Ultra-High-Sensitivity Submillimeter Mouse SPECT

Journal article (2015)

Authors

O. Ivashchenko RST/Biomedical Imaging - AS , University Medical Center Utrecht, MILabs B.V.
F. van der Have MILabs B.V., RST/Biomedical Imaging - AS , University Medical Center Utrecht
M.C. Goorden RST/Biomedical Imaging - AS
R.M. Ramakers MILabs B.V., University Medical Center Utrecht, RST/Biomedical Imaging - AS
F.J. Beekman University Medical Center Utrecht, MILabs B.V., RST/Biomedical Imaging - AS
Research Group
RST/Biomedical Imaging (AS) (TU Delft)
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Published Date

12-02-2015

Language

English

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Faculty

Applied Sciences

Department

RST/Radiation, Science and Technology

Research Group

RST/Biomedical Imaging

Abstract

SPECT with submegabecquerel amounts of tracer or subsecond time resolution would enable a wide range of new imaging protocols such as screening tracers with initially low yield or labeling efficiency, imaging low receptor densities, or even performing SPECT outside regular radiation laboratories. To this end we developed dedicated ultra-high-sensitivity pinhole SPECT.
METHODS:
A cylindric collimator with 54 focused 2.0-mm-diameter conical pinholes was manufactured and mounted in a stationary small-animal SPECT system. The system matrix for image reconstruction was calculated via a hybrid method based on both (99m)Tc point source measurements and ray-tracing analytic modeling. SPECT images were reconstructed using pixel-based ordered-subsets expectation maximization. Performance was evaluated with phantoms and low-dose bone, dynamic kidney, and cardiac mouse scans.
RESULTS:
The peak sensitivity reached 1.3% (13,080 cps/MBq). The reconstructed spatial resolution (rod visibility in a micro-Jaszczak phantom) was 0.85 mm. Even with only a quarter megabecquerel of activity, 30-min bone SPECT scans provided surprisingly high levels of detail. Dynamic dual-isotope kidney and (99m)Tc-sestamibi cardiac scans were acquired with a time-frame resolution down to 1 s.
CONCLUSION:
The high sensitivity achieved increases the range of mouse SPECT applications by enabling in vivo imaging with less than a megabecquerel of tracer activity or down to 1-s frame dynamics.

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