title: Radiographic properties of injected calcium hydroxylapatite: potential false positive findings on positron emission tomography.
abstract: OBJECTIVE
  To describe the positron emission tomography and computed tomography features of injected calcium hydroxylapatite, and to discuss how these may be mistaken for malignancy.
  
  
  METHODS
  Positron emission tomography is now readily employed in the staging and monitoring of patients with head and neck carcinoma. Concomitant with the growing use of this modality has been the increasing popularity of injected calcium hydroxylapatite to treat glottic incompetence secondary to vocal fold paralysis or following partial laryngectomy. A patient developed aspiration following near-total laryngectomy and subsequently underwent injection of calcium hydroxylapatite, with effective resolution of the aspiration. The patient underwent positron emission tomography scanning as part of routine tumour surveillance; this showed intense tracer uptake at the site of injection, and this pattern persisted for one year following injection.
  
  
  CONCLUSIONS
  As injectable calcium hydroxylapatite becomes more widely used, especially in the treatment of patients with a history of head and neck cancer, physicians should be aware it may cause a potentially misleading, false positive positron emission tomography finding.
authors.affiliation: Division of Laryngology, Department of Otolaryngology/Head and Neck Surgery, Stanford University Medical Center, Stanford, California, USA. edamrose@stanford.edu
authors.forename: E J
authors.initials: EJ
authors.lastname: Damrose
mesh_terms: D000368:Aged; D001672:Biocompatible Materials; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000601:surgery*; D017886:Durapatite; D005189:False Positive Reactions; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007825:Laryngectomy / Q000009:adverse effects; D008297:Male; D049268:Positron-Emission Tomography / Q000009:adverse effects* / Q000295:instrumentation; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D051598:Whole Body Imaging / Q000009:adverse effects / Q000295:instrumentation
chemical_list: D001672:Biocompatible Materials; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D017886:Durapatite