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Metrizamide
Metrizamide is a non-ionic iodine-based radiocontrast agent. It is also a density gradient medium for the centrifugation of biological particles. Historically metrizamide replaced iofendylate (trade names: Pantopaque, Myodil) as the contrast agent of choice for myelography (an X-ray study of the spine now largely replaced by MRI). The radio opacity characteristics are such that finer detail is displayed with metrizamide, as well as the advantage of reabsorption from spinal fluid and excretion from the body – since unlike iofendylate, metrizamide is a water-soluble substance. Both agents are administered by lumbar puncture (also referred to as a spinal tap or cisternal puncture), at the cervicocranial junction. The human patient is rolled from the lateral decubitus (lying on the side) to prone. Ankles are strapped to the end of a hard X-ray, CT, or MRI table. To obtain images of the cervical region the patient is then carefully tilted in the Trendelenberg position (head do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iofendylate
Iofendylate is a molecule that was used as a radiocontrast agent, typically for performing myelography studies. It was marketed under the trade names Pantopaque (in North America) and Myodil (rest of the world). Iofendylate is a highly lipophilic (oily) substance and as such it was recommended that the physician remove it from the patient at the end of the myelography study, which was a difficult and painful part of the procedure. Moreover, because complete removal could not always be achieved (or even attempted by some physicians), iofendylate's persistence in the body might sometimes lead to arachnoiditis, a potentially painful and debilitating lifelong disorder of the spine. As a result, the substance, which was used extensively for over three decades, became the subject of multiple lawsuits filed around the world. Iofendylate's use ceased when water-soluble agents suitable for spinal imaging (such as metrizamide) became available in the late 1970s. With those substances it wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiocontrast Agents
Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically iodine, or more rarely barium sulfate. The contrast agents absorb external X-rays, resulting in decreased exposure on the X-ray detector. This is different from radiopharmaceuticals used in nuclear medicine which emit radiation. Magnetic resonance imaging (MRI) functions through different principles and thus MRI contrast agents have a different mode of action. These compounds work by altering the magnetic properties of nearby hydrogen nuclei. Types and uses Radiocontrast agents used in X-ray examinations can be grouped in positive (iodinated agents, barium sulfate), and negative agents (air, carbon dioxide, methylcellulose). Iodine (circulatory system) Iodinated contrast contains iodine. It is the main type of radiocontrast used for intra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myelography
Myelography is a type of radiographic examination that uses a contrast medium (e.g. iodised oil) to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Historically the procedure involved the injection of a radiocontrast agent into the cervical or lumbar spine, followed by several X-ray projections. Today, myelography has largely been replaced by the use of MRI scans, although the technique is still sometimes used under certain circumstances – though now usually in conjunction with CT rather than X-ray projections. Types Cervical myelography This procedure is used to look for the level of where spinal cord disease occurs or compression of the spinal cord at the neck region for those who are unable or unwilling to undergone MRI scan of the spine. Lumbar myelography This procedure is to look for the level of spinal cord disease such as lumbar nerve root compression, cauda equina syndrome, conus medullaris lesions, and spinal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiocontrast Agent
Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically iodine, or more rarely barium sulfate. The contrast agents absorb external X-rays, resulting in decreased exposure on the X-ray detector. This is different from radiopharmaceuticals used in nuclear medicine which emit radiation. Magnetic resonance imaging (MRI) functions through different principles and thus MRI contrast agents have a different mode of action. These compounds work by altering the magnetic properties of nearby hydrogen nuclei. Types and uses Radiocontrast agents used in X-ray examinations can be grouped in positive (iodinated agents, barium sulfate), and negative agents (air, carbon dioxide, methylcellulose). Iodine (circulatory system) Iodinated contrast contains iodine. It is the main type of radiocontrast used for intra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-ionic
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convention. The net charge of an ion is not zero because its total number of electrons is unequal to its total number of protons. A cation is a positively charged ion with fewer electrons than protons (e.g. K+ (potassium ion)) while an anion is a negatively charged ion with more electrons than protons (e.g. Cl− (chloride ion) and OH− (hydroxide ion)). Opposite electric charges are pulled towards one another by electrostatic force, so cations and anions attract each other and readily form ionic compounds. Ions consisting of only a single atom are termed ''monatomic ions'', ''atomic ions'' or ''simple ions'', while ions consisting of two or more atoms are termed polyatomic ions or ''molecular ions''. If only a + or − is present, it indicates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cranial Cavity
The cranial cavity, also known as intracranial space, is the space within the skull that accommodates the brain. The skull is also known as the cranium. The cranial cavity is formed by eight cranial bones known as the neurocranium that in humans includes the skull cap and forms the protective case around the brain. The remainder of the skull is the facial skeleton. The meninges are three protective membranes that surround the brain to minimize damage to the brain in the case of head trauma. Meningitis is the inflammation of meninges caused by bacterial or viral infections. Structure The capacity of an adult human cranial cavity is 1,200–1,700 cm3. The spaces between meninges and the brain are filled with a clear cerebrospinal fluid, increasing the protection of the brain. Facial bones of the skull are not included in the cranial cavity. There are only eight cranial bones: The occipital, sphenoid, frontal, ethmoid, two parietal, and two temporal bones are fused to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodobenzene Derivatives
Iodobenzene is an aryl iodide and the simplest of the iodobenzenes, consisting of a benzene ring substituted with one iodine atom. Its chemical formula is . It is useful as a synthetic intermediate in organic chemistry. It is a volatile colorless liquid, although aged samples appear yellowish. Preparation Iodobenzene is commercially available, or it can be prepared in the laboratory from aniline via the diazotization reaction. In the first step, the amine functional group is Diazonium compound, diazotized with hydrochloric acid and sodium nitrite. Potassium iodide is added to the resultant phenyldiazonium chloride, causing nitrogen gas to evolve. The product is separated by steam distillation. : Alternatively, it can be produced by refluxing iodine and nitric acid with benzene. Reactions Since the C–I bond is weaker than C–Br or C–Cl, iodobenzene is more reactive than bromobenzene or chlorobenzene. Iodobenzene reacts readily with magnesium to form the Grignard reagent, ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food And Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food safety, tobacco products, caffeine products, dietary supplements, Prescription drug, prescription and Over-the-counter drug, over-the-counter pharmaceutical drugs (medications), vaccines, biopharmaceuticals, blood transfusions, medical devices, electromagnetic radiation emitting devices (ERED), cosmetics, Animal feed, animal foods & feed and Veterinary medicine, veterinary products. The FDA's primary focus is enforcement of the Federal Food, Drug, and Cosmetic Act (FD&C). However, the agency also enforces other laws, notably Section 361 of the Public Health Service Act as well as associated regulations. Much of this regulatory-enforcement work is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aphasia
Aphasia, also known as dysphasia, is an impairment in a person's ability to comprehend or formulate language because of dysfunction in specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in developed countries. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases (such as dementias). To be diagnosed with aphasia, a person's language must be significantly impaired in one or more of the four aspects of communication. In the case of progressive aphasia, a noticeable decline in language abilities over a short period of time is required. The four aspects of communication include spoken language production, spoken language comprehension, written language production, and written language comprehension. Impairments in any of these aspects can impact functional communication. The difficulties o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystonic
Dystonia is a neurological hyperkinetic movement disorder in which sustained or repetitive muscle contractions occur involuntarily, resulting in twisting and repetitive movements or abnormal fixed postures. The movements may resemble a tremor. Dystonia is often intensified or exacerbated by physical activity, and symptoms may progress into adjacent muscles. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning (e.g., lead poisoning) or reaction to pharmaceutical drugs, particularly neuroleptics, or stress. Treatment must be highly customized to the needs of the individual and may include oral medications, chemodenervation botulinum neurotoxin injections, physical therapy, or other supportive therapies, and surgical procedures such as deep brain stimulation. Classification There are multiple types of dystonia, and many diseases and conditions may cause dystonia. Dystonia is classified by clinical charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seizures
A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, or consciousness. Symptoms vary widely. Some seizures involve subtle changes, such as brief lapses in attention or awareness (as seen in absence seizures), while others cause generalized convulsions with loss of consciousness ( tonic–clonic seizures). Most seizures last less than two minutes and are followed by a postictal period of confusion, fatigue, or other symptoms. A seizure lasting longer than five minutes is a medical emergency known as status epilepticus. Seizures are classified as provoked, when triggered by a known cause such as fever, head trauma, or metabolic imbalance, or unprovoked, when no immediate trigger is identified. Recurrent unprovoked seizures define the neurological condition epilepsy. Clinical features Seizur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herniation
A hernia (: hernias or herniae, from Latin, meaning 'rupture') is the abnormal exit of tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides. The term is also used for the normal development of the intestinal tract, referring to the retraction of the intestine from the extra-embryonal navel coelom into the abdomen in the healthy embryo at about 7 weeks. Various types of hernias can occur, most commonly involving the abdomen, and specifically the groin. Groin hernias are most commonly inguinal hernias but may also be femoral hernias. Other types of hernias include hiatus, incisional, and umbilical hernias. Symptoms are present in about 66% of people with groin hernias. This may include pain or discomfort in the lower abdomen, especially with coughing, exercise, or urinating or defecating. Often, it gets worse throughout the day and improves when lying down. A bulge may appear at the site of hernia, that becomes larger when bending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
