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J Nucl Med. 2014 Aug;55(8):1368-74. doi: 10.2967/jnumed.113.136663. Epub 2014 Jun 5.

Performance assessment of a preclinical PET scanner with pinhole collimation by comparison to a coincidence-based small-animal PET scanner.

Author information

1
Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada mwalker@physics.ubc.ca.
2
Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands.
3
Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
4
Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands MILabs, Utrecht, The Netherlands; and Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
5
Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
6
Section Radiation, Detection and Medical Imaging, Delft University of Technology, Delft, The Netherlands MILabs, Utrecht, The Netherlands; and.

Abstract

PET imaging of rodents is increasingly used in preclinical research, but its utility is limited by spatial resolution and signal-to-noise ratio of the images. A recently developed preclinical PET system uses a clustered-pinhole collimator, enabling high-resolution, simultaneous imaging of PET and SPECT tracers. Pinhole collimation strongly departs from traditional electronic collimation achieved via coincidence detection in PET. We investigated the potential of such a design by direct comparison to a traditional PET scanner.

METHODS:

Two small-animal PET scanners, 1 with electronic collimation and 1 with physical collimation using clustered pinholes, were used to acquire data from Jaszczak (hot rod) and uniform phantoms. Mouse brain imaging using (18)F-FDG PET was performed on each system and compared with quantitative ex vivo autoradiography as a gold standard. Bone imaging using (18)F-NaF allowed comparison of imaging in the mouse body. Images were visually and quantitatively compared using measures of contrast and noise.

RESULTS:

Pinhole PET resolved the smallest rods (diameter, 0.85 mm) in the Jaszczak phantom, whereas the coincidence system resolved 1.1-mm-diameter rods. Contrast-to-noise ratios were better for pinhole PET when imaging small rods (<1.1 mm) for a wide range of activity levels, but this reversed for larger rods. Image uniformity on the coincidence system (<3%) was superior to that on the pinhole system (5%). The high (18)F-FDG uptake in the striatum of the mouse brain was fully resolved using the pinhole system, with contrast to nearby regions equaling that from autoradiography; a lower contrast was found using the coincidence PET system. For short-duration images (low-count), the coincidence system was superior.

CONCLUSION:

In the cases for which small regions need to be resolved in scans with reasonably high activity or reasonably long scan times, a first-generation clustered-pinhole system can provide image quality in terms of resolution, contrast, and the contrast-to-noise ratio superior to a traditional PET system.

KEYWORDS:

VECTor; pinhole PET; preclinical PET; small-animal PET

PMID:
24904110
DOI:
10.2967/jnumed.113.136663
[Indexed for MEDLINE]
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