Vital-dye enhanced fluorescence imaging of GI mucosa: metaplasia, neoplasia, inflammation

Abstract

Background: Confocal endomicroscopy has revolutionized endoscopy by offering subcellular images of the GI epithelium; however, the field of view is limited. Multiscale endoscopy platforms that use widefield imaging are needed to better direct the placement of high-resolution probes.

Design: Feasibility study.

Objective: This study evaluated the feasibility of a single agent, proflavine hemisulfate, as a contrast medium during both widefield and high-resolution imaging to characterize the morphologic changes associated with a variety of GI conditions.

Setting: The University of Texas MD Anderson Cancer Center, Houston, Texas, and Mount Sinai Medical Center, New York, New York. PATIENTS, INTERVENTIONS, AND MAIN OUTCOME MEASUREMENTS: Resected specimens were obtained from 15 patients undergoing EMR, esophagectomy, or colectomy. Proflavine hemisulfate, a vital fluorescent dye, was applied topically. The specimens were imaged with a widefield multispectral microscope and a high-resolution microendoscope. The images were compared with histopathologic examination.

Results: Widefield fluorescence imaging enhanced visualization of morphology, including the presence and spatial distribution of glands, glandular distortion, atrophy, and crowding. High-resolution imaging of widefield abnormal areas revealed that neoplastic progression corresponded to glandular heterogeneity and nuclear crowding in dysplasia, with glandular effacement in carcinoma. These widefield and high-resolution image features correlated well with the histopathologic features.

Limitations: This imaging approach must be validated in vivo with a larger sample size.

Conclusions: Multiscale proflavine-enhanced fluorescence imaging can delineate epithelial changes in a variety of GI conditions. Distorted glandular features seen with widefield imaging could serve as a critical bridge to high-resolution probe placement. An endoscopic platform combining the two modalities with a single vital dye may facilitate point-of-care decision making by providing real-time, in vivo diagnoses.

Figure 1

White-light image of squamo-columnar junction is shown (A). Widefield proflavine-fluorescence image (B) shows glandular detail in the Barrett’s region. High-resolution fluorescence image of squamous mucosa is shown (C) with corresponding histopathology (D). High-resolution image of BE from area, indicated in (B), shows large glands typical of intestinal metaplasia (E). Corresponding histopathology is shown in (F).

Figure 2

White-light image of Barrett’s-associated neoplasia is shown (A). Widefield proflavine-fluorescence image depicts irregular glands (B). High-resolution fluorescence image from area indicated in (B) shows areas of nuclear crowding (arrow) (C). Corresponding histopathology is shown (D).

Figure 3

White-light image normal colonic mucosa is shown (A). Widefield proflavine-fluorescence image shows evenly-spaced colonic crypts (B). High-resolution fluorescence image from area in (B) shows evenly spaced tubular structures (yellow arrow) and polarized nuclei at the crypt edges (white arrow) (C). Corresponding histopathology is shown (D).

Figure 4

White-light image dysplastic colonic mucosa is shown (A). Widefield proflavine-fluorescence image shows unevenly-spaced colonic crypts (B). The brightness of the lamina propria is variable (white boxes). High-resolution proflavine-fluorescence image from inked area indicated in (B) shows unevenly spaced tubular structures (yellow arrow) and areas of crowded nuclei (white arrow) (C). Corresponding histopathology is shown (D).

Figure 5

White-light image of severely dysplastic colonic mucosa with sub-surface adenocarcinoma is shown (A). Widefield proflavine-fluorescence image depicts irregularly shaped colonic crypts (B). High-resolution fluorescence image from area indicated in (B) shows irregularly shaped, unevenly spaced tubular structures (yellow arrow) and areas of crowded nuclei (white arrow) (C). Corresponding histopathology is shown (D).

Figure 6

White-light image of invasive adenocarcinoma is shown (A). Widefield proflavine-fluorescence image from area indicated in (A) depicts loss of regular glandular architecture (B). High-resolution fluorescence image from area indicated in (B) shows areas of dense nuclei (C). Corresponding histopathology is shown (D).

Figure 7

White-light image of an area of mildy active IBD is shown (A). Widefield proflavine-fluorescence image from area indicated in (A) depicts an irregular glandular pattern (B). High-resolution fluorescence image from area indicated in (B) shows an increase in distorted glands with cryptitis (arrow) and expanded lamina propria (C). Corresponding histopathology of active colitis is shown (D).

Figure 8

White-light image of an area of severely active IBD with ulcer is shown (A). Widefield proflavine-fluorescence image from area indicated in (A) depicts glandular irregularity (B). High-resolution fluorescence image from area indicated in (B) shows a dense nuclear presence in the lamina propria (C). Corresponding histopathology of severe colitis is shown (D).