Multimodal endoscope can quantify wide-field fluorescence detection of Barrett's neoplasia

Abstract

Background and study aims: To demonstrate the clinical use of a multimodal endoscope with a targeted fluorescently labeled peptide for quantitative detection of Barrett's neoplasia.

Patients and methods: We studied 50 patients with Barrett's esophagus using a prototype multimodal endoscope with a fluorescently labeled peptide. Co-registered fluorescence and reflectance images were converted to ratios to correct for differences in distance and geometry over the image field of view. The ratio images were segmented using a unique threshold that maximized the variance between high and low intensities to localize regions of high grade dysplasia (HGD) and esophageal adenocarcinoma (EAC).

Results: Early neoplasia (HGD and EAC) was identified with 94 % specificity and 96 % positive predictive value at a threshold of 1.49. The mean results for HGD and EAC were significantly greater than those for squamous/Barrett's esophagus and low grade dysplasia by one-way analysis of variance (ANOVA). The receiver operator characteristic curve for detection of early neoplasia had an area under the curve of 0.884. No adverse events associated with the endoscope or peptide were found.

Conclusion: A multimodal endoscope can quantify fluorescence images from targeted peptides to localize early Barrett's neoplasia. (ClinicalTrials.gov number NCT01630798.).

© Georg Thieme Verlag KG Stuttgart · New York.

Figures

Fig. 1

The molecular endoscope. a A standard definition charge-coupled device (CCD) detector (labeled WL in the diagram) is used for white-light imaging. A separate detector (F/R) is used to collect either fluorescence or reflectance images that are co-registered. A long-pass filter (LPF) blocks excitation light and allows fluorescence and reflectance to pass. The biopsy channel (B) is used to pass the spray catheter for peptide administration. b A xenon short-arc lamp provides white-light illumination (400 – 700 nm). Operated by a button on the endoscope handle, a rotating filter wheel moves in front of this lamp to produce either excitation for fluorescence (450 – 490nm) or illumination for reflectance (540 – 560nm) at 20 frames per second (fps). c–e Multimodal imaging is performed using: c white light; d fluorescence; and e reflectance. f The system, including endoscope, digitizer (D), video processor (VP), and light source (LS), is contained on a portable instrument cart.

Fig. 6

In vivo multimodal images of early neoplasia (high grade dysplasia [HGD]). a White-light image showing several areas of Barrett’s esophagus (labeled BE in the diagram), identified by salmon-red mucosa, surrounded by squamous epithelium but no macroscopically visible structural abnormalities to suggest the presence of neoplasia. b Fluorescence image showing a region of increased intensity (surrounding dashed line) found later to be HGD; the squamous epithelium shows a minimal background level. c Reflectance image, which is co-registered with the fluorescence image of part b. The reflectance and fluorescence images of parts b and c are combined to give d, the ratio image, which corrects for differences in detected fluorescence intensity caused only by distance. d Ratio image showing enhancement of the signal from HGD. e Intensities from fluorescence, reflectance, and ratio images along the dashed line shown in b – d, showing a peak at the location of the HGD. f Corresponding pathology showing histological features of HGD on a background of Barrett’s esophagus (BE), identified by the presence of goblet cells. (GEJ, gastroesophageal junction.)

Fig. 7

Localization of early neoplasia. a – c Red flag” contours (dashed red lines) were identified by segmenting the ratio images and are shown on representative fluorescence images of: a low grade dysplasia (LGD); BE, Barrett’s esophagus; b high grade dysplasia (HGD); c esophageal adenocarcinoma (EAC). The mean target/background ratio was measured from these regions for each patient. d–f Corresponding white-light images showing that these lesions appear flat in morphology and patchy in distribution, being difficult to distinguish from non-neoplastic Barrett’s esophagus. g–i Corresponding histology (stained with hematoxylin and eosin [H&E]) showing: g LGD with metaplastic tubules lined by atypical epithelium with enlarged and hyperchromatic nuclei that remain oriented toward the base of the epithelium; h HGD with several irregularly shaped tubules lined by epithelium with cytological features of HGD (arrow) and a few adjacent tubules that contain residual goblet cells reflecting the Barrett’s esophagus background (arrowhead); i EAC with a complex, back-to-back arrangement of tubules that are lined by markedly atypical epithelium with enlarged, crowded, and hyperchromatic nuclei with negligible mucus production and total lack of epithelial maturation toward the mucosal surface. In a few places, small clusters of dysplastic cells can be seen “budding” from larger tubules and infiltrating the lamina propria (arrow).

Fig. 8

Imaging performance. a The log-transformed mean target/background (T/B) ratios from the “red flag” contours for individual patients, grouped by the most advanced grade found on pathology (SQ, squamous; BE, Barrett’s esophagus; GEJ, gastroesophageal junction; LGD, low grade dysplasia; HGD, high grade dysplasia; EAC, esophageal adenocarcinoma), are shown on a log2 scale. The mean ± standard deviation values were 1.21 ± 0.03 for squamous (n= 3), 1.39 ±0.06 for Barrett’s esophagus (n=3), 1.27 ± 0.09 for GEJ (n=4), 1.39 ± 0.11 for LGD (n=7), 1.73± 0.39 for HGD (n=21), and 1.65 ± 0.23 for EAC (n=12). b A pairwise comparison of classifications showing the estimated fold-change and P values by one-way analysis of variance (ANOVA). c At a T/B ratio of 1.49 (dashed line), specificity was 94 % and positive predictive value (PPV) was 96 %; sensitivity was 76 % but increased with lower T/B ratios. d The receiver operating characteristic (ROC) curve for distinguishing early neoplasia (HGD and EAC) from the other classifications (squamous, Barrett’s esophagus, GEJ, and LGD) has an area under the curve (AUC) of 0.884 (95% confidence interval [CI] 0.793–0.975).

Video 1

Autofluorescence. Real-time white-light, fluorescence, and reflectance images of Barrett’s esophagus on molecular endoscopy prior to peptide administration shows minimal background. Online content including video sequences viewable at: http://dx.doi.org/10.1055/s-0034-1392803

Video 2

Barrett’s esophagus. Real-time white light, fluorescence, and reflectance images of Barrett’s esophagus on molecular endoscopy following topical administration of peptide shows minimal fluorescence intensity. Online content including video sequences viewable at: http://dx.doi.org/10.1055/s-0034-1392803

Video 3

Low grade dysplasia (LGD). Real-time white-light, fluorescence, and reflectance images of LGD on molecular endoscopy following topical peptide administration shows patchy regions of increased fluorescence intensity that were found to contain LGD on histology after endoscopic mucosal resection. Online content including video sequences viewable at: http://dx.doi.org/10.1055/s-0034-1392803

Video 4

High grade dysplasia (HGD). Real-time white-light, fluorescence, and reflectance images of HGD on molecular endoscopy following topical peptide administration shows a single region of increased fluorescence intensity that was found to contain HGD on histology after endoscopic mucosal resection. Online content including video sequences viewable at: http://dx.doi.org/10.1055/s-0034-1392803

Video 5

Esophageal adenocarcinoma (EAC). Real-time white-light, fluorescence, and reflectance images of EAC on molecular endoscopy following topical peptide administration shows several regions of increased fluorescence intensity that were found to contain EAC on histology after endoscopic mucosal resection. Online content including video sequences viewable at: http://dx.doi.org/10.1055/s-0034-1392803