Comparative Study of Imaging Characteristics of I-125 Imaging Using the Siemens Inveon Scanner and Siemens Symbia TruePoint

Objective: Although Iodine-125 (125I) has been widely used for in vitro studies because of its relatively long half-life (60.1 days), 125I imaging is limited because of its low energy (27 35 keV), even in an animal-dedicated system. In this study, imaging characteristics of 125I were assessed using a small animal-dedicated imaging system and clinical scanner. Methods: Using the Siemens Inveon and Siemens Symbia TruePoint systems, imaging characteristics such as resolution, sensitivity, and image quality were compared. Mouse high resolution (MHR-0.5), mouse general purpose (MGP-1.0), and mouse high sensitivity (MHS-2.0) collimators were used for the Inveon scanner, and low energy high-resolution (LEHR) and low energy all-purpose (LEAP) collimators were used for the Symbia TruePoint. For animal imaging, 16.8 MBq of 125I was administered to BALB/c mice intravenously, and the planar image and single-photon emission computed tomography (SPECT) were obtained using both scanners. Results: The resolution of 125I for the Inveon scanner was 3.98 mm full width at half maximum (FWHM) at a 30-mm distance with the MHR-0.5 collimator, and the value of Symbia scanner was 8.72 mm FWHM at a 30-mm distance with the LEHR collimator. The sensitivity of 125I for the Inveon scanner was 21.87 cps/MBq, and the value for the clinical scanner was 30.55 cps/MBq. The planar images of mice were successfully obtained at the level of evaluatCorresponding authors. Authors with equal contributions.