Performance evaluation of an Inveon PET preclinical scanner

Abstract

We evaluated the performance of an Inveon preclinical PET scanner (Siemens Medical Solutions), the latest MicroPET system. Spatial resolution was measured with a glass capillary tube (0.26 mm inside diameter, 0.29 mm wall thickness) filled with 18 F solution. Transaxial and axial resolutions were measured with the source placed parallel and perpendicular to the axis of the scanner. The sensitivity of the scanner was measured with a 22 Na point source, placed on the animal bed and positioned at different offsets from the center of the field of view (FOV), as well as at different energy and coincidence windows. The noise equivalent count rates (NECR) and the system scatter fraction were measured using rat-like (Φ = 60, L = 150 mm) and mouse-like (Φ = 25 mm, L = 70 mm) cylindrical phantoms. Line sources filled with high activity 18 F (>250 MBq) were inserted parallel to the axes of the phantoms (13.5 and 10 mm offset). For each phantom, list-mode data were collected over 24 h at 350-650 keV and 250-750 keV energy windows and 3.4 ns coincidence window. System scatter fraction was measured when the random event rates were below 1%. Performance phantoms consisting of cylinders with hot rod inserts filled with 18 F were imaged. In addition, we performed imaging studies that show the suitability of the Inveon scanner for imaging small structures such as those in mice with a variety of tracers. The radial, tangential and axial resolutions at the center of FOV were 1.46 mm, 1.49 and 1.15 mm, respectively. At a radial offset of 2 cm, the FWHM values were 1.73, 2.20 and 1.47 mm, respectively. At a coincidence window of 3.4 ns, the sensitivity was 5.75% for EW = 350-650 keV and 7.4% for EW = 250-750 keV. For an energy window of 350-650 keV, the peak NECR was 538 kcps at 131.4 MBq for the rat-like phantom, and 1734 kcps at 147.4 MBq for the mouse-like phantom. The system scatter fraction values were 0.22 for the rat phantom and 0.06 for the mouse phantom. The Inveon system presents high image resolution, low scatter fraction values and improved sensitivity and count rate performance.

Performance characterization of the Inveon preclinical small-animal PET/SPECT/CT system for multimodality imaging

“…We measured absolute sensitivity, free of photon attenuation and scatter, using an extrapolation method [19]. Absolute sensitivity in our study was comparable to the previous study [17]. The present results for scatter fraction and peak NEC differ slightly from those reported in previous studies because we used cylindrical phantoms of differing diameters.…”

“…The performances of the PET component of this system has recently been reported [14][15][16][17]; however, this is the first report to evaluate SPECT performance in comparison with PET performance. We evaluated the full performance measurements of the SPECT component and validated the basic characterization of the PET component.…”

“…The scanner acquires exclusively in 3D mode. The reconstruction methods have been described in detail in previous reports [14][15][16][17].…”

“…Several recent studies have reported the performance of the PET [14][15][16][17]; however, evaluation of the SPECT component and comparison of performance between PET and SPECT…”

Comparison of Reconstruction Methods in a Small Animal Cardiac Positron Emission Tomography Study Using a 18F-Labeled Myocardial Agent, [18F] FPTP

“…3D sinograms were then rebinned by the Fourier algorithm (FORE) (14,15). The acquired 3D sinograms were reconstructed in 2D using the FBP and OSEM2D algorithms, and in 3D using the OSEM3D and 3DRP algorithms (16). FBP reconstruction was performed using a ramp filter at the Nyquist frequency (0.5 cycles/pixel).…”