A “Stealth MRI” refers to an MRI scan taken specifically for use with the Medtronic StealthStation, a surgical navigation system that acts like a GPS for surgeons operating on the brain, spine, or sinuses. The MRI itself is a standard scan, but it’s acquired with specific settings so the navigation system can map the images onto your body during surgery. If your doctor ordered a “Stealth MRI,” you’re getting a regular MRI that will later guide a surgeon’s instruments in real time.
How the StealthStation Uses Your MRI
The StealthStation system takes your pre-operative MRI and builds a three-dimensional digital map of your anatomy. Before surgery begins, the system matches that digital map to your actual body through a process called registration. This can be done by touching specific points on your face or head with a tracked instrument, or by using a laser that bounces off your skin and is read by an infrared camera system. Some setups use small adhesive markers (called fiducials) placed on your skin before the MRI to create reliable reference points.
Once registration is complete, the surgeon can hold a tracked instrument near or inside the surgical site and see exactly where it sits on the MRI in real time. Three infrared cameras use spatial triangulation to track the position of instruments, achieving a mechanical accuracy of about 0.4 mm. In lab testing, the StealthStation S7 demonstrated accuracy between 0.2 mm and 0.3 mm on a test model with 51 target points. In real-world use on patients, accuracy varies more widely depending on the area being targeted, but the system consistently gives surgeons a level of spatial awareness that would be impossible with the naked eye alone.
Why the MRI Protocol Matters
Not just any MRI works for navigation. A Stealth MRI is acquired using a specific protocol: thin, evenly spaced image slices with no gaps, and particular contrast settings that let the software clearly distinguish between different tissues. The scan typically needs to cover the entire area of interest in a continuous volume. If the slices are too thick or the wrong sequences are used, the navigation software can’t accurately reconstruct the 3D anatomy, and the whole system becomes less reliable.
This is why your surgeon’s office may send you to a particular imaging center or provide the radiology team with detailed scanning instructions. The MRI machine itself is standard. The difference is entirely in how the scan is set up.
What Surgeries Use This Technology
Stealth navigation is used most commonly in neurosurgery, where millimeters of precision can mean the difference between removing a tumor completely and damaging critical brain tissue. It plays a central role in brain tumor removal, brain biopsies, and deep brain stimulation (DBS) surgery for conditions like Parkinson’s disease. In DBS procedures, surgeons fuse the pre-operative MRI with intraoperative CT images to confirm that electrodes are placed precisely in the targeted brain structure.
The system is also widely used in spinal surgery, where it helps guide the placement of screws and hardware, and in sinus surgery (ENT procedures), where the complex, tightly packed anatomy around the sinuses and eye sockets makes image guidance valuable. The latest version of the system, the StealthStation S8, includes dedicated software modules for cranial, ENT, DBS, and stereotactic procedures, along with tools that can automatically segment structures like tumors, the brain’s surface, and bone from the MRI data.
What to Expect as a Patient
If you’ve been told you need a Stealth MRI, the scan itself feels identical to any other MRI. You’ll lie in the scanner for roughly 30 to 60 minutes depending on what’s being imaged. The key differences happen behind the scenes: the technologist will use specific scanning parameters provided by your surgical team.
In some cases, small adhesive markers may be placed on your skin before the scan. These look like small stickers or dots and serve as reference points that appear on both the MRI and your body, helping the system align the two during surgery. Your surgical team will let you know if these are needed. If fiducial markers are used, it’s important not to move or remove them between the scan and your surgery date.
The S8 system also supports a “Touch-n-Go” registration method that simplifies the alignment process and can work without fiducial markers entirely. In this approach, the surgeon traces points along your facial contour at the start of surgery, and the system matches those points to the MRI data automatically.
How It Combines With Other Imaging
One of the more powerful features of modern Stealth navigation is its ability to merge multiple types of imaging. The S8’s fusion software can combine standard MRI with CT scans, functional MRI (which shows active brain regions), PET scans, and intraoperative imaging from systems like the O-arm, which takes CT-like images during surgery. This layered approach gives surgeons a richer picture than any single scan could provide.
During brain surgery, for example, a surgeon might start with a pre-operative MRI for detailed soft tissue anatomy, overlay functional MRI data showing which areas of the brain control speech or movement, and then use an intraoperative CT scan partway through the procedure to account for brain shift, the slight movement of brain tissue that occurs once the skull is opened. By fusing all of these datasets in real time, the navigation system stays accurate even as conditions change during the operation.