GPS accuracy for a robotic neurosurgeon
The MiniAture Robot for Surgical Applications (MARS) is already FDA-approved for orthopedic and spinal surgery. Now, Israeli scientists have given it GPS accuracy for keyhole neurosurgery. This is a minimally invasive procedure used for tumor biopsies or deep brain stimulation, but you need to know exactly where you operate. So the researchers have superimposed 'MRI or CT images of the patient's brain over an image of the current surgical situation.' This robot, which weighs about 230 grams, will get an additional arm to guide a needle or a probe weighing about 150 grams. It could appear on the market within 18 months, according to the team, and I hope it will be more accurate than an ordinary GPS device.
As you can see above, "the system automatically positions a mechanical guide to support keyhole drilling and insertion of a needle or probe based on predefined entry point and target locations in a preoperative CT/MRI image. It incorporates the miniature MARS robot mounted on the head immobilization clamp or directly on the patient skull via pins." (Credit: Hebrew University, Israel)
The MARS robot, which has been approved by the U.S. Food and Drug Administration, and which is sold by Mazor Surgical Technologies, has been reprogrammed by Professor Leo Joskowicz of Hebrew University for keyhole surgery. In his Computer Aided Surgery and Medical Image Processing Laboratory, he was helped by two PhD students, Ruby Shamir and Moti Freiman to build this miniature robot system for keyhole neurosurgery.
Here are more details provided by ISRAEL21c about this robotic neurosurgeon. "The robot itself (encased in a sterile blue plastic wrap) weighs in at only 230 grams. For keyhole surgery of the skull, it was fitted with a rigid arm (150 grams) that can guide a needle, probe or catheter to the exact spot that the surgeon wants to target. Targeting is the key word here, Joskowicz told ISRAEL21c. 'Most neurosurgical gestures involve targeting. Every millimeter counts, because you work close to nerve roots. You can compare the novel neuro-surgical robot to a GPS. We invented a method to superimpose an MRI or CT image of the patient's brain over an image of the current surgical situation.'"
As you can see above, "the module allows interactive visualization of the CT/MRI slices and the face surface, and enables the surgeon to define entry and target points and visualize the resulting needle trajectories (left). Based on the surgeon-defined entry and target points, and the robot mounting mode (on the skull or on the head clamp), the module computes a suggested preferred approximate robot base placement and its range. The computed robot base placement is such that the needle trajectories are at the center of the robot work volume. Placements away from it are assigned a score based on how far they are from the robot work volume center. The results are graphically shown to the surgeon (right), who can then select the approximate actual position to satisfy clinical criteria, such as avoiding placements near the cranial sinuses, temporal muscle, or emissary vein." (Credit: Hebrew University, Israel)
ISRAEL21c tells us more about how this system works. "Although the MRI or CT image is usually done a day before surgery, it has to be aligned with an in-the-operating-room face scan (eyes, nose, ears). Automatic registration takes only a few seconds. Once the coordinates are aligned, the robot is positioned on the skull in the vicinity of the entry point. Using the combined image input, the robot is ready to move to the optimal position."
On the left is an image of the MARS medical robot. (Credit: Hebrew University, Israel)
For more information about its new tasks, you can read a technical paper presented at the 8th International Conference on Medical Image Computing and Computer-Aided Intervention (MICCAI'2005), "Robot-assisted image-guided targeting for minimally invasive neurosurgery: planning, registration, and in-vitro experiment."
Here is the abstract. "This paper present a novel image-guided system for precise automatic targeting in keyhole minimally invasive neurosurgery. The system consists of a miniature robot fitted with a mechanical guide for needle/probe insertion. Intraoperatively, the robot is directly affixed to a head clamp or to the patient skull. It automatically positions itself with respect to predefined targets in a preoperative CT/MRI image following an anatomical registration with a intraoperative 3D surface scan of the patient facial features."
Here is a link to this technical paper (PDF format, 8 pages, 4.90 MB), from which the above images have been extracted. You also might want to read Ruby Shamir's thesis about "Miniature robot system for keyhole neurosurgery" (PDF format, 63 pages, 1.49 MB), which describes the genesis of this project. The picture of the MARS robot shown above comes from this document.
Sources: Sharon Kanon, ISRAEL21c, September 30, 2007; and various websites
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