Spatial Resolution and Sensitivity of the Inveon Small-Animal PET Scanner

The Inveon small-animal PET scanner is characterized by a large, 127-mm axial length and a 161-mm crystal ring diameter. The associated high sensitivity is obtained by using all lines of response (LORs) up to the maximum ring difference (MRD) of 79, for which the most oblique LORs form acceptance angles of 38.3° with transaxial planes. The result is 2 phenomena that are normally not encountered in PET scanners: a parallax or depth-of-interaction effect in the axial direction and the breakdown of Fourier rebinning (FORE). Both effects cause a deterioration of axial spatial resolution. Limiting the MRD to smaller values reduces this axial blurring at the cost of sensitivity. Alternatively, 3-dimensional (3D) reconstruction techniques can be used in which the rebinning step is absent. The aim of this study was to experimentally determine the spatial resolution and sensitivity of the Inveon for its whole field of view (FOV). Methods: Spatial resolution and sensitivity were measured using filtered backprojection (FBP) with FORE, FBP with LOR angle-weighted adapted FORE (AFORE), and 3D ordered-subset expectation maximization followed by maximum a posteriori reconstruction (OSEM3D/MAP). Results: Tangential and radial full width at half maximum (FWHM) showed almost no dependence on the MRD using FORE and FBP. Tangential FWHMs were 1.5 mm in the center of the FOV (CFOV) and 1.8 mm at the edge of the FOV (EFOV). Radial FWHMs were 1.5 and 3.0 mm in the CFOV and EFOV, respectively. In contrast, axial FWHMs increased with the MRD and ranged between 1.1 and 2.0 mm in the CFOV and between 1.5 and 2.7 mm in the EFOV for a MRD between 1 and 79. AFORE improved the axial resolution for a large part of the FOV, but image noise increased. OSEM3D/MAP yielded uniform spatial resolution in all directions, with an average FWHM of 1.65 ± 0.06 mm. Sensitivity in the CFOV for the default energy and coincidence time window was 0.068; peak sensitivity was 0.111. Conclusion: The Inveon showed high spatial resolution and high sensitivity, both of which can be maintained using OSEM3D/MAP reconstruction instead of rebinning and 2D algorithms.

[1]  R M Lewitt,et al.  Performance of the Fourier rebinning algorithm for PET with large acceptance angles. , 1998, Physics in medicine and biology.

[2]  B.E. Atkins,et al.  QuickSilver: A Flexible, Extensible, and High-Speed Architecture for Multi-Modality Imaging , 2006, 2006 IEEE Nuclear Science Symposium Conference Record.

[3]  D.F. Newport,et al.  A CompactPCI Based Event Routing Subsystem for PET and SPECT Data Acquisition , 2006, 2006 IEEE Nuclear Science Symposium Conference Record.

[4]  Frederic H Fahey,et al.  Data acquisition in PET imaging. , 2002, Journal of nuclear medicine technology.

[5]  J. S. Lee,et al.  Performance Measurement of the microPET Focus 120 Scanner , 2007, Journal of Nuclear Medicine.

[6]  R.A. Mintzer,et al.  Design and performance of a new pixelated- LSO/PSPMT gamma-ray detector for high resolution PET imaging , 2007, 2007 IEEE Nuclear Science Symposium Conference Record.

[7]  T D Cradduck,et al.  National electrical manufacturers association , 1983, Journal of the A.I.E.E..

[8]  Dominique Sappey-Marinier,et al.  Raytest ClearPET™, a new generation small animal PET scanner , 2007 .

[9]  Marc C. Huisman,et al.  Performance evaluation of the Philips MOSAIC small animal PET scanner , 2007, European Journal of Nuclear Medicine and Molecular Imaging.

[10]  Jurgen Seidel,et al.  Performance evaluation of the GE healthcare eXplore VISTA dual-ring small-animal PET scanner. , 2006, Journal of nuclear medicine : official publication, Society of Nuclear Medicine.

[11]  D.F. Newport,et al.  Continuously sampled digital pulse processing for inveon small animal PET scanner , 2007, 2007 IEEE Nuclear Science Symposium Conference Record.

[12]  Michel Defrise,et al.  Exact and approximate rebinning algorithms for 3-D PET data , 1997, IEEE Transactions on Medical Imaging.

[13]  I. Sarasola,et al.  Performance evaluation of raytest ClearPET−, a PET scanner for small and medium size animals , 2007, 2007 IEEE Nuclear Science Symposium Conference Record.

[14]  S. Cherry,et al.  Physics in Nuclear Medicine , 2004 .

[15]  Michael G Stabin,et al.  DECAY DATA FOR INTERNAL AND EXTERNAL DOSE ASSESSMENT , 2002, Health physics.

[16]  B.E. Atkins,et al.  A Data Acquisition, Event Processing and Coincidence Determination Module for a Distributed Parallel Processing Architecture for PET and SPECT Imaging , 2006, 2006 IEEE Nuclear Science Symposium Conference Record.