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Intraoperative Imaging Guidance for Sentinel Node Biopsy in Melanoma Using a Mobile Gamma Camera

Dengel, Lynn T. MD*; More, Mitali J. PhD; Judy, Patricia G. PhD; Petroni, Gina R. PhD§; Smolkin, Mark E. MS§; Rehm, Patrice K. MD; Majewski, Stan PhD; Williams, Mark B. PhD†‡; Slingluff, Craig L. Jr MD

doi: 10.1097/SLA.0b013e3181f9b709
Original Articles

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.

The false-negative rate for SLNB in melanoma is approximately 17%. Real-time, intraoperative mobile gamma camera imaging in SLNB is sensitive and provides clinically useful information to improve SLNB.

*Department of Surgery.

Department of Radiology.

§Department of Biomedical Engineering.

Department of Public Health Sciences, University of Virginia Health Systems, Charlottesville.

†‡Department of Radiology; West Virginia University, Morgantown.

Reprints: Craig L. Slingluff Jr, Department of Surgery, University of Virginia Health System, PO Box 800709, Charlottesville, VA 22908. E-mail: cls8h@Virginia.EDU.

Supported in part by the National Institutes of Health Cardiovascular Surgery Research Training grant (T32 HL007849) to L.T.D. and by Jefferson Lab in Newport News, Va.

The authors have no conflicts of interest to disclose.

Financial disclosure: There are no financial disclosures to report for this manuscript.

Commercial sponsorship: There was no commercial sponsorship for this study. Jefferson Lab in Newport News, Va, provided the mobile gamma camera for the study.

L.T.D. is primary party responsible for data collection and analysis and drafting and revising of the manuscript and gave final approval for the manuscript publication. M.J.M. worked with the surgical team in the operating room to assist with data collection, in addition to contributing toward image data analysis, and contributed to the revisions of the manuscript and gave final approval for the manuscript publication. P.G.J. worked with the surgical team in the operating room to assist with data collection, in addition to contributing toward image data analysis, and contributed to the revisions of the manuscript and gave final approval for the manuscript publication. G.R.P., primary statistician, contributed significantly to the design of the study, the analysis of the data, and the results section of the manuscript, and gave final approval for the manuscript publication. M.E.S., additional statistician, contributed significantly to the analysis of the data and the drafting of the results section of the manuscript and gave final approval for the manuscript publication. P.K.R., division head of nuclear medicine, contributed significantly to the design of the study and the analysis of the gamma probe data and also participated in the revision of the manuscript and gave final approval for the manuscript publication. S.M. was responsible for the development of the customized gamma camera used in this study and contributed significantly to data collection in the operating room and also contributed to the revisions of the manuscript and gave final approval for the manuscript publication. M.B.W. contributed significantly to the design of the pilot study, including the scientific methods and logistical details, participated in the initial drafting of the manuscript and revisions, and gave final approval for the manuscript publication. C.L.S. Jr, lead investigator on the design of the study, performed all surgical cases and assisted with data collection in the operating room, participated in the initial drafting of the manuscript and revisions, and gave final approval for the manuscript publication.

© 2011 Lippincott Williams & Wilkins, Inc.