Contrast Enhancement
Contrast enhancement is a descriptive term and does not always indicate an abnormality or specific disease. Normal structures like organs demonstrate enhancement as do abnormalities throughout the body.
What is contrast image enhancement?
Contrast enhancement allows us to see differences between normal tissues in the body to a greater degree. This can make normal tissues look different based on how much blood is flowing to them. The spleen enhances to a greater degree than the fat, muscle and bones.
Contrast enhancement allows us to better see abnormal tissues as well. Cancers or inflammatory conditions can enhance to a greater degree than normal tissues. These abnormalities will stand out to a greater degree than without contrast
What causes contrast enhancement?
Contrast enhancement can occur because a normal or abnormal structure has more blood flow or tends to accumulate contrast.
In the brain, contrast enhancement may mean a break down of the blood brain barrier.
How does contrast enhancement help?
Contrast enhancement helps us see abnormalities. We can also provide a more accurate diagnosis.
What are examples of contrast enhancement?
Many disease states are better seen after contrast. One example is cancer. It is easier to see on tests after contrast is given. Cancer will be highlighted in many cases because it has more blood supply then normal surrounding tissues.
Many benign lesions such as liver masses also have more contrast enhancement or a brighter appearance because they tend to accumulate the contrast more then the surrounding liver.
Contrast enhancement in CT scans
CT scans of all types are done with contrast to identify contrast enhancement. Contrast enhancement can be seen in normal structures like organs and blood vessels. We also see contrast enhancement of abnormalities like cancer and infection.
Usually reports will describe abnormal contrast enhancement. An abnormality will be described as contrast enhancing. This will mean that the abnormality has blood vessels feeding it and may have solid tissue. Water or cysts do not enhance because they are not fed by blood vessels.
Contrast enhancement in MRI
Same principles apply with MRI contrast. Abnormalities will be described as contrast enhancing. This will mean that there are blood vessels feeding the abnormality and it is composed of tissue. Cysts will be composed of water and will not enhance.
Is contrast enhancement worrisome?
No, the term does not specify a diagnosis or condition. The term is used to describe an abnormality. Both benign and life threatening conditions are described as contrast enhancing. The radiologist interpreting the study will provide a diagnosis or provide some possibilities.
What are the risks of giving contrast?
One of the major downsides of contrast agents is the possibility of allergic reactions. Most commonly these are minor. Hives or other minor reactions are most common. More severe reactions are reported in rare cases. The contrast will eventually be eliminated by your body and is not permanent.
Patients who have poorly functioning kidneys can develop further worsening of function in the case of contrast used for CT.Your kidney function will be measured in some cases before you get a CT scan.
A rare complication of getting gadolinium or MR contrast agents when you have poorly functioning kidneys is neurogenic systemic fibrosis which will cause scarring of your skin and organs. This is very uncommon with the newer contrast agents.
Overall, the benefits of getting contrast agents for CT and MRI outweighs any potential risks. Contrast helps us to reach a more accurate correct diagnosis. Contrast is also helpful because a normal exam will rule out more abnormalities.
Contrast enhancement in radiology: summary
Contrast enhancement in radiology studies is a descriptive term that does not provide a specific diagnosis or condition. This simply means that the differences between normal and abnormal structures is enhanced on a scan. This can be helpful in both seeing abnormalities and providing a diagnosis.
