image: Figure 1. Results from 3x3 grid phantom experiment with diameter of 120 mm. Top row: 3x3 grid phantom filling and components. Middle row: reconstructed A (triple coincidences highest energy photon ≥ 650 keV), B (triple coincidences with highest energy photon between 520-650 keV), and C (double coincidences with photons 450-600 keV) listmode datasets. Bottom row: unmixed single-isotope images showcasing the ability to measure three isotopes simultaneously.
Credit: Images created by SJ Zou et al., Stanford University, Stanford, CA.
New Orleans, Louisiana (June 21, 2025)—For the first time, a new PET imaging technique has successfully visualized three radiotracers in a single scan, according to findings presented at the Society of Nuclear Medicine and Molecular Imaging 2025 Annual Meeting. This innovation in multiplexed PET offers the potential to deliver a more comprehensive molecular profile of disease, enabling greater precision in both diagnosis and therapeutic assessment.
“The concept of multiplexed PET was reported more than a decade ago, but only with in the past five years have the needed radionuclides, radiochemistry, and clinical applications come together to make the approach very interesting,” said Sarah Zou, PhD candidate in electrical engineering at Stanford University in Stanford, California. “With the right tools now in place, our study utilized triplexed PET to image three isotopes in one session.”
Isotopes evaluated in the study included one pure positron emitter (18F in simulation and 64Cu in experiment) and two prompt-gamma+positron emitters (124I and 55Co). The abstract submitted in January showed success in simulation by resolving overlapping spheres of each isotope. Experimental measurements obtained with a 3x3 grid phantom containing mixtures of those three isotopes also demonstrated successful unmixing of each individual isotope (see Figure 1).
Photon coincidence data was sorted first by photon number and then by photon energy to create three listmode datasets. Researchers then used measured scaling factors to eliminate isotope crosstalk over the three datasets to recover single isotope images.
“This study demonstrates using both simulations and experiments strong potential for performing multiplexed PET with three—or even more—distinct isotopes,” stated Zou. “It offers a powerful tool for imaging biologically complex diseases like cancer that involve multiple biomarkers. By capturing this information in a single scan, we can provide clinicians with more detailed and precise insights, which may ultimately lead to improved patient outcomes.”
According to Zou, future work will focus on quantitative analysis, scatter and random corrections, and validating the triplexed PET method with more experimental data. With targeted updates to scanner hardware, firmware, and software by commercial manufacturers, this technology could become clinically viable within the next five years.
Abstract 252126. “Triplexed PET: Methods to Image Three Distinct Isotopes in a Single PET Imaging Session,” Sarah Zou, Muhammad Nasir Ullah, Derek Innes, Yug Shah, Garry Chinn, and Craig Levin, Stanford University, Stanford, California; and Hailey Houson and Suzanne Lapi, University of Alabama, Birmingham, Alabama.
Link to Abstract
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All 2025 SNMMI Annual Meeting abstracts can be found online.
About the Society of Nuclear Medicine and Molecular Imaging
The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and medical organization dedicated to advancing nuclear medicine, molecular imaging, and theranostics—precision medicine that allows diagnosis and treatment to be tailored to individual patients in order to achieve the best possible outcomes.
SNMMI’s members set the standard for molecular imaging and nuclear medicine practice by creating guidelines, sharing information through journals and meetings and leading advocacy on key issues that affect molecular imaging and therapy research and practice. For more information, visit www.snmmi.org.
Journal
Journal of Nuclear Medicine
Article Title
Triplexed PET: Methods to Image Three Distinct Isotopes in a Single PET Imaging Session