Biomedical subjects

B Kall

Publications and source records attributed to B Kall.

8 recordsLinked to original sources

PubMed1998

Computer-assisted image-guided surgery using the Regulus Navigator.

The term "frameless image-guided surgery" has become as well-known to surgeons as computerized tomography or operating room microscope over the past several years. The technologies behind this new surgery option include robotic arms, infra-red camera arrays (1D and 2D), ultrasound, robotic microscopes and magnetic field digitizers. The authors have shown the magnetic field technology incorporated in the Regulus Navigator to be a viable, accurate surgeon's tool by first integrating a conventional framed device and magnetic field frameless device, then advancing to the frameless device alone. During surgery a patient's anatomy is first registered to preoperatively acquired radiological data. Surgical instruments are tracked on interactive CT/MRI displays as the surgeon locates his point or volume-in-space within the surgical field and uses his own procedure/technique of choice for surgical treatment. A clinical trial of 221 patients showed an overall mean accuracy of 2.56 mm with a standard deviation of 1.15 mm for intraoperative registration. Major concerns of utilizing magnetic field technology in the operating room, such as interference from surrounding metallic objects and equipment, were proven manageable while maintaining acceptable accuracy.

Humans↗

PubMed1997

Pallidal targeting with the COMPASS system.

The authors describe their initial experience with the new pallidotomy targeting software for the COMPASS system. As COMPASS permits window and contrast settings to be changed at any time, multiple imaging modalities can be employed for targeting. This feature allowed the incorporation of fast-spin echo/inversion recovery (FSE/IR) magnetic resonance images (MRI) into the planning protocol. COMPASS has now been employed for 33 consecutive pallidotomies over the last year (July 96-June 97). A statistically significant reduction in the number of microelectrode recording trajectories required to physiologically localize sensorimotor globus pallidus interna (GPi) is noted in these cases as compared to the 41 cases performed in the previous year with a different computer planning system. The authors conclude that the COMPASS system accurately and efficiently targets the internal pallidum when FSE/IR MRI is employed. Nevertheless, pallidotomy should not be performed without neurophysiological localization.

Brain Mapping↗

PubMed1996

The interactive use of magnetoencephalography in stereotactic image-guided neurosurgery.

OBJECTIVE: To expand the use of magnetoencephalography (MEG) functional mapping in the operating room as well as preoperatively, a method of integrating the MEG sensorimotor mapping information into a stereotactic database, using computed tomographic scans, magnetic resonance imaging scans, and digital angiography, was developed. The combination of functional mapping and the stereotactic technique allows simultaneous viewing of the spatial relationship between the MEG-derived functional mapping, the radiological/structural anatomic characteristics, and the pathological abnormality. METHODS: MEG data were collected using a MAGNES II Biomagnetometer and were incorporated into the COMPASS frame-based and REGULUS frameless stereotactic systems. The transformation process, by calculating a translational vector and a rotation matrix, integrates functional and anatomic information that is then directly available intraoperatively in the stereotactic database. This procedure was employed in 10 patients undergoing computer-assisted stereotactic volumetric resections for lesions involving the sensorimotor cortex. The principles of coregistration and coordinate transformation are reviewed in the context of preoperative functional mapping. We introduce innovations to apply these techniques to intraoperative stereotactic systems. RESULTS: Tests of the accuracy of the intraoperative integration of functional information in patients and calibration phantoms indicated close agreement with earlier preoperative methods. The intraoperative availability of functional information was a significant aid to the surgeon because it provided more accurate information on the location of functional tissue than could be derived solely by radiological criteria. CONCLUSION: The real-time availability of functional mapping information in an interactive fashion can reduce surgical risk and minimize functional morbidity. Within the ever-expanding realm of functional mapping and image-guided neurosurgery, further progress and integration of these methods is critical for resection of lesions involving eloquent cortex.

Adult↗

PubMed1994

A stereotactic magnetic field digitizer.

A three-dimensional magnetic field digitizer has been interfaced the COMPASS Stereotactic System to act as a measuring device aiding in computer-assisted volumetric procedures. Reference points on the stereotactic headholder are used to create a transformation matrix to convert the digitizer coordinates to stereotactic coordinates, allowing the location of the stylus to be displayed on CT and reconstructed tumor volume images to maintain the surgeon's orientation. This technology is an adjunct to and employs treatment planning software of the system to calculate a target and determine a safe trajectory to a lesion. Environmental effects of the magnetic field have been studied to determine overall accuracy and reliability of the system. A device was developed to map the magnetic field in efforts to compensate for environmental effects. The device has been utilized on five procedures. We have found it to be a useful tool in aiding the surgeon in locating the surgical field preoperatively and maintaining orientation intraoperatively.

Humans↗

PubMed1983

Precision resection of intra-axial CNS lesions by CT-based stereotactic craniotomy and computer monitored CO2 laser.

This report describes an open stereotactic technique by which a tumour volume reconstructed in stereotactic space from CT data is removed by stereotactic CO2 laser vaporization. The position of the laser beam in relation to the tumour outlines is monitored by computer and displayed to the surgeon on a graphics display terminal in the operating room. Twenty-six (26) of these procedures have been performed on twenty-four (24) patients with deep-seated intra-axial neoplasms (23) and arteriovenous malformation (1). Post-operative CT scanning revealed no evidence of contrast enhancing lesions in nineteen (19) patients while a small amount of residual tumour was noted in five (5) patients post-operatively. This method has proven itself valuable for maintaining three-dimensional surgical orientation for the resection of intra-axial neoplasms from neurologically important areas.

Adult↗

PubMed1983

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.

Biopsy, Needle↗

PubMed1982

A computed tomographic stereotactic adaptation system.

An adaptation to render an existing popular stereotactic apparatus compatible with computed tomography (CT) is described. A localization system attaches to the stereotactic head holder and a simple computer program allows considerable accuracy in the translation of CT data into stereotactic space in the operating room.

Computers↗

PubMedDate not supplied

Stereotaxic laser ablation of intracranial lesions.

A technique is described which combines computed tomography-based stereotaxic localization and CO2 laser ablation of certain intracranial lesions with a high degree of accuracy. In 24 patients operated on with this technique, total ablation of the lesion was achieved in 19 and incomplete ablation in the other five. Though not perfect, this method is a new approach to intracranial lesions that promises to be more efficacious as future developments occur.

Brain Neoplasms↗