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Quantitative Imaging Of Yttrium-86 Pet with the Ecat Exact Hr + In 2D Mode

2004; Mary Ann Liebert, Inc.; Volume: 19; Issue: 4 Linguagem: Inglês

10.1089/cbr.2004.19.482

1557-8852

Thomas Kull, Jochen Ruckgaber, Rolf Weller, Sven N. Reske, Gerhard Glatting,

Advanced MRI Techniques and Applications

The radionuclide 86Y potentially allows for the precise assessment of tissue radioactivity biodistribution and, thus, extrapolation of a therapeutic dose of 90Y-labeled compounds. A method to obtain quantitative images from 86Y-PET measurements after a background correction and a recalibration is presented. Cylinder and body phantom measurements with 18F and 86Y using an ECAT EXACT HR+ tomograph were performed in 2D mode. A second-order series expansion is used to correct for the background of spurious coincidences in the sinogram. A recalibration of the positron emission tomography (PET) system, depending on the ratio of true coincidences and singles, is implemented. The correction for the nonannihilation coincidences with a second-order series expansion significantly improves the accuracy of quantitation: The lesion-to-background ratio is reproduced, and the variation of the activity concentration in the homogeneous background regions of the phantoms is smaller than 5%. The apparent activities in cold inserts of various densities is reduced to less than 15% of the concentration in the active region. The recalibration of the system works with a relative error of 0.2% ± 2.4%. In conclusion, the used approximations lead to improved uniformity and quantitative accuracy in 86Y-PET measurements with the ECAT EXACT HR+.