University of Washington

Lucent Medical Systems, Inc.

David R Haynor

Yongmin Kim

Robert N Golden

Christopher P Somogyi

Vikram Chalana

Todd Schoepflin

Gary Brian Sanders

Warren S Edwards

John D Sahr

Niko Pagoulatos

An object is tracked among a plurality of image frames. In an initial frame an operator selects an object. The object is distinguished from the remaining background portion of the image to yield a background and a foreground. A model of the background is used and updated in subsequent frames. A model of the foreground is used and updated in the subsequent frames. Pixels in subsequent frames are classified as belonging to the background or the foreground. In subsequent frames, decisions are made, including: which pixels do not belong to the background; which pixels in the foreground are to be updated; which pixels in the background were observed incorrectly in the current frame; and which background pixels are being observed for the first time. In addition, mask filtering is performed to correct errors, eliminate small islands and maintain spatial and temporal coherency of a foreground mask.

Video object tracking by estimating and subtracting background

Intraoperative ultrasound (US) is integrated with stereotactic systems, where a system interactively registers two-dimensional (2D) US and three-dimensional (3D) magnetic resonance (MR) images. The registration is based on tracking a US probe with a bC magnetic position sensor. A transformation algorithm is performed to transform coordinates of points between two different spaces, where MR and US image spaces are independently registered with the position sensor space and where coordinate points can be registered between the MR and US spaces. A calibration procedure can be performed, and a phantom can be used to determine and analyze registration errors. The registered MR images can reconstructed using either zero-order or first-order interpolation.

Apparatus and method for interactive 3D registration of ultrasound and magnetic resonance images based on a magnetic position sensor

A hierarchy of deformation operations is implemented to deform a template and match the deformed template to an object in a video frame. At each level, the constraints on the template deformations are relaxed, while the spatial range of the object boundary search is narrowed. At a highest level, an initial template is translated, rotated and scaled to coarsely locate the object within a given image frame. At a middle level, an affine transformation is implemented, globally or locally, to deform the template. For a local affine transformation process, a sup-portion, such as an articulation or appendage portion of the template is deformed. The middle level refines the template to get the template boundary close to the actual object boundary within a given frame. At the lowest level, a local segmentation algorithm is applied to deform the now close boundary to finely match the object boundary.

Video object tracking using a hierarchy of deformable templates

A device to detect the location of a plurality of magnets uses a plurality of magnetic sensors, having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by each of the plurality of magnets and provides data indicative of the direction of the magnets in a three-dimensional space. The device uses fundamental equations for electricity and magnetism that relate the measured magnetic field strength to the location and strength of the magnetic dipole for each of the plurality of magnets. The device may use an iterative process to determine the actual location and orientation of each magnet. An initial estimation of the location and orientation of each magnet results in the generation of predicted magnetic field values. The predicted magnetic field values are compared with the actual measured values provided by the magnetic sensors. Based on a difference between the predicted values and the measured values, the device estimates a new location for each of the magnets and calculates new predicted magnetic field strength values. The iteration process continues until the predicted values match the measured values within a desired degree of tolerance. At this point, the estimated location and orientation of each of the magnets matches the actual location within a predetermined degree of tolerance.

System and method to determine the location and orientation of an indwelling medical device

A device to detect the location of a magnet coupled to an indwelling medical device within a patient uses three or more sets of magnetic sensors each having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by the magnet and provides data indicative of the direction of the magnet in a three-dimensional space. The device uses findamental equations for electricity and magnetism that relate measured magnetic field strength and magnetic field gradient to the location and strength of a magnetic dipole. The device uses an iterative process to determine the actual location and orientation of the magnet. An initial estimate of the location and orientation of the magnet results in the generation of predicted magnetic field values. The predicted magnetic field values are compared with the actual measured values provided by the magnetic sensors. Based on the difference between the predicted values and the measured values, the device estimates a new location of the magnet and calculates new predicted magnetic field strength values. This iteration process continues until the predicted values match the measured values within a desired degree of tolerance. At that point, the estimated location matches the actual location within a predetermined degree of tolerance. A two-dimensional display provides an indication of the location of the magnet with respect to the housing of the detector. A depth indicator portion of the display can be used to provide a relative or absolute indication of the depth of the magnet within the patient.

Method to determine the location and orientation of an indwelling medical device

A device to detect the location of a magnet coupled to an indwelling medical device within a patient uses three or more sets of magnetic sensors each having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by the magnet and provides data indicative of the direction of the magnet in a three-dimensional space. The device uses fundamental equations for electricity and magnetism that relate measured magnetic field strength and magnetic field gradient to the location and strength of a magnetic dipole. The device uses an iterative process to determine the actual location and orientation of the magnet. An initial estimate of the location and orientation of the magnet results in the generation of predicted magnetic field values. The predicted magnetic field values are compared with the actual measured values provided by the magnetic sensors. Based on the difference between the predicted values and the measured values, the device estimates a new location of the magnet and calculates new predicted magnetic field strength values. This iteration process continues until the predicted values match the measured values within a desired degree of tolerance. At that point, the estimated location matches the actual location within a predetermined degree of tolerance. A two-dimensional display provides an indication of the location of the magnet with respect to the housing of the detector. A depth indicator portion of the display can be used to provide a relative or absolute indication of the depth of the magnet within the patient.

System and method to determine the location and orientation of an

An ultrasound system automatically measures fetal head size from ultrasound images. An ultrasound image of the fetal head is detected. A radial maxima point is identified on each of a plurality of radii extending from a substantially common vertex point within the fetal head image. Each radial maxima point corresponds to an ultrasound sample along its corresponding radius, and has a maximum ultrasound echo strength. A first curve is defined from the radial maxima points. The remaining unfiltered radial maxima points are fit to a second curve, and the second curve is the detected curved boundary. The detected curve boundary is modified to define an initial fetal head boundary. An inner fetal head boundary and outer fetal head boundary are derived from the initial fetal head boundary and a predetermined fetal skull thickness, and fetal head size is computed from the inner fetal head boundary and the outer fetal head boundary.

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Seattle, WA, United States of America

David R Haynor