Which statement about STIR MRI sequences is true?

Which statement about STIR MRI sequences is true?

• A. Fluid appears hyperintense
• B. Fluid appears hypointense
• C. STIR sequences are not used for fluids
• D. Cannot determine

Answer: (A)

STIR sequences are fat-suppressed T2-weighted MRI images. An inversion pulse nulls the signal from fat, so fat appears dark while fluids with high water content—such as edema, cystic fluid, or CSF—remain bright. This setup makes fluid-rich pathology stand out clearly, so fluids appear hyperintense. The idea that fluids would be dark or that STIR isn’t used for fluids goes against how the sequence enhances fluid contrast, which is precisely why STIR is favored for detecting edema and inflammatory changes in musculoskeletal imaging.

STIR sequences are fat-suppressed T2-weighted MRI images. An inversion pulse nulls the signal from fat, so fat appears dark while fluids with high water content—such as edema, cystic fluid, or CSF—remain bright. This setup makes fluid-rich pathology stand out clearly, so fluids appear hyperintense. The idea that fluids would be dark or that STIR isn’t used for fluids goes against how the sequence enhances fluid contrast, which is precisely why STIR is favored for detecting edema and inflammatory changes in musculoskeletal imaging.