Comparison of HRRT and HR+ Scanners

Purpose: To directly compare HRRT (high resolution brain) and HR+ (standard wholebody) PET only scanners for quantitative brain studies using three tracers with vastly different tracer distributions. Procedures: Healthy volunteers underwent successive scans on HR+ and HRRT scanners (in random order) using either (R)-[C]verapamil (n=6), [C]raclopride (n=7) or [C]flumazenil (n=7). For all tracers metabolite-corrected plasma input functions were generated. Results: After resolution matching, HRRT derived kinetic parameter values correlated well with those of HR+ for all tracers (intra-class correlation coefficients ≥0.78), having a good absolute interscanner test-retest variability (≤15%). However, systematic differences can be seen for HRRT derived kinetic parameter values (range: -13 to +15%). Conclusion: Quantification of kinetic parameters based on plasma input models leads to comparable results when spatial resolution between HRRT and HR+ data is matched. When using reference tissue models differences remain that are likely caused by differences in attenuation and scatter corrections and/or image reconstruction.