In Vivo Endoscopic Tissue Identification by Rapid Evaporative Ionization Mass Spectrometry (REIMS)

Abstract

Gastrointestinal cancers are al eading cause of mortality,accounting for 23 %ofcancer-related deaths worldwide.Inorder to improve outcomes from these cancers,novel tissue characterization methods are needed to facilitate accurate diagnosis.R apid evaporative ionization mass spectrometry (REIMS) is at echnique developed for the in vivo classification of human tissue through mass spectrometric analysis of aerosols released during electrosurgical dissection. This ionization technique was further developed by utilizing surface induced dissociation and was integrated with an endoscopic polypectomy snare to allow in vivo analysis of the gastrointestinal tract. We tested the classification performance of this novel endoscopic REIMS method in vivo.Itwas shown to be capable of differentiating between healthy layers of the intestinal wall, cancer,and adenomatous polyps based on the REIMS fingerprint of each tissue type in vivo.Despite increasing incidence,m ortality from cancer has generally been decreasing over the last four decades. [1,2] Endoscopy represents ac ore diagnostic tool for the early detection of gastrointestinal (GI) tumors,a nd it is routinely deployed in national screening programs that have played an important role in reducing the burden of this disease. [3] Conventional white-light endoscopic investigation of the GI tract with tissue biopsy is the gold standard method for the diagnosis of GI cancers. [4] However,u pt o7 .8 %ofu pper-GI cancers may be missed by this technique in patients who are subsequently diagnosed with cancer. [5] Moreover,t here is as ignificant economic and service burden on histopathology specialists who have to report on benign polyps,which may be found in 13.5 to 75 %ofcolonoscopies. [6] Amajor advantage of endoscopic intervention is that it provides al ess invasive therapeutic option compared to conventional open surgical approaches.Early-stage cancers and premalignant conditions are now routinely treated using endoscopic mucosal resection (EMR) techniques that utilize electrosurgical diathermy and radiofrequencyablation (RFA). [7] However,re-intervention is necessary in up to 41 %o fp atients owing to incomplete excision. [8] Hence,t here remains an eed to develop accurate in situ techniques for improving the adenoma detection rate (ADR) and for real-time chemical biopsies that can detect dysplasia or cancer in vivo to increase the efficacy and safety of endoscopic therapies.Enhanced endoscopic imaging technologies are currently being developed to address these requirements,with aspecific emphasis on spectroscopic characterization using elastic scattering spectroscopy,o ptical coherence tomography,a nd multimodal imaging combining Raman spectroscopy,a utofluorescence,a nd narrow band imaging. [9] However,o ptical strategies do not provide detailed information on tumor biology or chemistry and cannot be deployed during therapeutic procedures to provide data on cancer-margin status. Mass spectrometry (MS)-based identification of tissues has been employed in the context of MS imag...

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