Cross-validation study between the HRRT and the PET component of the SIGNA PET/MRI system with focus on neuroimaging

EJNMMI Physics

Table 1 System specification and performance parameters of the Siemens HRRT and GE SIGNA PET/MR system

	HRRT	SIGNA PET/MR
Crystal material	LSO/LYSO	Lutetium based
Crystal dimensions [mm³]	2.44 × 2.44 × 10	4.0 × 5.3 × 25
Number of crystals	119,808	20,160
Detector	PMTs	Si-PM
FOV (axial vs. transaxial) [cm]	25.2 x 31.2	25 × 60
Reported resolution (radial × tangential × axial) [mm]	2.3 × 2.3 × 2.5^a [7, 12]	3.48 × 3.43 × 4.67^b [8]
Reported sensitivity	2.9%^c [12]	23.3 cps/kBq^d [8]
Special characteristics	DOI correction	TOF (timing resolution < 400 ps), simultaneous PET/MRI

^aAt 1 cm tangential offset to the center of the FOV (reconstructed with a 3D ordinary Poisson-ordered subset expectation-maximization algorithm (OP-OSEM))
^bAt 1 cm tangential offset to the center of the FOV (reconstructed with a TOF OSEM algorithm with filter)
^cAt the center FOV based on the NEMA 2001 evaluation protocol; note that measured activity was normalized by the line source length in the scanner FOV (25 cm), rather than its entire length (70 cm)
^dAt the center FOV based on the NEMA 2012 evaluation protocol. Sensitivity of 23.3 cps/kBq is equivalent to 2.3%. When expressed in the same units as the sensitivity measured for the HRRT, the GE SIGNA sensitivity is estimated to be 6.5%