A long-term objective of this work is the development of a dedicated breast PET scanner that can be used for accurately characterizing and monitoring response of early stage breast tumors (stages I and II). This scanner will provide tomographic reconstructed images with very high resolution and sensitivity to detect, characterize, and monitor response in small tumors with low tracer uptake, something that is not performed well in the multi-purpose clinical PET scanners. It will be a partial ring scanner design in order to provide flexibility in imaging the whole breast (including chest wall) and possibly the axilla, to vary the detector separation for different breast sizes, to provide biopsy capability, as well as the potential to combine with other imaging modalities such as optical, mammography, or MR. Dedicated breast PET scanners currently available are forced to trade-off between spatial resolution and sensitivity, and until now the partial ring geometry leads one to choose between low contrast planar images or artifactual tomographic images with limited quantification capability. It is possible to achieve (improved) high quality tomographic images by rotating the detectors, but this adds complexity to the system and also restricts the dynamic imaging capabilities that are key to testing new radio-tracers. In contrast, our design will use time-of-flight (TOF) information to attain high quality and quantitative tomographic images for the partial ring scanner with stationary detectors, while maintaining high spatial resolution and sensitivity throughout the scanner field-of-view (FOV).
Our aims are four fold: (i) develop a detector which maintains very good timing resolution while using small and long crystals for high spatial resolution and sensitivity, (ii) demonstrate the extent by which TOF information can compensate for the missing projection data, and investigate the trade-offs involved between spatial resolution, sensitivity, and timing resolution, as well as scanner angular coverage, to achieve an optimal scanner design, (iii) develop a coincidence imaging setup, and (iv) develop data correction and imaging reconstruction techniques for quantitative images followed by a characterization of the imaging performance of the coincidence setup. The work will involve detector measurements and simulations for testing varying crystal sizes and surface finishes, different types of photo-multiplier tubes, and full detector arrays. Full system simulations will be performed based upon detector measurement results for varying scanner geometries as well. Finally, an optimal detector design will be developed into coincident detector arrays and imaging experiments will be performed to demonstrate its capabilities.

Public Health Relevance

Clinically for human imaging, limited spatial resolution and sensitivity of current generation of clinical PET scanners leads to reduced detection and quantification of small breast tumors. By developing a dedicated breast scanner with high resolution and sensitivity, as well as production of full tomographic images, will help in the detection and staging of early stage breast cancer. Hence, the development of a dedicated, TOF, breast scanner has the potential to significantly impact patient treatment for breast cancer.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Research Project (R01)
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Biomedical Imaging Technology Study Section (BMIT)
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Sastre, Antonio
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University of Pennsylvania
Schools of Medicine
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Surti, Suleman; Karp, Joel S (2016) Advances in time-of-flight PET. Phys Med 32:12-22
Matej, Samuel; Li, Yusheng; Panetta, Joseph et al. (2016) Image-based Modeling of PSF Deformation with Application to Limited Angle PET Data. IEEE Trans Nucl Sci 63:2599-2606
Surti, S; Karp, J S (2015) Impact of detector design on imaging performance of a long axial field-of-view, whole-body PET scanner. Phys Med Biol 60:5343-58
Surti, Suleman (2015) Update on time-of-flight PET imaging. J Nucl Med 56:98-105
Krishnamoorthy, Srilalan; LeGeyt, Benjamin; Werner, Matthew E et al. (2014) Design and performance of a high spatial resolution, time-of-flight PET detector. IEEE Trans Nucl Sci 61:1092-1098
Surti, S; Werner, M E; Karp, J S (2013) Study of PET scanner designs using clinical metrics to optimize the scanner axial FOV and crystal thickness. Phys Med Biol 58:3995-4012
Lee, Eunsin; Werner, Matthew E; Karp, Joel S et al. (2013) Design Optimization of a TOF, Breast PET Scanner. IEEE Trans Nucl Sci 60:1645-1652
Surti, S; Shore, Adam R; Karp, Joel S (2013) Design Study of a Whole-Body PET Scanner with Improved Spatial and Timing Resolution. IEEE Trans Nucl Sci 60:
Surti, Suleman (2013) Radionuclide methods and instrumentation for breast cancer detection and diagnosis. Semin Nucl Med 43:271-80
El Fakhri, Georges; Surti, Suleman; Trott, Cathryn M et al. (2011) Improvement in lesion detection with whole-body oncologic time-of-flight PET. J Nucl Med 52:347-53

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