Stable Compared to Prior on Radiology Reports: What It Means

ByA. Mendelson, MD
Please read the disclaimer

When you receive a radiology report, you may notice the phrase “stable compared to prior.” In radiology, doctors carefully compare current scans—like X-rays, CTs, or MRIs—to older studies to see if anything has changed. This phrase is a way of saying that what is being seen now looks the same as before.  Understanding this wording can help you feel more comfortable with your results and know what questions to ask your doctor.

What “Stable” Means in Imaging

In radiology, the word stable means that a finding—such as a spot, nodule, or other abnormality—has not changed in size, shape, or appearance over time.

For example:

  • A small lung nodule that measures the same on scans done six months apart is considered stable.

  • A liver cyst that looks the same across several CTs is also stable.

Stability is important because it usually suggests that the finding is not aggressive, not growing, and likely benign.

What “Compared to Prior” Means

Radiologists rarely look at just one image in isolation. They almost always compare the current study to prior exams. The “prior” refers to your earlier imaging studies—these could be from months or even years earlier.

By comparing the two, the radiologist can see whether a finding:

  • Has grown

  • Has shrunk

  • Looks different in density or intensity

  • Or remains unchanged

If unchanged, the report will often say “stable compared to prior.”

Why Stability Matters

When a finding is described as stable, it is usually good news. Medical conditions that are dangerous or malignant tend to grow, spread, or change their appearance over time. Stability suggests the opposite—that the process is not progressing.

Examples:

  • A stable brain lesion on MRI over years may represent a benign scar.

  • A stable adrenal mass is less concerning for cancer.

  • A stable lung nodule reduces the likelihood of lung cancer.

This does not mean follow-up is never needed, but it often lowers the level of worry.

Stable vs. Unchanged

Sometimes reports use the word unchanged instead of stable. These terms usually mean the same thing: the finding looks the same when compared to prior scans.

  • Stable often implies there has been more than one comparison over time, confirming no growth.

  • Unchanged usually refers to the current study compared to the most recent prior only.

Both mean no new changes are seen.

When Stability Still Needs Follow-Up

Even if something is stable, your doctor may recommend continued follow-up imaging. This depends on what the finding is and where it is located.

  • Small lung nodules may be followed over time with CT scans to be sure they stay stable.

  • Benign-appearing liver lesions may not need further follow-up after a couple of stable exams.

  • Post-surgery findings after a cancer diagnosis may be checked to confirm healing or absence of recurrence.

The key is that stability lowers suspicion, but it does not always eliminate the need for surveillance.

Stable but Symptomatic

Sometimes a finding may be stable on imaging but still cause symptoms. For example:

  • A stable degenerative disc bulge in the spine could still cause back pain.

  • Stable sinus inflammatory changes could still lead to sinus symptoms.

In these cases, the imaging shows no change, but the clinical situation may still require treatment.

Importance of Prior Imaging

The phrase “compared to prior” highlights why keeping track of your old studies is important. Radiologists rely heavily on these comparisons.

If prior studies are missing, the radiologist may not be able to say if a finding is stable. That is why many hospitals and imaging centers request older exams for review.

Having older images available often makes a big difference in reducing unnecessary tests and easing patient anxiety.

Practical Takeaway for Patients

If your report says “stable compared to prior”, it usually means there is no sign of growth or progression of the finding being followed. This is typically reassuring. However, you should:

  • Ask your doctor whether continued follow-up is needed

  • Keep copies of your old imaging for future comparison

  • Understand that stability does not always mean the finding is harmless, but it does lower the level of concern

Conclusion

“Stable compared to prior” is a phrase radiologists use to communicate that a finding looks the same as before. In most cases, this is reassuring and suggests no progression of disease. While follow-up may still be needed in some cases, stability is usually a positive result. Knowing this can help you interpret your report with less worry and have more informed conversations with your healthcare team.

References

https://www.radiologyinfo.org/en/info/all-about-your-radiology-report

https://www.radiologyinfo.org/en/radiology-reports

https://pmc.ncbi.nlm.nih.gov/articles/PMC7048540

Disclaimer: The content of this website is provided for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.

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