THE SIGNIFICANCE OF THREE PHASE BONE SCINTIGRAPHY AND 99MTC-HMPAO LABELED LEUKOCYTE SCINTIGRAPHY IN DIFFERENTIATING BETWEEN INFLAMMATION FROM ASEPTIC LOOSING OF HIP AND KNEE JOINT ENDOPROSTHESES AND THE CONTRIBUTION OF HYBRID SPECT / “LOW DOSE” CT TECHNIQUE

Upala ili aseptičko labavljenje endoproteze zgloba najčešće se javlja nekoliko mjeseci ili godina nakon prvotne kirurške ugradnje zgloba te se smatra se dugoročnom komplikacijom koja se razvija postupno tijekom vremena. Upala zglobnih endoproteza može se javiti u bilo kojoj dobi nakon operacije zamjene zgloba, najčešće u osoba starijih od 60 godina, najvjerojatnije zato što stariji pacijenti imaju slabiji imunološki sustav i smanjenu sposobnosti zacjeljivanja tkiva što povećava rizik od upale. Vrijeme od ugradnje endoproteze može biti značajno u razvoju upale zglobnih endoproteza jer omogućuje postupno trošenje endoproteza, što rezultira otpuštanjem čestica i krhotina iz materijala implantata. Tijekom vremena, ove čestice mogu potaknuti upalni odgovor u okolnim tkivima, što dovodi do upale ili aseptičkog labavljenja endoproteze. Osnovni kriterij uključenja u ovo istraživanje pozitivan je nalaz troetapne scintigrafije skeleta u sve tri faze snimanja koja može ukazivati na upalu ili aseptičko labavljenje. Nakon toga indicirana je scintigrafija s obilježenim leukocitima kako bi se ova dva stanja mogla razlikovati. Upravo rano difuzno nakupljanje, a potom i intenzivnije kasno nakupljanje obilježenih leukocita govori u prilog upalnom procesu. S druge strane, kada se govori o fokalnom nakupljanju aktivnosti, to više ide u prilog aseptičkom labavljenju. Hibridno SPECT/ niskodozno CT snimanje dodatno razlučuje upalu u koštanom tkivu od mekotkivne upale.Inflammation or aseptic loosening of the joint endoprosthesis most commonly occurs several months or years after the initial joint replacement surgery. It is considered a long-term complication that can develop gradually over time. Inflammation of joint endoprostheses is the most frequent in individuals over the age of 60. This is due to weaker immune system of older patients and slower healing abilities which can increase the risk of inflammation. The time from the insertion of the endoprosthesis can be significant in the development of joint endoprosthesis inflammation since it allows gradual damage of the endoprosthesis, resulting in the release of particles and debris from the implant material. Over time, these particles can trigger an inflammatory response in the surrounding tissues, leading to inflammation or aseptic loosening of the endoprosthesis. The basic criterion for inclusion in this research is a positive finding of three-phase bone scintigraphy in all three phases of imaging, which may indicate inflammation or aseptic loosening. Scintigraphy with marked leukocytes plays a significant role in distinguishing these two conditions. The early diffuse accumulation and then the more intense late accumulation of labeled leukocytes, indicates an inflammatory process. On the other hand, when focal accumulation is present aseptic loosening is primary diagnosis. Hybrid SPECT/low-dose CT imaging additionally differentiates inflammation in bone tissue from soft tissue inflammation