title: Near-infrared operating lamp for intraoperative molecular imaging of a mediastinal tumor.
abstract: BACKGROUND
  Near-Infrared (NIR) intraoperative molecular imaging is a new diagnostic modality utilized during cancer surgery for the identification of tumors, metastases and lymph nodes. Surgeons typically use headlamps during an operation to increase visible light; however, these light sources are not adapted to function simultaneously with NIR molecular imaging technology. Here, we design a NIR cancelling headlamp and utilize it during surgery to assess whether intraoperative molecular imaging of mediastinal tumors is possible.
  
  
  METHODS
  A NIR cancelling headlamp was designed and tested using NIR spectroscopy preoperatively. Next, a 46 year-old-female was referred to the thoracic surgery clinic for a 5.8 cm mediastinal mass noted on chest x-ray. Prior to surgery, she was given intravenous indocyanine green (ICG). Then, the prototype headlamp was used in conjunction with our intraoperative molecular imaging device. The tumor was imaged both in vivo and following resection prior to pathological examination.
  
  
  RESULTS
  NIR spectroscopy confirmed NIR light excitation of the unfiltered headlamp and the absence of NIR emitted light after addition of the filter. Next, in vivo imaging confirmed fluorescence of the tumor, but also demonstrated a significant amount of NIR background fluorescence emanating from the unfiltered headlamp. During imaging with the filtered headlamp, we again demonstrated a markedly fluorescent tumor but with a reduced false positive NIR signal. Final pathology was well-differentiated thymoma with negative surgical margins.
  
  
  CONCLUSIONS
  NIR intraoperative molecular imaging using a systemic injection of intravenous ICG was successful in localizing a thymoma. Additionally, a simple design and implementation of a NIR cancelling headlamp reduces false positive NIR fluorescence.
authors.affiliation: Department of Surgery, University of Pennsylvania and Philadelphia VA Medical Center, 6 White Building, 3400 Spruce Street, Philadelphia, PA, 19104, USA. janejkeating@gmail.com.
authors.forename: Jane
authors.initials: J
authors.lastname: Keating
authors.affiliation: Department of Surgery, University of Pennsylvania and Philadelphia VA Medical Center, 6 White Building, 3400 Spruce Street, Philadelphia, PA, 19104, USA. ryan.judy@uphs.upenn.edu.
authors.forename: Ryan
authors.initials: R
authors.lastname: Judy
authors.affiliation: Department of Surgery, University of Pennsylvania and Philadelphia VA Medical Center, 6 White Building, 3400 Spruce Street, Philadelphia, PA, 19104, USA. andrew.newton@uphs.upenn.edu.
authors.forename: Andrew
authors.initials: A
authors.lastname: Newton
authors.affiliation: Department of Surgery, University of Pennsylvania and Philadelphia VA Medical Center, 6 White Building, 3400 Spruce Street, Philadelphia, PA, 19104, USA. sunil.singhal@uphs.upenn.edu.
authors.forename: Sunil
authors.initials: S
authors.lastname: Singhal
mesh_terms: D004396:Coloring Agents / Q000494:pharmacology; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007208:Indocyanine Green / Q000494:pharmacology; D007432:Intraoperative Period; D008479:Mediastinal Neoplasms / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation* / Q000379:methods; D013945:Thymoma / Q000175:diagnosis*; D013953:Thymus Neoplasms / Q000175:diagnosis*
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green