Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
1996-10-07
2002-02-26
Couso, Jose L. (Department: 2624)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S128000, C382S130000, C382S131000, C382S133000
Reexamination Certificate
active
06351573
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an imaging device and method and, in particular, to a medical imaging device and method.
BACKGROUND OF THE INVENTION
While invasive surgery may have many beneficial effects, it can cause physical and psychological trauma to the patient from which recovery is difficult. A variety of minimally invasive surgical procedures are therefore being developed to minimize trauma to the patient. However, these procedures often require physicians to perform delicate procedures within a patient's body without being able to directly see the area of the patient's body on which they are working. It has therefore become necessary to develop imaging techniques to provide the medical practitioner with information about the interior of the patient's body.
Additionally, a non-surgical or pre-surgical medical evaluation of a patient frequently requires the difficult task of evaluating imaging from several different modalities along with a physical examination. This requires mental integration of numerous data sets from the separate imaging modalities, which are seen only at separate times by the physician.
A number of imaging techniques are commonly used today to gather two-, three- and four-dimensional data. These techniques include ultrasound, computerized X-ray tomography (CT), magnetic resonance imaging (MRI), electric potential tomography (EPT), positron emission tomography (PET), brain electrical activity mapping (BEAM), magnetic resonance angiography (MRA), single photon emission computed tomography (SPECT), magnetoelectro-encephalography (MEG), arterial contrast injection angiography, digital subtraction angiography and fluoroscopy. Each technique has attributes that make it more or less useful for creating certain kinds of images, for imaging a particular part of the patient's body, for demonstrating certain kinds of activity in those body parts and for aiding the surgeon in certain procedures. For example, MRI can be used to generate a three-dimensional representation of a patient's body at a chosen location. Because of the physical nature of the MRI imaging apparatus and the time that it takes to acquire certain kinds of images, however, it cannot conveniently be used in real time during a surgical procedure to show changes in the patient's body or to show the location of surgical instruments that have been placed in the body. Ultrasound images, on the other hand, may be generated in real time using a relatively small probe. The image generated, however, lacks the accuracy and three-dimensional detail provided by other imaging techniques.
Medical imaging systems that utilize multimodality images and/or position-indicating instruments are known in the prior art. Hunton, N.,
Computer Graphics World
(October 1992, pp. 71-72) describes a system that uses an ultrasonic position-indicating probe to reference MRI or CT images to locations on a patient's head. Three or four markers are attached to the patient's scalp prior to the MRI and/or CT scans. The resulting images of the patient's skull and brain and of the markers are stored in a computer's memory. Later, in the operating room, the surgeon calibrates a sonic probe with respect to the markers (and, therefore, with respect to the MRI or CT image) by touching the probe to each of the markers and generating a sonic signal which is picked by four microphones on the operating table. The timing of the signals received by each microphone provides probe position information to the computer. Information regarding probe position for each marker registers the probe with the MRI and/or CT image in the computer's memory. The probe can thereafter be inserted into the patient's brain. Sonic signals from the probe to the four microphones will show how the probe has moved within the MRI image of the patient's brain. The surgeon can use information of the probe's position to place other medical instruments at desired locations in the patient's brain. Since the probe is spacially located with respect to the operating table, one requirement of this system is that the patient's head be kept in the same position with respect to the operating table as well. Movement of the patient's head would require a recalibration of the sonic probe with the markers.
Grimson, W. E. L., et al., “An Automatic Registration Method for Frameless Stereotaxy, Image Guided Surgery, and Enhanced Reality Visualization,”
IEEE CVPR '
94
Proceedings
(June 1994, pp. 430-436) discuss a device which registers three-dimensional data with a patient's head on the operating table and calibrates the position of a video camera relative to the patient using distance information derived from a laser rangefinder, cross correlating laser rangefinder data with laser scan-line image data with medical image data. The system registers MRI or CT scan images to the patient's skin surface depth data obtained by the laser range scanner, then determines the position and orientation of a video camera relative to the patient by matching video images of the laser points on an object to reference three-dimensional laser data. The system, as described, does not function at an interactive rate, and hence, the system cannot transform images to reflect the changing point of view of an individual working on the patient. Because the system is dependent upon cumbersome equipment such as laser rangefinders which measure distance to a target, it cannot perform three-dimensional image transformations guided by ordinary intensity images. The article mentions hypothetically using head-mounted displays and positioning a stationary camera “in roughly the viewpoint of the surgeon, i.e. looking over her shoulder.” Although the article remarks that “viewer location can be continually tracked,” there is no discussion on how the authors would accomplish this.
Kalawasky, R., “The Science of Virtual Reality and Virtual Environments,” pp. 315-318 (Addison-Wesley 1993), describes an imaging system that uses a position sensing articulated arm integrated with a three-dimensional image processing system such as a CT scan device to provide three-dimensional information about a patient's skull and brain. As in the device described by Hunton, metallic markers are placed on the patient's scalp prior to the CT scan. A computer develops a three-dimensional image of the patient's skull (including the markers) by taking a series of “slices” or planar images at progressive locations, as is common for CT imaging, then interpolating between the slices to build the three-dimensional image. After obtaining the three-dimensional image, the articulated arm can be calibrated by correlating the marker locations with the spacial position of the arm. So long as the patient's head has not moved since the CT scan, the arm position on the exterior of the patient can be registered with the three-dimensional CT image.
Heilbrun, M. P., “The Evolution and Integration of Microcomputers Used with the Brown-Roberts-Wells (BRW) Image-guided Stereotactic System,” (in Kelly, P. J., et al. “Computers in Stereotactic Neurosurgery,” pp. 43-55 (Blackwell Scientific Publications 1992)) briefly mentions the future possibility of referencing (within the same image set) intracranial structures to external landmarks such as a nose. However, he does not describe how this would be accomplished, nor does he describe such a use for multimodality image comparison or compositing.
Peters, T. M., et al., (in Kelly, P. J., et al. “Computers in Stereotactic Neurosurgery,” p. 196 (Blackwell Scientific Publications 1992)) describe the use of a stereotactic frame with a system for using image analysis to read position markers on each tomographic slice taken by MR or CT, as indicated by the positions of cross-sections of N-shaped markers on the stereotactic frame. While this method is useful for registering previously acquired tomographic data, it does not help to register a surgeon's view to that data. Furthermor
Couso Jose L.
Do Anh Hong
Ritter Lang & Kaplan LLP
Schneider Medical Technologies, Inc.
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