Objective:Estimationofactivityaccumulatedintumorandorgansisveryimportantinpredictingtheresponseofradiopharmaceuticalstreatment.Inthisstudy,wesynthesized177Lutetium(177Lu)-trastuzumabironoxidenanoparticlesasadoubleradiopharmaceuticalagentfortreatmentandbetterestimationoforganactivityinanewwaybymagneticresonanceimaging（MRI）.Methods:177Lu-trastuzumab-ironoxidenanoparticlesweresynthesizedandallthequalitycontroltestssuchaslabelingyield,nanoparticlesizedetermination,stabilityinbufferandbloodserumupto4d,immunoreactivityandbiodistributioninnormalmiceweredetermined.Inmicebearingbreasttumor,liverandtumoractivitieswerecalculatedwiththreemethods:singlephotonemissioncomputedtomography（SPECT）,MRIandorganextraction,whichwerecomparedwitheachother.Results:Thegoodresultsofqualitycontroltests（labelingyield:61%±2%,meannanoparticlehydrodynamicsize:41±15nm,stabilityinbuffer:86%±5%,stabilityinbloodserum:80%±3%,immunoreactivity:80%±2%）indicatedthat177Lu-trastuzumab-ironoxidenanoparticlescouldbeusedasadoubleradiopharmaceuticalagentinmicebearingtumor.Resultsshowedthat177Lu-trastuzumab-ironoxidenanoparticleswithMRIhadtheabilitytomeasureorganactivitiesmoreaccuratethanSPECT.Conclusions:Co-conjugatingradiopharmaceuticaltoMRIcontrastagentssuchasironoxidenanoparticlesmaybeagoodwayforbetterdosimetryinnuclearmedicinetreatment.
