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.     

New diagnostic and therapeutic tools in stereotaxy

A definitive pathoanatomic diagnosis was achieved in 14 biopsies of deep cerebral tumors in which the Laitinen CT adapter was utilized. In 5 patients, a third-ventricular colloid cyst was aspirated or resected by stereotactic endoscopy, with excellent results after a mean follow-up time of 2.5 years. Several instruments, including a diagnostic ultrasound probe, an ultrasonic aspirator, a combination laser and an endoscope can be used stereotactically when mounted on a special instrument carrier. Integration of the Laitinen stereotactic device and the CT adapter was developed to allow noninvasive stereotactic radiotherapy in a conventional fractionation schedule by a standard linear accelerator. Technical experiences using this radiosurgical system in over 30 sessions for treating inoperable cerebral arteriovenous malformations are promising, but the follow-up time is too short for evaluating the clinical effect.     

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.     

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.     

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.     

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.     

Further experience in stereotactic pontine tractotomy

The problem with percutaneous and even stereotactic cordotomy is the difficulty in obtaining sufficiently high analgesic levels without autonomic complications, although the problem seemed to apply to relatively few patients since percutaneous and stereotactic spinal procedures achieved sufficiently high analgesic levels to encompass most patients' pain. There is a group of patients, however, with high pain in the shoulder and neck where conventional percutaneous and stereotactic spinal procedure are dangerous. From the standpoint of achieving high levels of analgesia with a low incidence of dysaesthesia, pontomedullary lesions appear to have advantages.     

New CT-guided stereotactic apparatus and clinical experience with intracerebral hematomas

The conventional Sugita stereotactic frame has been improved to perform CT-guided stereotactic surgery both in the CT and operating rooms. The development of our instrument and the software of the scanners' computer are presented. Newly designed equipment produced almost no artifacts on the CT image. Using the improved stereotactic frame, we have operated upon 44 intracerebral hematomas in the CT room. More than 80% of the cases had satisfactory results. Two complications were encountered, and 1 patient died from pneumonia. Our initial experience of the pre- and postoperative cerebral blood flow measurement with 133Xe inhalation method and single photon emission CT is described.     

Stereotactic radiofrequency lesion making

The physical principles of radiofrequency (RF) lesion making in stereotactic neurosurgery are summarized. Empirical data are given on the relationship between lesion size and lesioning parameters. Currently accepted ranges of lesioning parameters for selected stereotactic procedures are discussed. Advanced RF lesion electrode designs are described which improve the capabilities to reach and confirm targets.     

An alternative method to stereotactic inoculation of transplantable brain tumours in large numbers of rats

The rat 9L gliosarcoma brain tumour model has been widely used in brain cancer studies. Intracerebral implantation of the cells in the parietal lobe of the brain has been performed using the stereotactic or freehand inoculation methods. For large numbers of rats, we wished to develop a method more accurate and precise than the freehand method, but less labour intensive than the stereotactic method. A template implantation technique was developed and compared quantitatively with the stereotactic method. Rats were inoculated with either the template or stereotactic method at doses of 1000, 5000, 10000, 20000 or 40000 cells. Results of this comparison showed that the template method is precise and accurate for tumour placement within the brain cortex, and decreases labour requirements. Mean survival rates between groups were not significantly different at doses of 5000, 20000 or 40000 cells inoculated. Significance was seen at the low dose of 1000 cells (P < 0.001). This was attributable to an absence of tumour growth in five of six stereotactic rats in this group. Significance was also seen at the 10000 dose level (P < 0.05) with the stereotactic rats again surviving longer than the template rats. However, in this case all the stereotactic rats had tumour growth. Brain weights did not differ significantly between groups, except at the 1000 dose level where no growth of tumour occurred in five of the six stereotactic animals. Body weight gain within one week following surgery did not differ significantly between any of the groups at alpha = 0.05. Studies on rat cadavers showed no statistical difference in placement measurements between the stereotactic and template methods. These results indicate that the template method for intracerebrally implanting tumour cells in rats provides a precise, accurate and rapid procedure that maximizes reproducibility with a significant reduction in labour requirements, when compared with the conventional stereotactic methodology.     

Serious gastric perforation after second stereotactic body radiotherapy for peripheral lung cancer that recurred after initial stereotactic body radiotherapy: a case report

Background

In recent reports, re-irradiation with stereotactic body radiotherapy for lung tumors in patients previously treated with thoracic radiation therapy resulted in several serious toxicities. Serious non-lung toxicities were observed mostly in patients with central tumors, but we experienced a case of fatal gastric perforation after a second stereotactic body radiotherapy in a patient with a peripheral lung tumor.

Case presentation

An 83-year-old Asian man was diagnosed with T2N0M0 lung cancer in the form of squamous cell carcinoma in the lower lobe of his left lung. He was treated with stereotactic body radiotherapy of 40 Gy in 4 fractions and the tumor decreased in size in partial response. The local tumor recurred 8 months after the first stereotactic body radiotherapy, and he was re-irradiated with a second stereotactic body radiotherapy of 50 Gy in 4 fractions. A Sengstaken–Blakemore tube was inserted below his diaphragm by laparoscopic surgery before the second stereotactic body radiotherapy in order to reduce the stomach dose by keeping his stomach apart from the tumor. Two months after the second stereotactic body radiotherapy, he developed fatal gastric perforation and gastropleural fistula penetrating his diaphragm.

Conclusions

To the best of our knowledge, this is the first report about a gastric perforation after stereotactic body radiotherapy for lung tumors and it warns of serious complication of stereotactic body radiotherapy in not only centrally located but also peripherally located tumors like in this case.

     

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.     

Microcomputer stereotactic atlas

A stereotactic atlas to determine thalamic target sites has been incorporated into a microcomputer. Variability studies of the thalamus with mean and standard deviations of nuclear borders are depicted graphically for overlay onto operative images. Internal landmarks traditionally used to reference target points for functional stereotaxis may be determined by conventional ventriculography or derived from magnetic resonance scans. Modeling of polyline vertices established from gray scale contour mapping and atlas reconstructions further enhance the spatial understanding of relationships to midline structures. Computer integration of anatomic reference points, graphically depicted images and stereotactic atlas data into head frame coordinates can be accomplished. This method is consistent with established stereotactic techniques and allows the visual conceptualization of imaged and graphic data for functional stereotaxis.     

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.     

Creation of a three-dimensional atlas by interpolation from Schaltenbrand-Bailey's atlas

A 0.5-mm step atlas was interpolated from Schaltenbrand-Bailey's atlas. By serial display of the atlas with the desired rotation on a three-dimensional axis, a three-dimensional atlas was created. The newly created atlas can be used for computer-processed stereotactic data display. Any three-dimensionally located point can be displayed within 0.25 mm distance from the point, and spatial understanding of anatomical structures and stereotactic data is facilitated by the three-dimensional display.     

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.     

Computer-interactive stereotactic resection of deep-seated and centrally located intraaxial brain lesions

The carbon dioxide laser has been incorporated into a computer-interactive stereotactic system for precision resection of deep-seated intraaxial neoplasma defined by stereotactic computed tomography and magnetic resonance imaging. One hundred and ninety-seven procedures were performed on 191 patients having deep-seated lesions. Postoperative results have been satisfactory as regards the postoperative condition of the patient in consideration of the completeness of tumor removal achieved.     

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.