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SU‐C‐144‐07: Maximally Spaced Projection Sequencing in Electron Paramagnetic Resonance Imaging
Author(s) -
Redler G,
Epel B,
Halpern HJ
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4813996
Subject(s) - projection (relational algebra) , iterative reconstruction , image resolution , computer science , computer vision , artificial intelligence , temporal resolution , image quality , resolution (logic) , algorithm , physics , image (mathematics) , optics
Purpose: Electron paramagnetic resonance imaging (EPRI) is a projection based imaging modality that noninvasively provides 3D images of absolute oxygen concentration (pO 2 ) in vivo with excellent spatial and pO 2 resolution. When studying physiologic parameters, such as tissue pO 2 , in living animals, the situation is inherently dynamic. This may be due to physical movement during imaging leading to artifacts or physiologically relevant temporal changes in pO 2 (i.e. acute hypoxia). In order to properly study such a dynamic system, improvements in temporal resolution and experimental versatility are necessary. Methods: For projection based imaging, uniformly distributed projections Result in efficient use of data for image reconstruction. This has led to the current equal‐solid‐angle (ESA) spacing of projections for EPRI. However, acquisition sequencing must still be optimized in order to achieve uniformity throughout imaging. An object‐independent method for uniform acquisition of projections, using the ESA distribution for the final set of projections, is presented. Each successive projection is selected in such a way as to minimize the electrostatic potential energy between itself and prior projections, when projection direction points are considered to be point charges on the unit sphere. Results: This maximally spaced projection sequencing (MSPS) method significantly improves image quality for intermediate images reconstructed from incomplete projection sets. This enables useful real‐time reconstruction. Additionally, the MSPS method provides improved experimental versatility, reduced artifacts, and the ability to adjust temporal resolution post factum to best fit the data and its application. Conclusion: The MSPS method in EPRI provides necessary improvements in order to more appropriately image and study physiologic changes in a dynamic system. This work was supported by grants from the NIH (P41 EB002034 and R01 CA98575).