Ultrahigh resolution optical coherence tomography of Barrett's esophagus: preliminary descriptive clinical study correlating images with histology.

BACKGROUND AND STUDY AIMS: Endoscopic ultrahigh resolution optical coherence tomography (UHR OCT) achieves an axial image resolution of approximately 5 microm, which is 2 - 3 times finer than standard endoscopic OCT imaging. This study investigated the capability of endoscopic UHR OCT for imaging patients with Barrett's esophagus. PATIENTS AND METHODS: Fivty volunteers previously diagnosed with Barrett's esophagus underwent UHR OCT. Imaging was performed at 1.3 microm wavelengths with approximately 5 microm axial and approximately 15 microm transverse resolutions using a 1.8 mm/diameter linear-scanning catheter introduced through the accessory channel of a standard endoscope. OCT images were compared with endoscopic diagnosis and pinch biopsy histological appearances. RESULTS: UHR OCT images of normal esophagus, Barrett's esophagus, high grade dysplasia and esophageal adenocarcinoma were evaluated. UHR OCT images of the normal esophagus exhibited characteristic layered architecture with uniform epithelium, while images of Barrett's esophagus corresponded to crypt-like glandular structures. High grade dysplasia and esophageal adenocarcinoma images exhibited more heterogeneous structures corresponding to irregular, heterogeneous tissue morphology from distorted and cribriform or villiform glandular architecture. Fine features can be discerned more clearly with endoscopic UHR OCT. CONCLUSIONS: This study evaluated new endoscopic OCT technology and demonstrated the feasibility of carrying out UHR OCT imaging in conjunction with standard endoscopy for in vivo real-time imaging of Barrett's esophagus, dysplasia, and esophageal adenocarcinoma. A survey of normal and abnormal upper gastrointestinal tissues was performed using a research prototype OCT system with the highest axial resolution to date, and can serve as a baseline for future investigation.

Depth-resolved imaging of functional activation in the rat cerebral cortex using optical coherence tomography.

Co-registered optical coherence tomography (OCT) and video microscopy of the rat somatosensory cortex were acquired simultaneously through a thinned skull during forepaw electrical stimulation. Fractional signal change measured by OCT revealed a functional signal time course corresponding to the hemodynamic signal measurement made with video microscopy. OCT can provide high-resolution, cross-sectional images of functional neurovascular activation and may offer a new tool for basic neuroscience research in the important rat cerebral cortex model.

Micromotor endoscope catheter for in vivo, ultrahigh-resolution optical coherence tomography.

A distally actuated, rotational-scanning micromotor endoscope catheter probe is demonstrated for ultrahigh-resolution in vivo endoscopic optical coherence tomography (OCT) imaging. The probe permits focus adjustment for visualization of tissue morphology at varying depths with improved transverse resolution compared with standard OCT imaging probes. The distal actuation avoids nonuniform scanning motion artifacts that are present with other probe designs and can permit a wider range of imaging speeds. Ultrahigh-resolution endoscopic imaging is demonstrated in a rabbit with <4-microm axial resolution by use of a femtosecond Cr:forsterite laser light source. The micromotor endoscope catheter probe promises to improve OCT imaging performance in future endoscopic imaging applications.

High-resolution optical coherence microscopy for high-speed, in vivo cellular imaging.

Optical coherence microscopy (OCM) is demonstrated with a high-speed, broadband, reflective-grating phase modulator and a femtosecond Ti:Al2O3 laser. The novel system design permits high-resolution OCM imaging in a new operating regime in which a short coherence gate is used to relax the requirement for high-numerical-aperture confocal axial sectioning. In vivo cellular imaging is demonstrated in the Xenopus laevis tadpole and in human skin with a 3-microm coherence gate and a 30-microm confocal gate. The ability to achieve cellular imaging with a lower numerical aperture should facilitate the development of miniaturized probes for in vivo imaging applications.