Multiphoton microscopy for structure identification in human prostate and periprostatic tissue: implications in prostate cancer surgery

Abstract

Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? Prostate cancer surgery outcomes depend on an optimal balance of three aspects: complete removal of cancerous glands, preservation of nerves for sexual function and of sphincteric structures for urinary control. Current surgical techniques, even with the magnification provided by the robotic stereoscope, are insufficient to identify these structures in the surgical field. Multiphoton microscopy has been shown to produce high contrast images with subcellular resolution in fresh (unprocessed and unstained tissue) utilizing intrinsic tissue emission signals. We provide evidence that Multiphoton microscopy of freshly excised tissue from human radical prostatectomy specimens, without any processing or use of exogenous contrast, can identify all relevant prostatic and periprostatic structures. These include the prostatic acini, the stroma and the capsule, as well as periprostatic fascial structures such as loose connective tissue, nerves, blood vessels and fat, as well as areas of local inflammation. We also show that multiphoton microscopy is able to distinguish between normal prostate gland, those with benign hyperplasia, and those harboring cancer. OBJECTIVE • To test whether multiphoton microscopy (MPM) might allow identification of prostatic and periprostatic structures with magnification and resolution similar to gold standard histopathology. MATERIAL AND METHODS • The present study included 95 robotic radical prostatectomy patients who consented to participate in an Institutional Review Board‐approved study starting in 2007. • The types of specimens used for imaging were excised surgical margins and biopsies, and sections obtained from the excised prostate. • The specimens were imaged with a custom‐built MPM system. • All images were compared with haematoxylin/eosin histopathology of the same specimen. RESULTS • MPM of freshly excised, unprocessed and unstained tissue can identify all relevant prostatic and periprostatic structures, such as nerves, blood vessels, capsule, underlying acini and also pathological changes, including prostate cancer. • Histological confirmation and correlation of these structures and pathologies have validated the findings of MPM. CONCLUSIONS • MPM shows great promise as a tool for real‐time intra‐surgical histopathology without needing excision or administration of contrast agents. • The results will, however, need to be confirmed in true surgical settings using a miniaturized MPM microendoscope.