Stereotactic-computerized tomography interface device

A mechanical stereotactic-computerized tomography interface device (SCID) is attached to the head at three bony fixation points and, after rigid fixation to the scanning gantry, is zeroed to make scan and stereotactic space identical. The system is simple, reproducible, accurate and reliable and has been used for tumour and excisional biopsy, radiation planning and instillation of radioisotopes.     

Present and future developments of stereotactic technology

Incorporation of a surgical computer system into stereotactic methodology provides the facility for efficient utilization of the multiple data bases at the disposal of the modern stereotactician. Computed tomography, magnetic resonance imaging, and digital fluoroscopy data gathered in stereotactic conditions are digitized into a stereotactic surgical matrix for surgical planning and interactive surgical procedures. The advantages of this system are illustrated in stereotactic biopsy, interstitial irradiation, and laser resections of intracranial tumors.     

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.     

A new stereotactic instrument for use with computerized tomography and magnetic resonance imaging

The new stereotactic instrument has the advantages of use with computerized tomography (CT) or magnetic resonance imaging (MRI) without special adaptations of instruments, brain targets transferred directly from CT or MRI to apparatus, and use with conventional stereotactic techniques. The apparatus is designed to meet present demands of neurosurgical facilities of good standards and capabilities, encompassing present and future developments towards more efficient and less invasive brain operations.     

Computer-assisted stereotactic brain operations by means including computerized axial tomography.

With a computerized program system for stereotactic brain operations it becomes possible for the first time to react even before running a possible risk, e.g., in case of punctures in the midbrain, the brain stem, or in the hypothalamus, by simulating the operative procedure even before starting the operation itself. This is effected by the ability to change the penetration angle of the electrode or by choosing a different point of trepanation. The inclusion of computerized axial tomography, especially through the presentation of the CT scan, made to measure with the help of the linear transformation, and of the input of the cranial and ventricular coordinates through a digitizer, together with the coordinates resulting from the X-ray picture, brings the definition of the target point to a still greater optimum. Thus the safety and the precision of the stereotactic operation have been improved even further.     

Accuracy of the analysis of multiple small fragments of glial tumors obtained by stereotactic biopsy.

To examine the reliability of the diagnoses reached on multiple small fragments of cerebral glial tumors obtained via stereotactic biopsy, samples obtained from 100 consecutive glial tumors (during real or simulated biopsy) were studied by cytology and histology. In comparison to the definitive diagnosis made on the whole tumor, a correct positive diagnosis on the biopsy sample was made by histology in 96% of cases and by cytology in 93% of the cases (with 96% correct results when combining both methods). A correct identification of the tumor type and grade was achieved by histology in 82% of cases and by cytology in 80% of the cases (with 85% correct results when combining both methods). The limits of stereotactic biopsy are related to the difficulty of identifying all of the typical tumor features on tiny tissue fragments of a pleomorphic neoplasm, such as a glioma. This study demonstrates that better results may be obtained by using both cytology and histology to study multiple stereotactic biopsy samples from glial tumors.     

Transposition of target information from the magnetic resonance and computed tomography scan images to conventional X-ray stereotactic space

A technique to apply reconstructed X-ray computed tomography (CT) and magnetic resonance imaging (MRI) for target determination in stereotactic Bragg peak proton beam therapy of intracranial lesions was developed. Twenty-one benign intracranial tumors and vascular abnormalities were managed using this technique. Clinical features of these lesions, as well as targeting problems associated with the MRI and CT image interpretation, are presented.     

Accuracy of CT scans in identifying tumor tissue

The authors present their experience with stereotactic biopsy of brain tumors. Biopsies were obtained sequentially at different depths from the center of the tumor according to coordinates derived from computerized tomography (CT). Biopsies were obtained from 23 brain tumors: 17 gliomas, 5 metastases, and 1 lymphoma. In all a total of 137 biopsies were studied from both enhancing and nonenhancing areas. The tumor yield from these biopsies was 68 and 73%, respectively. It appears that tumor tissue may be obtained from both the enhancing periphery as well as the nonenhancing center of tumors.     

Computed tomography for determining liver iron content in primary haemochromatosis.

Dual-energy computed tomography (CT) was used to estimate hepatic iron concentration in eight patients with primary haemochromatosis with varying degrees of iron overload. The values corresponded closely with these derived from chemical analysis of liver tissue obtained by biopsy (correlation coefficient 0.993). Dual-energy CT therefore seems to provide an accurate and non-invasive alternative to liver biopsy as a means of measuring liver iron concentration in patients with primary haemochromatosis and possibly other iron overload states.     

Cerebral amyloidoma diagnosed intraoperatively with squash preparations: a case report

BACKGROUND: Amyloidoma (tumoral amyloidosis) is the rarest form of central nervous system (CNS) amyloidosis. CASE: A 51-year-old woman presented with recurrent right-sided otitis media and hearing loss. Computed tomography and magnetic resonance imaging revealed a mass in the right temporal lobe. Cytologic findings at the time of stereotactic biopsy for suspected glioma were compatible with amyloidoma. Subsequent histologic and electron microscopic findings confirmed the diagnosis of amyloidoma. Auxiliary testing ruled out systemic amyloidosis and plasma cell dyscrasia. CONCLUSION: To our knowledge, this is the first report on the cytologic findings in a case of CNS amyloidoma.     

Stereotaxy and thalamic masses. Survey of 44 cases

Thalamic masses are generally considered inoperable; little is known of the precise nature of these lesions. Stereotactic biopsy was performed in 44 patients, with no mortality and low morbidity (only 1 case of transitory hemiparesis). The stereotactic biopsy (minimum 5 specimens taken along the major axis of the lesion) showed that the majority of the young patients (less than 40 years) had low-grade glial neoplasms (grade I-II astrocytomas or oligodendrogliomas), while in older patients highly malignant tumors prevailed. Beside the neoplasms in the children and adults, we found granulomas, abscesses, infarcts, hemorrhages and glioses. Present neuroradiological methods cannot establish a final correct diagnosis in thalamic lesions, so stereotactic biopsy is recommended. A follow-up of 1-6 years is presented for 7 patients who underwent stereotactic 125I brachytherapy.     

The role of monopolar stimulation during computed-tomography-guided stereotactic biopsies

44 patients underwent intraoperative stimulation with a monopolar electrode prior to computed tomography (CT)-guided stereotactic biopsy. Stimulation at 2-100 Hz resulted in functional responses in 6/21 patients with subcortical or callosal lesions, 4/6 with basal ganglion lesions, 8/10 with thalamic and 4/4 with brainstem lesions. In all but 2 patients with mesencephalic lesions, where limited biopsy sites were available, an alternative biopsy site was used if a functional response was obtained. No morbidity was seen among these patients, although postbiopsy CT scans demonstrated small 3- to 7-mm hematomas in 5/11 patients. Retrospective review of 79 patients who underwent biopsies without stimulation demonstrated hematomas in 6/10 patients and a 3.3% transient surgical morbidity. These data indicate that postbiopsy hematomas are a relatively common occurrence, that intraoperative electrical stimulation within abnormal lesions can identify functional potential, and that avoidance of biopsies within these functional areas may be associated with reduced morbidity.     

Computer-assisted stereotactic biopsy of intracranial lesions

The use of a computer program that allows the integration of stereotactically gathered CT, MRI and digital angiographic data in the planning of a biopsy trajectory is described. This system has been used to perform 447 stereotactic biopsies in 439 patients. Intracranial hemorrhages occurred in three patients; combined morbidity and mortality was less than 1%. Incorporation of angiographic data and visualization of the surgical trajectory enhances the safety and accuracy of stereotactic biopsy of intracranial lesions.     

Single-scan stereotactic tumor biopsy and brachytherapy

Stereotactic tumor biopsy and brachytherapy catheter implantation can be accomplished with targets derived from computed axial tomography and magnetic resonance scans. Computer manipulation of image data allows both diagnostic and therapeutic procedures to be carried out from a single set of scan slices. This eliminates the need for repeat scanning as part of the surgical procedure. Microcomputer technology is sufficiently advanced to handle the images and graphics necessary for stereotactic neurosurgery. A system based on the IBM PC/AT designed for this purpose uses readily available graphics software and custom-designed imaging programs. Direct loading of computed axial or magnetic resonance scan images from magnetic tape can be accomplished. Determination of points, contours and volumes in three-dimensional space allows intraoperative alignment of image data and patient landmarks within the stereotactic head frame using pattern recognition overlays. Three-axis scaling for magnification correction along with rotational and linear data transformations provide the basis for single-scan stereotaxis. Interactive computer graphics integrate image, patient and frame coordinates for target determination. This method eliminates the need to design and fabricate nonmagnetic or radiolucent scanner-compatible devices.     

Experience using two CT-guided stereotactic biopsy methods

15 patients had intracranial CT-guided stereotactic biopsies. Biopsies were performed either with a Riechert-Mundinger stereotactic frame modified for use in the CT or by using the CT scan to establish the relationship of the intracranial lesion to identifiable bony landmarks, and subsequently performing the biopsy in a standard stereotactic frame. Both systems provided safe and accurate methods for obtaining intracranial tissue.     

Use of 18F-FDG positron emission tomography in the diagnosis and evaluation of the efficiency of treatment for resistant anxiety-obsessive disorders

The purpose of the investigation was to study the capacities of 18F-FDG positron emission tomography (PET) in the diagnosis and evaluation of the efficiency of treatment for resistant anxiety-obsessive disorders (AOD). 18F-FDG PET was performed in 21 patients with AOD. In 17 cases, the studies were made before and after therapy. Fourteen patients underwent stereotactic surgical intervention. Pretreatment 18F-FDG PET showed that the patients with AOD had hypermetabolism in the cingulated gyri, caudate nuclei, and thalamus in 7, 8, and 6 cases, respectively. A varying clinical improvement (by the Y-OCS and Spilberger scales) was observed in all the examinees after complex or drug treatment throughout the follow-up. According to the data of PET, these patients were observed to have significantly reduced metabolism of glucose in the anterior cingulated guri and its increased metabolism in the heads of the caudate nuclei and thalamus. The metabolic changes detected by PET are strongly and moderately correlated with the pattern of a clinical picture (p < 0.05). It is concluded that the use of 18F-FDG PET makes it possible to provide more accurate insight into the pathogenetic mechanisms responsible for the development of AOD, to objectify the choice of targeted intracerebral structures in order to perform stereotactic neurosurgical interventions, and to optimize drug therapy and to evaluate the efficiency of the treatment performed in early periods.     

Computer tomography-controlled stereotactic surgery

In computed tomography (CT)-controlled stereotactic surgery, the coordinate system of the CT scanner is applied to determine the target depth and direction as well as for readjustment of final probe direction. This method can be used for all types of stereotactic surgery for the brain.     

Multiplanar CT-guided stereotaxis and 125I interstitial radiotherapy. Image-guided tumor volume assessment, planning, dosimetric calculations, stereotactic biopsy and implantation of removable catheters

A method using Multiplanar CT-guided stereotactic biopsy and high-dose 125I interstitial radiotherapy in patients with malignant nonresectable or recurrent brain tumors is presented. Optimal interstitial radiotherapy requires careful preoperative planning, computer-assisted dosimetry, CT-guided stereotactic biopsy and implantation of catheters that will be loaded with 125I seeds. A method is presented by which the isodose curve distribution is adjusted to the tumor size, volume and axis, allowing treatment of the imaged and histologically determined border of the tumor with 60 Gy at a dose rate of 40 rad/h.     

Angiographic localizer for the BRW stereotactic system

Preliminary experience with a newly constructed angiographic localizer system for use in stereotactic neurosurgery is reported. This localizer ring, mounted on the BRW head ring, allows for the transformation of target points with known stereotactic coordinates (e.g., visible on computerized tomography scans) onto angiograms, as well as the determination of stereotactic coordinates of a set of points (e.g., arteriovenous malformations) indicated on at least two angiograms.     

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.