Contrast media is known as any substance that is introduced into the body system, cavity or organ to enhance tissue differential attenuation with a resultant increase in image contrast and therefore improve image visualization of information. Contrast medium can be administered in several different ways. For example; orally, intravenously or intravascular.
Contrast media classified by:
1. Radiopaque (positive) v.s Radiolucent (negative)
2. Ionic v.s Non – ionic
3. High Osmolar Contrast Media v.s Low Osmolar Contrast Media
There are some desired properties that a contrast media must maintain. They are as follows;
* Must be of appropriate viscosity
* Pharmacologically inert
* Chemically stable
* Non- carcinogenic
* Easy administration
* Minimal discomfort to patient
* High radio-contrast
* Concentration in required areas
* Ready and complete elimination
MAGNETIC RESONANCE IMAGING
Magnetic Resonance is the effect that occurs when an electromagnetic RF field that is alternating, or resonating, at the Larmor frequency is applied in addition to the static field, causing protons to alternate from parallel to antiparallel.
Magnetic Resonance Imaging (MRI) is the process of using a magnetic field and radiofrequencies to create sectional images of the body. The nucleus is spinning, which creates a nuclear magnetic moment. This rotating charge acts as a current loop and in turn produces a magnetic field. When a rotating nucleus is subjected to a magnetic field, it will begin to process. Magnetic Resonance imaging is accomplished through various measurements of this movement of the nuclear magnetic field.
MRI contrast media are used to improve the visibility of internal body structures. These contrast agents alter the relaxation times of atoms within the body tissues. The most commonly used compound of contrast enhancement in MRI is gadolinium based. MRI contrast agents may be administered intravenously or orally,...