Comparison of the uptake of ¹⁸F-NaF and ¹⁸F-FDG in apoE knock-out mice

Objectives To examine the uptake of the tracers ¹⁸F-NaF and ¹⁸F-FDG in a mouse model of atherosclerosis in order to determine if the uptake of tracers reflects the same elements of atherogenesis.

Methods Fourteen apolipoprotein E knock-out (apoE^-/-) mice were divided into two groups. One group received normal chow (N=8) for 31-32 weeks; the other group received a high-fat diet (N=6) for 31-32 weeks. Within the same week, the mice were scanned with ¹⁸F-NaF and ¹⁸F-FDG using a dedicated animal PET scanner. Furthermore, the animals were CT scanned (contrast enhanced). The tracer uptake in the aorta was measured and reported as SUV-values. Unpaired t-test and correlation analysis were used to evaluate the results.

Results The uptake of both ¹⁸F-NaF and ¹⁸F-FDG was increased in the aortas of apoE^-/- mice on high-fat diet compared to mice on normal chow (¹⁸F-NaF, 94% increase, p<0.001; ¹⁸F-FDG, 85% increase, p<0.01). However, only a weak correlation was found between the uptake of the two PET tracers (R²= 0.32; P=0.04).

Conclusions The results indicate that although the uptake of both ¹⁸F-NaF and ¹⁸F-FDG was upregulated with increased atherosclerosis, the two tracers seem to reflect different elements of the pathogenesis of atherosclerosis. Further studies involving immunohistochemistry and autoradiography are needed to substantiate these results.