title: Imaging appearance of dextranomer/hyaluronic acid copolymer implant injections for treatment of velopharyngeal insufficiency.
abstract: OBJECTIVE
  Dextranomer/hyaluronic acid copolymer implants are used in treating velopharyngeal insufficiency. These posterior nasopharyngeal implants can be mistaken for pathologic conditions such as retropharyngeal abscess on imaging. We studied the imaging appearance of dextranomer/hyaluronic acid copolymer implants in patients treated for velopharyngeal insufficiency.
  
  
  METHODS
  A consecutive series of patients with velopharyngeal insufficiency treated with dextranomer/hyaluronic acid copolymer were included in this study. Data on patient characteristics and volume of dextranomer/hyaluronic acid copolymer injected were obtained. Postoperative imaging characteristics on plain radiography, CT, and MR imaging were assessed. The imaging appearance of postoperative complications was determined.
  
  
  RESULTS
  Sixteen patients were included in this study. Seven patients underwent postoperative plain radiographs, 5 patients underwent CT, and 9 patients underwent MR imaging. Plain radiographs demonstrated soft-tissue swelling in the retropharyngeal space, which resolved at 1 month. On CT, dextranomer/hyaluronic acid copolymer implants appeared as bilateral nasopharyngeal soft-tissue masses isoattenuated to hypoattenuated relative to muscle in 80% (4/5) of patients. On MR imaging, dextranomer/hyaluronic acid copolymer implants appeared as bilateral nasopharyngeal soft-tissue masses that were isointense to muscle on T1 (8/9, 88.9%) and hyperintense to muscle on T2 (8/9, 88.9%) and demonstrated no restricted diffusion (4/4, 100.0%) or peripheral enhancement (7/7, 100.0%).
  
  
  CONCLUSIONS
  The normal postoperative findings of posterior nasopharyngeal dextranomer/hyaluronic acid copolymer injection on MR imaging is characterized by the presence of bilateral nasopharyngeal soft-tissue masses that are isointense to muscle on T1 and hyperintense on T2, with no restricted diffusion or peripheral enhancement. Velopharyngeal dextranomer/hyaluronic acid copolymer implants are iso- to hypoattenuated to muscle on CT and are not visible radiographically once associated implantation-related swelling has resolved.
authors: From the Departments of Radiology (W.B., J.I.L.) brinjikji.waleed@mayo.edu.
authors: W
authors: W
authors: Brinjikji
authors: Otorhinolaryngology (S.A.C.), Mayo Clinic, Rochester, Minnesota.
authors: S A
authors: SA
authors: Cofer
authors: From the Departments of Radiology (W.B., J.I.L.).
authors: J I
authors: JI
authors: Lane
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003911:Dextrans / Q000008:administration & dosage*; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage*; D007267:Injections; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis*; D019736:Prostheses and Implants; D017703:Retropharyngeal Abscess / Q000175:diagnosis; D014057:Tomography, X-Ray Computed; D014681:Velopharyngeal Insufficiency / Q000175:diagnosis* / Q000601:surgery*; D055815:Young Adult
chemical_list: D003911:Dextrans; C487487:dextranomer-hyaluronic acid copolymer; D006820:Hyaluronic Acid