A low-cost PCI-bus-based ultrasound system for use in image-guided neurosurgery.

A low-cost PCI-bus-based ultrasound sub-system has been developed and integrated into the image-guided neurosurgery system currently in use at the Cleveland Clinic. Two software applications have been developed that integrate real-time ultrasound images with preoperative MR and CT data sets. By tracking the position of the ultrasound probe during surgery, it is possible to display a real time ultrasound image and the corresponding (preoperative) oblique CT or MR slice. This provides immediate positional feedback to the neurosurgeon during the surgical procedure.

Manual vs robotically assisted laparoscopic surgery in the performance of basic manipulation and suturing tasks.

OBJECTIVE: To compare the surgical performance of manual and robotically assisted laparoscopic instruments on basic maneuvers and intracorporeal suturing in inanimate models. DESIGN: A set of laparoscopic tasks was used to evaluate basic endoscopic movements and intracorporeal suturing: positioning a cylinder on a Peg-Board, dropping beads into receptacles, running a 25-cm rope, and capping a hypodermic needle. Intracorporeal knot tying and running a suture through predetermined points were evaluated separately. The sutures used for these tasks were 2-0 and 4-0 silk and 6-0 and 7-0 polypropylene. PARTICIPANTS: Twenty surgeons completed the set of laparoscopic tasks manually and then with a robotically assisted system. None had used the robotic system before. MAIN OUTCOME MEASURES: Time required to complete the tasks and the precision in performing them. RESULTS: The robotic system accurately reproduced the movements of the surgeons and filtered their hand tremors efficiently. In the basic tasks, operative times were significantly longer for the robotic system (P<.001). In the suturing tasks, operative times were longer with the use of the robotic system for sutures sizes 2-0 and 4-0 (P<.001). However, time differences were not significant for suture sizes 6-0 and 7-0 (P> or =.07). Precision measurements were similar for all tasks using the manual instruments and the robotically assisted system. No significant differences were found between the performance of advanced laparoscopic surgeons and laparoscopic fellows. CONCLUSIONS: Laparoscopic maneuvering and suturing is faster and just as precise when performed manually as when performed with the prototype robotic system. These differences in speed are inversely proportional to the size of the suture. Future generations of the robotic system may eliminate these differences.

Differential ventricular expansion in hydrocephalus.

In the large canine model of acquired obstructive hydrocephalus that we have developed recently, computer-assisted 3-dimensional morphometry has been performed on T1-weighted Spin Echo MRI images from adult dogs before and after the induction of hydrocephalus. To date, 7 hydrocephalic animals have been analyzed that survived 7-83 days (median = 54) after receiving injections of cyanoacrylate glue into the anterior fourth ventricle. Measurements were obtained from lateral, 3rd, and 4th ventricles. The volumes of the left and right lateral ventricles were symmetrical before and after induction. Mean lateral ventricle volume increased 424% from a baseline of 0.63 cc to a post-induction value of 3.30 cc (p < 0.01 with unpaired t-test). In contrast, the 3rd ventricle expanded 187% from a mean of 0.15 cc to 0.43 cc (p < 0.05). The combined volume of the lateral and 3rd ventricles increased 369% from a mean of 0.78 cc to 3.69 cc (p < 0.01). Evans' ratios, which are used routinely in the clinical setting, were also obtained from linear measurements of the lateral ventricle width divided by brain width at the level of the foramen of Monro. These values exhibited only a 94% increase from mean baseline ratios of 0.17 to post-induction ratios of 0.33 (p < 0.05). These findings indicate that in mechanically-induced obstructive hydrocephalus the relative expansion of the lateral ventricles is greater than that of the 3rd ventricle. In addition, volumetric measurements of the lateral and 3rd ventricles suggest that the extent of ventriculomegaly is 3-4 times greater than estimated by Evans' ratios.

Robotic surgical instruments for dexterity enhancement in thoracoscopic coronary artery bypass graft.

OBJECTIVES: Endoscopically sutured vascular anastomoses are complex, time consuming, and require great dexterity. We decided to evaluate performance enhancement using a robotic device to create sutured coronary artery bypass anastomoses with endoscopic techniques in a plastic model. METHODS: Seven coronary artery bypass anastomoses were endoscopically created in a plastic model using a robotic enhancement technology (Computer Motion, Goleta, CA). Anastomoses were created with a single running suture (7-0 monofilament). Our endpoints were operative time, intraoperative incidents, stability and dexterity of the robotic system, surgeon's fatigue, and anastomotic patency. RESULTS: Operative time was 46+/-12 min (mean+/-SD). There were no intraoperative incidents. Patency was confirmed in all anastomoses. The system's stability and dexterity were high. Surgeon's fatigue was mild. CONCLUSION: The use of robotic enhancement technology leads to an efficient performance of sutured coronary artery bypass anastomoses in a plastic model. The robotic device enhances dexterity, precision, and reduces surgeon's fatigue while preserving the quality of hand suturing.

Target and trajectory guidance for interactive surgical navigation systems.

The proliferation of interactive surgical navigation systems (ISN) is evidence of their ability to provide useful information about current location and orientation at surgery. The utility of these systems would potentially expand with intuitive methods to guide the user towards a predefined target(s) along a predefined trajectory. A system of target and trajectory guidance is described comprised of three components: (1) auto-push that displays the plane perpendicular to the present trajectory that contains the preselected target and the distance from probe tip to this plane; (2) concentric circles and collinear spheres where spheres representing the target, entry point and wand tip are projected onto the 'autopush' plane as circles, thereby visually defining the rotations and translations required to reorient the wand to the predefined target and trajectory, and (3) projected trajectories where the ideal wand trajectory is projected onto two orthogonal planes, each of which contain the present wand trajectory. Together, these enhancements enable users of ISN to easily access small, deep intracranial structures along predefined surgical trajectories.

Application of frameless stereotaxy to pedicle screw fixation of the spine.

Interactive frameless stereotaxy has been successfully applied to intracranial surgery. It has contributed to the improved localization of deep-seated brain lesions and has demonstrated a potential for reducing both operative time and morbidity. However, it has not been as effectively applied to spinal surgery. The authors describe the application of frameless stereotactic techniques to spinal surgery, specifically pedicle screw fixation of the lumbosacral spine. Preoperative axial computerized tomography (CT) images of the appropriate spinal segments are obtained and loaded onto a high-speed graphics supercomputer workstation. Intraoperatively, these images can be linked to the appropriate spinal anatomy by a sonic localization digitizer device that is interfaced with the computer workstation. This permits the surgeon to place a pointing device (sonic wand) on any exposed spinal bone landmark in the operative field and obtain multiplanar reconstructed CT images projected in near-real time on the workstation screen. The images can be manipulated to assist the surgeon in determining the proper entry point for a pedicle screw as well as defining the appropriate trajectory in the axial and sagittal planes. It can also define the correct screw length and diameter for each pedicle to be instrumented. The authors applied this device to the insertion of 150 screws into the lumbosacral spines of 30 patients. One hundred forty-nine screws were assessed to be satisfactorily placed by postoperative CT and plain film radiography. In this report the authors discuss their use of this device in the clinical setting and review their preliminary results of frameless stereotaxy applied to spinal surgery. On the basis of their findings, the authors conclude that frameless stereotactic technology can be successfully applied to spinal surgery.

Intracranial meningioma resection using frameless stereotaxy.

Thirty-four consecutive patients with intracranial meningiomas underwent 35 resections aided by an interactive surgical navigation system (ISN; "frameless stereotaxy"). System capabilities include real-time display of wand location, orientation, and relationship to nearby structures using multiplanar and three-dimensional presentation of magnetic resonance imaging (MRI) and/or computed tomography (CT) data obtained perioperatively. There were 16 patients with convexity tumors, five patients with sphenoid wing tumors, five patients with falx or parasagittal tumors, and eight patients with skull base tumors (two each: petroclival, cavernous sinus, olfactory groove, and planum sphenoidale). the ISN system was used to locate a minimal craniotomy (i.e., trephine) in 11 (32%) patients, to optimize bone flap design in 13 (38%) patients, to identify the location of parasagittal draining veins in five (15%) patients, and to locate the carotid or basilar arteries in 11 (32%) patients. The techniques provided limited benefit in cranial nerve preservation. No patient had permanent central neurologic morbidity. Where intended preoperatively, tumor resection was complete (i.e., > 98%) in all patients as determined via postoperative MRI. Interactive surgical navigation is a useful adjunct in the operative management of some patients with intracranial meningiomas.

Adaptation of personal projection television to a head-mounted display for intra-operative viewing of neuroimaging.

We describe an adaptation of a personal projection television for intra-operative viewing of conventional neuroimaging and frameless stereotaxy displays. In addition to image display, the device provides surgical magnification and eye protection from body fluids. Image data is first processed by a scan converter to provide a National Standards Television Committee (NTSC) television signal. The adjustable optics of the system display are permanently secured to avoid displacement during surgery. A virtual image of the data is projected to an apparent size of four feet in the inferior visual field of the surgeon's dominant eye. Magnification is provided by the surgical telescopes mounted in the visor. Resolution of the device is consistent with that obtained in a slice of computed tomography or magnetic resonance imaging data. Optimal display of multiplanar data awaits improvement in density of the light emitting diode device used for image generation.

Use of a frameless, armless stereotactic wand for brain tumor localization with two-dimensional and three-dimensional neuroimaging.

Preliminary experience with a frameless, armless stereotactic localization system in brain tumor surgery is presented. The localizing wand emits ultrasonic pulses that are detected by a table-mounted array of microphones--with triangulation of the emitter positions. The wand tip and trajectory are determined by proprietary computer software. Real-time display of this information is presented in multiple, two-dimensional or three-dimensional displays. Forty-eight patients underwent 52 craniotomies for brain tumors. The wand was used to assist in placing a minimal craniotomy in 48 cases, to determine the tumor/brain interface in 27 cases, to localize subcortical tumors in 14 cases, and to correlate the physiological mapping with the surface anatomy in 5 cases. In 12 instances, the wand was used in conjunction with frame stereotaxy and found to be comparable or superior. Triplanar (coronal, sagittal, transverse) two-dimensional images provided sufficient information for the detection of tumor boundaries but proved difficult to use to access a subcortical lesion; two-dimensional or three-dimensional images along the localization axis were more helpful. Frameless stereotaxy with this sonic wand system proved to be a useful adjunct to open-tumor biopsy or resection.

Stereotactically guided thrombolysis of deep cerebral hemorrhage: preliminary results.

BACKGROUND: The neurologic outcome from conventional medical or surgical therapy of intracerebral hemorrhage (ICH) is poor; however, stereotactically guided instillation of thrombolytic agents to dissolve parenchymal clots due to hypertensive hemorrhage has recently produced results equal to or better than those obtained with conventional therapies. OBJECTIVE: To determine whether stereotactic thrombolysis of deep ICH is safe and effective. METHODS: We administered urokinase to clots in four patients with hypertensive ICH. After the hemorrhage was localized using angiography and computed tomography-assisted stereotactic technique, a ventricular catheter was used to administer urokinase to the clot. RESULTS: Preliminary results showed dramatic reduction in clot volume within 48 hours of initiating treatment and modest clinical improvement in all four patients. No further hemorrhages were seen after treatment. Three patients ultimately died of non-neurologic causes. CONCLUSIONS: With careful patient selection, stereotaxy-assisted thrombolytic therapy may be an advance in the treatment of certain cases of ICH.

Intraoperative localization using an armless, frameless stereotactic wand. Technical note.

A technique of "frameless" stereotaxy that allows real-time intraoperative neurosurgical localization is described. The system is composed of four components: a hand-held probe containing two ultrasonic emitters, a microphone array that is rigidly affixed to the operating table in proximity to the surgical field, hardware to control and detect timing of signal production and reception, and a color graphics computer workstation with software to calculate and present the location of the probe tip on reconstructed neuroimaging studies. Unlike previously reported mechanical or sonic navigational devices, this system is adaptable to a wide array of neurosurgical instruments, allows free movement of the operating table and conventional patient draping, and has accuracy in the hostile operating room environment that rivals that of frame stereotaxy. In the operating room environment, using four pulse pairs with the wand positioned optimally, reproducibility of a point in space is +/- 0.6 mm. The wand has a broad range of orientations that maintain error at or below 1.0 mm. The mean error when measuring distances within a 1000-cu cm cube is 1.1 +/- 1.0 mm (1.0% +/- 0.7%). The ability to localize a fourth point (a target) in space is typically within 1.5 mm (using computerized tomography scans with a 1-mm slice thickness) but is dependent on several variables. This technology provides a powerful yet flexible tool in the neurosurgical operating room.

Registration of EEG electrodes with three-dimensional neuroimaging using a frameless, armless stereotactic wand.

A technique of image and electrode registration has been developed that allows electroencephalogram electrode location to be merged with 2-D or 3-D MRI or CT. An armless, frameless stereotactic localization system that may be used in or out of the operating room is used to generate spatial data for surface and accessible intracranial electrodes. Acquisition of electrode position data may be obtained before or after neuroimaging and the locations of additional electrodes added at any time. The methodology of this system and representative cases with MRI imaging are presented.

Modifications of the compass stereotactic magnetic resonance localizer: technical note.

Head size, shape, or optimal anterior support placement can preclude stereotactic localization using the Compass magnetic resonance imaging (MRI) localizer. The described modifications of MRI localization largely overcome these limitations and should allow for safer, more versatile MRI stereotactic localization with the Compass system in more patients than using standard techniques.

Stereotactic magnetic resonance angiography.

Visualization of the surgical trajectory with respect to the cerebral vasculature may enhance the safety of some stereotactic neurosurgical procedures. Traditional stereotactic angiography is tedious and, being an invasive procedure, poses some risk to the patient. A technique of projecting a stereotactically defined surgical trajectory onto magnetic resonance angiograms is presented.