Single‐scan rest/stress imaging ¹⁸F‐labeled flow tracers

Abstract

Purpose:The authors report a novel measurement strategy to obtain both rest and stress blood flow during a single, relatively short, scan session. Methods: Measurement of rest-stress myocardial blood flow with long-lived tracers usually requires separate scan sessions to remove the confounding effects of residual radioactivity concentration in the blood and tissue. The innovation of this method is to treat the rest-stress scan as a single entity in which the flow parameters change due to pharmacological challenge. With this approach the fate of a tracer molecule is naturally accounted for, no matter if it was introduced during the rest or stress phase of the study. Two new dual-injection kinetic models are considered that represent the response to pharmacological stress as a transitional or transient increase of myocardial blood flow. The authors present the theory of the method followed by the specific application of the theory to 18 F-Flurpiridaz, a new myocardial flow-imaging agent. Results: Myocardial blood flow was accurately and precisely estimated from a single-scan rest/stress study for the long half-lived tracer 18 F-Flurpiridaz. By accounting for the time-dependence of the kinetic parameters, the proposed models achieved good accuracy and precision (5%) under different vasodilators and different ischemic states. Conclusions: Detailed simulations predict that accurate and precise rest-stress blood flow measurements can be obtained in 20-30 min.

Impact of motion and partial volume effects correction on PET myocardial perfusion imaging using simultaneous PET-MR

“…Since only the first 10 minutes of dynamic PET data were used for MBF estimation and because 18 F-Flurpiridaz binds to MC-1 and shows very high retention, k 4 = 0 was assumed for the duration of the study. We also fixed k 3 at a nominal value ( k 3 = 0.06 min −1) to improve stability of the estimated kinetic parameters, as proposed by Alpert et al (Alpert et al ., 2012). Whole-blood TACs were obtained using cylindrical volumes-of-interest (VOI) (~1×1×2cm3) centered in the basal portions of the left ventricle (LV) and right ventricle (RV) blood-pools in the Ungated images.…”

Direct parametric reconstruction in dynamic PET myocardial perfusion imaging:in vivostudies

“…Although a two-tissue compartment model has been traditionally reported for modeling the kinetics of 18 F-flurpiridaz (Nekolla et al, 2009, Alpert et al, 2012), in this work, we used a one-tissue compartment model for modeling the kinetics of this tracer. In their study, Nekolla et al (Nekolla et al, 2009) showed that the one-tissue compartment model, as applied to a short acquisition window after injection (2 minutes), yields K 1 values which are very close to the ones obtained with a two-tissue compartment model applied to a longer data acquisition window (10 to 20 minutes after injection).…”

“…We also plan to implement the kinetic model developed by Alpert et al (Alpert et al, 2012) to perform direct estimation of rest and stress K 1 within a single scanning session.…”

Measuring myocardial perfusion: the role of PET, MRI and CT

“…F-18 labelled tracers do not need an on-site cyclotron due to a half-life of 109 min, and even with the long halflife, it may be possible to obtain rest and stress MPI in one protocol within 20e30 min. 42 …”