Optimization of helical acquisition parameters to preserve uniformity of mouse whole body using multipinhole collimator in single-photon emission computed tomography

Abstract

Focusing on whole-body uniformity in small-animal single-photon emission computed tomography (SPECT), we examined the optimal helical acquisition parameters using five-pinhole collimators for mouse imaging. SPECT images of an 80-mm-long cylindrical phantom with 99mTc solution were acquired using an Inveon multimodality imaging platform. The bed travels used in this study were 0, 30, 60, 90 and 120 mm, and the numbers of revolutions traversed during the SPECT scan were 1.0, 2.0, 3.0, 4.0, 5.0 and 7.0, respectively. Artifacts that degrade uniformity in reconstructed images were conspicuous when the bed travel was smaller than the object length. Regarding the distal-to-center ratio (DCR) of SPECT values in the object’s axial direction, the DCR nearest to the ideal ratio of 1.00 was 1.02 in the optimal uniformity with 4.0 revolutions and a bed travel of 120 mm. Moreover, the helical acquisition using these parameters suppressed the formation of artifacts. We proposed the optimal parameters in whole-body helical SPECT; the bed travel was sufficiently larger than the object length; the 4.0 or more revolutions were required for a pitch of approximately 30 mm/revolution. The optimal acquisition parameters in SPECT to preserve uniformity would contribute to the accurate quantification of whole-body biodistribution. Keywords: Helical acquisition, Multipinhole collimator, Computed tomography, SPECT