With and without contrast
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Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
In plain language
The same area was scanned twice, once before dye was injected and once after, so the two sets can be compared. The comparison is the point: what changes between them tells the radiologist how blood is reaching a structure.
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Where you'll see this
The technique section of CT and MRI reports.
Your report may word it “Pre- and post-contrast”, “With and without IV contrast” or “Non-contrast”. These mean the same thing.
Questions worth asking your doctor
- Did this scan use the right technique to answer my question?
- Would contrast, or a different sequence, show something this one could not?
- Do I need another scan, or is this one enough?
How often does this turn up?
This phrase appears in the technique line of a great many CT and MRI reports, and it describes exactly what it says: the same area was scanned twice, once before contrast was given and once after. It is the standard approach whenever the question being asked depends on which tissues take up contrast, and it is why some appointments take longer and involve a cannula.
Does it mean something is wrong?
The phrase describes method, not findings, and it does not imply that anything was suspected or found. Doing both is simply how a radiologist tells the difference between something that was already bright and something that became bright — a distinction impossible to make from the post-contrast images alone. If your scan was done without contrast, that is equally normal and means the question did not require it; many do not.
What to do with it
What follows comes from the findings rather than the technique. In the findings you may see the word enhancing, which means an area took up contrast and therefore has a blood supply — a fact the radiologist uses to tell tissue types apart, not a verdict in itself. If you had contrast, the usual advice afterwards is simply to drink normally.
Frequently asked questions
- Why scan twice instead of just after contrast?
- Because without the before images there is no way to know whether something bright became bright. Blood, calcification and some tissues are already bright before any contrast is given, so comparing the two sets is the only way to say that an area genuinely enhanced.
- Does needing contrast mean they suspect something serious?
- No. Whether contrast is used is decided by the type of question, not by the level of concern. Many entirely routine scans use it and many investigations of serious questions do not.
- What does enhancement mean in the findings?
- That an area took up contrast, which indicates it has a blood supply. It is a descriptive fact used to characterise tissue — plenty of normal structures enhance strongly — rather than a finding that is good or bad on its own.
How the scan was taken
Where this word comes up
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