Brown-Roberts-Wells stereotactic frame modifications to accomplish magnetic resonance imaging guidance in three planes

The Brown-Roberts-Wells (BRW) computer tomography (CT) stereotactic guidance system has been modified to accommodate magnetic resonance imaging (MRI). A smaller head ring, which fits in standard MRI head coils, is constructed of a non-ferromagnetic aluminum ring that is split to prevent eddy currents and anodized to prevent MRI image distortion and resolution degradation. A new localizing device has been designed in a box configuration, which allows BRW stereotactic coordinates to be calculated from coronal and sagittal MRI images, in addition to axial images. The system was tested utilizing a phantom and T1- and T2-weighted images. Using 5-mm MRI scan slices, targets were localized accurately to a 5-mm cube in three combined planes. Optimized calibration of both low field strength (0.3 T) and high field strength (1.5 T) MRI systems is necessary to obtain thin slice (5 mm) images with acceptable image resolution. To date, 10 patients have had MRI stereotactic localization of brain lesions that were better defined by MRI than CT.     

An applicability study on a CT-guided stereotactic technique for functional neurosurgery

When a CT-guided stereotactic technique for functional neurosurgery is adopted, extremely precise targeting is needed to obtain satisfactory surgical results. In this study the authors have investigated the accuracy of the target points determined by CT-guided techniques and compared with those of conventional roentgenographically controlled stereotactic procedures. Stereotactic surgery, employing the Brown-Roberts-Wells (BRW) system, was performed contemporarily 26 times in 23 patients, that is, 9 times in 8 patients for functional neurosurgery using with the roentgenographic method, and 17 times in 15 patients with the CT-guided method only for intracranial neoplasm biopsy. As a result, there were no problems of accuracy of determining the target points by CT-guided stereotactic surgery with the BRW system. When applying this technique for functional neurosurgery, it should be pointed out that there could be a discrepancy within 2 mm from the conventional target determination.     

Helmet for infant skull fixation during stereotactic neurosurgery

A thermoplastic helmet was designed to allow the use of the Leksell stereotactic frame in infants.     

Experience in the first 100 patients undergoing computerized tomography-guided stereotactic procedures utilizing the Brown-Roberts-Wells guidance system

A series of 100 patients undergoing CT-guided stereotactic procedures for biopsy and/or drainage (n = 87), deep brain electrode placement (n = 9), endoscopy (n = 1), and functional lesioning (n = 3) was reviewed. Only 1 patient required general anesthesia. There were 4 procedural related hematomas, only 1 of which was symptomatic. No other complications were encountered.     

Digital radiography for target point evaluation in stereotactic neurosurgery

Today, the usual target point evaluation during stereotactic operations using planar X-ray films can be supplemented by digital video storage. The picture-delivering system is a digital X-ray video chain which replaces the X-ray film. Evaluation of target point coordinates as well as parameters of electrode approach and positioning are determined by a microcomputer. Such an inexpensive system is described.     

Real-time three-dimensional graphic reconstructions using Brown-Roberts-Wells frame coordinates in a microcomputer environment

A desktop microcomputer environment that utilizes Brown-Roberts-Wells (BRW) frame coordinates for creation of three-dimensional depiction of operator-defined intracranial structures has been developed. The system allows direct reading of Siemens CT scan images from a floppy disc, structural edge definition, and reconstruction of defined images. The system is used in the operating room to view scans, perform standard BRW stereotactic functions, and create three-dimensional graphics for such tasks as defining tumor margins, conceptualizing positional relationships of intracranial structures, and radiation planning.     

Computer graphics with computerized tomography for functional neurosurgery

A computer graphics technique for computer-assisted stereotactic surgery is presented. The program is designed to aid the surgeon by presenting an on-line graphics display of stereotactic probes and electrodes superimposed on cross sections of the human brain stem. This technique simulates an otherwise blind surgical procedure on a graphics screen for use during surgery. An earlier system based around the DEC MINC-11 BA computer system has been used by the authors for the performance of stereotactic surgery with conventional ventriculography. This system has been upgraded and is now configured about an even more compact microprocessor-based hardware system with expanded graphics capabilities, which also allows its use with computerized tomography.     

Stereotactic CT scanning for the biopsy of intracranial lesions and functional neurosurgery

This report describes a system for incorporation of stereotactic CT scanning data, stereotactic arteriographic data and a computer-generated stereotactic atlas into a three-dimensional matrix utilizing an operating room computer. 86 patients have undergone computer-assisted stereotactic biopsies of intracranial lesions without mortality or neurologic morbidity. Neuroablative and neuroaugmentative procedures have been performed on 5 patients using the CT stereotactic atlas with good correlation with target points determined by ventriculography and microelectrode recording.     

A novel stereotactic frame for real PET-guided biopsies: A preclinical proof-of-concept

Purpose: To design, build and test a stereotactic device that allows PET image-guided biopsies to be performed. Methods: An initial prototype consisting of four main pieces, one of which contains radioactive markers to make it visible in the PET images, was built using a 3D printer. Once the device is mounted, a spherical coordinate system is built with the entrance needle point in the skin as the origin of coordinates. Two in-house software programs, namely getCoord.ijm, which obtains the spherical coordinates of the tumour tissue to be biopsied, and getNeedle.ijm, which virtualizes the inner needle tip once the puncture has taken place, were written. This prototype was tested on an FDG-doped phantom to characterize both the accuracy of the system and the procedure time. Results: Up to 11 complete biopsy procedures were conducted. The mean total procedure time was less than 20 min, which is less than the procedure time of conventional standard CT-guided biopsies. The overall accuracy of the system was found to be 5.0 ± 1.3 mm, which outperforms the criterion used in routine clinical practice when targeting tumours with a diameter of 10 mm. Conclusions: A stereotactic frame to conduct real PET image-guided biopsies has been designed and built. A proof-of-concept was performed to characterize the system. The procedure time and accuracy of the system were found to meet the current needs of physicians performing biopsies.     

X-ray and magnetic resonance stereotaxy for functional and nonfunctional neurosurgery

By means of new plastic stereotactic ring and head fixers, stereotactic procedures can be combined with MRI, with stereotactic coordinates obtained from the MRI images. The method was rechecked against CT stereotaxy and shows a good correspondence of the target coordinates. With MRI stereotaxy, structures near bony regions will be more accessible than with CT stereotaxy. Moreover, the MRI procedure seems to have advantages for functional therapy without the necessity of contrast ventriculography.     

Three-dimensional reconstruction of neuroradiological data within a stereotactic frame of reference for surgery of visible targets

Three-dimensional information obtained with neuroradiological exams performed under stereotactic conditions is displayed on a surgical console within the graphic reconstruction of the geometry of stereotactic frames. Planning of convenient probe trajectories can be carried out taking into account all data derived from different diagnostic techniques.     

Use of intraoperative stimulation in the selection of target sites for CT-guided stereotactic biopsies

We have utilized intraoperative stimulation to establish the functional nature of tissue to be biopsied in 20 patients undergoing CT-guided stereotactic biopsies. We have performed from 1-4 stimulations at 2-100 Hz using a monopolar and/or bipolar electrode at the intended target sites. Thresholds for motor and sensory response have been obtained. Stimulation results have ranged from sensory changes to tonic/clonic motor activity of the contralateral body and face.     

Use of geminiviral vectors for functional genomics

Virus-induced gene silencing (VIGS) can be used to study the function of a gene by downregulating its expression and analyzing the resulting phenotype. VIGS is a handy tool that is less time consuming and labor intensive than other methods for generating mutants. Geminiviruses are particularly convenient and valuable choices as VIGS vectors in functional genomics. The small size of their DNA genome, the simplicity of the methods for inoculation, their wide host range and their conserved genome organization are just a few of the advantageous characteristics that this group of viruses has to offer. Geminivirus-based vectors have proved to be very efficient in VIGS systems, and further development of these systems will most probably permit their application in studies of the functional genomics of important crops that are recalcitrant to other forms of analysis.     

Use of neurosurgery for psychological disorder in British Isles during 1974--6.

All 44 neurosurgical units in the British Isles replied to a postal questionnaire asking about their use of neurosurgery during 1974--6 for functional mental illness. A total of 431 operations was reported, representing a yearly rate of 3.4 operations per million population aged over 15. The numbers of operations declined from 158 in 1974 to 119 in 1976. Four units did two-thirds of the operations. Stereotactic methods for locating the site for the lesion were used in two-thirds of procedures. Mood disorders, anxiety states, and obsessive-compulsive neurosis were the conditions most commonly treated.     

Identifying cardiovascular neurocircuitry involved in the exercise pressor reflex in humans using functional neurosurgery

Groups III and IV afferents carry sensory information regarding the muscle exercise pressor reflex, although the central integrating circuits of the reflex in humans are still poorly defined. Emerging evidence reports that the periaqueductal gray (PAG) could be a major site for integrating the "central command" component that initiates the cardiovascular response to exercise, since this area is activated during exercise and direct stimulation of the dorsal PAG causes an increase in arterial blood pressure (ABP) in humans. Here we recorded local field potentials (LFPs) from various "deep" brain nuclei during exercise tasks designed to elicit the muscle pressor reflex. The patients studied had undergone neurosurgery for the treatment of movement or pain disorders, thus had electrodes implanted stereotactically either in the PAG, subthalamic nucleus, globus pallidus interna, thalamus, hypothalamus, or anterior cingulate cortex. Fast Fourier transform analysis was applied to the neurograms to identify the power of fundamental spectral frequencies. Our PAG patients showed significant increases in LFP power at frequencies from 4 to 8 Hz (P < 0.01), 8 to 12 Hz (P < 0.001), and 12 to 25 Hz (P < 0.001). These periods were associated with maintained elevated ABP during muscle occlusion following exercise. Further increases in exercise intensity resulted in corresponding increases in PAG activity and ABP. No significant changes were seen in the activity of other nuclei during occlusion. These electrophysiological data provide direct evidence for a role of the PAG in the integrating neurocircuitry of the exercise pressor reflex in humans.