title: Detecting near-the-injection-site sentinel nodes in head and neck melanomas with a high-resolution portable gamma camera.
abstract: BACKGROUND
  In head/neck melanomas, near-the-injection-site sentinel nodes (NIS-SNs) may be missed on planar lymphoscintigraphy and/or SPECT/CT. The aim of the present study is to establish the performance of a portable gamma camera (PGC) to detect NIS-SNs in a simulation phantom set-up, and subsequently in head/neck melanoma patients scheduled for a SN procedure.
  
  
  METHODS
  Five plastic Eppendorf tubes filled with technetium-99m-albumin nanocolloid were used to simulate 4 radiotracer deposit sites, as traditionally injected in melanoma patients, and 1 NIS-SN. A PGC was used with 2 pinhole collimators (2.5 and 4.0 mm). Image acquisition time was 1 minute with the camera positioned at various distances (range 1.5-15.5 cm). Results were compared with conventional lymphoscintigraphy and SPECT/CT acquired with a dual-head gamma camera as well with a gamma probe. Additionally, the same PGC setting was used in a case series of 3 patients with head/neck melanomas.
  
  
  RESULTS
  The simulated NIS-SN was differentiated from the injection site at a distance of 3 mm with the 2.5-mm pinhole and at 5 mm with the 4-mm pinhole when the PGC was positioned at 1.5 cm distance. Planar lymphoscintigraphy, SPECT/CT, and the gamma probe depicted the NIS-SN separated from the injection site at distances of 7, 10, and 22 mm, respectively. In all 3 patients, 6 NIS-SNs were depicted with the PGC.
  
  
  CONCLUSIONS
  A high-resolution PGC, positioned close to the skin, is able to detect SNs at distances of at least 3 mm from the injection site. A further clinical evaluation of this device to establish its added value in reducing false-negative procedures and potential recurrences is necessary.
authors.affiliation: From the *Technical Medicine, Faculty of Science and Technology, University of Twente, Enschede; †Department of Nuclear Medicine, The Netherlands Cancer Institute, Amsterdam; and ‡Department of Head and Neck Surgery and Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Daan
authors.initials: D
authors.lastname: Hellingman
authors.forename: Linda J
authors.initials: LJ
authors.lastname: de Wit-van der Veen
authors.forename: W Martin C
authors.initials: WM
authors.lastname: Klop
authors.forename: Renato A Valdés
authors.initials: RA
authors.lastname: Olmos
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D015902:Gamma Cameras; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology; D064847:Multimodal Imaging; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013668:Technetium Tc 99m Aggregated Albumin; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; C083602:technetium Tc 99m nanocolloid