Verification of image quality and quantification in whole-body positron emission tomography with continuous bed motion.

Abstract

Whole-body dynamic imaging using positron emission tomography (PET) facilitates the quantification of tracer kinetics. It is potentially valuable for the differential diagnosis of tumors and for the evaluation of therapeutic efficacy. In whole-body dynamic PET with continuous bed motion (CBM) (WBDCBM-PET), the pass number and bed velocity are key considerations. In the present study, we aimed to investigate the effect of a combination of pass number and bed velocity on the quantitative accuracy and quality of WBDCBM-PET images. In this study, WBDCBM-PET imaging was performed at a body phantom using seven bed velocity settings in combination with pass numbers. The resulting image quality was evaluated. For comparing different acquisition settings, the dynamic index (DI) was obtained using the following formula: [P/S], where P represents the pass number, and S represents the bed velocity (mm/s). The following physical parameters were evaluated: noise equivalent count at phantom (NECphantom), percent background variability (N10mm), percent contrast of the 10mm hot sphere (QH, 10mm), the QH, 10mm/N10mm ratio, and the maximum standardized uptake value (SUVmax). Furthermore, visual evaluation was performed. The NECphantom was equivalent for the same DI settings regardless of the bed velocity. The N10mm exhibited an inverse correlation (r < - 0.89) with the DI. QH,10mm was not affected by DI, and a correlation between QH,10mm/N10mm ratio and DI was found at all the velocities (r > 0.93). The SUVmax of the spheres was not influenced by the DI. The coefficient of variations caused by bed velocity decreased in larger spheres. There was no significant difference between the bed velocities on visual evaluation. The quantitative accuracy and image quality achieved with WBDCBM-PET was comparable to that achieved with non-dynamic CBM, regardless of the pass number and bed velocity used during imaging for a given acquisition time.