title: A novel method to localize antibody-targeted cancer deposits intraoperatively using handheld PET beta and gamma probes.
abstract: BACKGROUND
  Assessing cancer margins, lymph nodes, and small cancer deposits intraoperatively can be challenging. A new device has become available that allows the detection of positron emission tomography (PET) radiotracers through both high-energy gamma and short-range beta emissions. These PET probes are handheld, allowing for real-time evaluation of cancer using a tool that provides surgeons with better intraoperative assessment of tumor sites.
  
  
  METHODS
  Within the context of two institutional review board (IRB)-approved protocols investigating new applications of antibody-labeled PET scanning, (124)I-labeled humanized monoclonal antibodies specific for colorectal cancer (huA33) and renal tumors (cG250) were constructed. Patients underwent preoperative PET scans, approximately seven days post-tracer infusion, when tumor-to-nontumor ratios were high. Suspected tumor deposits were evaluated intraoperatively with handheld beta and gamma PET probes.
  
  
  RESULTS
  Handheld PET probes detected emissions from all tumors. Count rates from the gamma probe on tumor ranged from 48 to 306 cps, and for the beta probe ranged from 18 to 190 cps. Gamma and beta emissions exhibited a strong positive correlation. The ratio of gamma and beta counts was at least twice that of the background counts for all tumors evaluated.
  
  
  CONCLUSIONS
  This study is the first to demonstrate the utility of beta probes for the intraoperative detection of radiolabeled antibodies targeting cancer. Importantly, the recorded beta count rates from the beta probe correlate with the count rates from the high-energy gamma probe. Furthermore, the beta probe may offer superior specificity for real-time localization of small tumor deposits, compared to gamma probes. The intraoperative portable PET probe may prove a valuable bridge to combining tumor biology and PET technology to guide surgical therapy.
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. strongv@mskcc.org
authors.forename: Vivian E
authors.initials: VE
authors.lastname: Strong
authors.forename: John
authors.initials: J
authors.lastname: Humm
authors.forename: Paul
authors.initials: P
authors.lastname: Russo
authors.forename: Achim
authors.initials: A
authors.lastname: Jungbluth
authors.forename: W Douglas
authors.initials: WD
authors.lastname: Wong
authors.forename: Farhad
authors.initials: F
authors.lastname: Daghighian
authors.forename: Lloyd
authors.initials: L
authors.lastname: Old
authors.forename: Yuman
authors.initials: Y
authors.lastname: Fong
authors.forename: Steven M
authors.initials: SM
authors.lastname: Larson
mesh_terms: D000911:Antibodies, Monoclonal; D001610:Beta Particles; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D005720:Gamma Rays; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D007457:Iodine Radioisotopes; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D049268:Positron-Emission Tomography
chemical_list: D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes