Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “STEREOTAXIC TECHNICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1993

A frameless stereotactic approach to neurosurgical planning based on retrospective patient-image registration. Technical note.

A frameless stereotactic device interfacing an electromagnetic three-dimensional (3-D) digitizer to a computer workstation is described. The patient-image coordinate transformation was found by retrospectively registering a digitizer-derived model of the patient's scalp with a magnetic resonance (MR) imaging-derived model of the same surface. This procedure was performed with routine imaging data, eliminating the need to obtain special-purpose MR images with fiducial markers in place. After patient-image fusion was achieved, a hand-held digitizing stylus was moved over the scalp and tracked in real time on cross-sectional and 3-D brain images on the computer screen. This device was used for presurgical localization of lesions in 10 patients with meningeal and superficial brain tumors. The results suggest that the system is accurate enough (typical error range 3 to 8 mm) to enable the surgeon to reduce the craniotomy to one-half the size advisable with conventional qualitative presurgical planning.

Adult↗
PubMed1999

Endoscopic neurosurgery "around the corner" with a rigid endoscope. Technical note.

Endoscopically "working around the corner" is presently restricted to the use of flexible endoscopes or an endoscope-assisted microneurosurgical (EAM) technique. In order to overcome the limitations of these solutions, endoscopic equipment and techniques were developed for "working around the corner" with rigid endoscopes. A steering insert with a 5 French working channel is capable of steering instruments around the corner by actively bending the guiding track and consecutively the instrument. A special fixation device enables strict axial rotation of the endoscope in the operating field. Endoscopic procedures "around the corner", including aqueductal stenting, pellucidotomy, third ventriculostomy and biopsy were performed in human cadavers. Special features of the used pediatric neuroendoscope system, i.e., reliable fixation, axial rotation, and controlled steering of instruments, increase the safety and reduce the surgical traumatization in selected cases, such as obstructive hydrocephalus due to a mass lesion in the posterior third ventricle, since endoscopic third ventriculostomy and biopsy can be performed through the same burr hole trephination. Limitations of this technique are given by the size of the foramen of Monro and the height of the third ventricle as well as by the bending angle of the instruments (40-50 degrees).

Biopsy↗
PubMed2000

Mathematical theory of stereotactic coordinate transformation: elimination of rotational targeting error by addition of a third reference point. Technical note.

All frame-based stereotactic procedures require localization of an anatomical target within the coordinate system of the stereotactic frame. If the target is defined by its coordinates given in a stereotactic atlas (indirect localization), the neurosurgeon faces the mathematical task of transforming atlas coordinates into frame coordinates. In the method usually used, the frame coordinates of two reference points (the anterior and posterior commissures) are obtained from computerized tomography or magnetic resonance images, and serve as the basis for the coordinate transformation. This two-point algorithm relies on the additional assumption that the frame sits on the patient's head without exhibiting roll, that is, rotation about the anteroposterior axis (y axis). Usually this assumption is nearly, but not exactly, correct. An amount of roll as small as 3 degrees can cause a targeting error on the order of 1 mm when a two-point algorithm is used. This potential source of error can be eliminated by using a new method of coordinate transformation, the derivation of which is mathematically reported in this article. The new method requires a third reference point located in the midsagittal plane, in addition to the two commissural reference points.

Algorithms↗
PubMed2006

A comparison of the accuracy of two minimally invasive breast biopsy methods: a systematic literature review and meta-analysis.

OBJECTIVE: The primary objective was to quantify and compare the accuracy and failure rates of directional vacuum assisted biopsy (DVAB) and core needle biopsy (CNB) when used under stereotactic (ST) guidance to biopsy suspicious breast lesions identified with screening mammography. METHODS: We performed a systematic review of the literature published from January 1996 to July 2004, reporting all-comers populations in Western-style health care systems (i.e., North America, Europe, Australia or New Zealand), referred after screening mammography for breast biopsy using DVAB or CNB under ST guidance. Meta-analyses were conducted for DVAB and CNB, using open surgical biopsy and/or long-term clinical and/or mammogram follow-up as the diagnostic reference standard. The main outcomes of interest were those of greatest clinical relevance, i.e., miss rates and underestimation rates for malignancy. Also, technical failure rate and non-diagnostic rate were assessed for each biopsy method. RESULTS: Thirty-five studies qualified for the review. There were 12 studies with a DVAB group (n=5,119 patients), and 25 studies with a CNB group (n=6,236). There were no studies including both a DVAB and a CNB group, thus precluding any direct, within-study comparisons of accuracy. Overall agreement rate between DVAB and the reference standard was 97.3%, and between CNB and the reference standard, 93.5%. The frequency of technical failures with CNB was slightly higher than DVAB (5.7 vs. 1.5%), as was the frequency of non-diagnostic samples (2.1 vs. 0%). Of the non-diagnostic CNB samples, 23% were subsequently found to be malignant on reference standard. In multivariate analyses using four covariates (procedure type, geographic location, reference standard, and patient position), there were no significant predictors of agreement rates, but some variables were significant predictors of miss rates. For benign to malignant upgrades, study location was a significant predictor, with more upgrades in non-NA locations. For atypia to malignant upgrades, the type of procedure was a significant predictor, with more underestimations in CNB studies. CONCLUSION: The best available evidence suggests that, in screening populations referred for minimally invasive breast biopsy biopsy requiring ST guidance, DVAB may provide lower miss and underestimation rates for clinically relevant diagnoses than does CNB.

Biopsy↗
PubMed1984

Curved biopsy needle for stereotactic surgery: a technical note.

Needle brain biopsy and aspiration is an important technique for the diagnosis of tumors and for the evacuation of fluid collections. Current biopsy methods use a straight needle, which has the disadvantage of requiring multiple passes through the overlying brain to obtain multiple biopsies. Furthermore, a straight needle does not give optimal samples of tumor for diagnosis because the needle passes through the viable rim of the tumor instead of along it. We are reporting a curved plastic biopsy needle suitable for computed tomography-guided biopsy. It remains inside an outer guide catheter that holds it straight until it reaches the edge of the tissue to be biopsied. At this point, the needle is advanced beyond the guide catheter and obtains the biopsy sample by passing around the edge of a tumor. This can in principle produce an improvement in diagnostic yield. Furthermore, multiple biopsies of the tumor from a single guide catheter position are possible. The surgeon rotates the curved needle within its guide catheter to redirect it before the needle emerges, and a different biopsy is then obtained without reinsertion. This avoids multiple punctures of the overlying uninvolved tissue. We are reporting the technique and beginning an evaluation of it.

Biopsy, Needle↗
PubMed2000

Modified stereotactic insertion of the Ommaya reservoir. Technical note.

Ommaya reservoirs are used primarily for the repeated injection of intrathecal chemotherapy for leptomeningeal metastasis from hematopoietic and solid malignancies. Insertion of this device in a relatively large nondisplaced ventricle is not a difficult task, but challenges arise when the ventricle is small and/or displaced. Different techniques have been developed to overcome this difficulty, most of which include the use of stereotactic frames. Further improvements would be beneficial. The technique described in this paper depends on a stereotactic frame; however, the modification proposed by the authors removes the arc system from the surgical field before the actual surgical procedure is begun. Removal of the arc improves access to the surgical field as well as preparation and draping of the surgical site and minimizes potential breaks in sterile technique, which ultimately reduces the incidence of infection. A twist-drill hole along the path of the chosen trajectory becomes an external guide for the ventricular catheter. The technique is easy, user friendly, and results in an unencumbered sterile field and reliable cannulation of small ventricles. A simple stereotactic technique for Ommaya reservoir insertion has been described. It should lower the chance of infection in this group of patients, most of whom have suppressed immune systems.

Cerebral Ventricles↗
PubMed2004

Phase I clinical evaluation of near-simultaneous computed tomographic image-guided stereotactic body radiotherapy for spinal metastases.

PURPOSE: To evaluate in a Phase I study the safety, feasibility, and patient-positioning accuracy of treating patients with intensity-modulated, near-simultaneous, computed tomographic (CT) image-guided stereotactic body radiotherapy (SBRT). PATIENTS AND METHODS: Fifteen consecutive patients with metastatic spinal disease who met protocol eligibility criteria were entered into a Phase I clinical trial. Each patient received five treatments of intensity-modulated, near-simultaneous CT image-guided SBRT, for a total of 75 treatments with 90 isocenter setups during the course of the study. Patients uniformly received 30 Gy (if possible) of radiotherapy in 5 fractions to the clinical target volume. The total dose was constrained by limiting the spinal cord to a maximum dose of 10 Gy. To verify correct daily patient positioning before each treatment and to determine the daily treatment setup error after radiation delivery, axial CT scans were taken before and immediately after each treatment without moving the patient from the treatment position, for comparison with the planning CT scan. Toxicity was measured using the Common Toxicity Criteria, the Late Effects of Normal Tissue scoring system and a neurologic function scale. Follow-up was conducted 4 weeks after completion of SBRT, and then 2, 3, 6, 9, 12, and every 6 months thereafter. RESULTS: The procedure was technically feasible to perform in all patients. No neurologic toxicity was observed in any patient. The median follow-up time was 9 months (range 6-16). The Clopper-Pearson upper bound on the probability of paralysis with 95% confidence is no greater than 0.181. The positional setup error was determined to be within 1 mm of planning isocenter. CONCLUSIONS: This Phase I study shows that intensity-modulated, near simultaneous, CT image-guided SBRT is a feasible, and highly precise technique for the noninvasive treatment of spinal metastases. Although no paralysis has developed in the 15 patients treated, continued monitoring for spinal cord toxicity is warranted, as larger numbers of patients will be needed to more precisely define the upper bound on the probability of spinal cord myelopathy.

Adolescent↗
PubMed1984

Computed tomographic guidance stereotaxis in the management of lesions of the third ventricular region.

The initial management strategies for lesions of the 3rd ventricular region are often controversial. Current techniques for computed tomographic guidance stereotaxis allow accurate access to any intracranial point. A Brown-Roberts-Wells stereotactic system was used as a technical adjunct in the initial management of 42 mass lesions of the 3rd ventricular region. Objectives included biopsy, culture, aspiration, visualization, and installment of drainage conduits. Forty-five point placements were accomplished, and 140 tissue specimens were retrieved without complication. The pathological diagnosis was substantiated in all cases and included lesions of developmental (1 case), neoplastic (31 cases), and infectious (10 cases) origins. Information based on stereotactic assessment provided a rational substrate for the initiation of management, which included craniotomy, cerebrospinal fluid diversion, radiotherapy, chemotherapy, and antibiotic or antiviral therapies. Based on this experience, it is apparent that these methods offer acceptably safe and accurate access to lesions of the entire 3rd ventricular region. Histological or microbiological diagnosis without the need for craniotomy may be readily realized and offers logical guidance for therapeutic strategies. Dependent on the pathological condition, definitive treatment may be achieved.

Adolescent↗
PubMed2002

Dynamic changes during evacuation of a left temporal abscess in open MRI: technical case report.

We demonstrate the usefulness of "near real-time" neuro-navigation by open MRI systems for guidance of stereotactic evacuation of intracranial abscesses. A 70-year-old patient was referred to our institution with an intracranial left temporal abscess. He presented with headache, senso-motor aphasia and mild right hemiparesis. The abscess (35 x 25 mm) was stereotactically evacuated under MRI guidance, and a recurrence of a daughter abscess was again evacuated on the 9th postoperative day. "Near real-time" imaging showed an indentation of the abscess wall of 11 mm along the trajectory. A thermosensitive MRI protocol demonstrated a higher temperature around the abscess capsule than in the brain tissue more distant to the capsule, demonstrating the inflammatory process. The patient had 6 weeks of antibiotic therapy for gram-negative bacteria and was discharged with improved clinical symptoms 5 weeks after admission. Follow-up CT 2 months postoperatively showed a complete resolution of the abscess. Open MRI-guided interventions with "near real-time" imaging demonstrate the anatomical changes during an ongoing procedure and can be accommodated for enhancing the overall precision of stereotactic procedures. Thermosensitive MRI protocols are capable of revealing temperature gradients around inflammatory processes.

Aged↗
PubMedDate not supplied

Technique and technical problems associated with implantation of neuroaugmentive devices.

The effectiveness of implantation of depth electrodes for pain control in (a) the primary thalamic relay nuclei, and (b) the periventricular gray matter or periaqueductal gray matter is reviewed. In a series of 39 patients, 14 achieved relief with no further need for medication, 16 were able to reduce their drug intake and 9 experienced no relief. These results are compared to those for a series of 76 patients reported on by an international study group of neurological surgeons. 61 patients in this series were considered to have had a successful result immediately after implantation of the electrode, but at the time of follow-up only 42 were still in this category. The implantation of depth electrodes requires a technique that fulfills the following criteria: (1) the procedure must be performed in a fully awake, cooperative patient; (2) a precise stereotactic technique must be employed, and (3) the effects of stimulation must be evaluated before the implant is made permanent. The most common complication was infection at the implantation site; this can be reduced by the use of Teflon-insulated percutaneous leads. Other complications include erosion of the hardware through the scalp and internal migration of the electrodes.

Cerebral Aqueduct↗
PubMed2000

Scalp marking for a craniotomy using a laser pointer during preoperative computed tomographic imaging: technical note.

OBJECTIVE: The preoperative localization of superficial intracranial lesions is often necessary for accurate burr hole placement or craniotomy siting. It is not always easy, however, to localize the lesions over the scalp working only from computed tomographic images. We developed a simple method for such localization using a laser pointer during the preoperative computed tomographic examination. METHODS: The angle of incidence, extending from a point on the scalp to the center of the computed tomographic image, is measured by the software included with the scanner. In the gantry, at the same angle as on the image, a laser is beamed from a handmade projector onto the patient's scalp toward the center of the gantry. The point illuminated on the patient's head corresponds to that on the image. The device and the method are described in detail herein. RESULTS: We applied this technique to mark the area for the craniotomy before surgery in five patients with superficial brain tumors. At the time of surgery, it was confirmed that the tumors were circumscribed precisely. CONCLUSION: The technique is easy to perform and useful in the preoperative planning for a craniotomy. In addition, the device is easily constructed and inexpensive.

Brain Neoplasms↗
PubMed2001

Computer-assisted neurosurgical navigational system for transsphenoidal surgery--technical note.

Transsphenoidal surgery carries the risk of carotid artery injury even for very experienced neurosurgeons. The computer-assisted neurosurgical (CANS) navigational system was used to obtain more precise guidance, based on the axial and coronal images during the transsphenoidal approach for nine pituitary adenomas. The CANS navigator consists of a three-dimensional digitizer, a computer, and a graphic unit, which utilizes electromagnetic coupling technology to detect the spatial position of a suction tube attached to a magnetic sensor. Preoperatively, the magnetic resonance images are transferred and stored in the computer and the tip of the suction tube is shown on a real-time basis superimposed on the preoperative images. The CANS navigation system correctly displayed the surgical orientation and provided localization in all nine patients. No intraoperative complications were associated with the use of this system. However, outflow of cerebrospinal fluid during tumor removal may affect the accuracy, so the position of the probe when the tumor is removed must be accurately determined. The CANS navigator enables precise localization of the suction tube during the transsphenoidal approach and allows safer and less-invasive surgery.

Acromegaly↗
PubMed1998

Interactive image-guided neuroendoscopy: development and early clinical experience.

Technical advances and pioneering surgeons have established neuroendoscopy as an accepted diagnostic and therapeutic tool. The clinical indications for endoscopy, variety of operative techniques and number of endoscopic surgeons continue to increase steadily. However, there are fundamental limits to the scope of freehand endoscopy principally governed by the need for direct vision of anatomical and pathological structures. In addition, whilst the expert neuroendoscopist is only occasionally disorientated by complex distorted anatomy, the rising number of novices are likely to be mislead relatively often. We report the integration of neuroendoscopy with an optical neuronavigation system to provide interactive image-guided neuroendoscopy. This combination both removes the constraining requirement for direct vision and provides accurate localisation to guide the surgeon during surgery. We describe the clinical application of this method to two cases where image-guided endoscopy was essential to the safe completion of the procedure.

Adult↗
PubMed1999

Integration of preoperative and intraoperative functional brain mapping in a frameless stereotactic environment for lesions near eloquent cortex. Technical note.

The authors present a method of incorporating preoperative noninvasive functional brain mapping data into the frameless stereotactic magnetic resonance (MR) imaging dataset used for image-guided resection of brain lesions located near eloquent cortex. They report the use of functional (f)MR imaging and magnetic source (MS) imaging for preoperative mapping of eloquent cortex in difficult cases of brain tumor resection such as those in which there are large expansive masses or in which reoperations are required and the anatomy is distorted from prior treatments. To correlate methods of preoperative and intraoperative mapping localization directly, the authors have developed techniques of importing preoperative MS and fMR imaging data into an image-guided frameless stereotactic computer workstation. The data appear as a seamless overlay on the same preoperative volumetric MR imaging dataset used for stereotactic guidance during the operation. Intraoperatively identified functional locations mapped by cortical stimulation are recorded as digitally registered points. This approach should prove useful in assessing the accuracy and reliability of various preoperative functional brain mapping techniques.

Adult↗
PubMed2002

MRI- and skull x-ray-based approaches to evaluate the position of deep brain stimulation electrode contacts--a technical note.

Deep brain stimulation (DBS) has developed into an established therapy for the treatment of movement disorders, most commonly Parkinson's disease and tremor of different etiology. The subthalamic nucleus (STN) has evolved as the preferred target for DBS in patients with idiopathic Parkinson's disease. The principal target for DBS in tremor patients is the ventrolateral thalamus which has been explored for ablative procedures (thalamotomy) for some decades. Detailed information about the exact site of chronic stimulation, i.e. the location of the active electrode contacts, are important to map the actual subcortical structures modulating the therapeutic effects of DBS. We compared two different methods not requiring intra-operative teleradiography to determine the stereotactic coordinates of single electrode contacts, (i) correlation of pre- and post-operative MRI, and (ii) post-operative stereotactic skull x-ray. For seven patients implanted bilateral with quadripolar DBS electrodes the coordinates for each contact were determined by both approaches. This revealed for a total of 56 electrode contacts a median euclidean 3D-difference between both methods of 1.18 mm (range 0.42 to 1.93 mm). These data suggest that both approaches may be used to determine the position of single electrode contacts.

Electric Stimulation Therapy↗
PubMed1999

Cranionavigator combining a high-speed drill and a navigation system for skull base surgery--technical note.

Drilling of the skull base bone without damaging the important inside structures and with the correct orientation is very difficult even with the help of the anatomical landmarks. Monitoring of the location and direction of the drill tip and indications of the removed part of the bone during the drilling procedure enhances safety and achieves less invasive neurosurgery. We have developed a novel cranionavigator by combining a high-speed drill with a neurosurgical navigation system. To reduce the positional error to less than 1.5 mm, the position sensor (magnetic field sensor) must be attached 5 cm from the metallic fan portion of the drill and the sensor kept at least 10 cm away from the operating microscope. Simulation studies with the cranionavigator using two dried skulls and three cadaver heads were performed before clinical application. Clinically, this surgical instrument was used in four patients with the skull base tumor. The cranionavigator helped to safely drill the skull base bone in a shorter time by dynamic and real-time display of the precise operating site and extent of bone drilling on the preoperative computed tomography scans or magnetic resonance images. The cranionavigator is a very helpful instrument for skull base surgery in the hands of neurosurgeons with extensive expertise and anatomical knowledge.

Craniotomy↗
PubMedDate not supplied

[Technical and diagnostic difficulties in stereotactic biopsy in children].

The paper presents technical and diagnostic problems associated with stereotactic biopsies in children. Between the years 1992 and 2000, in the Dept. of Neurosurgery, Child's Health Center, we performed 132 stereotactic procedures, including 110 biopsies. In 15 cases bleeding developed from the biopsy site; in this group we performed 3 craniotomies for open haematoma evacuation, 1 child died (mesencephalic glioblastoma multiforme). The remaining 2 children recovered with no additional neurologic sequelae related to this complication. Since 1997 we use the Nashold needle to obtain tissue samples. This enables us to take larger and fewer samples with less risk of bleeding. The biopsy was non-diagnostic in 3 cases. In 1 case we observed a slight movement of the child's head in relation to the stereotactic frame when the patient was moved from the CT-scanner to the operating theater. In order to avoid such problems in the future and to facilitate transposition of heavy and paretic or unconscious patients, we devised a hard board with side handles. Methods designed to overcome these and other difficulties are described.

Adolescent↗
PubMed2000

Follow-up of benign results of stereotactic core breast biopsy.

RATIONALE AND OBJECTIVES: The purpose of this study was to obtain long-term follow-up data on women with benign histologic results of a breast stereotactic core needle biopsy (CNB). MATERIALS AND METHODS: Mammography charts of 300 consecutive women who underwent prone stereotactic CNB with digital radiography were reviewed. Women with frankly malignant or suspicious histologic findings (51 patients) or a technically unsuccessful stereotactic CNB (one patient) were excluded. The remaining 248 benign core biopsies in 229 women were included in the study. RESULTS: Follow-up mammograms were obtained for 152 lesions with benign histologic results following stereotactic CNB. The mean length of follow-up after stereotactic CNB was 34.6 months. Cancer was diagnosed in six women who underwent surgical biopsies 1/2 to 30 months after benign stereotactic CNB. An initial chart review demonstrated that no follow-up data were available for 64 lesions, and information was missing for an additional seven. CONCLUSION: SCNB remains a sampling procedure that can result in false-negative histologic results. Intrinsic procedural issues were identified that could minimize the potential for missing a malignancy. Goals for patient compliance with follow-up recommendations fell short of expectations.

Adult↗