Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-10-22
2003-07-01
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S437000, C600S461000, C600S407000
Reexamination Certificate
active
06585651
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and method for percutaneous determination of locations associated with a surface of an organ.
BACKGROUND OF THE INVENTION
Medical imaging is used extensively in orthopaedics to view the state of musculo-skeletal structures that require correction, repair or replacement. Planar X-ray, X-ray computed tomography (CT) and magnetic resonance imaging (MRI) are image modalities used preoperatively to diagnose and plan surgical interventions. Transfer of image data to the surgical theater, however, is still mainly intuitive. Computer assisted surgery (CAS), image guided surgery and medical robotics provide a quantitative link between medical imaging using images acquired preoperatively or intraoperatively and surgical actions allowing the surgeon to view, in real time, the orientation of the surgical instruments relative to the patient. This provides the surgeon with a means to precisely navigate and plan tool movements with respect to normally hidden anatomical structures.
A key issue in computer assisted surgery (CAS) is to establish a relationship between the patient's intraoperative position within an on-site coordinate system and the data of the medical images. The process of computing a transformation from coordinates within an on-site coordinate system to image coordinates is referred to as “registration” or “matching”. In the new field of computer assisted surgery (CAS), light-weight “dynamic reference bases” allow the surgeon to freely manipulate the patient during complex procedures without losing valuable image generated data. Registration or matching implies obtaining coordinates of points in the medical image reference frame and in the on-site three-dimensional coordinate system in space from the position measurement device.
Current registration processes are invasive requiring the surgeon to have direct access to fiducial markers implanted in the bone or specific, predetermined landmarks on bone surfaces that are digitized with a positioning device. Recent developments allow the surgeon to obtain a number of points of the bone with the positioning device and this “cloud of points” can be mathematically fit onto the medical image (e.g. Computer tomogram CT) of the bone surface through an optimization algorithm. This process is termed “surface matching.” Although these invasive registration processes have greatly improved the versatility of CAS systems, they require large incisions or transcutaneous needles that pierce the skin and touch the surface of the bone. Because orthopaedic surgery often involves bones hidden deep beneath soft tissues, open procedures can expose the patient to both significant risks of infection and long recovery times.
U.S. Pat. No. 5,447,154 to Cinquin, et al. discloses a method for determining the position of an organ and for positioning a therapeutic or diagnostic tool as a function of three-dimensional images. The images can be preoperative images, such as X-ray computed tomography (CT) images or Magnetic Resonance Images (MRI) of a patient's organ. A device provides a sparse set of three-dimensional surface points on the organ of interest during surgery. These surface points are registered (matched) with the three-dimensional functional image, which contains far more detailed information on the organ's surface morphology. Echography probes are used to intra-operatively obtain the sparse set of three-dimensional surface points of the organ. The organ surface is obtained by analyzing a reconstructed two-dimensional “image slice” provided by the ultrasound probe. Both the ultrasound probe and the organ are instrumented with a three-dimensional position tracking device which allows calculation of the identified surface point in 3D space with respect to the patient.
A device for recording ultrasound images is disclosed by W098/08112 to Emmenegger et al. The position of each ultrasound image is uniquely defined with respect to any arbitrary three-dimensional coordinate system in space through determination of the position and orientation of the ultrasound head. The device comprises an ultrasound head, which can be freely moved by hand, an ultrasound recording apparatus and a three-dimensional position measurement system to determine the position of the ultrasound head. The position of the ultrasound head is determined by measuring lengths of at least three points affixed to the ultrasound head. The length measurements are realized via interchanging electromagnetic energy between markers attached to the ultrasound head and sensors that are part of the position measurement system.
A disadvantage of known methods and devices is the use of reconstructed ultrasound images to intra-operatively identify points on the organ's surface. Identifying points associated with an organ surface from a noisy ultrasound-generated image is difficult. Much information on exact anatomy contour is lost in image reconstruction and conversion to a video signal and digitization of this signal. Because ultrasound systems are generally designed to image soft tissues, they are sensitive to small changes in acoustic impedances. This produces a considerable amount of “noise” in the constructed image and obscures the surface of the bone. Using the video output of these systems further degrades the signal. The picture must then be manually segmented (i.e. finding the surface of the bone), which requires operator input. Once the picture has been segmented, the surface points can be automatically fitted to the coordinate system of the preoperatively acquired CT image. A practical minimally invasive registration would greatly expand the usefulness of CAS technology.
SUMMARY OF THE INVENTION
One embodiment of the present invention relates to a percutaneous-point determination device for percutaneous determination of coordinates of points associated with the surface of an organ of an animal, such as a human. The organ is preferably a bone. Locations of the points are preferably determined within an on-site coordinate system by processing data obtained from a reflection of a focused one-dimensional ultrasound beam from the organ. The associated points are preferably located at or on the surface of the organ, such as a landmark of a bone.
The device can be used to, for example, determine specific anatomical landmarks, such as the spinous process, and left and right superior facet joints, to be used for paired point matching. The device can also be used to determine a cloud of points associated with the organ surface to be used for surface matching a medical image to the organ.
The device includes a processor to process ultrasound data received from the ultrasound device to thereby provide accurate information on anatomical surface location. The ultrasound data are preferably a raw signal. The processing may be performed in real-time.
The ultrasound beam preferably has a sufficiently narrow width to minimize detection of dispersed signals. The coordinates of points can be determined with at least about 0.5 mm axial accuracy and location of the point in the 3-D coordinate system can be determined with an accuracy of less than about 1 mm.
In a preferred embodiment, the percutaneous-point determination device includes an ultrasound device configured to emit an ultrasound beam along an ultrasound beam axis. The ultrasound beam is preferably focused. The ultrasound beam axis preferably has a known orientation, such as a known orientation with respect to the ultrasound device.
The ultrasound device includes at least three preferably non-collinear markers. The markers can include energy emitting, receiving, or reflecting elements. Energy emitting elements include light emitting elements such as, for example, light emitting diodes (LED's) and infrared light emitting diodes (IRED's). Alternative energy emitting elements include, for example, acoustic transmitters and coils configured to establish a magnetic field.
Energy receiving elements include light sensitive elements, such as, for example, photodio
Moulder J. Christopher
Nolte Lutz Peter
Sati Marwan
Scherrer José L.
Wentkowski Michael
Jung William
Lateef Marvin M.
Pennie & Edmonds LLP
Synthes AG Chur
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