title: Radioembolization and the Dynamic Role of (90)Y PET/CT.
abstract: Before the advent of tomographic imaging, it was postulated that decay of (90) Y to the 0(+) excited state of (90)Zr may result in emission of a positron-electron pair. While the branching ratio for pair-production is small (~32 × 10(-6)), PET has been successfully used to image (90) Y in numerous recent patients and phantom studies. (90) Y PET imaging has been performed on a variety of PET/CT systems, with and without time-of-flight (TOF) and/or resolution recovery capabilities as well as on both bismuth-germanate and lutetium yttrium orthosilicate (LYSO)-based scanners. On all systems, resolution and contrast superior to bremsstrahlung SPECT has been reported. The intrinsic radioactivity present in LYSO-based PET scanners is a potential limitation associated with accurate quantification of (90) Y. However, intrinsic radioactivity has been shown to have a negligible effect at the high activity concentrations common in (90) Y radioembolization. Accurate quantification is possible on a variety of PET scanner models, with or without TOF, although TOF improves accuracy at lower activity concentrations. Quantitative (90) Y PET images can be transformed into 3-dimensional (3D) maps of absorbed dose based on the premise that the (90) Y activity distribution does not change after infusion. This transformation has been accomplished in several ways, although the most common is with the use of 3D dose-point-kernel convolution. From a clinical standpoint, (90) Y PET provides a superior post-infusion evaluation of treatment technical success owing to its improved resolution. Absorbed dose maps generated from quantitative PET data can be used to predict treatment efficacy and manage patient follow-up. For patients who receive multiple treatments, this information can also be used to provide patient-specific treatment-planning for successive therapies, potentially improving response. The broad utilization of (90) Y PET has the potential to provide a wealth of dose-response information, which may lead to development of improved radioembolization treatment-planning models in the future.
authors.affiliation: The University of Tennessee Medical Center , Knoxville, TN , USA ; The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Pasciak
authors.affiliation: The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA.
authors.forename: Austin C
authors.initials: AC
authors.lastname: Bourgeois
authors.affiliation: Mayo Clinic , Jacksonville, FL , USA.
authors.forename: J Mark
authors.initials: JM
authors.lastname: McKinney
authors.affiliation: The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA ; University of Virginia Medical Center , Charlotte, VA , USA.
authors.forename: Ted T
authors.initials: TT
authors.lastname: Chang
authors.affiliation: The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA.
authors.forename: Dustin R
authors.initials: DR
authors.lastname: Osborne
authors.affiliation: The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA.
authors.forename: Shelley N
authors.initials: SN
authors.lastname: Acuff
authors.affiliation: The University of Tennessee Graduate School of Medicine , Knoxville, TN , USA.
authors.forename: Yong C
authors.initials: YC
authors.lastname: Bradley
keywords: 90 Y PET; post-treatment imaging; quantitative imaging; radioembolization; radioembolization dosimetry