Abstract
We report photoacoustic and ultrasonic endoscopic images of two intact rabbit esophagi. To investigate the esophageal lumen structure and microvasculature, we performed in vivo and ex vivo imaging studies using a 3.8-mm diameter photoacoustic endoscope and correlated the images with histology. Several interesting anatomic structures were newly found in both the in vivo and ex vivo images, which demonstrates the potential clinical utility of this endoscopic imaging modality. In the ex vivo imaging experiment, we acquired high-resolution motion-artifact-free three-dimensional photoacoustic images of the vasculatures distributed in the walls of the esophagi and extending to the neighboring mediastinal regions. Blood vessels with apparent diameters as small as 190 μm were resolved. Moreover, by taking advantage of the dual-mode high-resolution photoacoustic and ultrasound endoscopy, we could better identify and characterize the anatomic structures of the esophageal lumen, such as the mucosal and submucosal layers in the esophageal wall, and an esophageal branch of the thoracic aorta. In this paper, we present the first photoacoustic images showing the vasculature of a vertebrate esophagus and discuss the potential clinical applications and future development of photoacoustic endoscopy.
Highlights
Diseases of the epithelium, such as Barrett’s esophagus [1], can be precursors to high-grade dysplasia and adenocarcinoma; 85% of all cancers originate in the epithelium [2,3]
Esophageal signals were separated from the mediastinal signals based on the depth and structure of the signal in the B-scan image; accurate separation was complicated by motion artifacts
To show the effect of the motion artifacts on the image quality degradation, we present the in vivo and ex vivo PA and US esophageal radial-maximum amplitude projection (RMAP) images in S2 Fig. and present only the in vivo and ex vivo PA-RMAP images in S3 Fig. with ex vivo imaging, we could acquire reliable esophageal US-RMAP images for the two animals, which was not possible in the in vivo experiment
Summary
Diseases of the epithelium, such as Barrett’s esophagus [1], can be precursors to high-grade dysplasia and adenocarcinoma; 85% of all cancers originate in the epithelium [2,3]. It is well known that early detection of esophageal adenocarcinoma improves treatment outcomes. Considerable effort has focused on improving the endoscopic surveillance programs employed to routinely monitor patients with Barrett’s esophagus [1,4,5]. Endoscopic ultrasound (EUS) [6,7,8] is the dominant clinical tomographic endoscopic tool used to diagnose many diseases in the gastrointestinal (GI) tract. EUS is unable to provide sufficiently informative microscopic images, such as of the microvasculature, which has been shown to be PLOS ONE | DOI:10.1371/journal.pone.0120269. EUS is unable to provide sufficiently informative microscopic images, such as of the microvasculature, which has been shown to be PLOS ONE | DOI:10.1371/journal.pone.0120269 April 15, 2015
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