APPLICATIONS OF TECHNOLOGY:
- Dynamic diagnostic imaging
- Research on tissue perfusion and metabolism
- Accurate quantitation of coronary flow reserve, tissue perfusion, and viability
- Applicable with slowly rotating SPECT scanners or with PET scanners
Scientists at Berkeley Lab have developed a computer program that uses data from single-photon emission computed tomography (SPECT) to quantify and create images of dynamic blood flow in living tissue. This tool will improve noninvasive diagnosis and assessment of diseases using SPECT scanners, which are more common and less expensive than positron emission tomography (PET) scanners. The software generates system matrices that use SPECT data to provide accurate arterial input functions—mathematical functions describing the flow of blood into tissue over time. These functions can be used to quantify regional tissue perfusion and viability, as well as coronary flow reserve. The software can also be applied directly to PET data for cases when these scans are available.
The scientists tested the system by applying it to data from three patients who underwent PET scans of the heart. These data were used to simulate projection data that would be obtained from the same patients with a slowly rotating double-headed SPECT scanner. The simulated SPECT data was then processed with both existing software, which uses a standard three-dimensional (3D) technique at multiple time points, and the new software, which uses a spatiotemporal (4D) technique. The results from each type of software were compared to the original PET results as an indicator of accuracy. The 4D technique was more accurate than the 3D technique in measuring arterial input functions. The 4D program also produced accurate time-activity curves for blood and myocardium and used these to estimate the tissue uptake rate parameter, K1. In addition, the software was able to compensate for errors introduced by radiotracer signal attenuation, collimation-induced blurring, and changes in radiotracer distribution during camera rotation.
Dynamic imaging of tissue to visualize and quantify blood flow and regional metabolic rates is useful in assessing cardiac and other diseases, as well as normal physiology. While this type of imaging can be performed with PET scanners, these scanners are rare, expensive, require a nearby cyclotron or generator, and can only image one type of isotope at a time. MRI images may also be useful but not all patients can undergo MRI scans. SPECT scanners are more common, convenient, and less expensive than PET scanners and more readily tolerated than MRI scans. However, SPECT scanners have limited capability for dynamic imaging, because, unlike PET scanners, their cameras must rotate slowly about the body as the radiotracer distribution changes. The Berkeley Lab software overcomes these limitations, allowing the more accessible SPECT scanners to provide objective, quantitative data for diagnosis and research.
DEVELOPMENT STAGE: Demonstrated in pilot study of human participants without cardiac disease and in animals.
STATUS: Copyrighted. Available for licensing or collaborative research.
FOR MORE INFORMATION:
Reutter BW, GT Gullberg, R Boutchko, K Balakrishnan, EH Botvinick, RH Huesman. “Fully 4-D dynamic cardiac SPECT image reconstruction using spatiotemporal B-spline voxelization,” IEEE Nuclear Science Symposium Conference Record, pp. 4217-4221 (2007).
Reutter BW, GT Gullberg, RH Huesman. “Direct least-squares estimation of spatiotemporal distributions from dynamic SPECT projections using a spatial segmentation and temporal B-splines,” IEEE Transactions on Medical Imaging 19;434-450 (2000).
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