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.     

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.     

Technique of stereotactic biopsy of two cranial target employing spherical coordinates to define a single trajectory

A 'spherical coordinate system' has been developed to allow either stereotactic biopsy of two intracranial lesions using a single predetermined trajectory or biopsy of a single lesion through an existing burr hole. By means of the Gildenberg technique, the CT coordinates of the targets (or target and burr hole) are obtained. These are employed in three simple trigonometric equations to give three coordinates-two angles for the probe carrier (theta and alpha) and the radius (T) of a sphere, defined by one target as the center and the other target on the surface. These can be utilized in the Todd-Wells stereotactic frame. This system was evaluated using hollow skulls and crossed 30-gauge wire for phantom targets. The system was tried on ten different target combinations, and eight successful trajectories were obtained to within 3 mm. Two target combinations were inaccessible because of technical limitations of the Todd-Wells frame. This 'spherical coordinate system' can decrease the time to localize multiple targets as well as minimize the number of passes.     

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.     

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.     

Factors determining survival of patients with malignant gliomas diagnosed by stereotactic biopsy

We analyzed the prognostic significance of tumor histology, location, treatment, and selected clinical features at presentation in 91 consecutive patients with malignant gliomas diagnosed by stereotactic biopsy. In 64 patients with glioblastoma multiforme (GBM) the following factors were associated with longer survival: lobar tumor location, adequate radiation therapy (RT) tumor dose 5,000-6,000 cGy, Karnofsky performance rating (KPR) at presentation greater than or equal to 70, and a normal level of consciousness before biopsy. In 27 patients with anaplastic astrocytoma, factors associated with longer survival were lobar tumor location, adequate RT, age less than 40 years at presentation, and a history of seizures. Delayed cytoreductive surgery in lobar GBM extended median survival but did not improve long-term survival. For patients with deep or midline malignant gliomas and for selected patients with lobar tumors, stereotactic biopsy followed by RT may be the most reasonable initial treatment strategy.     

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.     

MRI contribution to the stereotactic management of cerebral tumours

Of 67 patients with cerebral tumours studied by MRI, 60 underwent stereotactic biopsy for histological diagnosis. The data from MRI were compared with those obtained from the CT scan with regard to the pathological diagnosis. The tumoural nature and extent of a lesion were better revealed by MRI. The single or multiple localization of the process was also seen better by MRI. Moreover, the sagittal-plane views shown by MRI provide much more accurate target placement and probe guiding for an orthogonal stereotactic approach. Finally, a post-biopsy MRI can show the biopsy site in relation to the tumour better.     

Stereotactic biopsy for deep-seated intracerebral lesions. Correlation between computer tomography, positron emission tomography and electrophysiological activity

In 16 cases of stereotactic deep brain biopsy, a correlative study was made by computer tomography, positron emission tomography, and electrophysiological depth recording. This multimodal study is shown to be of great value in stereotactic biopsy of deep-seated cerebral lesions.     

Transcranial Doppler ultrasonography: stereotactically guided examinations using magnetic resonance angiography]

The accurate localization of specific intracranial blood vessels is a major difficulty with transcranial Doppler sonography (TCD). It was the purpose of this study to develop a system enabling stereotactic navigation during a TCD examination on the basis of high-resolution three-dimensional magnetic resonance angiographic (MRA) data. During TCD, the examiner is provided--on a computer screen--with a projected view of the respective intracranial vessel anatomy. With the aid of an optoelectronic localization system, the spatial orientation and localization of the US probe is determined in real time, and correlated with the patient's MRA data using a dedicated stereotactic mask. Subsequently, the US beam and the points of insonation are displayed on the screen overlaid on the vessel anatomy. In this way the examiner gains real time control of the localization of the respective intracranial vessel insonated. Points of insonation can be stored and recalled for follow-up examinations. In addition to the successful verification of the system, it was shown that, in comparison with conventional TCD, stereotactic navigation distinctly improves the reproducibility of repeat TCD examinations.     

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.     

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.     

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.     

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.     

Cryptic vascular malformations diagnosed by stereotactic biopsies--a preliminary study

A series of 14 cryptic vascular malformations (CVM) deeply situated or localized in functional cortical areas were diagnosed by serial stereotactic biopsies. No history was suggestive of hemorrhage, despite a substantial hematoma being evacuated during biopsy procedures in 4 patients. Retrospectively, CVM without hematoma were found to have certain characteristics that should raise the suspicion as to the correct diagnosis. At the time of discharge from the hospital, only 1 patient had mild aggravation of a preexisting motor deficit, which further improved. Serial stereotactic biopsies provided the required histological diagnosis with relatively low risk.     

Hemodynamic and histologic characterization of a swine (Sus scrofa domestica) model of chronic pulmonary arterial hypertension

The purpose of this work was to develop and characterize an aortopulmonary shunt model of chronic pulmonary hypertension in swine and provide sequential hemodynamic, angiographic, and histologic data by using an experimental endoarterial biopsy catheter. Nine Yucatan female microswine (Sus scrofa domestica) underwent surgical anastomosis of the left pulmonary artery to the descending aorta. Sequential hemodynamic, angiographic, and pulmonary vascular samples were obtained. Six pigs (mean weight, 22.4±5.3 kg; mean age, 7.3±2.7 mo at surgery) survived long-term (6 mo) and consistently developed marked pulmonary arterial hypertension. Angiography showed characteristic central pulmonary arterial enlargement and peripheral tortuosity and pruning. The biopsy catheter was safe and effective in obtaining pulmonary endoarterial samples for histologic studies, which showed neointimal and medial changes. Autopsy confirmed severe pulmonary vascular changes, including concentric obstructive neointimal and plexiform-like lesions. This swine model showed hemodynamic, angiographic, and histologic characteristics of chronic pulmonary arterial hypertension that mimicked the arterial pulmonary hypertension of systemic-to-pulmonary arterial shunts in humans. Experimental data obtained using this and other models and application of an in vivo endoarterial biopsy technique may aid in understanding mechanisms and developing therapies for experimental and human pulmonary arterial hypertension.     

Reliability of stereotactic biopsy. A model to test the value of diagnoses obtained from small fragments of nervous system tumors

Because of the variability of the structural features of cerebral tumors, the characteristics observed in biopsy samples may not be representative of the whole neoplasm. The reliability of cerebral stereotactic biopsy is therefore greatly debated. In order to test the value of diagnoses based on biopsy samples, the authors compared histological and cytological data obtained from a small fragment of a tumor with the definitive diagnosis obtained from surgical or necropsy specimens. An analysis of 64 cases is reported, where a correct diagnosis from the biopsy sample was achieved in 92.2% of the cases. Neuroglial tumors were more difficult to characterize than other types of intracranial tumors, with an accuracy of 81.5%.     

Stereotactic neurosurgery and computerized tomographic scanning

The marriage of computerized tomographic (CT) scanning and stereotactic surgery opens up new technical possibilities, as it becomes feasible to introduce a probe into any lesion which is identified on a CT scan. The various CT stereotactic techniques are reviewed, and generally involve four variations. The head holder of a standard stereotactic apparatus can be adapted to the CT scanner to interdigitate the coordinates of both devices in a known relationship. Second, some types of CT scanners allow the visualization of the vertical coordinate. Third, a stereotactic microdrive can be incorporated into the scanner. Finally, a simple aiming device can be attached to the patient's head and repeated scans taken as the probe is advanced to the target. Various authors have reported the use of techniques for biopsy, aspiration of cysts or hematomas, insertion of radioisotopes, or as an adjunct to open surgery.     

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.     

Quality assurance procedure for a gamma guided stereotactic breast biopsy system

A quality assurance procedure has been developed for a prototype gamma-ray guided stereotactic biopsy system. The system consists of a compact small-field-of-view gamma-ray camera mounted to the rotational arm of a Lorad stereotactic biopsy system. The small-field-of-view gamma-ray camera has been developed for clinical applications where mammographic X-ray localization is not possible. Marker sources that can be imaged with the gamma-camera have been designed and built for quality assurance testing and to provide a fiducial reference mark. An algorithm for determining the three dimensional location of a region of interest, such as a lesion, relative to the fiducial mark has been implemented into the software control of the camera. This system can be used to determine the three-dimensional location of a region of interest from a stereo pair of images and that information can be used to guide a biopsy needle to that site. Point source phantom tests performed with the system have demonstrated that the camera can be used to localize a point of interest to within 1 mm, which is satisfactory for its use in needle localization.