Abstract
The goal of this study was to validate the use of a magnetic resonance-compatible blood sampler (BS) with the detector system based on lutetium oxyorthosilicate scintillator and avalanche photodiodes for small animal positron emission tomography (PET). Methods: Five rats underwent a 60 min 18F-FDG study. For each animal, the arterial input function (AIF) was derived from the BS recording, from manual blood sampling (MS) and from the PET image. These AIFs were used for kinetic modelling of the striatum using the two tissue irreversible compartment model. The MS-based technique with a dispersion correction served as a reference approach and the kinetic parameters (KPs) estimated with the BS- and the image-derived (ID) AIFs were compared to the reference values. Additionally, the effect of applying a population-based plasma versus whole blood activity ratio (p/wb) and the dispersion correction were assessed. Results: The K1, k2 and k3 values estimated with the reference approach were 0.174±0.037 mL/min/cm3, 0.342±0.080 1/min and 0.048±0.009 1/min, respectively. The corresponding parameters obtained with the BS- and ID-AIFs deviated from these values by 0.6-18.8 % and 16.7-47.9 %, respectively. To compensate for the error in the BS-based technique, data from one blood sample manually collected at the end of the experiment were combined with the data from the first 10 min of the BS recording. This approach allowed reducing the deviation in the KPs to 1.8-6.3 %. Using the p/wb ratio led to the 1.7-8.3 % difference from the reference parameters. The sensitivity of the BS was 23 %, the energy resolution for the 511 keV photo peak was 19 % and the timing resolution was 11.2 ns. Conclusion: Online recording of the blood activity level with the BS allows precise measurement of the AIF, without losing the blood volume. Combining the BS data with one manually collected blood sample is the most accurate approach for the data analysis. The high sensitivity of the device may allow applying lower radioactivity doses.
- Animal Imaging
- PET
- Radiotracer Tissue Kinetics
- PET
- arterial input function
- blood sampler
- kinetic modelling
- Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.