Enhanced Cerenkov Optical 3-dimensional Reconstruction Tomography

AimThrough Cerenkov radiation energy translation effect?CRET?,Cerenkov luminescence signal could be enhanced,we explored three kinds of rare earth nanoparticles?RENPs?which possessed the CREF effect and aimed to find the most efficient one.Besides,depending on the enhanced optical signal and Cerenkov optical signal,we performed the 3-dimensional?3-D?reconstruction and tried to find the advantages of the 3-D reconstruction depending on the enhanced optical signal.Methods1.The Cerenkov effect abilities of ⁶⁸Ga and ¹⁸F-FDG were compared to choose the radionuclide with best Cerenkov effect ability.The most suitable rare earth oxide were selected to obtain the strongest Cerenkov luminescence signals in vitro by mixed ⁶⁸Ga?740k Bq?with various rare earth oxides(Gd SO,Eu₂O₃,and Y₂O₃:Eu³⁺)?10 mg/m L?separately.2.In order to found out the relationship between the enhanced optical intensity and the activities of radionuclide or the concentration of the RENPs,different activities of ⁶⁸Ga?3700 k Bq,1850 k Bq,925 k Bq,463 k Bq,231 k Bq?0 k Bq?were used to excited Y₂O₃:Eu³⁺RENPs with a fixed concentration?10 mg/m L?,and similarly,different concentrations of Y₂O₃:Eu³⁺RENPs?10.0 mg/m L,5.0 mg/m L,2.5 mg/m L,1.25 mg/m L,0.63 mg/m L and 0 mg/m L?were excited by ⁶⁸Ga with a fixed activity?3700 k Bq?.3.Two same transparent tubes respectively contained ⁶⁸Ga?370 k Bq?or ⁶⁸Ga?370 k Bq?+RENPs?1mg?were paralleled placed in the bottom of a container,different depth?1,2,3,4,5 mm?of tissue simulated liquid covered the tubes and then the optical imaging were acquired.4.Depending on the in vitro phantom models,in vivo implanted models and in vivo bladder models,the 3-D reconstruction tomography were respectively performed depending on the enhanced optical imaging or Cerenkov luminescence imaging.ANOVA and Student's t test was used for data analysis.Results1.⁶⁸Ga has stronger Cerenkov effect compared with ¹⁸F-FDG and Y₂O₃:Eu³⁺is more efficient in enhancing the Cerenkov luminescence signal than other rare earth oxides?3.67-fold,p<0.05?.2.We further found that when the concentration of the RENPs were fixed,the optical signal intensity has a robust linear relationship with the activity of the ⁶⁸Ga?R²=0.99?,and when the activity of ⁶⁸Ga was fixed,the similar relationship between the optical intensity and the concentration of the RENPs.3.By establishing the depth gradient model,we found that the penetration depth of enhanced optical signal was more than 5 mm,while the Cerenkov optical signal was less than 3 mm.4.The in vitro phantom study?0.41±0.03 vs.0.20±0.04,p<0.05?,in vivo implanted study?0.43±0.14 vs.0.16±0.06,p<0.05?and in vivo bladder study?0.49±0.02 vs.0.25±0.04,p<0.05?indicated that the enhanced optical signal could improve the accuracy of reconstruction,which providing more reliable spatial information than Cerenkov luminescence signal.ConclusionThe Y₂O₃:Eu³⁺RENPs could significantly enhance the luminescence signal of radionuclide,improve the ability of penetration of Cerenkov luminescence.The 3-D reconstruction depending on the enhanced optical signal could provide more precise spatial location information of the radionuclide such as ⁶⁸Ga than that depending on Cerenkov luminescence,which contributed to its further applications in biology radionuclide optical imaging.