Interval change
Read Your Scan Editorial Team·Last updated
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
"Interval" means since the last scan — so "no interval change" is one of the better sentences in radiology: whatever is there has not moved, grown or spread in the time between the two studies.
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Where you'll see this
The impression of any follow-up scan, where a comparison study is listed at the top.
Your report may word it “No interval change”, “Interval development” or “In the interval”. These mean the same thing.
Questions worth asking your doctor
- Compared with my last scan, is this better, worse, or the same?
- How much change would matter enough to do something about it?
- When should the next scan be, and what would you be looking for?
How often does this turn up?
Interval change means what has altered between this scan and a previous one, and it appears whenever a comparison study is available. The interval is simply the time between the two. It is the most valuable kind of information in radiology, which is why the comparison line at the top of a report matters so much.
Does it mean something is wrong?
The phrase no significant interval change is one of the most reassuring sentences a report can contain, and it deserves more weight than any description of the finding itself. Something that has not altered over months or years is very rarely a problem, however alarming its name. Conversely, interval change describing growth or progression is where attention belongs — the change, not the size, is the signal. The word significant is doing work here too: small variations in measurement between studies are expected and are not treated as real change.
What to do with it
Where nothing has changed, follow-up intervals often lengthen or stop entirely, since stability has answered the question. Where something has changed, what follows depends on what and by how much — many surveillance protocols define in advance how much growth prompts action, so the response is usually already decided rather than improvised.
Frequently asked questions
- What does no significant interval change mean?
- That the finding looks essentially the same as on the previous scan. It is one of the strongest reassurances in radiology, because stability over time is the best evidence available that something is benign.
- Why does the comparison date matter?
- Because stability over five years means far more than stability over five weeks. The length of the interval determines how much reassurance the comparison provides, which is why the date of the prior study is always stated.
- A small measurement change was called insignificant. Why?
- Because measurements vary between studies for technical reasons — slice position, angle, and who measured. Radiologists set thresholds below which a difference is treated as noise rather than growth, which avoids acting on measurement error.
Comparison with an earlier scan
Where this word comes up
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