title: Parathyroid imaging: the importance of pinhole collimation with both single- and dual-tracer acquisition.
abstract: Our objective was to rigorously compare pinhole and parallel-hole collimation in an intrapatient, intrastudy design in 2 parathyroid imaging protocols: the first was dual-phase (99m)Tc-sestamibi imaging, and the second was dual-phase (99m)Tc-sestamibi plus dual-tracer ((99m)Tc-sestamibi and (123)I) simultaneous-acquisition subtraction imaging.
  
  
  METHODS
  Thirty-three patients with 37 surgically proven nonectopic parathyroid adenomas were evaluated. Anterior pinhole and parallel-hole images of the neck were available for (99m)Tc-sestamibi at 15 min and 3 h, and for simultaneously acquired (99m)Tc-sestamibi and (123)I subtraction at 15 min, all from a single study. The images were modified so that all had a square border and so that the thyroid filled approximately three quarters of the image. The images were evaluated by 2 experienced nuclear medicine physicians who did not know the surgical results or whether the images were acquired with pinhole or parallel-hole collimation. The observers indicated the location of any identified adenoma and graded the certainty of diagnosis on a 3-point scale.
  
  
  RESULTS
  The localization success rate for the 2 observers combined for the single-tracer dual-phase images was 66.2% with pinhole collimation and 43.2% with parallel-hole collimation (P < 0.0001). The localization success rate with the addition of the dual-tracer simultaneous-acquisition subtraction image was 83.8% with pinhole collimation and 62.2% with parallel-hole collimation (P = 0.0018). In addition, the degree of certainty of localization was greater with pinhole collimation with both imaging protocols (P < 0.001 in both cases).
  
  
  CONCLUSIONS
  In the anterior projection, pinhole collimation is superior to parallel-hole collimation for parathyroid imaging with either dual-phase (99m)Tc-sestamibi or dual-phase (99m)Tc-sestamibi plus dual-tracer ((99m)Tc-sestamibi and (123)I) simultaneous-acquisition subtraction.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, University of Colorado School of Medicine, Aurora, CO 80113, USA. william.klingensmith@ucdenver.edu
authors.forename: William C
authors.initials: WC
authors.lastname: Klingensmith
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Koo
authors.forename: Adam
authors.initials: A
authors.lastname: Summerlin
authors.forename: Bradley W
authors.initials: BW
authors.lastname: Fehrenbach
authors.forename: Ramesh
authors.initials: R
authors.lastname: Karki
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Shulman
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Raeburn
authors.forename: Robert C
authors.initials: RC
authors.lastname: McIntyre
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000000981:diagnostic imaging* / Q000601:surgery; D011849:Radioactive Tracers; D011877:Radionuclide Imaging / Q000379:methods*; D013382:Subtraction Technique; D017256:Technetium Tc 99m Sestamibi
chemical_list: D007457:Iodine Radioisotopes; D011849:Radioactive Tracers; D017256:Technetium Tc 99m Sestamibi
keywords: dual-tracer subtraction; parathyroid imaging; pinhole collimator