RADIODIAGNOSIS CONTRAST MEDIA

Contrast Media/Contrast Agents

Definition : Contrast agent is a substance used to increase the contrast of the structure and fluid within the body in medical imaging.

Types : There are 2 types of contrast media

1. Negative contrast media

2. Positive contrast media

• Negative Contrast Media : Negative contrast media have low specific gravity.

• Negative contrast media is more radiolucent to x rays than soft tissue.
• Negative contrast media appears black in the radiograph.

Ex : Gas, Air, Carbon dio oxide, and Oxygen.



• Positive Contrast Media : Positive contrast media consists of elements of high atomic number.

• Positive contrast media absorbs more x rays than soft tissue or bone.
• Positive contrast media is radiopaque to x rays and appears white in the radiograph.

Ex : Barium Sulphate and Iodinated compound 

• Iodinated Contrast Media : 

 Iodinated contrast media is a form of intravenous radio contrast containing iodine which enhances the vascular structure and organ within the body during radiographic procedure

Properties of iodinated contrast:

The iodinated contrast media is water soluble.

The radio density of iodinated contrast is 25 to 30 HU (Hounsfield Unit).

The iodinated contrast media is radiopaque to x rays and appears white in the radiograph.

• There are 2 types of iodinated contrast

 Ionic Contrast

 Non Ionic Contrast

• Ionic Contrast : Ionic contrast have high osmolality

Ex : Diatrizoate, Metrizoate, and Iothalamate.

• Non Ionic Contrast:
Non ionic Contrast have lower osmolality.

Ex: Iohexol, Iopromide, and Iodexanole.


Possible Toxicity :
• Nausia
• Cardiac Arrest
• Shortness of Breath
• Vomiting.


                             

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                           BHARAT GOYAL (RT)

     GEETANJALI MEDICAL COLLEGE AND HOSPITAL