title: Novel handheld PET probes provide intraoperative localization of PET-avid lymph nodes.
abstract: BACKGROUND
  The accurate intraoperative localization of malignant nodes can pose a challenge to the surgical oncologist. Positron emission tomography (PET) scanning has significantly increased our ability to detect suspicious lesions. We investigated the ability of a novel, handheld tool to evaluate suspicious nodes intraoperatively and to correlate its findings with those seen on preoperative PET scan.
  
  
  METHODS
  Ten nude rats were inoculated with a lymphogenic mesothelioma tumor line and followed weekly with PET scan studies. When suspicious lymph nodes were found, animals were dissected and the intraoperative amount of tissue radiation was analyzed as "tumor-to-background ratio" (TBR) using the PET probes.
  
  
  RESULTS
  The intraoperative probe was used to guide dissections and select high-risk nodes based on their specific radiotracer uptake. A total of 52 nodes were harvested; eight of these were suspicious on preoperative PET scan studies. Using a TBR of 2.5, the intraoperative probes were able to localize all suspicious nodes previously seen on PET scan. Both gamma (sensitivity: 100%; specificity: 86%; positive predictive value (PPV): 57%; negative predictive value (NPV): 100%) and beta (sensitivity: 88%; specificity: 91%; PPV: 64%; NPV: 98%) probes showed an excellent area under the curve (AUC) in the receiver operating characteristic analysis (ROC). Both probes had an AUC of 0.95 for localizing suspicious nodes on PET scan. Furthermore, the AUC for detecting malignancy for the gamma probe was 0.90 (95% confidence interval (CI), 0.83-0.99), and for the beta probe it was 0.97 (95% CI, 0.94-1.0), suggesting a better performance of the beta probe for detecting malignancy.
  
  
  CONCLUSIONS
  This novel tool may be used synergistically with the PET scan examination to maximize intraoperative nodal selection and sampling.
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Segundo J
authors.initials: SJ
authors.lastname: González
authors.forename: Joyce
authors.initials: J
authors.lastname: Wong
authors.forename: Lorena
authors.initials: L
authors.lastname: González
authors.forename: Peter
authors.initials: P
authors.lastname: Brader
authors.forename: Maureen
authors.initials: M
authors.lastname: Zakowski
authors.forename: Mithat
authors.initials: M
authors.lastname: Gönen
authors.forename: Yuman
authors.initials: Y
authors.lastname: Fong
authors.forename: Vivian E
authors.initials: VE
authors.lastname: Strong
mesh_terms: D000818:Animals; D019788:Fluorodeoxyglucose F18; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging* / Q000473:pathology; D008654:Mesothelioma / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D011237:Predictive Value of Tests; D012372:ROC Curve; D011859:Radiography; D019275:Radiopharmaceuticals; D051381:Rats; D011923:Rats, Nude; D012680:Sensitivity and Specificity; D014183:Transplantation, Heterologous
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18