentally on another imaging modality. This article is an overview on ultrasonographic features of thyroid nodules, which are used to determine the need for biopsy with fine needle...

Asterion

The asterion is the junction on the side of the posteroinferior calvarium where three sutures meet: parietomastoid suture occipitomastoid suture lambdoid suture It represents the site of the closed mastoid fontanelle. It is located at the posterior end of the parietotemporal suture, whereas ...

Asteroid hyalosis

Asteroid hyalosis is a degenerative condition of the eye where there is an accumulation of calcium soaps in the vitreous chamber. Epidemiology The prevalence increases with age from 0.2% in 43-54-year-olds to 2.9% in 75-86-year-olds. The overall prevalence is 1.2%. It is more commonly unilater...

Asymmetric fatty bone marrow of the petrous apex

Asymmetric pneumatization of petrous apex is a frequent normal anatomic variant resulting in asymmetric fatty bone marrow within the petrous apex. It is a common incidental finding on brain and skull base MRI. Clinical presentation Asymptomatic. Pathology Asymmetric pneumatization of the pet...

ATA guidelines for assessment of thyroid nodules

The American Thyroid Association (ATA) guidelines for assessment of thyroid nodules are meant to improve inter- and intra-reader consistency during assessment of thyroid nodules on ultrasound, and to facilitate communication with referring endocrinologists. The 2015 guidelines stress the import...

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