Intraoperative MRI guided brain surgery - to see beyond the surgical field
Approximately a year ago, a special model for intraoperative MRI was introduced for use in the Department of Neurosurgery at Hadassah Ein Kerem. This is a mobile device of 0.125 Tesla strength that was produced especially for neurosurgical operations by the Israeli company, "Odin". With this, Hadassah joins one of the few centers in the Western world that routinely uses intraoperatove MRI during brain surgery.
The introduction of this sophisticated MRI imaging device into the operating room has been a continuation of the process of equipping and strengthening the technology transferred to the department of surgery in general, and neurosurgery in particular. Intraoperative MRI stands at the center of the process as does its use in real-time for improving surgical outcomes and increasing patient safety during the performance of surgery.
Intraoperative MRI, as opposed to diagnostic MRI, is a small, portable device that has a low magnetic field strength. It can be mobilized within the operating room by one person, to be placed relatively easily under the surgical table so that the magnetic poles are on both sides of the patient's head at the time of MRI imaging. Imaging pictures are achieved at good resolution and within an average timespan of 3 to 7.5 minutes for an imaging series. In addition, the device is equipped with a navigation system - intraoperative guidance, which is based on an infrared camera that tracks various surgical instruments during the procedure, and shows the surgeon their exact location on the updated imaging acquired a few minutes previously.
The advantages of intraoperative MRI are:
* Up to date and reliable imaging that reflects the situation in the surgical field in real time, and provides a broader overall view of the brain from all round or distant areas. This global vision of the brain during surgery is important primarily because of the fact that brain tissue moves and changes its place in the intra-cranial space as an operation progresses, a phenomenon called brain shift.
* The ability to navigate accurately (recorded error of up to 2 mm) allows opening of the skull at the desired place and size as well as minimimal skin incision and sawing of a window in the bone; arrival at the surgical target via a short and safe path, and inspecting and following up of the degree of resection of the lesion, especially when dealing with a brain tumor.
* The possibility to identify bleeding in the brain during surgery beyond the field observed directly by the surgeon, and to treat it on time.
* Accurate anatomical identification of vital brain centers around the surgical field while avoiding accidental damage to them, an action which is very difficult to perform in operations on hemispheral tumors via the standard technique without guidance from an MRI navigation system.
* The possibility of computerized integration of other pre-operative imaging methods such as PET and other types of MRI.
* At the end of the surgery, a final imaging series is acquired to ensure that all the aims of surgery were achieved. This imaging is also used as a basis for future follow-up and eliminates the need for performing an immediate post-operative MRI with a diagnostic device as is accepted today after surgeries performed using standard techniques.
Indications for the use of intraoperative MRI are many and varied:
* Resection of primary or metastatic tumors of the cerebrum and/or the brain ventricles in transsphenoidal surgeries for the removal of pituitary tumors.
* Performing particularly difficult brain biopsies especially when dealing with a small deep target.
* Inserting catheters to cancerous brain ventricles or others for drainage, or injection of chemotherapy in some skull base surgeries.
Intraoperative MRI guided surgeries are routinely performed at Hadassah Hospital in cooperation with the Department of Anesthesia, the Operating Room department, and the Medical Engineering department. All procedures performed until now have been declared a complete success, displaying maximum achievement of the operating goals while maintaining the safety of the patient and shortening the average length of hospital stay after brain surgery. The shortening in the duration of hospitalization has been achieved due to less complications and lower neurological morbidity rates particularly in imaging-guided surgeries.