title: Towards automated spectroscopic tissue classification in thyroid and parathyroid surgery.
abstract: BACKGROUND
  In (para-)thyroid surgery iatrogenic parathyroid injury should be prevented. To aid the surgeons' eye, a camera system enabling parathyroid-specific image enhancement would be useful. Hyperspectral camera technology might work, provided that the spectral signature of parathyroid tissue offers enough specific features to be reliably and automatically distinguished from surrounding tissues. As a first step to investigate this, we examined the feasibility of wide band diffuse reflectance spectroscopy (DRS) for automated spectroscopic tissue classification, using silicon (Si) and indium-gallium-arsenide (InGaAs) sensors.
  
  
  METHODS
  DRS (350-1830 nm) was performed during (para-)thyroid resections. From the acquired spectra 36 features at predefined wavelengths were extracted. The best features for classification of parathyroid from adipose or thyroid were assessed by binary logistic regression for Si- and InGaAs-sensor ranges. Classification performance was evaluated by leave-one-out cross-validation.
  
  
  RESULTS
  In 19 patients 299 spectra were recorded (62 tissue sites: thyroid = 23, parathyroid = 21, adipose = 18). Classification accuracy of parathyroid-adipose was, respectively, 79% (Si), 82% (InGaAs) and 97% (Si/InGaAs combined). Parathyroid-thyroid classification accuracies were 80% (Si), 75% (InGaAs), 82% (Si/InGaAs combined).
  
  
  CONCLUSIONS
  Si and InGaAs sensors are fairly accurate for automated spectroscopic classification of parathyroid, adipose and thyroid tissues. Combination of both sensor technologies improves accuracy. Follow-up research, aimed towards hyperspectral imaging seems justified. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Surgery, Maastricht University Medical Center & NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, Maastricht, The Netherlands.|van't Hoff Program on Medical Photonics, Netherlands Organization for Applied Scientific Research TNO, Delft, The Netherlands.
authors.forename: Rutger M
authors.initials: RM
authors.lastname: Schols
authors.affiliation: van't Hoff Program on Medical Photonics, Netherlands Organization for Applied Scientific Research TNO, Delft, The Netherlands.
authors.forename: Lejla
authors.initials: L
authors.lastname: Alic
authors.affiliation: van't Hoff Program on Medical Photonics, Netherlands Organization for Applied Scientific Research TNO, Delft, The Netherlands.|Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
authors.forename: Fokko P
authors.initials: FP
authors.lastname: Wieringa
authors.affiliation: Department of Surgery, Maastricht University Medical Center & NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: Nicole D
authors.initials: ND
authors.lastname: Bouvy
authors.affiliation: Department of Surgery, Maastricht University Medical Center & NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: Laurents P S
authors.initials: LP
authors.lastname: Stassen
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001152:Arsenicals; D001331:Automation; D002138:Calibration; D001330:Electronic Data Processing; D004867:Equipment Design; D005260:Female; D005708:Gallium; D006801:Humans; D007204:Indium; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000000981:diagnostic imaging* / Q000293:injuries / Q000601:surgery*; D012044:Regression Analysis; D012825:Silicon; D013053:Spectrophotometry; D013057:Spectrum Analysis / Q000379:methods*; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000293:injuries / Q000601:surgery*; D055815:Young Adult
chemical_list: D001152:Arsenicals; D007204:Indium; C043055:gallium arsenide; D005708:Gallium; C076773:indium arsenide; D012825:Silicon
keywords: adipose tissue; automated tissue classification; diffuse reflectance spectroscopy; parathyroid; thyroid; thyroid and parathyroid surgery