Reproducibility of Static and Dynamic 18F-FDG, 18F-FLT, and 18F-FMISO MicroPET Studies in a Murine Model of HER2+ Breast Cancer

Purpose

The objective of this study is to determine the reproducibility of static 2-deoxy-2-[¹⁸F]fluoro-D-glucose (¹⁸F-FDG), 3′-deoxy-3′-[¹⁸F]fluorothymidine (¹⁸F-FLT), and [¹⁸F]-fluoromisonidazole (¹⁸F-FMISO) microPET measurements, as well as kinetic parameters returned from analyses of dynamic ¹⁸F-FLT and ¹⁸F-FMISO data.

Procedures

HER2+ xenografts were established in nude mice. Dynamic data were acquired for 60 min, followed by a repeat injection and second scan 6 h later. Reproducibility was assessed for the percent-injected dose per gram (%ID/g) for each radiotracer, and with kinetic parameters (K ₁ –k ₄ , K _i ) for ¹⁸F-FLT and ¹⁸F-FMISO.

Results

The value needed to reflect a change in tumor physiology is given by the 95 % confidence interval (CI), which is ±14, ±5, and ±6 % for ¹⁸F-FDG (n?=?12), ¹⁸F-FLT (n?=?11), and ¹⁸F-FMISO (n?=?11) %ID/g, respectively. V _d (=K ₁ /k ₂), k ₃, and K _FLT are the most reproducible ¹⁸F-FLT (n?=?9) kinetic parameters, with 95 % CIs of ±18, ±10, and ±18 %, respectively. V _d and K _FMISO are the most reproducible ¹⁸F-FMISO kinetic parameters (n?=?7) with 95 % CIs of ±16 and ±14 %, respectively.

Conclusions

Percent-injected dose per gram measurements are reproducible and appropriate for detecting treatment-induced changes. Kinetic parameters have larger threshold values, but are potentially sufficiently reproducible to detect treatment response.