Brain MRI (with and without contrast)

What it is

Healthy brain tissue is shielded from the bloodstream by a barrier that keeps injected dye out. When that barrier is broken — by a tumor, by active inflammation, by infection, by new blood vessels growing where they should not — the dye leaks in and that spot brightens. A picture taken after gadolinium on its own cannot tell you that, because something bright after the injection might simply have been bright before. So the study is run in two halves: a complete set of images first, then gadolinium into a vein, then the same regions imaged again. The radiologist reads the difference. That is why this code exists separately from a brain MRI without contrast, and why it costs more: it is a longer appointment, an injected drug, and more image sets to interpret.

Why it is done

• To look for a brain tumor, or to check one already known about for growth or recurrence
• To assess multiple sclerosis, where enhancing lesions indicate current activity rather than old damage
• To look for infection or an abscess in the brain or its coverings
• To examine the brain after surgery or radiation, where distinguishing scar from returning disease is the whole question
• To follow up an abnormality seen on an earlier scan that was done without contrast

What to expect

An IV line is placed before the scan. Patients are screened carefully first for metal implants, pacemakers and other devices, because the magnet is always on, and are asked about kidney function, since gadolinium is cleared by the kidneys. The scan takes place inside a narrow tube, is loud enough that earplugs or headphones are provided, and requires lying still — the before and after images have to line up. Expect this to run longer than a brain MRI without contrast, commonly around an hour in total including the injection partway through. It is painless apart from the needle. A radiologist reads the images afterward and reports to the ordering doctor.

Questions worth asking

• Ask whether the contrast portion is needed for your question. A brain MRI without contrast is a distinctly cheaper code, and for headaches, most strokes and head injury it is often the version ordered.
• Is the gadolinium itself billed as a separate drug or supply line, in addition to the scan?
• Is an MRA of the brain being done in the same appointment? That is a separate code and a separate charge even though you never leave the machine.
• Hospital radiology departments and freestanding imaging centres can quote very different prices for the identical code. Ask for the price at both before scheduling.
• If your plan requires prior authorization for MRI with contrast, confirm it is on file before the appointment — a denial after the fact leaves the full amount with you.