Method and apparatus for correlating a body with an image of the body

• US 6,096,050 A
• Filed: 03/19/1999
• Issued: 08/01/2000
• Est. Priority Date: 09/19/1997
• Status: Expired due to Term

• Current Assignee: Brainlab AG
• Original Assignee: Surgical Navigation Specialist Inc (International Business Machines Corporation)
• Inventors: Audette, Michel Albert
• Primary Examiner(s): Buiz, Michael
• Assistant Examiner(s): LEWIS, WILLIAM W
• Application Number:
  US09/272,250
• Time in Patent Office: 501 Days
• Field of Search: 606/130, 128/653.1, 128/665, 128/653.2, 364/413.13, 324/318, 324/305, 324/309
• US Class Current: 606/130
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/363 Use of fiducial points
• CPC Class Codes: A61B 2090/364 Correlation of different images or relation of image positions in respect to the body
• CPC Class Codes: A61B 2090/365 augmented reality, i.e. correlating a live optical image with another image
• CPC Class Codes: A61B 2090/3954 magnetic, e.g. NMR or MRI
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: G06T 2207/10072 Tomographic images
• CPC Class Codes: G06T 2207/30016 Brain
• CPC Class Codes: G06T 7/33 using feature-based methods

Abstract

The present invention provides a system and process for correlating points on a spatial body to corresponding points on a database body formed from pre-aquired images of the spatial body. The system and process involve matching the spatial points with the corresponding database points using relative positional information between the spatial points and the database points. Symmetric false matches are detected and discarded by fitting the spatial points and database points to a first and second closed body, respectively, and comparing the orientation of the spatial points and the database points projected onto the closed bodies. In a preferred embodiment, the orientations of the spatial points and database points are compared by calculating, with respect to a matched spatial point, the longitudinal coordinates of the spatial points neighbouring the matched spatial point and calculating, with respect to the matched database point, the longitudinal coordinates of the database points neighbouring the matched database point, and comparing the difference in longitude between the points. If the difference in longitude of the spatial points corresponds to the difference in longitude of the database points, the match of the matched spatial point to the matched database point will be validated. Otherwise, the match will be considered a symmetric false match and discarded. Once at least three spatial points have been matched to corresponding database points, and the matches have been confirmed not to be false matches, a registration procedure is performed registering the spatial body to the database body by calculating a transformation mapping using the three matched pairs.

Claims

1. A method for automatically correlating a plurality of spatial points on a spatial body to corresponding plurality of data points on a database body, comprising the steps of:

(a) selecting a group of spatial points and for each spatial point determining the relative position between the selected point and the remaining spatial points in the group;

(b) selecting a group of data points, and for each data point determining the relative position between the selected data point and the remaining data points; and

(c) comparing the spatial relationship for each data point and each spatial point using the relative position information to determine a match between the spatial and data points to thereby correlate the spatial points with the data points.

2. A method as defined in claim 1, said methods including testing a matched spatial point for determining whether it is a desired spatial point or an undesired symmetric spatial point.

3. A method as defined in claim 1, including the steps of detecting and discarding symmetric false matches by fitting the spatial points and database points to a first and second closed body, respectively.

4. A method as defined in claim 3, including the step of comparing the orientation of the spatial points and of the database points projected on the closed bodies.

5. A method for independently correlating a plurality of spatial points on a spatial body to corresponding plurality of data points on a database body comprising the steps of:

(a) projection of at least four data points, including a reference point, on to a first surface and a first orientation;

(b) projection of at least four data points, including a second reference point on to a second surface and a second orientation;

(c) comparing the orientation of the spatial points and database points; and

(d) deriving a match signal.