What Is MRI Contrast Media?
The MRI Contrasts are a chemical substances to use the visualize the internal organs in the human body In MRI system. The MRI contrasts are help to detection and diagnosis of any abnormalities in body. The Gadolinium based contrast used in MRI. The Gadolinium is a rare earth material of lanthanide group with atomic number is 64. The free Gadolinium do not get excreted from the body. The Gadolinium ions are toxic so the Gadolinium ions mixed with chelates such as DTPA that cause their rapid and total renal excretion. After injected of Gadolinium contrast in the body, they effect the decreasing the relaxation time of tissue and enhancing proton relaxation. The contrast effect the both T1 and T2. The T1 images are taken before and after I.V injected of contrast media. The T1 weighted images obtain show enhancement of abnormal tissue. After injected of contrast media in body , it takes 5 min to show sufficient enhancement in lesions. The effect remain for Upto 45 min after injection and satisfactory enhancement is still possible for Upto 1 hour after injection.
The dose has been found be 0.2 ml/sec kilogram of body weight.
Types Of MRI Contrast Media :- Two types of MRI contrast media.
A) Positive Contrast media.
B) Negative contrast media.
A) Positive Contrast media :- In MRI positive contrast media has high atomic number. The positive contrast enhanced the body tissues so image looks like a bright on MRI. It reduce the T1 relaxation time. They have small molecular weight compound containing as their active element Gadolinium, manganese or iron.
B) Negative contrast media:- The negative contrast media has low atomic number. It appearing predominantly dark image in MRI. It has small particulate aggregates often termed super paramagnetic iron oxide. It has Short T1 and T2 relaxation times.
Side Effects Of MRI Contrast Media.
The side effects of MRI contrast media are very rare.
1. Warmth
2. Pain at injection site
3. Seizure
4. Strange taste
5. Nausea
6. Headache
7. Dizziness
8. Anaphylactoid reactions may occur (at the present time seven episodes have been reported to Schering worldwide) and so medical cover should be readily available, as should resuscitation equipment. Of these the first two are the most common, but in all they add up to only about 3% of injections (Schering Technical Brochure).
The Mri contrast is very important while doing brain scan course is used to enhance the pathology especially the patient with CA