Real-time oncological guidance using diffuse reflectance spectroscopy in electrosurgery: the effect of coagulation on tissue discrimination

Abstract

In breast surgery, a lack of knowledge about what is below the tissue surface may lead to positive tumor margins and iatrogenic damage. Diffuse reflectance spectroscopy (DRS) is a spectroscopic technique that can distinguish between healthy and tumor tissue making it a suitable technology for intraoperative guidance. However, because tumor surgeries are often performed with an electrosurgical knife, the effect of a coagulated tissue layer on DRS measurements must be taken into account. It is evaluated whether real-time DRS measurements obtained with a photonic electrosurgical knife could provide useful information of tissue properties also when tissue is coagulated and cut. The size of the coagulated area is determined and the effect of its presence on DR spectra is studied using ex vivo porcine adipose and muscle tissue. A coagulated tissue layer with a depth of 0.1 to 0.4 mm is observed after coagulating muscle with an electrosurgical knife. The results show that the effect of coagulating adipose tissue is negligible. Using the fat/water ratio's calculated from the measured spectra of the photonic electrosurgical knife, it was possible to determine the distance from the instrument tip to a tissue transition during cutting. In conclusion, the photonic electrosurgical knife can determine tissue properties of coagulated and cut tissue and has, therefore, the potential to provide real-time feedback about the presence of breast tumor margins during cutting, helping surgeons to establish negative margins and improve patient outcome.

Intraoperative tumor margin assessment using diffuse reflectance spectroscopy: the effect of electrosurgery on tissue discrimination using ex vivo animal tissue models

“…D) The setup to investigate the DRS signal deterioration after electrosurgery with three different sets of optical fiber, Clean Fiber (unused fiber), Muscle Fiber (contaminated with muscle tissue), and Fat Fiber (contaminated with adipose tissue) on three different surfaces (white reference, porcine muscle, and porcine adipose tissue). more detail in previous publications [3,20,30]. The measured spectra were used as the input for a Philips custom-developed software.…”

“…Briefly, similar as in Ref. [3] in all the experiments, the healthy breast tissue and tumor tissue were simulated by porcine adipose tissue and porcine muscle tissue, respectively.…”

“…The standard surgical treatment for early-stage breast cancer patients is breastconserving surgery (BCS), in which the surgeon aims to remove the tumor while maintaining the natural shape of the breast as much as possible [2]. It has been shown that lack of direct view over the surgical site or surgeon's failure to determine the exact position of the tumor based on preoperative images may lead to incomplete resection of the tumor and incidence of positive margin [3]. Positive margins occur when the excised tumor is not surrounded by at least 2 mm of healthy tissue.…”

“…These changes can increase the scattering, decrease the depth of photon penetration and alter its optical properties [26][27][28][29]. However, recently, Adank et al showed that the DRS system is capable to distinguish muscle tissue from adipose tissue even after cutting or coagulating both tissues using an electrosurgical knife [3]. Based on these results, integrating the DRS system into the electrosurgical knife seems to be a promising approach to provide the surgeon with real-time oncological guidance during cancer surgery.…”

Feasibility of Ex Vivo Margin Assessment with Hyperspectral Imaging during Breast-Conserving Surgery: From Imaging Tissue Slices to Imaging Lumpectomy Specimen

“…However, since this wavelength range was excluded after wavelength reduction, this effect of cauterization was expected to be minimal. In a study by Adank et al, the influence of cutting by coagulation on diffuse reflectance spectra in the NIR was small in muscle tissue and nonexistent in adipose tissue [29]. Therefore, we expect a minimum effect in the NIR wavelength region.…”