Thicker MRI slices can make a brain tumor look bigger
Original title: Quantification of the Impact of Slice Thickness on Volumetric Analysis of Brain Tumors.
How far along is this research?
- Lab cells
- Animals
- Review
- Tested in people
This was tested in people. That is the most reliable kind of research we share.
This used scans from real people, but it is about measuring tumors, not treating them.
The short version
The way an MRI is taken can change the tumor size it shows.
What was studied. Doctors measured tumor size on MRI scans from 46 people with glioblastoma: A glioma that is given grade 4. Grade 4 is the highest grade there is. The tumor grows fast. Treatment usually starts soon after it is found. It often means surgery, and then radiation and chemotherapy. See the glossary. Each tumor was measured three ways, using slices 1 mm, 3 mm, and 5 mm thick.
What they found. Thicker slices gave bigger tumor sizes. The average size was 36.4 cm3 with the 1 mm slices, 38.6 cm3 with the 3 mm slices, and 41.0 cm3 with the 5 mm slices. On the 5 mm slices, the sizes were off by 16% from the thin slice measure.
What this means, and what it doesn't
What it could mean: The tumor size in a scan report depends partly on how the scan was done. Sizes taken from thin and thick slices should not be compared to each other. The study team says thin 1 mm scans are best for measuring tumors.
What it doesn't mean: This does not mean a tumor has grown or shrunk. The study is about how tumors are measured, not about a new treatment. It is not a cure and it does not change anyone's care plan. It also does not mean past scans were wrong. If you have questions, ask your care team how your scans were taken.
Source: PubMed, November 1, 2026 · Read the original
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