Articles
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16,861 results found
Article
Medical abbreviations and acronyms (N)
This article contains a list of commonly used medical abbreviations and acronyms that start with the letter N and may be encountered in medicine and radiology (please keep the main list and any sublists in alphabetic order).
A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R ...
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Electrical impedance tomography
Electrical impedance tomography (EIT) is a type of imaging based on sending small amounts of electrical current across tissue (when used for medical imaging), and measuring conductivity. Such measurements are done with electrodes around the object measured, and reconstruction algorithms are used...
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Infratemporal fossa
The infratemporal fossa is a complex space of the face that lies posterolateral to the maxillary sinus, below the skull base, and between the pharyngeal sidewall and mandibular ramus. It overlaps with the masticator space and prestyloid parapharyngeal space.
Gross anatomy
The infratemporal fos...
Article
Temozolomide
Temozolomide is an oral chemotherapeutic drug primarily used in the treatment of astrocytomas, oligodendrogliomas and glioblastoma, often in conjunction with radiotherapy (Stupp protocol).
Mechanism of action
Temozolomide is an alkylating agent. It adds a methyl group to the purine bases of DN...
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Methylguanine-DNA methyltransferase (MGMT)
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that is important in predicting the effects of alkylating chemotherapeutic agents (e.g. temozolomide) in the treatment of high-grade gliomas (astrocytomas and glioblastomas).
Mechanism of action
MGMT is an enzyme that removes...
Article
Stupp protocol
The Stupp protocol has become the standard of care for the treatment of high-grade astrocytoma and glioblastoma since its publication in 2005 and has led to significant survival improvements 1. It consists of radiotherapy and concomitant chemotherapy with temozolomide, an alkylating agent.
Prot...
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Lipoma
Lipomas are benign tumors composed of mature adipocytes. They are the most common soft tissue tumor, seen in ~2% of the population.
Epidemiology
Patients typically present in adulthood (5th-7th decades).
Associations
In some cases, multiple lipomas are associated with syndromes and other di...
Article
Nevoid hyperkeratosis of the nipple and the areola
Nevoid hyperkeratosis of the nipple and the areola (NHNA) is a rare, idiopathic, and benign dermatological condition of the nipple and areola.
Epidemiology
Most often seen in females of reproductive age, especially during the 2nd and 3rd decades of life. Less than 70 cases have been reported t...
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Monochorionic monoamniotic twin pregnancy
A monochorionic monoamniotic (MCMA) twin pregnancy is a subtype of monozygotic twin pregnancy. These fetuses share a single chorionic sac, a single amniotic sac, and, in general, a single yolk sac.
Epidemiology
It accounts for the minority (~5%) of monozygotic twin pregnancies and ~1-2% of al...
Article
Spinal epidural venous plexus congestion
Spinal epidural venous plexus congestion or dilatation is typically a complication of other pathologies.
Clinical presentation
Radiculopathy caused by the dilated epidural veins is not uncommon 1. More severe symptoms such as cauda equina compression syndrome have been reported 6, 7.
Patholo...
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Schneiderian papilloma
Schneiderian papillomas, also known as sinonasal papillomas, are benign sinonasal tumors that arise from the Schneiderian epithelium of the nasal cavity and paranasal sinuses.
Epidemiology
Schneiderian papillomas account for ~2.5% (range 0.4-4.7%) of sinonasal tumors 2.
Pathology
The WHO cl...
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Placental site trophoblastic tumor
Placental site trophoblastic tumors (PSTT) are rare and one of the least common (~0.2% 7) forms of gestational trophoblastic disease.
Epidemiology
Placental site trophoblastic tumors typically occur in women of reproductive age with an average age of ~30 years. They may occur after a normal pr...
Article
Craniovertebral junction anomalies
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to an acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression, and obstructive hydrocephalus.
Pathology
The craniovertebral junction ...
Article
Bone marrow
Bone marrow is ubiquitous throughout the skeleton, primarily composed of hematopoietic cells and fat cells between bony trabeculae and fibrous retinacula. It performs numerous physiological functions and dynamically changes during normal aging and in response to stressors and pathology. Although...
Article
Gastric lymph node stations
The gastric lymph node stations were originally divided into 16 groups, as proposed by the Japanese Research Society for Gastric Cancer in 1973.
Gross anatomy
There are three major groups of lymph drainage from the stomach, namely, left gastric, gastroepiploic, and pyloric nodes 4, as shown in...
Article
Diffuse hepatic steatosis (grading)
Grading of diffuse hepatic steatosis on ultrasound has been used to communicate to the clinician about the extent of fatty changes in the liver.
Grading using ultrasound B-mode
grade I: diffusely increased hepatic echogenicity but periportal and diaphragmatic echogenicity is still appreciable...
Article
Vagal schwannoma
Vagal schwannomas are uncommon benign masses that can occur anywhere along the course of the vagus nerve but most commonly occur in the cervical region.
Epidemiology
Most commonly occurs in the 3rd to 5th decades. No sex predilection 3.
Clinical presentation
Patients may be asymptomatic. Whe...
Article
Pituitary macroadenoma
Pituitary macroadenomas are the most common suprasellar mass in adults, and responsible for the majority of transsphenoidal hypophysectomies. They are defined as pituitary adenomas greater than 10 mm in size and are approximately twice as common as pituitary microadenomas.
On imaging, they usu...
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Sinding-Larsen-Johansson disease
Sinding-Larsen-Johansson disease, also known as Sinding-Larsen disease or Larsen-Johansson syndrome, affects the proximal end of the patellar tendon as it inserts into the inferior pole of the patella. It represents a chronic traction injury of the immature osteotendinous junction. It is a close...
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Posterior ciliary arteries
The posterior ciliary arteries are usually paired branches arising from the ophthalmic artery, one medial and one lateral, each giving off a number of branches that supply the uvea 1.
Close to the optic nerve, are the short posterior ciliary arteries, usually numbering 16-20; these supply the p...
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