Evaluation of the Genisys4, a Bench-Top Preclinical PET Scanner

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Abstract
The Genisys4 is a small bench-top preclinical PET scanner designed to enable imaging in biology, biochemistry, and pharmacology laboratories and imaging centers. Here, we compare its performance with that of a well-established preclinical PET scanner. Methods: Subcutaneous and lung tumor xenografts were used to compare lesion detectability and treatment responses to chemotherapy (gemcitabine) using 18F-FDG PET. The size of subcutaneous xenografts (L1210 and L1210-10K leukemia cells) and lung metastases (B-16 melanoma cells) was measured on small-animal CT images. Tumor 18F-FDG uptake was expressed as percentage injected dose per gram. Using list-mode data, serial images of the left ventricular blood pool were used to generate time–activity curves. Results: Subcutaneous xenografts (range, 4–12 mm; mean ± SD, 6.1 ± 1.7 mm) and lung metastases (range, 1–5 mm; mean, 2.1 ± 1.2 mm) were detected equally well with both scanners. Tumor 18F-FDG uptake measured with both scanners was highly correlated for subcutaneous xenografts (r2 = 0.93) and lung metastases (r2 = 0.83). The new Genisys4 scanner and the established scanner provided comparable treatment response information (r2 = 0.93). Dynamic imaging sequences permitted the generation of left ventricular blood-pool time–activity curves with both scanners. Conclusion: Using subcutaneous and lung xenografts, a novel and an established preclinical PET scanner provided equivalent information with regard to lesion detection, tumor 18F-FDG uptake, tumor response to treatment, and generation of time–activity curves. Thus, the Genisys4 provides a small, efficient bench-top preclinical PET alternative for quantitatively studying murine tumor models in biology, biochemistry, and pharmacology laboratories and preclinical imaging centers.