title: Retrospective analysis of postinjection ultrasound imaging after platelet-rich plasma or autologous blood: observational review of anatomic distribution of injected material.
abstract: OBJECTIVE
  Characterization of the distribution and imaging characteristics of platelet-rich plasma (PRP) and autologous blood after injection is currently limited despite the growing use. We sought to improve understanding of the distribution of PRP or autologous blood after it has been injected into a tendon to evaluate whether injected materials truly stayed within the local region of injection.
  
  
  METHODS
  Fifty ultrasound-guided PRP or autologous blood injections performed for tendinopathy were retrospectively reviewed. Consensus review of the imaging data was performed by two radiologists to characterize the distribution of the injectate (i.e., within the tendon, along the tendon sheath, along the paratenon, or leakage into the adjacent joint or surrounding soft tissues). The presence of fluid and microbubbles from the injectate served as an indicator of material distribution.
  
  
  RESULTS
  Image review verified the injectate within the tendon in 100% of cases. In 98% of reviewed cases, injected PRP or autologous blood dissected beyond the local injection site (defined as >2 cm from the site of injection) and was identified in adjacent soft tissues in 51% of cases. Visualization of injectate along a paratenon or tendon sheath (when applicable) was seen in 86% and 100% of cases respectively; however, intraarticular extension was uncommon (8%).
  
  
  CONCLUSIONS
  Our study showed that postinjection imaging may be of value in assessing the anatomic distribution of injectate after intratendinous therapy. Furthermore, our initial review found that in the majority of cases injected blood products tended to distribute beyond the local area of injection.
authors.affiliation: Department of Radiology, New York-Presbyterian Hospital/Weill Cornell Medical College, New York, NY 10016, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Loftus
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Endo
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Adler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001769:Blood; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D053657:Platelet-Rich Plasma / Q000000981:diagnostic imaging*; D052256:Tendinopathy / Q000000981:diagnostic imaging* / Q000628:therapy*; D013710:Tendons / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D055815:Young Adult