Gastrointestinal Endoscopy
Volume 71, Issue 6 , Page 1100, May 2010

Differential path-length spectroscopy: a tool for quantitative assessment of blood oxygen saturation in microvessels

Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus Medical Centre

Department of Gastroenterology and Hepatology, Erasmus Medical Centre

Center for Optical Diagnostics and Therapy, Department of Radiation Oncology, Erasmus Medical Centre, Rotterdam, The Netherlands

Article Outline

 

To the Editor:

We thank Dr. Leung for his editorial1 on our article2 in which he raises 2 interesting issues: First is the in vivo validation of differential path-length spectroscopy (DPS) measurements. Although rigorous quantitative ex vivo validation of DPS measurements has been reported,3 a quantitative in vivo validation of the technique is not easy to perform because the technology examines only the most superficial tissue layers (<200 μm deep4), which contain only microvascular blood vessels. Qualitative in vivo validation of DPS has been shown by its response to photodynamic therapy5 and its correlation with expression of hypoxia-inducible factor 1a6 as well as in animal experiments.

Regarding the second issue, that “conscientious investigators should exercise prudence in cautioning readers” with respect to “unintended consequences” of new technologies, such as “increasing the costs of health care” and “raising undue anxiety in high-risk patient,” we do not even hint at a possible diagnostic role for DPS in the search for premalignant lesions in the GI tract. Instead, DPS is used to acquire scientific knowledge about the blood oxygen saturation in the microvessels for different pathologic grades of Barrett's mucosa.

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References 

  1. Leung FW. Search for premalignant mucosal lesions: does endoscopic measurement of oxygen saturation by differential path-length spectroscopy help?. Gastrointest Endosc. 2009;70:7–8
  2. Amelink A, Haringsma J, Sterenborg HJCM. Noninvasive measurement of oxygen saturation of the microvascular blood in Barrett's dysplasia by use of optical spectroscopy. Gastrointest Endosc. 2009;70:1–6
  3. Amelink A, Christiaanse T, Sterenborg HJCM. Effect of hemoglobin extinction spectra on optical spectroscopic measurements of blood oxygen saturation. Opt Lett. 2009;34:1525–1527
  4. Amelink A, Bard MPL, Burgers JA, et al. Single scattering spectroscopy for the endoscopic analysis of particle size in superficial layers of turbid media. Appl Opt. 2003;42:4095–4101
  5. Amelink A, van der Ploeg-van den Heuvel A, de Wolf WJ, et al. Monitoring PDT by means of superficial reflectance spectroscopy. J Photochem Photobiol B. 2005;79:243–251
  6. Aerts JGJV, Amelink A, van der Leest C, et al. HIF1a expression in bronchial biopsies correlates with tumor microvascular saturation determined using optical spectroscopy. Lung Cancer. 2007;57:317–321

PII: S0016-5107(09)02420-1

doi:10.1016/j.gie.2009.08.020

Refers to article:

  • Search for premalignant mucosal lesions: does endoscopic measurement of oxygen saturation by differential path-length spectroscopy help?

    Felix W. Leung
    Gastrointestinal Endoscopy July 2009 (Vol. 70, Issue 1, Pages 7-8)

  • Noninvasive measurement of oxygen saturation of the microvascular blood in Barrett's dysplasia by use of optical spectroscopy , 02 March 2009

    Arjen Amelink, Jelle Haringsma, Henricus J.C.M. Sterenborg
    Gastrointestinal Endoscopy July 2009 (Vol. 70, Issue 1, Pages 1-6)

Gastrointestinal Endoscopy
Volume 71, Issue 6 , Page 1100, May 2010

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