Intelligent operating theater using intraoperative open-MRI.
ABSTRACT Malignant brain tumors vary among patients and are characterized by their irregular shapes and infiltration. Localization of functional areas in the brain also differs among patients, and excess removal of tumor near eloquent areas may increase the risk of damage of function, such as motor paresis and speech disturbance. Recent progress in magnetic resonance (MR) imaging technology has enabled acquisition of intraoperative images and totally changed the neurosurgery of malignant brain tumors. Before, surgeons could merely speculate about the results of surgical manipulation and have no certainty about procedure outcomes until postoperative examination. Because intraoperative MR images allow visualization of the size of residual tumor(s) and the positional relationship between the tumor(s) and eloquent areas, surgeons are now able to achieve safe and reliable surgery. As an example, positional error on preoperative MR images caused by shifting of the brain (brain shift), a long-standing annoyance for surgeons, has been resolved using intraoperative MR images for surgical navigation, allowing precise resection. Two types of open-MR imaging scanner, a 0.2- or 0.3-tesla hamburger-type scanner with a horizontal gap and a 0.12- or 0.5-tesla double doughnut-type scanner with a vertical gap, are now available in the operating theater, and 1.5-tesla bore-type scanners are available. A 3.0-tesla bore-type scanner is planned. Intraoperative MR imaging includes diffusion-tensor and diffusion-weighted imaging, which allows visualization of nerve fibers in the white matter, especially the pyramidal tract. Such images are valuable aids in the precise resection of residual lesions of malignant brain tumors near eloquent areas without injuring motor function.
- SourceAvailable from: Akio Morita[Show abstract] [Hide abstract]
ABSTRACT: Magnetic resonance imaging (MRI) during surgery has been proven to improve surgical outcomes, but the current intraoperative MRI systems are too large to install in standard operating suites. Although one compact system is available, its imaging quality is not ideal. We have developed a new compact intraoperative MRI system and evaluated its use for safety and efficacy. This new system has a magnetic gantry: a permanent magnet of 0.23T and an interpolar distance of 32 cm. The gantry system weighs 2.8 tons and the 5-gauss line is within the circle of 2.6 m. We created a new field-of-view head coil and a canopy-style radiofrequency shield for this system. A clinical trial was initiated and the system has been used in 44 patients. This system is significantly smaller than previous intraoperative MRI systems. High-quality T2 images could discriminate tumor from normal brain tissue and identify anatomical landmarks for accurate surgery. The average imaging procedure took 45.5 minutes, and no clinical complications or MRI system failures occurred. Floating organisms or particles were minimal (1/200L maximum). This intraoperative, compact, low-magnetic-field MRI system can be installed in standard operating suites to provide relatively high-quality images without sacrificing safety. We believe such a system facilitates the introduction of the intraoperative MRI.Neurosurgery 01/2014; · 2.53 Impact Factor
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ABSTRACT: Neuronavigation systems have been developed for image-guided neurosurgery to aid in the accurate resection of malignant brain tumors. Therefore, the accuracy of the neuronavigation is important. However, many factors can reduce the navigation accuracy during surgery. Before craniotomy, the patient's head is secured to a head frame with head pins; this fixation may cause displacement of fiducial markers and reduce the accuracy. We term this phenomenon skin shift. In this study, the extent of skin shift and its effect on navigation accuracy were determined by use of both preoperative magnetic resonance imaging (MRI) scans acquired before fixation and intraoperative MRI scans acquired after fixation. We measured the displacement of the fiducial markers by using fusion images obtained by integrating preoperative and intraoperative MRI scans. We also evaluated the navigation accuracy of registration based on preoperative and on intraoperative MRI. The mean (± SD) extent of skin shift was 5.34 (± 2.65) mm. The navigation accuracy of registration based on preoperative MRI was 4.06 (± 2.25) mm, and that of registration based on intraoperative MRI was 2.51 (± 1.32) mm. No significant correlation was observed between the extent of skin shift and the distance between the head pins and fiducial markers (p > 0.05). The navigation accuracy of registration based on intraoperative MRI was significantly higher than that of registration based on preoperative MRI (p < 0.001). The results indicated that skin shift was caused by the fixation, and that this shift reduced the navigation accuracy. Intraoperative MRI can correct the effect of skin shift.Radiological Physics and Technology 01/2011; 4(1):37-42.
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ABSTRACT: The dedicated intraoperative examination monitor for awake surgery (IEMAS) was originally developed by us to facilitate the process of brain mapping during awake craniotomy and successfully used in 186 neurosurgical procedures. This information-sharing device provides the opportunity for all members of the surgical team to visualize a wide spectrum of the integrated intraoperative information related to the condition of the patient, nuances of the surgical procedure, and details of the cortical mapping, practically without interruption of the surgical manipulations. The wide set of both anatomical and functional parameters, such as view of the patient's mimic and face movements while answering the specific questions, type of the examination test, position of the surgical instruments, parameters of the bispectral index monitor, and general view of the surgical field through the operating microscope, is presented compactly in one screen with several displays. However, the initially designed IEMAS system was occasionally affected by interruption or detachment of the connecting cables, which sometimes interfered with its effective clinical use. Therefore, a new modification of the device was developed. The specific feature is installation of wireless information transmitting technology using audio-visual transmitters and receivers for transfer of images and verbal information. The modified IEMAS system is very convenient to use in the narrow space of the operating room.Neurologia medico-chirurgica 01/2011; 51(6):472-6. · 0.49 Impact Factor