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.
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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; · 3.03 Impact Factor
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ABSTRACT: In this paper, we describe a robotic ultrasound (US) probe scanning system for reducing the manual tasks of US technicians and assisting in interventional procedures. The system consists of a probe scanning robot that uses McKibben artificial muscles, an optical tracking device, and in-house software for volume reconstruction and the automatic guidance of surgical tools. The proposed system is lightweight and safe due to the use of artificial muscles, and it allows for positional control of the B-scan plane through the transformation of US calibration. We employed the robotic system in two applications: robotic three-dimensional (3D) ultrasound and automatic ultrasound guidance. To clarify the system’s feasibility, we performed phantom and human liver volume reconstructions, as well as needle guidance. The volume qualities of the reconstruction were validated by cross-correlation with reference echograms and reslicing of the reconstructed volumes. The correlation values were 0.80 ± 0.06 for the phantom and 0.53 ± 0.06 for the human liver. Regarding the needle guidance, we confirmed that the B-scan plane automatically followed the needle. The translation and rotation errors were -0.10 ± 1.26 mm and -0.22 ± 1.81 degrees, respectively. The analysis of frequency response confirmed that the system could stably follow a motion of less than 0.3 Hz. The experimental results demonstrate that the robotic probe scanning system has great potential for yielding acceptable 3D volumes using two-dimensional (2D) ultrasound and assisting interventional procedures under US guidance.Advanced Biomedical Engineering. 10/2014;
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ABSTRACT: Brain tumors are among the most feared complications of cancer and they occur in 20-40% of adult cancer patients. Despite numerous advances in treatment, the prognosis for these patients is poor, with a median survival of 4-8 months. The primary reasons for poor survival rate are the lack of good continuous imaging modality for intraoperative intracranial procedures and the inability to remove the complete tumor tissue due to its placement in the brain and the corresponding space constraints to reach it. Intraoperative magnetic resonance imaging (MRI) supplements the surgeon's visual and tactile senses in a way that no other imaging device can achieve resulting in less trauma to surrounding healthy brain tissue during surgery. To minimize the trauma to surrounding healthy brain tissue, it would be beneficial to operate through a narrow surgical corridor dissected by the neurosurgeon. Facilitating tumor removal by accessing regions outside the direct "line-of- sight" of the neurosurgical corridor will require a highly dexterous, small cross section, and MRI-compatible robot. Developing such a robot is extremely challenging task. In this paper we report a preliminary design of 6-DOF robot for possible application in neurosurgery. The robot actuators and body parts are constructed from MRI compatible materials. The current prototype is 0.36" in diameter and weighs only 0.0289 N (2.95 grams). The device was actuated using Flexinol® which is a shape memory alloy manufactured by Dynalloy, Inc. The end-effector forces ranged from 12 mN to 50 mN depending on the robot configuration. The end-effector force to robot weight ratio varied from 0.41 to 1.73. During trials the robot motion was repeatable and the range of motion of the robot was about 90 degrees for the end-effector when one side shape memory alloy (SMA) channel was actuated. The actuation time from the start to finish was about 2.5 s.01/2008;