title: Subtraction SPECT for parathyroid scintigraphy based on maximization of mutual information.
abstract: Our objective was to investigate the feasibility of subtraction for SPECT images of (99m)Tc-MIBI double-phase parathyroid scintigraphy.
  
  
  METHODS
  Fourteen patients with hyperparathyroidism were enrolled in the present study. Histopathologically, excised tissue specimens showed hyperplasia in 11 patients and adenoma in 3 patients. Both ultrasonography and (99m)Tc-sestamibi (MIBI) SPECT images were obtained from all patients. As standard lines to ensure that patient positioning remained identical between the different phases, we used the cross-marker produced by a pair of laser pointers, the orbitomeatal line, and the vertical midline through the patient's nose. Data processing was performed with software that enables image registration by maximization of mutual information. The results of subtraction SPECT imaging were compared with those of ultrasonography.
  
  
  RESULTS
  The registration of double-phase SPECT images was successful in all patients when the salivary glands were excluded from the image reconstruction region. The overall sensitivities of scintigraphy and ultrasonography were 90.9% (40/44) and 70.5% (31/44), respectively, with respective specificities of 83.3% (10/12) and 75.0% (9/12). Scintigraphy and ultrasonography showed accuracies of 92.8% (52/56) and 71.4% (40/56), respectively.
  
  
  CONCLUSIONS
  The new technique used in the present study allowed the subtraction for SPECT images. The sensitivity of parathyroid lesion detection using this technique was superior to that of ultrasonography.
authors.affiliation: Department of Radiological Technology, Sumitomo Hospital, Nakanoshima, Kita-ku, Osaka, Japan. hara-narihiro@sumitomo-hp.or.jp
authors.forename: Narihiro
authors.initials: N
authors.lastname: Hara
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Takayama
authors.forename: Masahisa
authors.initials: M
authors.lastname: Onoguchi
authors.forename: Norikazu
authors.initials: N
authors.lastname: Obane
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Miyati
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yoshioka
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Minoru
authors.initials: M
authors.lastname: Honda
mesh_terms: D000328:Adult; D000368:Aged; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi