X-ray or gamma ray systems or devices – Specific application – Computerized tomography
Reexamination Certificate
2001-06-28
2002-08-13
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Computerized tomography
C378S004000, C378S020000
Reexamination Certificate
active
06434215
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates generally to computed tomography (CT) imaging, and more particularly to reliable cardiac imaging using a CT system.
Generating an image of a human heart for diagnosis requires temporal and spatial resolution difficult to achieve. Specifically, during a CT scan, an x-ray source and an x-ray detector rotate around a patient as the patient heart continues to beat and cycle through various cardiac phases. The movement of the heart during the scan can result in undesirable image artifacts, and less than satisfactory temporal and spatial resolution.
If an entire three-dimensional (3D) volume of the heart could be scanned instantaneously during a particular cardiac phase, a cardiac image could be generated using image reconstruction methods which are the same as the reconstruction methods used for a non-moving body part. However, such a CT scan of a beating heart cannot be performed instantaneously.
Therefore, in cardiac imaging, positional data as well as cardiac data typically is obtained simultaneously with the scan, and such additional data is utilized in performing image reconstruction. Associating positional and/or cardiac data with the scan data sometimes is referred to herein as tagging. Such tagging is performed by storing the positional or cardiac data with the scan data itself (e.g., as a digital word) or by storing positional or cardiac data in a table that is correlated to the scan data.
With respect to the positional information, the z-location of the patient, or patient table, is associated with the acquired scan data so that the patient position for the particular scan data is known. Additionally, electrocardiogram (EKG) data is collected simultaneously with the scan data, and the scan data is tagged with the EKG data. The EKG data identifies the cardiac phase of the heart when the scan data was collected. As a result, and for the collected scan data, the z-location and cardiac phase are known. Collecting EKG data, however, requires EKG equipment and additional patient preparation.
By knowing the z-location at which scan data was collected, and by knowing the particular cardiac phase of the heart when such scan data was collected, then the scan data for a particular z-location during a particular cardiac phase can be identified and used in image reconstruction processing. For example, scan data for a particular z-location and a particular cardiac phase can be used to generate images having a desired spatial and temporal resolution. If scan data for different cardiac phases or different z-locations is utilized in generating such images, then such images may not have the desired spatial and temporal resolution.
SUMMARY OF INVENTION
In one aspect, a method is provided for reconstructing an image of a beating heart in vivo. The method includes acquiring projection data for at least one z-location within a projection space and for at least one cardiac cycle, determining peaks in first order normalized spatial moments for the projection space using the projection data, and reconstructing the image utilizing peaks in the first order spatial moments.
In another aspect, a system is provided for reconstructing an image of a beating heart in vivo. The system includes a computed tomography (CT) device including an x-ray source, an x-ray detector aligned with the x-ray source, a data acquisition system (DAS) for collecting data from the x-ray detector, and an image reconstructor for reconstructing an image from the collected data. The system acquires projection data for at least one z-location within a projection space and for at least one cardiac cycle, and correlates a plurality of views with z-location information, such that each view includes projection data acquired at the respective z-location. Furthermore, the system extracts projection data for a region of interest (ROI) within each z-location, determines peaks in first order spatial moments for the projection space using the projection data, and reconstructs the three-dimensional image utilizing peaks in the first order spatial moments.
In yet another aspect, a computer readable medium encoded with a program is provided for processing projection data for at least one z-location within a projection space, and for at least one cardiac cycle, to construct images of a beating heart in vivo. A computer, operating under the control of the program, extracts projection data for a region of interest (ROI) within each z-location, and determines peaks in first order spatial moments for the projection space using the projection data.
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Armstrong Teasdale LLP
Bruce David V.
General Electric Company
Hobden Pamela R.
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