Clinical feasibility of 90Y digital PET/CT for imaging microsphere biodistribution following radioembolization.
PURPOSE
The purpose of this study was to evaluate the clinical feasibility of next generation solid-state digital photon counting PET/CT (dPET/CT) technology and imaging findings in patients following 90Y microsphere radioembolization in comparison with standard of care (SOC) bremsstrahlung SPECT/CT (bSPECT/CT).


METHODS
Five patients underwent SOC 90Y bremsstrahlung imaging immediately following routine radioembolization with 3.5 ± 1.7 GBq of 90Y-labeled glass microspheres. All patients also underwent dPET/CT imaging at 29 ± 11 h following radioembolization. Matched pairs comparison was used to compare image quality, image contrast and 90Y biodistribution between dPET/CT and bSPECT/CT images. Volumetric assessments of 90Y activity using different isocontour thresholds on dPET/CT and bSPECT/CT images were also compared.


RESULTS
Digital PET/CT consistently provided better visual image quality and 90Y-to-background image contrast while depicting 90Y biodistribution than bSPECT/CT. Isocontour volumetric assessment using a 1% threshold precisely outlined 90Y activity and the treatment volume on dPET/CT images, whereas a more restrictive 20% threshold on bSPECT/CT images was needed to obtain comparable treatment volumes. The use of a less restrictive 10% threshold isocontour on bSPECT/CT images grossly overestimated the treatment volume when compared with the 1% threshold on dPET/CT images.


CONCLUSIONS
Digital PET/CT is clinically feasible for the assessment of 90Y microsphere biodistribution following radioembolization, and provides better visual image quality and image contrast than routine bSPECT/CT with comparable acquisition times. With further optimization and clinical validation, dPET technology may allow faster and more accurate imaging-based assessment of 90Y microsphere biodistribution.
['Wright|Chadwick L|CL|', 'Binzel|Katherine|K|', 'Zhang|Jun|J|', 'Wuthrick|Evan J|EJ|', 'Knopp|Michael V|MV|']
D004621:Embolization, Therapeutic D005240:Feasibility Studies D006801:Humans D008863:Microspheres D000072078:Positron Emission Tomography Computed Tomography D014018:Tissue Distribution D015021:Yttrium Radioisotopes
Digital PET/CT 90Y microsphere radioembolization Assessment of biodistribution