An MRI (magnetic resonance imaging) scan uses a magnetic field, not X-rays, to show soft tissue in detail. It's not needed for every patient — a CT scan is usually enough for routine sinus problems. MRI adds the most value in a smaller number of more complex situations, described below. For the basics of how MRI compares with a CT scan, see Understanding CT and MRI Scans.
Complex Chronic Rhinosinusitis
Most chronic rhinosinusitis is evaluated with a CT scan alone. An MRI may be added in more complex cases — for example, if there's concern about disease extending beyond the sinuses, or to better assess soft tissue that a CT scan doesn't show as clearly.
Nose, Sinus & Skull Base Tumors
MRI is especially useful for tumors, since it shows soft tissue detail that helps determine how far a growth extends — including whether it reaches the brain, nerves, or other structures near the skull base. It's often used together with a CT scan, which shows the surrounding bone.
CSF Leaks
MRI with contrast can help confirm and localize a CSF (cerebrospinal fluid) leak, particularly when the exact site isn't clear from a CT scan alone.
What to Expect
An MRI takes longer than a CT scan, usually 30–45 minutes, and means lying still inside a scanner. Some MRI scans use an injected dye to show certain tissues more clearly.