Assessment of photobleaching during endoscopic autofluorescence imaging of the lower GI tract

Review of successful pathways for regulatory approvals in open-field fluorescence-guided surgery

SIGNIFICANCE

The modern use of fluorescence in surgery came iteratively through new devices and pre-existing imaging agents, with indications that were paved via regulatory approvals and device clearances. These events led to a growing set of surgery subspecialty uses.

AIM

This article outlines the key milestones that initiated commercially marketed systems and agents by highlighting temporal sequences and strategic decisions between them, with the goal of helping to inform future successes.

APPROACH

A review of successful regulatory approvals and the sequences between them was completed for companies that achieved US Food and Drug Administration (FDA) premarket approval or new drug approvals (NDAs) or device clearances in the fields of fluorescent imaging agents, open surgery imaging devices, and their approved medical indications.

RESULTS

Angiography agents, indocyanine green and fluorescein, were approved for human use as absorbing dyes, and this use in retinal imaging was the precursor to lateral translation into tissue perfusion imaging in the last two decades with a growing number of devices. Many FDA cleared devices for open fluorescence-guided surgery used the predicate created by the SPY SP2000 system. This first system was 510(k) cleared for angiography imaging with a unique split predicate from x-ray imaging of vasculature and retinal fluorescence angiography. Since that time, the lateral spread of open surgery devices being cleared for new indications has been occurring with a growth of adoption in surgical subspecialties. Growth into new surgical subspecialties has been achieved by leveraging different NDAs and clearances between indications, such that medical uses have broadened over time.

CONCLUSIONS

Key decisions made by developers to advance specific device clearances and NDAs have been based upon existing optical fluorescent agents. The historical lessons and regulatory trends in newer indications and contrast agents can help the field evolve via successful investment in new systems and applications.

The benefits of targeted endoscopic biopsy performed using the autofluorescence based diagnostic technique in 67 cases of diagnostically difficult gastrointestinal tumors

INTRODUCTION

The search for new diagnostic and therapeutic procedures is an essential task in contemporary oncology. The purpose of our study was the evaluation of the practical usefulness of autofluorescence endoscopy (AFE) using the Onco-LIFE system, compared with the use of white light endoscopy (WLE), and the estimation of the correlation between the histopathological evaluation with the degree of lesions' Numerical Color Value (NCV index) and the method's sensitivity and specificity valuation.

MATERIAL

67 patients were analyzed at the Center for Laser Diagnostics and Therapy. All patients previously had a gastrointestinal tract tumor, which appeared malignant, but without histopathological confirmation. We measured NCV, estimated the correlation of the clinical diagnosis based on histopathological evaluation with the degree of NCV index from gastrointestinal lesions, and calculated the sensitivity and specificity of this method.

RESULTS

In the group of 67 patients, we found 44 cases of primary or secondary cancers and 7 cases of non-epithelial malignancies. In this group (51 patients) we identified 13 colorectal cancers and 38 upper gastrointestinal cancers. Based on the NCV index at NCV > 1.0, we revealed, that the sensitivity for malignant neoplastic lesions was 100% and the specificity was 73%, while for NCV > 1.5, the sensitivity for malignant neoplastic lesions was 86% and the specificity 100%.

CONCLUSION

AFE using the Onco-LIFE system is a helpful tool to perform targeted biopsies at the outset. A significant correlation was found between lesions' NCV index and the grade of dysplasia or tumor malignancy. AFE sensitivity and specificity is higher than WLE. Further studies are needed, especially performed by expert endoscopists.

Diffuse reflectance spectroscopy in Barrett's esophagus: developing a large field-of-view screening method discriminating dysplasia from metaplasia

We evaluated diffuse reflectance spectroscopy implemented as a small field-of-view technique for discrimination of dysplasia from metaplasia in Barrett's esophagus as an adjuvant to autofluorescence endoscopy. Using linear discriminant analysis on 2579 spectra measured in 54 patients identified an optimum a 4-wavelength classifier (at 485, 513, 598 and 629 nm). Sensitivity and specificity for a test data set were 0.67 and 0.85, respectively. Spectroscopic results show that this technique could be implemented in wide-field imaging mode to improve the accuracy of existing endoscopy techniques for finding early pre-malignant lesions in Barrett's esophagus. Results show that the discrimination occurs likely due to redistribution of blood content in the tissue sensed by the optical probing with the wavelength-dependent sampling depth.

Novel focused OCT-LIF endoscope

Combined optical coherence tomography (OCT) and laser-induced fluorescence (LIF) endoscopy has shown higher sensitivity and specificity for distinguishing normal tissue from adenoma when compared to either modality alone. Endoscope optical design is complicated by the large wavelength difference between the two systems. A new high-resolution endoscope 2 mm in diameter is presented that can create focused beams from the ultraviolet to near-infrared. A reflective design ball lens operates achromatically over a large wavelength range, and employs TIR at two faces and reflection at a third internal mirrored face. The 1:1 imaging system obtains theoretically diffraction-limited spots for both the OCT (1300 nm) and LIF (325 nm) channels.