Patrick J. Kelly

Computer-assisted stereotactic microsurgery for the treatment of intracranial neoplasms.

This paper describes a stereotactic CO2 laser system for the removal of intra-axial, intracranial neoplasms. The volume of the neoplasm is transferred into stereotactic space by computer reconstruction of data derived by computed tomography (CT) performed under stereotactic conditions. The tumor volume is sliced in a plane orthogonal to the surgical approach, and slices at specific distances from the focal point of the stereotactic frame are displayed on a graphics monitor in the operating suite along with a cursor representing the position of the surgical laser. Laser vaporization of sequential slices of the tumor results in a cavity, the formation of which is monitored by anteroposterior and lateral roentgenograms. Fifteen stereotactic laser procedures have been performed on 13 patients, and the results are discussed. By this method, it is theoretically possible to remove all of an intracranial neoplasm detected by CT scanning.

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

SummaryThis 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 intraaxial 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.

A stereotactic approach to deep-seated central nervous system neoplasms using the carbon dioxide laser

This report describes a technique in which deep-seated CNS neoplasms, the volume and shape of which had been determined and stereotactically localized by computer reconstruction of CT data, were vaporized with a carbon dioxide laser attached to a stereotactic frame. The clinical results with 6 patients treated by this technique are presented.

Transposition of volumetric information derived from computed tomography scanning into stereotactic space

A method for translation of a tumor volume defined by computed tomography (CT) into stereotactic space using a CT-comparible stereotactic headholder, localizing system, arc--quadrant stereotactic instrument, and operating room computer system is described. Clinical applications, including computer-assisted stereotactic laser resection of deep-seated neoplasms of the central nervous system and simulation of stereotactically implanted radionuclide sources, are discussed.

A microstereotactic approach to deep-seated arteriovenous malformations

Abstract This report describes an open stereotactic approach for the treatment of a deep-seated arteriovenous malformation. Stereoscopic arteriography and a stereotactically directed carbon dioxide laser beam were utilized for total excision of the malformation.

Computer Simulation for the Stereotactic Placement of Interstitial Radionuclide Sources into Computed Tomography-defined Tumor Volumes

This report describes a method for the preoperative determination of radioactive interstitial source placement within computed tomography (CT)-defined tumor boundaries. The method utilizes CT data obtained under stereotactic conditions. Tumor boundaries are digitized from CT slices and are retained in a three-dimensional computer matrix. A solid tumor volume is created by an interpolation program and may be sliced orthogonal to any specific stereotactic surgical view line. The surgeon may simulate radioactive source placement within the slices and view the resultant isodose configuration against tumor contours on successive slices. Once the best source placement has been determined, the computer outputs the mechanical adjustments that will be necessary on a stereotactic frame located in the operating room for the stereotactic placement of each source and gives the length of each source. Sources are stereotactically implanted utilizing a double-catheter afterloading technique.

Microelectrode Recording for the Somatotopic Placement of Stereotactic Thalamic Lesions in the Treatment of Parkinsonian and Cerebellar Intention Tremor

Patients with parkinsonian tremor and rigidity and cerebellar intention tremor can be effectively treated with thalamic lesions provided that an accurate neurophysiologic method is employed to compensate for individual spatial variability of subcortical structures. The method described employs a technique of microelectrode recording in which the homuncular organization in ventralis posterior is explored and gives information as to the ideal laterality of lateral thalamic nuclear mass lesions for the treatment of tremor. This procedure has been used in 11 patients, 9 with Parkinsons disease and 2 with cerebellar intention tremor with good results and no complications to date.

An overview of CT based stereotactic systems for the localization of intracranial lesions.

Computed tomography, with its inherent accuracy in identifying and localizing intracranial lesions, has been adapted by several groups for use in stereotactic neurosurgical procedures. The systems range from the use of data obtained on conventional CT scans to installation of a dedicated CT scanner in the operating room equipped for stereotactic surgery. Although the GE-8800 scanner is used most frequently, others are also suitable. Adaptations of standard commercially available stereotactic frames are used by some groups while others designed frames specifically for this purpose. The paper is an overview of systems described in the literature to date.

Functional Stereotactic Surgery Utilizing CT Data and Computer Generated Stereotactic Atlas

Stereotactic atlases attempt to relate the position of subcortical structures to intracranial landmarks detected by radiographic methods7,8. Considerable anatomic variability exists between individual brains. Subcortical structures have no consistent quantitative relationship to radiologically determined landmarks1,3. This variability increases in direct proportion to the distance the substructure lies from particular landmarks8.Although anterior-posterior and superior-inferior measurements from stereotactic atlases can be adjusted for variations in the intracommissural distance and thalamic height, there is no anatomical landmark detected by ordinary radiographic techniques which allows correction for medial lateral variability in the position of the internal capsule or the axial configuration of the thalamus and third ventricle. Fortunately, these structures are usually visualized on quality CT scans.

Computer Assisted Stereotactic Biopsies Utilizing CT and Digitized Arteriographic Data

This report describes a Computer based method for stereotactic biopsy of intracranial lesions detected by CT scanning. Points within a tumor or an entire interpolated tumor volume are created from digitized CT slices and suspended within a 3-dimensional Computer matrix. Vessel segments from digitized stereoscopic cerebral angiograms obtained under stereotactic conditions may also be included in the Computer matrix. The Computer calculates the mechanical adjustments on an arc-quadrant stereotactic frame which place the center of a tumor volume or digitized point within the tumor into the focal point of the frame and define an avascular trajectory by which the tumor may be biopsied. Stereotactic biopsies have been performed on eighty-six (86) patients without mortality or neurologic morbidity.