title: Intraoperative imaging guidance for sentinel node biopsy in melanoma using a mobile gamma camera.
abstract: OBJECTIVE
  To evaluate the sensitivity and clinical utility of intraoperative mobile gamma camera (MGC) imaging in sentinel lymph node biopsy (SLNB) in melanoma.
  
  
  BACKGROUND
  The false-negative rate for SLNB for melanoma is approximately 17%, for which failure to identify the sentinel lymph node (SLN) is a major cause. Intraoperative imaging may aid in detection of SLN near the primary site, in ambiguous locations, and after excision of each SLN. The present pilot study reports outcomes with a prototype MGC designed for rapid intraoperative image acquisition. We hypothesized that intraoperative use of the MGC would be feasible and that sensitivity would be at least 90%.
  
  
  METHODS
  From April to September 2008, 20 patients underwent Tc99 sulfur colloid lymphoscintigraphy, and SLNB was performed with use of a conventional fixed gamma camera (FGC), and gamma probe followed by intraoperative MGC imaging. Sensitivity was calculated for each detection method. Intraoperative logistical challenges were scored. Cases in which MGC provided clinical benefit were recorded.
  
  
  RESULTS
  Sensitivity for detecting SLN basins was 97% for the FGC and 90% for the MGC. A total of 46 SLN were identified: 32 (70%) were identified as distinct hot spots by preoperative FGC imaging, 31 (67%) by preoperative MGC imaging, and 43 (93%) by MGC imaging pre- or intraoperatively. The gamma probe identified 44 (96%) independent of MGC imaging. The MGC provided defined clinical benefit as an addition to standard practice in 5 (25%) of 20 patients. Mean score for MGC logistic feasibility was 2 on a scale of 1-9 (1 = best).
  
  
  CONCLUSIONS
  Intraoperative MGC imaging provides additional information when standard techniques fail or are ambiguous. Sensitivity is 90% and can be increased. This pilot study has identified ways to improve the usefulness of an MGC for intraoperative imaging, which holds promise for reducing false negatives of SLNB for melanoma.
authors.affiliation: Department of Surgery, University of Virginia Health Systems, Charlottesville, 22908, USA.
authors.forename: Lynn T
authors.initials: LT
authors.lastname: Dengel
authors.forename: Mitali J
authors.initials: MJ
authors.lastname: More
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Judy
authors.forename: Gina R
authors.initials: GR
authors.lastname: Petroni
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smolkin
authors.forename: Patrice K
authors.initials: PK
authors.lastname: Rehm
authors.forename: Stan
authors.initials: S
authors.lastname: Majewski
authors.forename: Mark B
authors.initials: MB
authors.lastname: Williams
authors.forename: Craig L
authors.initials: CL
authors.lastname: Slingluff
mesh_terms: D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D015902:Gamma Cameras; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008545:Melanoma / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D009367:Neoplasm Staging; D010865:Pilot Projects; D011877:Radionuclide Imaging / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000295:instrumentation* / Q000379:methods; D012878:Skin Neoplasms / Q000473:pathology* / Q000601:surgery; D018709:Statistics, Nonparametric; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome