Dietrich Meyer-Ebrecht

Bio: Dietrich Meyer-Ebrecht is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Digital image & Picture archiving and communication system. The author has an hindex of 16, co-authored 80 publications receiving 1257 citations. Previous affiliations of Dietrich Meyer-Ebrecht include Information Technology Institute.

Process and device for the reproducible optical representation of a surgical operation

Abstract: The process comprises the steps of creating three reference points at an object and taking a tomogram of the object such that the three reference points define a first set of positional data in the tomogram. The object is then non-rigidly placed on a support for operation thereupon by an instrument which is mounted at a flexible arm containing sensors for sensing the movements of an instrument tip. The instrument tip is placed at the three reference points in order to create a second set of positional data which are in a fixed relationship to the first set of positional data. When the instrument is inserted into the object placed on the support, the positional data of the instrument tip during the insertion movement are sensed and related to the first set of positional data via the fixed relationship between the first and second sets of positional data. The positions of the inserted instrument within the object are thus reproduced in the tomogram for indicating and displaying, monitoring and recording purposes.

Computer-assisted surgery

Abstract: Computer-assisted surgery (CAS), a new navigation aid for skull-base surgery, is discussed. The system described combines 3-D coordinate measurement techniques, voxel processing methods, and pseudo-3-D image presentations to support preoperative planning of therapy, path-finding during the operation itself, and postoperative therapy control. The surgeon employs a hand-guided electromechanical 3-D-coordinate digitizer to locate points of interest within the operative field. The coordinates measured this way are correlated with a voxel model of the object gained by a preceding computed-tomography examination. With a prototype system the accuracy of this method has proven to be better than +or-1 mm. The system has been successfully applied in more than 60 ear-nose-throat operations and four neurosurgical procedures. The computer hardware and integration of the system into an experimental picture archiving and communication system are discussed. >

Process and device for optical representation of surgical operations

Abstract: For the purpose of documenting the performance and outcome of a surgical operation, in hidden parts of the body, the instantaneous position of the surgical instrument (31) or its course are represented during the operation and recorded for subsequent examination. To this end, tomograms (41) provided with at least three measurement points (42) on the patient are stored in a computer and can be displayed on a screen (22). In addition, the positions of the three measuremnt points (42) and that of the surgical instrument are determined before and after insertion by a co-ordinate measuring device (1), these positions are superimposed on the corresponding tomographs (41) on the screen (22) and stored in a data store. This process and the device (co-ordinate measuring device) are particularly suited for the representation and documentation of surgical operations.

CAS (computer assisted surgery). A new procedure in head and neck surgery

Abstract: Computer assisted surgery (CAS) is a new imaging technique designed to assist the head and neck surgeon during surgery. This method is based upon a three-dimensional volume model of the patient's skull generated by computer tomographic imaging procedures such as CT and MR. Body points can be marked in the 3-D model by intra-operative correlation of model and patient using a volume digitizer. Real-time positioning of surgical instruments without visual control can be achieved. The use of the system in surgery of the skull base, orbit and the paranasal sinuses is demonstrated.

Navigation Support for Surgery by Means of Optical Position Detection

Abstract: In an interdisciplinary research project a “navigation” support for scull base surgery has been developed. By combining 3D position measurement techniques, digital image processing and 3D display techniques the spatial position and orientation of an operating instrument is being visualized on a display, which shows a CT-generated view of the operation area.

Method and apparatus for performing minimally invasive cardiac procedures

Abstract: A system for performing minimally invasive cardiac procedures. The system includes a pair of surgical instruments that are coupled to a pair of robotic arms. The instruments have end effectors that can be manipulated to hold and suture tissue. The robotic arms are coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the end effectors. The movement of the handles is scaled so that the end effectors have a corresponding movement that is different, typically smaller, than the movement performed by the hands of the surgeon. The scale factor is adjustable so that the surgeon can control the resolution of the end effector movement. The movement of the end effector can be controlled by an input button, so that the end effector only moves when the button is depressed by the surgeon. The input button allows the surgeon to adjust the position of the handles without moving the end effector, so that the handles can be moved to a more comfortable position. The system may also have a robotically controlled endoscope which allows the surgeon to remotely view the surgical site. A cardiac procedure can be performed by making small incisions in the patient's skin and inserting the instruments and endoscope into the patient. The surgeon manipulates the handles and moves the end effectors to perform a cardiac procedure such as a coronary artery bypass graft.

Computer and Robot Vision

Abstract: Computer and Robot Vision Vol. 1, by R.M. Haralick and Linda G. Shapiro, Addison-Wesley, 1992, ISBN 0-201-10887-1.

Survey: interpolation methods in medical image processing

Abstract: Image interpolation techniques often are required in medical imaging for image generation (e.g., discrete back projection for inverse Radon transform) and processing such as compression or resampling. Since the ideal interpolation function spatially is unlimited, several interpolation kernels of finite size have been introduced. This paper compares 1) truncated and windowed sine; 2) nearest neighbor; 3) linear; 4) quadratic; 5) cubic B-spline; 6) cubic; g) Lagrange; and 7) Gaussian interpolation and approximation techniques with kernel sizes from 1/spl times/1 up to 8/spl times/8. The comparison is done by: 1) spatial and Fourier analyses; 2) computational complexity as well as runtime evaluations; and 3) qualitative and quantitative interpolation error determinations for particular interpolation tasks which were taken from common situations in medical image processing. For local and Fourier analyses, a standardized notation is introduced and fundamental properties of interpolators are derived. Successful methods should be direct current (DC)-constant and interpolators rather than DC-inconstant or approximators. Each method's parameters are tuned with respect to those properties. This results in three novel kernels, which are introduced in this paper and proven to be within the best choices for medical image interpolation: the 6/spl times/6 Blackman-Harris windowed sinc interpolator, and the C2-continuous cubic kernels with N=6 and N=8 supporting points. For quantitative error evaluations, a set of 50 direct digital X-rays was used. They have been selected arbitrarily from clinical routine. In general, large kernel sizes were found to be superior to small interpolation masks. Except for truncated sine interpolators, all kernels with N=6 or larger sizes perform significantly better than N=2 or N=3 point methods (p/spl Lt/0.005). However, the differences within the group of large-sized kernels were not significant. Summarizing the results, the cubic 6/spl times/6 interpolator with continuous second derivatives, as defined in (24), can be recommended for most common interpolation tasks. It appears to be the fastest six-point kernel to implement computationally. It provides eminent local and Fourier properties, is easy to implement, and has only small errors. The same characteristics apply to B-spline interpolation, but the 6/spl times/6 cubic avoids the intrinsic border effects produced by the B-spline technique. However, the goal of this study was not to determine an overall best method, but to present a comprehensive catalogue of methods in a uniform terminology, to define general properties and requirements of local techniques, and to enable the reader to select that method which is optimal for his specific application in medical imaging.

Navigation system for cardiac therapies

Abstract: An image guided catheter navigation system for navigating a region of a patient includes an imaging device, a tracking device, a controller, and a display. The imaging device generates images of the region of the patient. The tracking device tracks the location of the catheter in the region of the patient. The controller superimposes an icon representing the catheter onto the images generated from the imaging device based upon the location of the catheter. The display displays the image of the region with the catheter superimposed onto the image at the current location of the catheter.