Precise rubidium-82 infusion system for cardiac perfusion measurement using three-dimensional positron emission tomography

Abstract

Introduction. Quantitative myocardial perfusion measurements using positron emission tomography (PET) can be improved by introducing diagnostic tracers at a constant rate of activity. 82Rb can be produced cost effectively by eluting a 82Sr/82Rb generator with saline; however, it exhibits an undesirable, but reproducible, activity rate variation. Previously, a threshold-comparison algorithm controlled saline flow through either generator or bypass line using an on/off valve, to simulate constant-activity elutions. Methods. In this work a mechanical system and control software is developed to control tracer infusion. The valve is cycled at 5Hz and its duty-cycle controlled by a predictive-corrective algorithm in order to reduce measurable activity rate fluctuations. Results. Precision increases (RMS error improves from >40% to ∼14%) as does the range of relative activities that can be eluted from the generator. Conclusion. The proposed method demonstrates superior precision and flexibility. However, further tests must be conducted to ensure that the precision of the system does not deteriorate over time.