title: Diagnostic dilemmas in parathyroid scintigraphy.
abstract: OBJECTIVE
  Tc-99m MIBI scintigraphy can be useful for preoperative localization of parathyroid adenomas, despite its limited sensitivity. To refine interpretation, the authors conducted prospective reviews of the scintigraphic studies of patients with concomitant thyroid nodular disease and revised the false-negative and false-positive results.
  
  
  METHODS
  Seventy-seven patients with primary hyperparathyroidism, associated with a solitary parathyroid adenoma, underwent dual-phase MIBI scintigraphy with subsequent injection of Tc-99m pertechnetate before surgery. The false-negative and false-positive scintigraphic findings were identified and revised.
  
  
  RESULTS
  After surgery, revision of 19 false-negative scans of the total 77 studies led to the demonstration of an adenoma in seven patients. In five of the seven studies, the adenoma had been overlooked as a result of rapid tracer washout. Two additional small focal lesions would have also been identified if subtraction had been used for differences in contour of the MIBI and pertechnetate images. Four studies were interpreted falsely as abnormal, leading to a positive predictive value of 91%; three were associated with thyroid nodular disease.
  
  
  CONCLUSIONS
  Differential washout of MIBI from thyroid and parathyroid tissue is not universal. When MIBI is washed out rapidly from parathyroid adenomas, subtraction of a thyroid image should be performed and differences in contour delineated to localize the adenoma accurately. Some, but not all, thyroid lesions account for the false-positive findings.
authors.affiliation: Department of Nuclear Medicine, Hadassah University Hospital, Jerusalem, Israel. yodphat@hadassah.org.il
authors.forename: Y
authors.initials: Y
authors.lastname: Krausz
authors.forename: E
authors.initials: E
authors.lastname: Shiloni
authors.forename: M
authors.initials: M
authors.lastname: Bocher
authors.forename: S
authors.initials: S
authors.lastname: Agranovicz
authors.forename: B
authors.initials: B
authors.lastname: Manos
authors.forename: R
authors.initials: R
authors.lastname: Chisin
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging*; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D006961:Hyperparathyroidism / Q000000981:diagnostic imaging*; D010280:Parathyroid Glands / Q000000981:diagnostic imaging; D010282:Parathyroid Neoplasms / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D017256:Technetium Tc 99m Sestamibi
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi