title: 3-phase dual-energy CT scan as a feasible salvage imaging modality for the identification of non-localizing parathyroid adenomas: a prospective study.
abstract: OBJECTIVE
  Accurate pre-operative imaging of parathyroid adenomas (PAs) is essential for successful minimally invasive surgery; however, rates of non-localizing PAs can be as high as 18 %. Multiphasic dual-energy CT (DECT) has the potential to increase accuracy of PA detection by enabling creation of paired material maps and spectral tissue characterization. This study prospectively evaluated the utility of 3-phase DECT for PA identification in patients with failed localizatio n via standard imaging.
  
  
  METHODS
  Patients with primary hyperparathyroidism and non-localizing PAs underwent a 3 phase post-contrast DECT scan acquired at 25, 55, and 85 s. The scans were prospectively evaluated by two head and neck radiologists. Pre-operative localization was compared to intraoperative localization and final histopathology. A post-hoc DECT spectral density characterization was performed on pathologically-proven PAs.
  
  
  RESULTS
  Out of 29 patients with primary hyperparathyroidism and non-localized PAs, DECT identified candidates in 26. Of the 23 patients who underwent parathyroidectomy, DECT provided precise anatomic localization in 20 patients (PPV = 87.0%), one with multi-gland disease. The virtual unenhanced images were not found to be useful for diagnosis but successful diagnosis was made without an unenhanced phase regardless. Spectral analysis demonstrated a distinct spectral Hounsfield attenuation curve for PAs compared to lymph nodes on arterial phase images.
  
  
  CONCLUSIONS
  3-phase DECT without an unenhanced phase is a feasible salvage imaging modality for previously non-localizing parathyroid adenomas. Optimal interpretation is achieved based on a combination of perfusion characteristics and other morphologic features. Advanced spectral DECT analysis has the potential for further increasing accuracy of PA identification in the future.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Roskies
authors.affiliation: Department of Radiology, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hier
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Payne
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Mlynarek
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Veronique
authors.initials: V
authors.lastname: Forest
authors.affiliation: Department of Radiology, Jewish General Hospital & McGill University, Montreal, Quebec, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Levental
authors.affiliation: Department of Radiology, Jewish General Hospital & McGill University, Montreal, Quebec, Canada. rforghani@jgh.mcgill.ca.|Segal Cancer Centre and Lady Davis Institute for Medical Research, Jewish General Hospital & McGillUniversity, Montreal, Quebec, Canada. rforghani@jgh.mcgill.ca.
authors.forename: Reza
authors.initials: R
authors.lastname: Forghani
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000601:surgery; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D061330:Multidetector Computed Tomography / Q000379:methods*; D010282:Parathyroid Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D016105:Parathyroidectomy / Q000379:methods; D057234:Preoperative Period; D011446:Prospective Studies; D015203:Reproducibility of Results