Resolution improvement in emission optical projection tomography.
A new imaging technique called emission optical projection tomography (eOPT), essentially an optical version of single-photon emission computed tomography (SPECT), provides molecular specificity, resolution on the order of microns to tens of microns, and large specimen coverage ( approximately 1 cubic centimetre). It is ideally suited to gene expression studies in embryos. Reconstructed eOPT images suffer from blurring that worsens as the distance from the axis of rotation increases. This blur is caused in part by the defocusing of the lens' point-spread function, which increases with object distance from the focal plane. In this paper, we describe a frequency space filter based on the frequency-distance relationship of sinograms to deconvolve the distance-dependent point-spread function and exclude highly defocused data from the eOPT sinograms prior to reconstruction. The method is shown to reduce the volume at half-maximum of the reconstructed point-spread function to approximately 20% the original, and the volume at 10% maximum to approximately 6% the original. As an illustration, the visibility of fine details in the vasculature of a 9.5 day old mouse embryo is dramatically improved.
Walls
Johnathon R
JR
Mouse Imaging Centre, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada. johnathon.walls@utoronto.ca
Sled
John G
JG
Sharpe
James
J
Henkelman
R Mark
RM
D000818:Animals; D003198:Computer Simulation; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000098:blood supply; D021621:Imaging, Three-Dimensional; D051379:Mice; D041622:Tomography, Optical / Q000379:methods*