TY - JOUR T1 - Predictive model for a Rb-82 generator bolus times as a function of generator lifetime JF - Journal of Nuclear Medicine Technology JO - J. Nucl. Med. Technol. DO - 10.2967/jnmt.120.256917 SP - jnmt.120.256917 AU - Alexander Warn Scott II AU - Mark C Hyun AU - Jennifer T Kim Y1 - 2021/09/01 UR - http://tech.snmjournals.org/content/early/2021/09/27/jnmt.120.256917.abstract N2 - Rationale: 82Rb cardiac PET is largely used to study myocardial perfusion with function, and to calculate myocardial blood flow (MBF) and coronary flow reserve (CFR) or myocardial flow reserve (MFR). Although the dosing activity of 82Rb is determined by the patient weight, the infusion volume and activity concentration varies with the age of the 82Rb generator. We sought to predict the needed bolus volume of 82Rb to help evaluate the accuracy of MBF findings. Methods: Data was collected from de-identified tickets of an 82Rb generator, including the instantaneous eluted activity flow rate. The times to reach 4 activity levels of 20, 30, 40, and 45 mCi (740, 1110, 1480, and 1665 MBq respectively) were also calculated. The activity flow rate for the largest bolus was fitted to determine the functional form. The time to reach each bolus level was fitted as a function of the generator age and 95% confidence limits were created. Results: The activity flow rate was fitted with a growth-saturation model, allowing a calculation of bolus volume. The amplitude of the fit was observed to also be influenced by the time since last elution, and possibly other clinical factors. Elution times to reach the 4 activity levels were plotted vs. generator age. The linearized data was fitted and 95% confidence limits were created symmetrically around the fit. The 95% CL band allowed a prediction of elution time to achieve each bolus size for future generators, as a function only of generator age. Conclusion: A predictive model was created for elution times from this brand of 82Rb generator as a function of generator age. The value of this model is in determining if the necessary amount of activity can be extracted from a generator before reaching one of the backup infusion settings, such as volume limits per administration, given a generator age. Some sites may also wish to control the bolus duration for better MBF calculations, since predicting the time for the injection to complete may determine if MBF and CFR calculations are meaningful. ER -