Wide-field optical spectroscopy system integrating reflectance and spatial frequency domain imaging to measure attenuation-corrected intrinsic tissue fluorescence in radical prostatectomy specimens.

Emile Beaulieu,Audrey Laurence,Fred Saad,Frédéric Leblond,Guillaume Sheehy,Mirela Birlea,Leticia Angulo-Rodriguez,Roula Albadine,Mathieu Latour,Dominique Trudel

doi:10.1364/boe.388482

Abstract

The development of a multimodal optical imaging system is presented that integrates endogenous fluorescence and diffuse reflectance spectroscopy with single-wavelength spatial frequency domain imaging (SFDI) and surface profilometry. The system images specimens at visible wavelengths with a spatial resolution of 70 µm, a field of view of 25 cm2 and a depth of field of ∼1.5 cm. The results of phantom experiments are presented demonstrating the system retrieves absorption and reduced scattering coefficient maps using SFDI with <6% reconstruction errors. A phase-shifting profilometry technique is implemented and the resulting 3-D surface used to compute a geometric correction ensuring optical properties reconstruction errors are maintained to <6% in curved media with height variations <20 mm. Combining SFDI-computed optical properties with data from diffuse reflectance spectra is shown to correct fluorescence using a model based on light transport in tissue theory. The system is used to image a human prostate, demonstrating its ability to distinguish prostatic tissue (anterior stroma, hyperplasia, peripheral zone) from extra-prostatic tissue (urethra, ejaculatory ducts, peri-prostatic tissue). These techniques could be integrated in robotic-assisted surgical systems to enhance information provided to surgeons and improve procedural accuracy by minimizing the risk of damage to extra-prostatic tissue during radical prostatectomy procedures and eventually detect residual cancer.

Highlights

Prostate cancer is the most common cancer in American men, and it is associated with increasing incidence rates [1,2,3]
This demonstrated new quantitative tissue biomarkers that could potentially distinguish biologically distinct regions, including prostatic vs. extra-prostatic structures. It is the first step in a larger-scale project aiming to automate tissue characterization during radical prostatectomy procedures to limit the risk of tissue damage and eventually assess whether optical spectroscopy can detect cancer that has invaded beyond the confines of the prostate organ
In the spatial frequency domain imaging (SFDI)-based reconstruction of absorption and reduced scattering that was reported here, the average errors across both low and high absorption phantom experiments were similar to other studies [54,57,76,77,78,79]

Summary

Introduction

Prostate cancer is the most common cancer in American men, and it is associated with increasing incidence rates [1,2,3]. Surgery can be recommended for higher risk prostate cancers and in that case the only curative treatment is radical prostatectomy. Less extended margins lower the risk of damage to surrounding tissue and increase post-procedure patient satisfaction by reducing side effects [17,18]. Positive margins from un-resected cancer extending beyond the prostate decrease survival rates and lead to additional treatments [19,20]. Radical prostatectomy procedures are performed by balancing the need to remove the entire prostate and leave no residual tumor tissue against the need to minimize healthy tissue damage

Methods

Results

Conclusion