Contrast Media
Contrast media are retailers which can be used to photo organs or frame systems after their advent into the frame cavities or via vessels. The contrast media are of types:
1. Positive contrast media: These have an excessive atomic weight consisting of barium sulfate and natural iodine compounds.
2. Negative contrast media: These have low atomic weight consisting of air, oxygen, carbon dioxide used especially for gynaecocracy, retroperitoneal pneumography, air encephalography, diagnostic pneumoperitoneum.
1st technology intravascular contrast media
Strontium bromide, bismuth in oil, and lipiodol had been the earliest intravascular contrast media. Sodium iodide became extensively utilized however observed to be toxic.
The first actual natural iodide for use became a pyridine ring containing one atom of iodine in keeping with the molecule. This became outdated with the aid of using mono- or diiodinated pyridone compounds.
2d technology of contrast media
An iodinated benzene ring compound became synthesized in the early Nineteen Fifties referred to as hippurate. This became the precursor of contemporary-day ionic water-soluble contrast retailers which can be triiodinated, completely substituted benzene ring derivatives. Diatrizoate (Urografin) and acetrizoate molecules belonged to this technology.
3rd technology intravascular contrast media
The route of molecular amendment in those ionic compounds became modified to the cognizance of their osmolality. With the addition of nonionizing glucose moiety, the triiodinated benzoic acid spinoff will become a non-ionic compound, metrizamide.
An entire new own circle of relatives of compounds primarily based totally on metrizamide became advanced which has decreased osmolality in answer and decreased chemotoxicity. These are iopamidol, iohexol, ioglucamide and iopromide. Unlike metrizamide, they may be all furnished in answer.
Hexabrix, Na methyl glucamine ioxaglate is any other low osmolality contrast medium. It includes triiodinated substituted benzoic acids related with the aid of using a small facet chain. The hexabrix, therefore, has 6 iodine atoms in keeping with the molecule offering the equal iodine particle ratio of 3: 1 as non-ionic contrast media.
4th technology of intravascular contrast media
In this technology of assessment (contrast media) media, the osmolality became decreased further. A dimer this is non-ionic is iotasul. Iotasul has much less than 1/2 of the osmolality of metrizamide at extraordinarily excessive awareness of four hundred mg I/ML/Plasma. Others on this organization are control and iotrolan.
Properties of contrast media
The best contrast media ought to have the following properties:
1. Osmolality: Ionic dimers (hexabrix) and non-ionic monomers like third technology contrast media have osmolality approximately 50% that of traditional contrast media, while non-ionic dimers (which can be 4th technology contrast media) have the osmolality of approximately 25% of traditional assessment media.
2. Viscosity: Must be of appropriate viscosity as in keeping with the requirement of the organ to be investigated like urethrography, hysterosalpingography, etc. More viscous contrast is used even as in angiography, a fantastically fluid contrast medium is used. The more recent technology of contrast media has a slightly extended viscosity that's strongly dependent on room temperature. These contrast media are much less viscous at frame temperature than at room temperature.
3. Toxicity: Should be safe and safe. It relies upon on:
Osmolality
Electric price
Chemotoxicity
Hypersensitivity
Non-ionic media don't have any price so that they have decreased toxicity.
4. Must produce good enough contrast: Dense contrast medium needs to be used wherein contrast medium diluted without delay after injection even as it needs to be much less dense in a biliary tract in order now no longer too difficult to understand the calculi.
5. It ought to have good enough miscibility as suitable for the diploma of examination.
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