Rapid Multi-Tracer PET Tumor Imaging With $^{18}{\hbox {F-FDG}}$ and Secondary Shorter-Lived Tracers

Abstract

Rapid multi-tracer PET, where two to three PET tracers are rapidly scanned with staggered injections, can recover certain imaging measures for each tracer based on differences in tracer kinetics and decay. We previously showed that single-tracer imaging measures can be recovered to a certain extent from rapid dual-tracer 62 Cu -PTSM (blood flow) + 62 Cu -ATSM (hypoxia) tumor imaging. In this work, the feasibility of rapidly imaging 18 F-FDG plus one or two of these shorter-lived secondary tracers was evaluated in the same tumor model. Dynamic PET imaging was performed in four dogs with pre-existing tumors, and the raw scan data was combined to emulate 60 minute long dual-and triple-tracer scans, using the single-tracer scans as gold standards. The multi-tracer data were processed for static (SUV) and kinetic (K 1 , K net ) endpoints for each tracer, followed by linear regression analysis of multi-tracer versus single-tracer results. Static and quantitative dynamic imaging measures of FDG were both accurately recovered from the multi-tracer scans, closely matching the single-tracer FDG standards (R > 0.99). Quantitative blood flow information, as measured by PTSM K 1 and SUV, was also accurately recovered from the multi-tracer scans (R = 0.97). Recovery of ATSM kinetic parameters proved more difficult, though the ATSM SUV was reasonably well recovered (R = 0.92). We conclude that certain additional information from one to two shorter-lived PET tracers may be measured in a rapid multi-tracer scan alongside FDG without compromising the assessment of glucose metabolism. Such additional and complementary information has the potential to improve tumor characterization in vivo, warranting further investigation of rapid multi-tracer techniques. Index TermsMulti-tracer imaging; positron emission tomography (PET) NIH Public Access

Hypoxia Imaging in Gliomas With 18F-Fluoromisonidazole PET: Toward Clinical Translation

“…Since its proposal by Huang et al, 177 multiple studies have investigated techniques that could allow for multiplexing PET imaging. [178][179][180][181][182][183][184][185] Simultaneous acquisition of multiple tracers is a feasible solution, would eliminate the issues of image registration and physiological changes, and is highly suited to 18 F-FMISO hypoxia imaging. However, further research is required to fully develop the concept of simultaneous multiplexing of 18 F-FMISO with other PET oncology tracers.…”

Application of separable parameter space techniques to multi-tracer PET compartment modeling

“…Unlike multi-isotope SPECT, where energy discrimination can be used to identify photons from each tracer, all PET tracers give rise to indistinguishable 511 keV photon pairs. It has been previously shown that, when using dynamic scanning with staggered injections, the imaging signals from 2–3 PET tracers can be reliably recovered through application of appropriate kinetic constraints for each tracer (Koeppe et al 1998, Koeppe et al 2001, Converse et al 2004, Koeppe et al 2004, Kadrmas and Rust 2005, Kudomi et al 2005, Rust and Kadrmas 2006, Black et al 2008, 2009, Gao et al 2009, Joshi et al 2009, Kadrmas et al 2010, 2013, Kadrmas and Hoffman 2013). Perhaps the most robust multi-tracer PET signal-separation algorithms rely upon parallel compartment modeling of all tracers present in order to apply the kinetic constraints and recover imaging estimates from each individual tracer.…”

18F-Alfatide II and 18F-FDG Dual-Tracer Dynamic PET for Parametric, Early Prediction of Tumor Response to Therapy

“…By taking advantage of the distinct kinetics of different tracers, nearly simultaneous multi-tracer imaging can be achieved by closely staggering tracer injections during a single scan (13–17). Many studies using simulated data have demonstrated the feasibility of signal separation with dual tracer dynamic PET imaging (13–17).…”

“…Many studies using simulated data have demonstrated the feasibility of signal separation with dual tracer dynamic PET imaging (13–17). PET imaging with different tracers that partially overlap in time has advantages, relative to PET imaging with widely separated administration of the tracers, by reducing the cost and time of the imaging, and by providing complementary information under quasi-constant physiological conditions (14, 18).…”