Method and system for defining a volume of interest in a physiological image
A method and apparatus for defining a volume of interest in a physiological image based upon an anatomical image. The method and system acquires an anatomical image of a volume of interest using a first imaging modality. A physiological image is acquired using a second imaging modality different from the first imaging modality. An outline of the volume of interest is defined on the anatomical image and applied to the physiological image to define the volume of interest m the physiological image. Based upon the outline, the system and method assigns binary values to voxels within the outline to more accurately define the volume of interest.
1. A method comprising:
reconstructing an anatomical image having a first resolution using a first imaging modality;
reconstructing a physiological image having a second resolution lower than the first resolution using a second imaging modality, the physiological image including a plurality of voxels;
identifying a target boundary of the target in the anatomical image;
registering the target boundary of the target on the physiological image;
identifying voxels of the physiological image that are completely within the target boundary;
calculating an inner activity value by summing activity levels of the voxels of the physiological image completely within the target boundary;
identifying partial volume voxels of the physiological image that include the target boundary;
assigning a weight to each of the partial volume voxels;
multiplying the weight of each partial volume voxel by an average target activity level to determine a modified activity level for each partial volume voxel;
calculating a partial volume activity value by summing the modified activity levels of the partial volume voxels;
combining the inner activity value and the partial volume activity; and
modifying the physiological image using the combined inner activity value and partial volume activity to provide a corrected physiological image.
2. The method of claim 1 wherein the weight assigned to a given one of the partial volume voxels is based on a volume of the given one of the partial volume voxels within the boundary.
3. The method of claim 1 wherein the first imaging modality is a computed tomography (CT) imaging system.
4. The method of claim 1 wherein the second imaging modality is a nuclear imaging modality.
5. A multi-modality imaging system comprising:
a first imaging modality apparatus operable to reconstruct an anatomical image of a target, the anatomical image having a first resolution;
a second imaging modality apparatus operable to reconstruct a physiological image of the target, the physiological image having a second resolution lower than the first resolution;
an image enhancement module comprising at least one processor programmed to:
acquire the anatomical image from the first imaging modality apparatus;
acquire the physiological image from the second imaging modality apparatus, the physiological image including a plurality of voxels;
identify a target boundary of the target in the anatomical image;
register the target boundary of the target to the physiological image;
identify voxels of the physiological image that are completely within the target boundary;
calculate an inner activity value by summing activity levels of the voxels of the physiological image completely within the target boundary;
identify partial volume voxels of the physiological image that include the target boundary;
assign a weight to each of the partial volume voxels;
multiply the weight of each partial volume voxel by an average target activity level to determine a modified activity level for each partial volume voxel;
calculate a partial volume activity value by summing the modified activity levels of the partial volume voxels;
combine the inner activity value and the partial volume activity; and
modify the physiological image using the combined inner activity value and partial volume activity to provide a corrected physiological image.
6. The multi-modality imaging system of claim 5 wherein the weight assigned to each of the partial volume voxels is based on a volume of the partial volume voxel within the target boundary.
7. A non-transitory computer-readable medium encoded with a program to instruct a computer to:
acquire an anatomical image having a first resolution using a first imaging modality;
acquire a physiological image having a second resolution lower than the first resolution using a second imaging modality, the physiological image including a plurality of voxels;
identify a target boundary of the target in the anatomical image;
apply the target boundary of the target to the physiological image;
identify voxels of the physiological image that are completely within the target boundary;
calculate an inner activity value by summing activity levels of the voxels of the physiological image completely within the target boundary;
identify partial volume voxels of the physiological image that include the target boundary;
assign a weight to each of the partial volume voxels;
multiply the weight of each partial volume voxel by an average target activity level to determine a modified activity level for each partial volume voxel;
calculate a partial volume activity value by summing the modified activity levels of the partial volume voxels;
combine the inner activity value and the partial volume activity; and
modify the physiological image using the combined inner activity value and partial volume activity to provide a corrected physiological image.