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Results for “STEREOTAXIC TECHNICS”

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At least 415 records · Page 23Linked to original sources
PubMed1996

Evaluation of nonpalpable solid breast masses with stereotaxic large-needle core biopsy using a dedicated unit.

OBJECTIVE: In our institution for the past 4 years, stereotaxic core breast biopsy using a 14-gauge needle has been offered as an alternative to surgical excision. The purpose of this paper is to describe our protocol, results, and lessons learned from our experience. MATERIALS AND METHODS: From August 1991 to July 1995, 388 stereotaxic needle core biopsies of clinically occult, noncalcified, mammographically detected solid masses were performed. In this group, 103 patients underwent subsequent surgical excision. Another 169 have had follow-up examinations 1 year or more after their biopsies. RESULTS: Of the 61 patients diagnosed with a malignant process on core biopsy, all had confirmation on subsequent surgical excision. Forty-one of the 42 core biopsies that showed a benign process were subsequently confirmed on surgical excision. One patient with atypical ductal hyperplasia on core biopsy had ductal carcinoma in situ on surgical excision. Patients with 169 benign masses on core biopsy have been followed for at least 1 year by mammography. Of these women, 110 have been followed for at least 2 years, and no malignant lesions have been found. CONCLUSION: Stereotaxic large-needle core biopsy appears to be an accurate alternative to surgical excision for evaluating a solid breast mass. However, the mammographic appearance, technical quality of the biopsy, and pathologic findings in each patient must be correlated to ensure the highest possible accuracy when using this technique.

Adult↗
PubMed2001

An MKM-mounted instrument holder for frameless point-stereotactic procedures: a phantom-based accuracy evaluation.

To enable the use of the Mehrkoordinaten Manipulator (MKM) robotic navigation system for frameless point stereotactic procedures, a new instrument holder is presented. A phantom-based accuracy study was performed in which this new method was compared with frame-based procedures performed using the Brown-Roberts-Wells (BRW) stereotactic frame. The authors acquired computerized tomography scans of a test phantom, consisting of 19 acrylic plastic target rods on a circular base. These images were used in frame-based (BRW) and frameless (MKM) localization experiments. In both cases the authors calculated the distances between the actual target positions and the positions reached stereotactically. The mean application accuracy (target registration error) was 0.68 mm when the BRW frame was used and 0.96 mm when the MKM system was used after manual repositioning of the microscope (p < 0.001). Positioning accomplished using robotics only demonstrated a slightly larger inaccuracy: 1.47 mm (p < 0.005). Because the surgeon is concerned with the largest error in an individual case rather than the mean error in a large number of cases, the mean + three standard deviations was also compared. This value differed very little between the manually positioned MKM system and the BRW frame (2.04 mm and 1.84 mm, respectively). Although repeatability per target appeared to be slightly better when the BRW frame was used, accuracy was more homogeneous over the phantom volume when the MKM system was used (both differences were not significant). In conclusion, the accuracy of point stereotactic procedures performed using an instrument holder attached to the system is comparable with the accuracy of procedures involving a stereotactic frame. Moreover, the frameless techniques and robotic features of the MKM enable a more surgeon- and patient-friendly stereotactic procedure.

Biopsy↗
PubMedDate not supplied

[Interest of glioma 26 in the selected chemotherapy of intracranial tumors (author's transl)].

Glioma 26 (G26) is a chemically induced ependymoblastoma of mouse. It was used through sub-cutaneous and/or intracranial injection in 7 experiences which showed that this experimental model was able to select drugs acting on intracranial tumors : nitrosourea (CCNU), VM 26, procarbazine (PCB). Combination chemotherapy (VM 26-CCNU ; VM 26 CCNU-PCB) was more active than monochemotherapy in 2 out of 3 experiences. It seems that the variability of the results is at least partly due to the important tumoral necrosis in tumors treated by combination chemotherapy and to technical problems. The latters can be avoided by the mechanical dispersion of tumor cells and by their injection through a stereotaxic frame. Selection of drugs is easier and cheaper to perform with G 26 than with other in vivo and in vitro experimental models. The main problem for all models remains their lack of specificity.

Animals↗
PubMed1998

[Robotics in neurosurgery: current status and future prospects].

Neurosurgery is in essence a field of application development for robots, based on multimodal image guidance. Specific motorized tools have already been developed and routinely applied in stereotaxy to position a probe holder or in conventional neurosurgery to hold a microscope oriented towards a given target. The potentialities of these approaches have triggered industrial developments which are now commercially available. These systems use databases, primarily coming from multimodal numerical images from X-ray radiology to magnetic resonance imaging. These spatially encoded data are transferred through digital networks to workstations where images can be processed and surgical procedures are pre-planned, then transferred to the robotic systems to which they are connected. We have been using a stereotaxic robot since 1989 and a microscope robot since 1995 in various surgical routine procedures. The future of these applications rely mainly on the technical progress in informatics, about image recognition to adapt the pre-planning to the actual surgical situation, to correct brain shifts (for instance), about image fusion, integrated knowledge such as brain atlases, as well as virtual reality. The future developments, covering surgical procedure, research and teaching, are sure to be far beyond our wildest expectations.

Forecasting↗
PubMed2003

Image-guided frameless stereotactic biopsy sampling of parasellar lesions. Technical note.

Interactive image-guided neuronavigation was used to obtain biopsy specimens of cavernous sinus (CS) tumors via the foramen ovale. In this study the authors demonstrated a minimally invasive approach in the management of these lesions. In four patients, whose ages ranged from 29 to 89 years (mean 61.2 years) and who harbored undefined lesions invading the CS, neuronavigation was used to perform frameless stereotactic fine-needle biopsy sampling through the foramen ovale. The biopsy site was confirmed on postoperative computerized tomography scanning. The frameless technique was accurate in displaying a real-time trajectory of the biopsy needle throughout the procedure. The lesions within the CS were approached precisely and safely. Diagnostic tissue was obtained in all cases and treatment was administered with the aid of stereotactic radiosurgery or fractionated stereotactic radiotherapy. The patients were discharged after an overnight stay with no complications. Neuronavigation is a precise and useful tool for image-guided biopsy sampling of CS tumors via the foramen ovale.

Adult↗
PubMedDate not supplied

One whisker whisking: unit recording during conditioned whisking in rats.

Understanding of the functional neurobiology of the rodent whisker system would be advanced by neurobehavioral studies in awake, behaving animals that combine unit recording from structures at various levels of the system with quantitative characterization of the kinematics and temporal organization of whisking. Such studies require the solution of a number of methodological problems. These include: chronic recording procedures ensuring unit isolation, stability and maximum yield, monitoring and display of unit activity and whisker movements within the same (ms) timeframe and behavioral paradigms which bring whisking movement parameters under the control of the experimenter rather than the rat. Here we describe a head-fixed rodent preparation which makes possible chronic recording of unit activity in the awake, whisking rat, combined with real-time, high resolution monitoring of whisker and pad movements in two dimensions and under behavioral control. While the head-fixed "whisking" preparation has some inherent limitations, it may be used to address a number of important neurobehavioral problems. We suggest that it should contribute significantly to understanding the functional neurobiology of the whisker system.

Animals↗