Biomedical subjects

L Nolte

Publications and source records attributed to L Nolte.

5 recordsLinked to original sources

PubMed1996

Image-guided computer-assisted spine surgery: a pilot study on pedicle screw fixation.

As the pedicle offers a strong point of attachment to the spine, several instrumentation systems using screws that go through the pedicle into the vertebral body have been developed to provide internal stability. All pedicle screw systems share the risk of damage to adjacent neural structures as a result of improper screw placement. A computer-assisted system allowing precise preoperative planning and real-time intraoperative interactive image localization has been implemented for spine instrumentation to optimize transpedicular spine fixation. A validation study was performed in an in vitro set-up drilling 20 pedicle pilot holes in lumbar vertebrae. An analysis in 77 histological cuts showed an ideal location in 70 with no case of injury to the pedicle cortex. We discuss initial clinical experience on cases of posterior lumbar stabilization. Interactive computer-assisted spine surgery provides an accurate and safe approach for transpedicular screw fixation and may provide a useful tool for optimization of spine surgery.

Bone Screws↗

PubMed1996

Vascular malformations of the brain. Surgical management using interactive image guidance.

This article describes the use of interactive image guidance in the surgical management of vascular malformations (VMs). Indications include VMs located in or around eloquent brain regions such as speech and motor sensory areas. The image guidance provides a three-dimensional view of the actual vascular malformations through computer simulation and an accurate means of determining its position in relation to adjacent brain structures (anatomic localization).

Adolescent↗

PubMed1994

Effects of non-esterified fatty acids on insulin-stimulated glucose transport in isolated skeletal muscle from patients with type 2 (non-insulin-dependent) diabetes mellitus.

The influence of elevated levels of oleate on insulin-stimulated 3-0-methylglucose transport was assessed in vitro, in isolated skeletal muscle obtained from patients with type 2 (non-insulin-dependent) diabetes mellitus (n = 7) and control subjects (n = 8). An increase in oleate levels from 0.3 to 1.0 mmol/l induced a 3.7-fold increase in the rate of oleate oxidation (P < 0.01) in skeletal muscle from control subjects. However, the rate of insulin-stimulated 3-0-methylglucose transport was not altered in isolated skeletal muscle from the control subjects or the type 2 diabetic patients following exposure to 1.0 mmol/l oleate. This observation indicates that elevation of non-esterified fatty acids to a high physiological level has no inhibitory effect on glucose transport.

3-O-Methylglucose↗

PubMed1994

Interactive intraoperative localization using an infrared-based system.

Conventional stereotactic surgery has evolved from a ring-based system with a simple software which calculated few parameters to frameless intraoperative localization systems that provide the surgeon with real-time localization and correlation with several imaging modalities. The localization system described in this paper is an opto-electronic system that uses infrared emitters and three precalibrated CCD cameras. The system was chosen among others for the following reasons: it tracks target points defined by up to 256 miniature light emitting diodes, and its accuracy in locating the spatial position of a diode marker in the operating volume 1.0 x 1.0 m at a distance of 2.0 m is 0.1 mm with a resolution better than 0.01 mm. Systems like this one can track and define the position and orientation of any object in the field view of the camera. This is done by attaching a few small infrared emitters (light emitting diodes) to the surface of each 'rigid body' (surgical instrument) being tracked. Subsequently, through a calibration process a corresponding rigid body file is created. This rigid body file represents this particular object (i.e. surgical tool, microscope) and defines a local coordinate system that identifies each translation and orientation of that tool with respect to the camera coordinate system. This in turn is transferred into the computed tomographic/magnetic resonance imaging coordinate system by a process referred to as coordinate matching. Fiducial markers are placed on the patient's head prior to image scanning.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography, Digital Subtraction↗

PubMed1993

Interactive intraoperative localization using an infrared-based system.

We discuss new methods of localizing and treating brain lesions for both the conventional method of a base-ring fixed to the patient's skull (referred to as frame-based procedures) and the new method of frameless procedures (no base ring). Frame-based procedures are used for finding a precise instrument position during neurosurgical procedures, such as stereotactic biopsy of deep-seated lesions, placing electrodes for functional stereotaxis or catheters with radioactive seeds for brachytherapy, or even the placement of a stereotactic retractor or endoscope for removal or internal decompression of lesions. In such procedures, the intraoperative image localization of instruments becomes useful as it tracks instruments as they travel through the preplanned trajectory. Additional intraoperative digitization of surgical instruments, e.g., bipolar suction, biopsy forceps, microscope, ultrasound probe, etc, can be achieved during the stereotactic resection of eloquent areas or deep intracranial lesions by adding an infrared-based system. Frameless procedures broaden the range of surgical approaches, image guidance planning, and operative procedures, since no ring is attached to the patient's head which might interfere with the surgical approach, and offers logistic advantages in scheduling diagnostic studies. Frameless diagnostic studies employ anatomical markers and/or surface matching techniques for data registration in the computer software surgical preplanning program. This simplifies scheduling of the procedures since the image study does not need to be acquired the same day as surgery. Frameless diagnostic studies allow for the use of more than one type of imaging data for planning and optimization of surgical procedures, and greatly improve patient tolerance and comfort during these procedures and during surgery, as compared with frame-based procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Analog-Digital Conversion↗