Subtraction of projection data in medical diagnostic imaging
Background information is subtracted from projection data in medical diagnostic imaging. The background is removed using data acquired in a single rotational sweep of a C-arm. The removal may be by masking out a target, leaving the background, in the data as constructed into a volume. For subtraction, the masked background information is projected to a plane and subtracted from the data representing the plane.
1. A method for subtraction of re-projection data in medical diagnostic imaging, the method comprising:
acquiring C-arm x-ray data in frames representing a left ventricle of a patient projected to different planes, the frames acquired at different times;
constructing, with a processor, the C-arm x-ray data into volume data representing a volume of the patient, the volume of the patient including the left ventricle;
masking, with the processor, the left ventricle from the volume data;
projecting, with the processor, the volume data without the left ventricle to one of the planes corresponding to one of the frames;
subtracting, with the processor, the projected volume data from the C-arm x-ray data of the one frame; and
generating an image of the left ventricle as a function of a result of the subtracting.
2. The method of claim 1 wherein acquiring comprises acquiring the C-arm x-ray data as a rotational angiocardiogram.
3. The method of claim 1 wherein acquiring comprises acquiring with a single sweep of a C-arm and without contrast agent.
4. The method of claim 1 wherein constructing comprises applying an algebraic reconstruction technique.
5. The method of claim 4 wherein applying the algebraic reconstruction technique comprises applying a simultaneous algebraic reconstruction technique.
6. The method of claim 1 wherein constructing comprises constructing the volume data as a static volume from the frames representing different phases of a cardiac cycle.
7. The method of claim 1 wherein masking comprises masking voxels enclosed by an epicardium of the left ventricle.
8. The method of claim 1 wherein masking comprises masking with a marginal space learnt algorithm.
9. The method of claim 1 wherein masking comprises masking with a transitional zone with varying weights as a function of distance away from a blood pool of the left ventricle.
10. The method of claim 1 wherein projecting comprises projecting as a function of an overlapping interpolation kernel.
11. The method of claim 1 wherein projecting comprises ray driven re-projecting based on a C-arm geometry.
12. The method of claim 1 wherein projecting and subtracting are repeated for different planes and corresponding frames.
13. The method of claim 1 wherein generating comprises segmenting a blood pool of the left ventricle based on the result of the subtracting, extracting a three-dimensional dynamic left ventricle model based on the segmenting, and displaying the image representing the model.
14. In a non-transitory computer readable storage medium having stored therein data representing instructions executable by a programmed processor for subtraction of projection data in medical diagnostic imaging, the storage medium comprising instructions for:
acquiring a sequence of projection data as an angiocardiogram of a left ventricle without contrast agents from a single sweep of a C-arm rotating and translating about a patient;
identifying background information in the projection data of the sequence, the identifying comprising forming voxels representing a volume from the projection data of the sequence and masking the voxels for a region of interest different than the background information from the volume; projecting the volume data without the left ventricles;
removing the background information from the projection data of the sequence by rendering the masked voxels to a plane associated with a frame of the projection volume data, and subtracting the rendered voxels of the plane from the projection data of the frame; and generating an image of the left ventricle as a function of a result of the subtracting.
15. The non-transitory computer readable storage medium of claim 14 wherein removing in the volume format comprises removing with a static volume generated from the projection data representing different phases of a physiological cycle.
16. A system for subtraction of re-projection data in medical diagnostic imaging, the system comprising:
a C-arm configured to rotate from a single sweep of a patient to acquire a sequence of projection data as an angiocardiogram of a left ventricle without contrast agents projected to different planes ;
a memory configured to store the projection images representing a sequence of two-dimensional regions of the left ventricle over time; and
a processor configured to reconstruct volume data representing a static three-dimensional region from the projection images of the sequence wherein the volume of the patient includes the left ventricle, mask values of the left ventricle from the volume data for a target in the static three-dimensional region,
project the volume data with the masked values to two-dimensions corresponding to a first of the projection images without the left ventricles to one of the planes corresponding to one of the frames, subtract the projection of the volume data from the first of the projection images, and generating an image of the left ventricle as a function of a result of the subtracting.